阅读说明：本技术 用于自动组装探头的设备和方法 (Apparatus and method for automatically assembling a probe ) 是由 罗伯特·苏布伦尼 戴维·赫里班 约翰克里斯多夫·维兰 乔斯林·佩罗 弗洛伦特·佩罗乔 安妮 于 2019-02-14 设计创作，主要内容包括：一种用于自动组装用于测试集成在半导体晶片上的电子器件的探头的设备(1),包括支撑件(6)和至少一个保持装置(7a,7b)。所述支撑件适于支撑至少两个平行的导引件(2),所述导引件具有多个相应的导引孔(3),所述保持装置适于保持待容纳在导引件(2)的导引孔(3)中的接触式探针(4)。适当地,支撑件(6)是适于根据在第一位置和第二位置之间预设的轨迹移动的可移动支撑件,在所述第一位置,所述接触式探针(4)由所述保持装置(7a,7b)保持在所述导引孔(3)外部的预定位置,在所述第二位置,保持在所述预定位置的所述接触式探针(4)被容纳在一组基本上彼此同心的导引孔(3)中。(An apparatus (1) for automatically assembling probes for testing electronic devices integrated on semiconductor wafers comprises a support (6) and at least one holding device (7a, 7 b). The support is adapted to support at least two parallel guides (2) having a plurality of corresponding guide holes (3), and the holding means is adapted to hold a contact probe (4) to be received in the guide holes (3) of the guides (2). Suitably, the support (6) is a movable support adapted to move according to a trajectory preset between a first position, in which the contact probe (4) is held in a predetermined position outside the guide hole (3) by the holding means (7a, 7b), and a second position, in which the contact probe (4) held in said predetermined position is housed in a set of guide holes (3) substantially concentric to each other.)

1. An apparatus (1) for automatically assembling probes for testing electronic devices, said apparatus (1) comprising a support (6) adapted to support at least two parallel guides (2) provided with a plurality of respective guide holes (3) and at least one retaining device (7a, 7b) adapted to retain contact probes (4) to be received in said guide holes (3), said apparatus (1) being characterized in that said support (1) is a movable support adapted to move according to a preset trajectory between a first position, in which said contact probes (4) are retained in a predetermined position outside said guide holes (3) by said retaining device (7a, 7b), and a second position, in which said contact probes (4) retained in said predetermined position are received in a set of guide holes (3) substantially concentric to each other The apparatus (1) further comprises an actuator of the support (6) and a central unit (10) connected to the actuator, the trajectory being calculated in the central unit (10) as a function of a profile (P) of the contact probe (4), the central unit (10) being adapted to convert the profile (P) into Control Instructions (CI) sent to the actuator of the support (6).

2. An apparatus (1) according to claim 1, characterized in that it comprises a first vision system (11') connected to said central unit (10), said first vision system (11') capturing an image (Img ' a, Img ' b) of said contact probe (4) held in said predetermined position by said at least one holding device (7a, 7b), said profile (P) of said contact probe (4) being calculated from said image (Img ' a, Img ' b) acquired by said first vision system (11 ').

3. The apparatus (1) according to claim 2, characterized in that said first vision system (11') comprises at least one pair of high resolution cameras (11a, 11b) arranged at said support (6), said cameras (11a, 11b) forming a stereoscopic vision system for forming an image of said contact probe (4).

4. The apparatus (1) according to any one of the preceding claims, characterized in that said support (6) is a hexapod with six degrees of freedom of movement adjusted by said actuator.

5. Apparatus (1) according to any one of the preceding claims, characterized in that said at least one holding device (7a, 7b) of said contact probe (4) is a terminal element of a robotized arm (13) adapted to move between said support (6) and a housing element (14) adapted to house a plurality of contact probes (4).

6. Apparatus (1) according to claim 5, wherein said robotized arm (13) comprises a first end (13a) having first retaining means (7a) and a second end (13b) having second retaining means (7b), wherein one of said first and second retaining means (7a, 7b) is apt to retain a contact probe (4) in said predetermined position, while the other retaining means (7b, 7a) is apt to pick up simultaneously a contact probe (4) coming from said housing element (14).

7. Apparatus (1) according to claim 5, characterized in that it further comprises a second vision system (11 ") which captures an image (Img") of the contact probe (4) housed in the housing element (14), the central unit (10) being adapted to perform a first evaluation of the profile (P) of the contact probe (4) in the housing element (14) for a preliminary discarding of the contact probe (4) on the basis of the image (Img ") captured by the second vision system (11).

8. Apparatus (1) according to any one of the preceding claims, characterized in that said at least one holding device (7a, 7b) comprises at least one pair of end-effectors (8) extending from a body (9) thereof and at least one first force sensor integrated in said body (9) and apt to measure a holding intensity exerted by said end-effectors (8) on said contact probe (4), said apparatus (1) comprising a feedback system adapted to regulate the holding intensity exerted by said end-effectors (8) on said contact probe (4).

9. Apparatus (1) according to any one of the preceding claims, characterized in that said at least one holding device (7a, 7b) comprises at least one second force sensor adapted to measure the force exerted by said contact probe (4) on said guide (2) during the movement of said support (6).

10. Apparatus (1) according to claim 9, characterized in that said at least one second force sensor is connected to said central unit (10) and is adapted to send thereto data (Dat) relating to said force exerted by said contact probe (4) on said guide (2), said central unit (10) being adapted to process said data (Dat) to generate information about said force as a function of the position of said contact probe (4) in said guide (2) and, if said force exceeds a predetermined value, to correct said trajectory of said support (6) or to interrupt and repeat the movement of said support (6) according to the same trajectory.

11. Device (1) according to any one of the preceding claims, characterized in that it comprises at least one further vision system (11) adapted to evaluate from which guide hole (3) the contact probe (4) emerges.

12. A method for automatically assembling probes for testing electronic devices, the method comprising at least the steps of:

-placing at least two parallel guides (2) on a support (6), said guides (2) being provided with a plurality of respective guide holes (3);

-stacking the parallel guides (2) so that the respective guide holes (3) are substantially concentric to each other; and

holding a contact probe (4) to be received in the guide hole (3) of the guide (2) by at least one holding device (7a, 7b),

the method is characterized by further comprising the steps of:

capturing an image (Img 'a, Img' b) of the touch probe (4) by a first vision system (11 ");

-sending said images (Img 'a, Img' b) to a central unit (10) and obtaining a profile (P) of said contact probe (4) from said projections obtained from said images (Img 'a, Img' b);

-converting the profile (P) of the contact probe (4) into control Commands (CI) for actuators of the support (6);

-transmitting said control Commands (CI) from said central unit (10) to said actuators of said supports (6); and

-moving the support (6) according to said trajectory between a first position, in which the contact probe (4) is held in a predetermined position outside the guide hole (3) by means of said at least one holding means (7a, 7b), and a second position, in which the contact probe (4) held in said predetermined position is housed in a set of guide holes (3) substantially concentric to each other.

13. Method according to claim 12, wherein the step of converting the profile (P) into the Control Instructions (CI) is preceded by a step of comparing the profile (P) of the contact probe (4) with a nominal expected profile for the contact probe (4), the method comprising the subsequent steps of: discarding the contact probe (4) if the obtained profile (P) differs significantly from the expected profile, the comparing step comprising evaluating skewness of the contact probe (4) and/or evaluating local deformation of the contact probe (4).

14. Method according to claim 12 or 13, wherein said profile (P) is obtained by:

-identifying a plurality of points (12) along a body (4') of the contact probe (4);

-interpolating said points (12).

15. The method according to any one of claims 12 to 14, further comprising the step of:

-calculating the coordinates of the guide holes (3) of the guide (2); and

storing the coordinates in the central unit (10),

wherein the coordinates are calculated relative to a point of the guide (2) that is invariant to its rotation, and

wherein the Control Instructions (CI) take into account both the profile (P) of the contact probe (4) and the coordinates of the guide hole (3).

16. Method according to any one of claims 12 to 15, further comprising the step of moving a robotized arm (13) between said support (6) and a housing element (14) suitable for housing a plurality of contact probes (4), wherein said robotized arm (13) comprises a first end (13a) having first retaining means (7a) and a second end (13b) having second retaining means (7b), one of said first and second retaining means (7a, 7b) being suitable for retaining a contact probe (4) in said predetermined position of said support (6) and the other retaining means (7b, 7a) being suitable for picking up a contact probe (4) from said housing element (14), said steps of retaining and picking up occurring simultaneously for different contact probes (4) and respectively at said support (6) and at said second retaining means (7b) by means of said first retaining means (7a) and said second retaining means (7b) The receiving elements (14) are alternately arranged.

17. The method of claim 16, further comprising the steps of: capturing an image (Img ") of the contact probe (4) housed in the housing element (14) by a second vision system (11"), the method comprising a subsequent step of discarding the contact probe based on the image (Img ") of the second vision system (11").

18. The method according to any one of claims 12 to 17, further comprising the step of: -detecting, by means of at least one force sensor integrated in said at least one holding device (7a, 7b), a force exerted by said contact probe (4) on said guide (2) during the movement of said support (6).

19. Method according to claim 18, wherein said step of detecting said force exerted by said contact probe (4) on said guide (2) is followed by a step of sending data (Dat) about said force to said central unit (10), and a step of processing said data (Dat) to generate information about said force as a function of the position of said contact probe (4) in said guide (2).

20. The method according to claim 18 or 19, comprising the steps of: -correcting the trajectory of the support (6) if the force exceeds a predetermined value, or the steps of: if said force exceeds a predetermined value, interrupting and repeating the movement of said support (6) with the same trajectory.

21. Method according to any one of claims 12 to 20, wherein said steps are repeated in a preset order for each set of concentric guide holes (3) of said guide (2), each set following a specific trajectory each time calculated according to the profile (P) of the contact probe to be housed therein.

Technical Field

The present invention relates to a device and a corresponding method for automatically assembling probes for testing electronic devices integrated on a semiconductor wafer and is described below with reference to this field of application, the sole purpose of which is to simplify the presentation.

Background

As is known, a probe head is an electronic device suitable for electrically connecting a plurality of contact pads of a microstructure (for example an integrated device) with corresponding channels of a test apparatus performing a functional test thereof, in particular an electrical test or generally a test.

Tests performed on integrated devices are particularly useful at the manufacturing stage to detect and isolate defective devices. Therefore, probes are typically used to electrically test devices integrated on the wafer prior to dicing and assembly into packages.

Typically, the probe head comprises a plurality of movable contact elements or contact probes held by at least one pair of guides or supports which are substantially plate-shaped and parallel to each other. The guides are equipped with suitable guide holes and are arranged at a distance from each other, leaving free space or air gap for the movement and possible deformation of the contact probe slidably received in the guide hole. The pair of guides includes, in particular, an upper guide and a lower guide each provided with a guide hole in which a contact probe, which is generally formed of a wire of a special alloy having good electrical and mechanical properties, axially slides.

The pressing of the probe head on the device itself, during which the contact probe bends in the air gap between the guides and slides in the associated guide holes, ensures a good connection between the contact probe of the probe head and the contact pad of the device under test. Such probes are commonly referred to as "vertical probes".

According to a known method, a probe head of the above-mentioned type can be assembled by means of a robot which places the contact probes in respective guide holes of a guide fixed on a suitable support, which is also fixed. In particular, the movable holding means holds the contact probes as vertically as possible and inserts them into the guide holes of the guide according to a certain preset sequence.

A drawback of this solution is that the assembly of the probe head is in great relation to the shape of the contact probe and the relative alignment of the guide holes of the guides of the probe head itself, which features are not controllable and limit the effectiveness of the assembly. In some cases, when the profile of the probe is particularly irregular and/or the relative guide holes of the guides are misaligned seriously, the assembly may not be successful (i.e. the probe cannot be somehow inserted into the guide hole) and may even lead to breakage of the probe, in any case leading to an undesired interruption of the manufacturing process.

An apparatus for installing a test nail into a text fixture is described in U.S. patent No. US5,841,292 issued in the name of laguerre (Gallagher) (Star Technology Group, Inc.) at 24/11 of 1998.

In practice, the automatic assembly method presents such frequent problems, and therefore manual assembly by professional operators is still preferable, who can also be assisted by cameras and lighting systems. Obviously, said manual assembly has time and costs related to the skill of the professional operator and does not allow high production scale or to cope with peak demands, the time required to train the professional operator being generally longer than the peak times of production requiring such a professional operator.

The technical problem underlying the present invention is to provide an apparatus and a corresponding method for assembling a probe head that allow to overcome the limitations and drawbacks that still currently affect known solutions, and in particular solutions that enable an efficient and rapid automatic assembly of a probe head, without being limited by the shape of the contact probe and the relative alignment of the guide holes that must accommodate said contact probe, thus allowing an improved control of the assembly process.

Disclosure of Invention

The solution idea underlying the present invention is to realise an apparatus for automatically assembling a probe head in which, instead of moving the holding means towards the guide hole of the guide of the probe head to be assembled (and therefore not moving the contact probe), a support on which the guide is arranged is moved, having a plurality of degrees of freedom of movement and able to follow a suitable trajectory calculated from the profile of the contact probe, to fit the guide onto the probe held in a predetermined position by the holding means, by means of suitable holding means.

Based on the idea of solution, the above technical problem is solved by a device for automatically assembling probes for testing electronic components, comprising a support adapted to support at least two guides parallel and superimposed to each other, the guides having a plurality of respective guide holes, and at least one holding means adapted to hold contact probes to be received in said guide holes of said guides, said device being characterized in that the support is a movable support adapted to move according to a preset trajectory between a first position, in which the contact probes are held in a predetermined position outside the guide holes by the at least one holding means, and a second position, in which the guide holes are received in a set of guide holes substantially concentric to each other and formed in said at least two guides.

More specifically, the present invention includes the following additional and optional features, which may be employed individually or in combination if desired.

According to one aspect of the invention, the apparatus may comprise an actuator of the support and a central unit connected to said actuator, the central unit calculating the trajectory from the profile of the contact probe, said central unit being adapted to convert said profile into control instructions sent to the actuator of the support.

According to another aspect of the invention, the apparatus may comprise a first vision system connected to the central unit, the first vision system capturing images of the touch probe held in a predetermined position of the support by at least one holding device, the contour of the touch probe being calculated from said images acquired by said first vision system.

According to another aspect of the invention, the first vision system may comprise at least one pair of high resolution cameras arranged at the support, said cameras forming a stereoscopic vision system for forming an image of the contact probe.

Further, the support may be a hexapod having six degrees of freedom of movement adjusted by the actuator.

According to another aspect of the invention, the at least one holding means of the contact probe may be a terminal element of a robot arm, movable between a support and a receiving element adapted to receive a plurality of contact probes.

In particular, the robot arm may comprise a first end having a first holding means and a second end having a second holding means, wherein one of the first or second holding means is adapted to hold the contact probe in a predetermined position of the support and the other holding means is adapted to simultaneously pick up the contact probe from the receiving element.

The apparatus of the invention may further comprise a second vision system capturing images of the contact probe housed in the housing element, the central unit being adapted to perform a first evaluation of the profile of the contact probe in said housing element for a preliminary discarding of the contact probe, based on the images captured by said second vision system.

According to another aspect of the invention, at least one holding device may comprise at least one pair of end effectors extending from a body thereof, and at least one first force sensor integrated in the body and adapted to measure a holding strength of the contact probe by the end effector, the apparatus comprising a feedback system adapted to adjust the holding strength of the contact probe by the end effector.

According to yet another aspect of the invention, the at least one holding device may comprise at least one second force sensor adapted to measure a force exerted by the touch probe on the guide during movement of the support.

Furthermore, the at least one second force sensor may be connected to the central unit and adapted to send thereto data about the force exerted by the contact probe on the guide, the central unit being adapted to process said data to generate information about said force as a function of the position of the contact probe in the guide, and, if said force exceeds a predetermined value, to be able to correct the trajectory of the support or to interrupt and repeat the movement of said support with the same trajectory.

The device may finally comprise at least one further vision system adapted to assess from which guide hole the contact probe emerges.

The invention also relates to a method for automatically assembling a probe for testing electronic devices, said method comprising at least the following steps:

-placing at least two parallel guides on a support, said guides being provided with a plurality of respective guide holes;

-stacking the parallel guides so that the respective guide holes are substantially concentric with each other; and

-holding a contact probe to be received in a guide hole of a guide by at least one holding means,

the method is characterized by comprising the following steps: moving the support according to a preset trajectory between a first position, in which the contact probe is held in a predetermined position outside the guide hole by at least one holding device, and a second position, in which the contact probe held in said predetermined position is accommodated in a set of guide holes substantially concentric to each other.

According to an aspect of the invention, at least the following steps may be performed before the moving step:

-capturing an image of the touch probe by a first vision system;

-sending said image to a central unit and obtaining the contour of the contact probe from the projections obtained from said image;

-converting the contour of the contact probe into control commands of the actuators of the support; and

-transmitting said control commands from the central unit to the actuators of the support so that the support can move according to said trajectory.

According to another aspect of the invention, before the step of converting the profile into control commands, a step of comparing the profile of the contact probe with a nominal profile of the contact probe may be performed, the method comprising the subsequent steps of: discarding the contact probe if the obtained profile is far from the nominal profile expected for the particular contact probe, the comparing step comprising evaluating a skewness of the contact probe and/or evaluating a local deformation of the contact probe.

In particular, the profile can be obtained by:

-identifying a plurality of points along the body of the contact probe; and

-interpolating said points.

According to an aspect of the invention, the method may further comprise the steps of:

-calculating the coordinates of the guide holes of the guide; and

-storing the coordinates in a central unit,

wherein the calculation of the coordinates is performed with respect to a point of the guide which does not change upon rotation of the guide, and wherein the control instructions take into account both the profile of the contact probe and the coordinates of the guide hole.

The method may further comprise the step of moving the robot arm between the support and a receiving element adapted to receive a plurality of contact probes, wherein the robot arm comprises a first end and a second end, the first end comprising first holding means and the second end comprising second holding means, one of the first or second holding means being adapted to hold a contact probe in a predetermined position on the support and the other holding means being adapted to pick up a contact probe from the receiving element, said holding and picking steps taking place simultaneously on different contact probes and being performed alternately at the support and the receiving element by the first holding means and the second holding means, respectively.

The method may further comprise the step of capturing an image of a touch probe accommodated in the accommodation element by means of a second vision system, the method comprising a subsequent step of discarding the touch probe based on said image of said second vision system.

The method may further comprise the steps of: the force exerted by the contact probe on the guide during movement of the support is detected by at least one force sensor integrated in at least one holding device.

It can also be said that after the step of calculating the force exerted by the contact probe on the guide, a step of sending data on said force to the central unit and a step of processing said data to generate information on said force as a function of the position of the contact probe in the guide can be performed.

The method may further comprise the steps of: correcting the trajectory of the support if said force exceeds a predetermined value; alternatively, if said force exceeds a predetermined value, the step of movement of the support is interrupted and repeated with the same trajectory.

Finally, the steps of the method may be repeated for each set of concentric guide holes of the guide in a preset order, the holes of each set of holes following a specific trajectory each time calculated according to the profile of the contact probe to be housed therein.

The characteristics and advantages of the device and of the method according to the invention will be apparent from the following description of embodiments, given by way of non-limiting example, and with reference to the accompanying drawings.

Drawings

In the drawings:

fig. 1 schematically shows an apparatus for automatically assembling a probe according to the invention.

FIG. 2 schematically illustrates a touch probe, the profile of which is obtained by the apparatus and method of the present invention;

figure 3 schematically illustrates a pair of parallel guides that receive the contact probes in respective guide holes; and

fig. 4A and 4B schematically show a holding device of a contact probe according to the present invention.

Detailed Description

With reference to the said figures, and in particular to the example of figure 1, there is described herein a device according to the invention, indicated schematically and in general with 1, comprising means for automatically assembling a probe according to the method that will be explained hereinafter.

It should be noted that the figures represent schematic diagrams and are not drawn to scale, but are drawn to emphasize important features of the invention. Furthermore, in the drawings, the different elements are schematically shown, as their shape may vary depending on the desired application. It should also be noted that in the drawings, like reference numerals refer to elements that are identical in shape or function.

The probe to be assembled by the apparatus 1 is suitable for testing electronic devices integrated on semiconductor wafers and comprises at least one pair of parallel guides 2 spaced by an air gap. The guides 2 are provided with respective guide holes 3 for slidably receiving a plurality of contact probes. In the present specification, the contact probes are each denoted by reference numeral 4. It should be further emphasized that the respective guide holes accommodating the different guides of a single contact probe 4 are substantially concentric with each other. In particular, the mutually concentric guide holes of the different guides form a single set of concentric guide holes of a plurality of sets of concentric guide holes, each set of concentric guide holes being adapted to receive a different contact probe.

In the preferred example, the probe comprises two pairs of parallel guides 2, i.e. a first pair of upper guides and a second pair of lower guides, separated from each other by a further air gap. In this respect, it is pointed out that in fig. 1 only one pair of guides 2 is shown, but as mentioned above, the invention is not limited to a preset number of guides 2, these figures being only a non-limiting exemplary form of the invention.

As shown in fig. 1, the apparatus 1 more generally comprises a support element 5, on which support element 5 all the main components of the apparatus 1 are arranged. As a non-limiting example of the invention, the support element 5 may be an optical platform equipped with an anti-vibration system (for example, a pneumatic compressed air system) so that the assembly process disclosed in the present invention is not disturbed by possible vibrations of the surrounding environment.

Furthermore, the device 1 comprises a support 6 placed on the support element 5, on which support 6 the guides 2 of the probe to be assembled are arranged, said guides 2 being superimposed on one another and the respective guide holes being placed concentrically so as to form sets of concentric guide holes for assembling various contact probes. As will be described in detail below, the support 6 is a unique element of the present invention.

The apparatus 1 further comprises at least one holding device 7a adapted to hold the contact probe 4 in a predetermined position on the support 6. For the sake of simplicity of illustration, fig. 1 shows only one contact probe 4 and only one guide hole 3 for each guide 2, which is obviously only exemplary.

Advantageously, according to the invention, the contact probe 4 is held in a predetermined position by means of a holding device 7a, while the support 6 is a movable support adapted to move the guide 2 arranged thereon towards the contact probe 4 to fit the guide 2 onto said contact probe 4. As a result, according to the present invention, instead of moving and inserting the contact probe 4 into the guide hole 3 of the guide 2 of the probe to be assembled, the guide 2 is moved toward the contact probe 4 through the support 6 to fit the guide 2 to the contact probe 4. In other words, the guide 2 of the probe head to be assembled is moved by the support 6 so that the guide hole 3 of said guide 2 reaches the contact probe 4 to be accommodated therein.

Thus, according to the invention, the support 6 is a movable support between a first position (also referred to herein as "rest position") and a second position (also referred to herein as "assembly position"). In the first position, the contact probe 4 is held by the holding means 7a in a predetermined position outside the guide hole 3, and in the second position, the contact probe 4, still held in said predetermined position by the holding means 7a, is housed in the guide hole 3, in particular in a set of guide holes 3 substantially concentric to each other and obtained in different guides 2.

This solution is of great advantage because the movement of the support 6 supporting the guide 2 has a greater freedom with respect to the retention means 7a of the contact probe 4, so that it can be assembled efficiently even if said contact probe 4 has an irregular profile or if the guide holes 3 of the guide 2 are not perfectly aligned with each other, as will be clarified below. It is well known that movement of a contact probe requires the application of a force which, due to the very small dimensions of the probe, often causes it to deform or even break, resulting in overall damage to the components or failure of the assembled probe to operate correctly.

For example, in a preferred embodiment of the invention, the support 6 is a robot hexapod, i.e. it is a support with six movable support elements or legs 6' provided with suitable actuators, said hexapod thus having six degrees of freedom of movement. Such a support 6 has a high precision and repeatability of the movements with tolerances of less than one thousandth of a degree (0.001 deg.). As such, such support 6 is able to perform a minimum amount of movement, still less than 0.001 °, allowing fine adjustments to the assembly process.

Suitably, the support 6 moves according to a very precise trajectory calculated in a central unit 10, the central unit 10 being included in the apparatus 1 and provided with processing means, such as a PC or generally any computerized unit. The central unit 10 is suitably connected to the actuator of the support 6 which causes the movement of the support 6.

Specifically, the trajectory of the movement of the support 6 is calculated from the profile P of the contact probe 4 that must be accommodated in the guide hole 3. The central unit 10 is adapted to convert said profile P into control commands CI sent to the actuators of the support 6 to allow the support 6 to move according to said trajectory. In other words, the support element 6' of the support 6, and in particular the actuator thereof, receives control commands CI from the central unit 10 to impart to said support 6 an appropriate trajectory according to the profile P of the contact probe 4. This also allows the assembly process of a contact probe 4 having an irregular profile P, from which the trajectory of the support 6 is precisely calculated.

In order to obtain the profile P of the touch probe 4, the apparatus 1 comprises a first vision system 11 'connected to the central unit 10, which first vision system 11' in turn comprises at least one pair of cameras 11a and 11b, the cameras 11a and 11b being adapted to capture, from the holding element 7a, respective images Img 'a and Img' b of the touch probe 4 held in a predetermined position. The cameras 11a and 11b are connected to the central unit 10 and send the captured images Img 'a and Img' b thereto, so that the central unit 10 can obtain the profile P of the contact probe 4 from the images Img 'a and Img' b.

The cameras 11a and 11b are high-resolution cameras, for example 10 megapixels or more, and are arranged at the support 6 (in particular, they are arranged at their focal distance) so as to take over the contact probe 4 held at the support 6 in the most appropriate manner, thereby forming a stereoscopic vision system.

In particular, once the images Img ' a and Img ' b have been captured by the cameras 11a and 11b, and once projections of the touch probe 4 have been obtained from the images Img ' a and Img ' b on two orthogonal planes, the profile P of the touch probe 4 is obtained by identifying a plurality of points 12 along the body 4' of the touch probe 4. The interpolation of the points 12 thus provides the profile P of the probe, as shown schematically in figure 2.

Obviously, the above steps are repeated for each contact probe 4 and for each set of concentric guide holes, since in different sets different contact probes 4 with different profiles P must be accommodated. As a result, the support 6 moves according to a different trajectory each time, which takes into account the profile P of the different contact probes 4.

Therefore, in the present invention, the guide 2, and in particular the guide hole 3 thereof, is suitably made to move with the movement of the support 6 according to a trajectory calculated each time according to the profile P of the contact probe 4 to be housed therein. This is schematically illustrated in fig. 3, in which a pair of parallel guides 2 is shown, said pair of parallel guides 2 accommodating, due to the movement of the support 6, the contact probes 4 in the respective guide holes 3. In particular, by sending control commands to the actuator CI of the support 6, i.e. to the support 6', the centre C of the guide hole 3, which must accommodate the contact probe 4 held by the holding means 7a, is forced to follow a preset trajectory, i.e. to follow the profile P of the contact probe 4. In other words, during the movement of the support 6, the coordinates of the centre C of the guide hole 3 substantially coincide with the coordinates of the profile P of the contact probe 4, as shown in fig. 3.

In this respect, it is noted that the coordinates of the guide hole 3 are calculated with respect to a point of the set of guides 2 that does not change further with its rotation, and therefore this point is the center of rotation of said guide 3. Said coordinates are then provided to the central unit 10 to calculate the trajectory of the support 6, as will also be described in detail below. In other words, to ensure correct operation of the apparatus 1, the coordinates of the centers C of all the guide holes 3 are calculated with respect to a common reference frame, the origin of which is the center of rotation of the guide 2.

Nominally, the origin of the coordinate system is placed in the center of a support frame (not shown in the figures) which in turn rests on a support 6 which supports the guide 2 during assembly. In particular, the points are evaluated from time to time according to the arrangement of the guides 2 on the support frame.

Referring now to fig. 4A and 4B, the holding device 7a comprises at least one pair of end effectors or gripping elements 8 adapted to hold the contact probe 4, said end effectors 8 extending from a body 9, the body 9 preferably being made of a piezoelectric material. In this way, the body 9 of the holding element 7a, deformed by the piezoelectric effect, causes a movement of the end-effector 8 connected thereto, said end-effector 8 being therefore able to pick up and hold the contact probe 4. In other words, the holding device 7a is substantially in the shape of a clip, wherein the clamping element is arranged on a body preferably made of piezoelectric material.

Furthermore, the end-effectors 8 are suitably shaped to ensure effective retention of the contact probe 4 with a rod-like body, at least one of said end-effectors 8 comprising, at its end, a recess 8r forming a housing seat for said contact probe 4.

It is to be noted, however, that the retaining means 7a is not limited to the above-described type, the described embodiment being only a non-limiting example of the scope of the invention, as any other suitable retaining means may be formed.

The holding means 7a is adapted to apply a force to the contact probe 4 held by its end-effector 8 sufficient to hold it in place without causing local deformation or breakage thereof. The holding device 7a may suitably comprise a first force sensor integrated therein, said force sensor being adapted to measure the strength with which its end effector 8 holds the contact probe 4 with a resolution of, for example, about 1 mN. Thus, the apparatus 1 comprises a feedback system adapted to adjust the holding strength of the end effector 8 on the contact probe 4 after receiving the strength value measured by the first force sensor. In this way, it is possible to avoid holding the contact probes 4 with excessive force, thus avoiding damaging them. Further, the holding device 7a is formed to hold the contact probe 4 without substantially applying any vibration thereto.

Still referring now to fig. 1, the holding device 7a is a terminal element of the robot arm 13, which is movable between the support 6 and a housing element 14 adapted to house a plurality of contact probes 4.

The housing element 14 is a support in which a plurality of contact probes 4 are held, for example by a gel, and on which the probes are arranged so that they can be easily picked up, the housing element 14 not being discussed further in this disclosure, since this is a conventional housing element.

In a preferred embodiment of the invention, the robotized arm 13 comprises a first end 13a and a second opposite end 13b, the first end 13a in turn comprising the first retaining means 7a and the second opposite end 13b in turn comprising the second retaining means 7b identical to the first retaining means 7 a.

In particular, one of the first or second holding devices 7a or 7b is adapted to hold the contact probe 4 in a predetermined position on the support 6, while the other holding device 7b or 7a is adapted to pick up a different contact probe 4 from the housing element 14. In this way, the assembly of one contact probe is carried out simultaneously with the pick-up of a different probe, and once the assembly of the contact probe is finished (i.e. after the support 6 has returned to the rest position), the robotized arm 13 is moved (for example, rotated around its central point) and, thanks to the movement of said robotized arm 13, the holding elements 7a and 7b reverse their position so that the different probe that has been picked up is brought to the support 6, the new contact probe is picked up by the other holding means, with the consequent speeding up of the assembly process, in particular eliminating any waiting times associated with the pick-up of the new probe.

Furthermore, according to an embodiment of the invention, the apparatus 1 further comprises a second vision system 11 "that captures an image Img" of the contact probe 4 housed in the housing element 14. The second vision system 11 ″ may comprise a single camera, generally with a lower resolution than the two cameras 11a and 11b of the first vision system 11', since it is intended to check the profile P of the contact probe 4, which is less accurate than said first vision system 11'.

In particular, after sending the captured image Img "at the central unit 10, said central unit 10 makes a first evaluation of the profile P of the contact probe 4 in the housing element 14 on the basis of said image Img". It is in fact possible to obtain some preliminary parameters from the image Img "so that the profile of the contact probe can be preliminarily evaluated, with the result that contact probes whose parameters obtained from the image Img" are outside the predetermined parameters can already be discarded (and therefore not picked up) in this step. In other words, by means of the second vision system 11 ", it is possible to discard beforehand the contact probe on the basis of parameters that can only be evaluated with one camera and therefore on the basis of a single two-dimensional image.

In practice, the first vision system 11 "is adapted to perform a metrology, quantitative inspection (by calculating parameters such as skewness and/or local deformations) of the touch probe, as will be explained in more detail below, while the second vision system 11" is adapted to perform a qualitative inspection of the touch probe.

Furthermore, the device comprises at least two vision systems (e.g. two other cameras), denoted in the present disclosure by reference numerals 11 up and 11 down. Arranged above the support 6 on the vision system 11 and performing the overall control of the whole apparatus 1, while arranged below the vision system 11 below the support 6 and adapted to verify the correct assembly of the touch probe 4, for example to verify from which guide hole 3 the touch probe 4 emerges at the end of the assembly process.

Furthermore, the device of the invention is suitably illuminated by an illumination system of the axial or annular led type.

Furthermore, advantageously, according to the invention, in order to obtain complete information about the assembly process, the holding means 7a and 7b comprise at least one second force sensor adapted to measure the deformations to which the contact probe 4 is subjected during the movement of the support 6.

More specifically, the sensor integrated in the holding device is adapted to measure the force exerted by the contact probe 4 on the guide 2 of the probe head to be assembled. In other words, by measuring the force exerted by the contact probe 4 on the end effector 8 during movement of the support 6, the force exerted by the probe on the guide can be measured, thereby verifying correct assembly.

Suitably, the second force sensor is connected to the central unit 10 and is adapted to send to the central unit 10 data Dat relating to the force exerted by the touch probe 4 on the guide 2 during assembly and therefore during movement of the support 6. In this case, the central unit 10 is able to process the received data Dat in order to generate information about the force exerted by the contact probe 4 on the guide 2 as a function of the position of the contact probe 4 in said guide 2 (for example as a function of the position of the end of the contact probe 4). Furthermore, a graph of the force exerted by the contact probe 4 as a function of the position of the contact probe 4 in the guide 2 can be generated in the central unit 10 on the basis of said information, said graph being displayed on a suitable display device connected to the central unit 10 (for example a computer screen), so that visual information about said force is also made available.

If the measured force exceeds a predetermined value, the central unit 10 is adapted to correct the control commands CI sent to the actuators of the support 6 and therefore its trajectory, so that the value of said force is within the admissible limits, in order to obtain an optimal assembly.

Alternatively, if the measured force exceeds a predetermined value, the central unit 10 is adapted to arrest the movement of the support 6 and to try again the assembly a predetermined number of times starting from the beginning with the same trajectory.

Typically, the value of the applied force is about 10 μ N, the working range of the second force sensor is 40mN, and the resolution is at least 40 μ N.

For example, if during assembly the end of the contact probe abuts against a guide or is inserted in the wrong guide hole, it will be detected that the force exerted by said contact probe is too great, indicating that there is an error in the assembly process, which can be corrected by recalibrating the trajectory of the support 6, which error is not easily detected under the aforementioned further vision system 11. Thus, the second force sensor allows for precise control of the entire assembly process beyond the vision system 11.

The apparatus 1 may be provided with suitable movement means, for example electric or hydraulic motors, associated with the support 6, in particular with the actuators of the support 6, and with the robotized arm 13, and possibly also with a set of cameras, so as to position the apparatus 1 more in different operating conditions of the apparatus 1.

As previously mentioned, the invention also relates to a method for automatically assembling a probe for testing electronic devices integrated on a semiconductor wafer. In particular, the method comprises at least the following preliminary steps: at least two parallel guides 2 are arranged on a support 6, said parallel guides 2 being provided with a plurality of respective guide holes 3, and the contact probes 4 to be received in the respective guide holes 3 of said guides 2 are held by at least one holding means 7 a. Suitably, the guides 2 are superimposed on each other and the respective guide holes 3 are placed concentrically and form sets of concentric guide holes, a particular contact probe 4 being housed in each set of concentric guide holes.

Advantageously, according to the invention, the support 6 is a movable support and the method comprises the following steps: the support 6 is moved on the basis of a preset trajectory between a first position (also called "rest position") in which the contact probe 4 is held in a predetermined position outside the guide hole 3 by the holding means 7a, and a second position (also called "assembly position") in which the contact probe 4, still held firmly in said predetermined position, is housed in guide holes that are substantially concentric to each other (i.e. in a set of concentric guide holes). At the end of said step, the support 6 is therefore returned to the first position and is ready to be moved again to receive a new contact probe 4 in the guide hole 3 of the guide 2.

The trajectory according to which the support 6 moves can be calculated from the profile P of the contact probes 4 to be housed in the guide holes 3 concentric to each other.

For this purpose, the step of moving the support 6 described above is preceded by a step of capturing, by the first vision system 11', images Img ' a and Img ' b of the touch probe 4 held in a predetermined position of the support 6 by the holding means 7 a.

In a preferred embodiment of the invention, the first vision system 11 "comprises at least two cameras 11a and 11b constituting a stereo vision system. In this way, the profile P of the contact probe 4 can be obtained in a very precise manner.

Thus, the step of capturing the images Img 'a and Img' b is followed by a step of sending said images Img 'a and Img' b to the central unit 10, in which central unit 10 the profile P of the contact probe 4 is obtained from said images as described above.

The central unit 10 is therefore adapted to convert the profile P of the contact probe 4 thus obtained into control commands CI for the actuators of said support 6, in particular for the supporting elements 6' thereof, said step of converting the profile P being followed by a step of transmitting said control commands CI from the central unit 10 to said actuators, so that said support 6 can move according to a suitable trajectory.

The holding device 7a is a terminal element of a mobile robot arm 13 controlled by the central unit 10. In order to optimise the assembly of the probe, the method of the invention further comprises the step of moving the robot arm 13 between the support 6 and the housing element 14, the housing element 14 being adapted to receive a plurality of contact probes 4 to be received in the guide holes 3.

In particular, the robotized arm 13 comprises a first end 13a and a second opposite end 13b, the first end 13a in turn comprising the first retaining means 7a and the second opposite end 13b in turn comprising the second retaining means 7 b. Suitably, one of the first or second holding means 7a or 7b is adapted to hold the contact probe 4 in a predetermined position at the support 6, while the other holding means 7b or 7a is adapted to pick up the contact probe from the receiving element 14 at the same time.

According to the invention, the above-mentioned holding and picking steps are performed simultaneously and alternately by the first holding means 7a and the second holding means 7b according to the position of the ends 13a and 13b of the robot arm 13. The robot arm 13 can be rotated around its center point, for example. In other words, due to the movement of the robotized arm 13, the retaining device 7a or 7b previously located at the support 6 is located at the housing element 14 and vice versa.

Furthermore, the method of the invention comprises a step of capturing an image Img "of the contact probe 4 housed in the housing element 14, this step being performed by a second vision system 11", the second vision system 11 "comprising at least one camera connected to the central unit 10. This step may be followed by a subsequent step of discarding the contact probe if the probe parameters assessed by the image Img "are very different from the nominal parameters of the contact probe.

Even if the second vision system 11 ″ provides a first rejection of very irregular touch probes, the above-mentioned step of converting the profile P of the touch probe 4 at the support 6 into control instructions CI is preceded by a step of comparing said profile P with a nominal profile of said touch probe, which is stored in the central unit 10.

Thus, if the profile P obtained is far from the nominal profile, for example outside a predetermined range around the nominal profile, or in a calculation parameter far from the theoretical value, the method of the invention comprises a subsequent discarding step of the contact probe 4, so as to avoid assembling a contact probe whose profile is too irregular. In particular, by means of the first vision system 11', the curvature or deflection of the touch probe 4 can be calculated and compared with the nominal deflection value of the particular touch probe. In other words, skewness is a measure of how far a contact probe is in straightness from a theoretical probe. Additionally or alternatively, other metrology parameters may also be calculated, such as local variations in the profile of the contact probe (e.g., local variations in concavity or stain) to assess the suitability of the contact probe to be assembled, such as discarding profiles with concavity variations. In any case, it should be noted that all these parameters are compared each time with the specific parameters of a specific type of contact probe.

It should be noted that by the step of identifying a plurality of points 12 along the body 4' of said contact probe 4, the profile P of the contact probe 4 is obtained in the projection of the contact probe 4 from the captured images Img ' a and Img ' b on two orthogonal planes. Then, after this step, said points 12 are interpolated, said interpolation providing a profile P from which the trajectory of the support 6 is obtained. For example, interpolation can be performed with points having a pitch varying from 5 μm to 15 μm, preferably 10 μm. Obviously, the criteria of interpolation, definition and choice of the number of points may vary according to need and/or to the situation, for example it may vary according to the type of contact probe to be assembled.

It is also possible to provide a step of calculating the coordinates of the guiding holes 3 of each guide 2 and storing said coordinates in the central unit 10. In particular, the calculation of the coordinates of the guide holes 3 is based on the precise measurement of the guide 2 before the guide holes are aligned.

In particular, the coordinates are calculated with respect to a point of the guide 2 that does not further change with its rotation (i.e., the center of rotation of the guide 2). In other words, the point (the center of rotation of the guide) is the origin of a reference system relative to which the coordinates of all points of the probe (e.g. the center coordinates of the guide hole 3) are calculated.

Advantageously, according to the invention, the control command CI is sent to the support 6 and therefore its trajectory taking into account the profile P of the contact probe 4 and the coordinates of the guide hole 3.

In particular, the invention allows the central unit 10 to take into account not only the profile P of the contact probe 4, but also the relative misalignments of the guide holes 3 of the different guides 2, calculated according to the coordinates of the guide holes 3 provided to the central unit 10. Furthermore, the central unit 10 also takes into account how the coordinates of each point of the guide 2 change during the movement of the support 6 when calculating the trajectory, in order to make optimal control of the assembly process.

Obviously, the assembly process is only started after a suitable initial calibration step of the apparatus 1, in which, for example, the deformations undergone by the guide holes during the movement of the support 6 are adjusted.

Depending on the profile P of the contact probe 4, the central unit 10 can also select the guide holes 3 in which to accommodate the contact probe 4 according to the coordinates and the misalignment of the guide holes 3.

In order to obtain full control of the assembly process, there is also provided the step of detecting the force exerted by the contact probe 4 on the guide 2 during the movement of the support 6, said force being detected by at least one force sensor integrated in the retaining means 7a and 7 b.

Then, the step of calculating the force exerted by the contact probe 4 is followed by a step of sending data Dat relating to said force to the central unit 10. The data Dat are processed as a function of the position of the contact probe 4 between said guides 2. In other words, the central unit 10 processes the data Dat and generates information about the force exerted by the contact probe 4 on the guide as a function of the position of the contact probe 4 in said guide 2. Furthermore, the central unit 10 generates a diagram of the variation of the force (deformation) of the contact probes 4 as a function of position, which is visible on a suitable display device and in this way it is possible to see what variation of said contact probes 4 between the guides 2 has occurred during assembly.

Suitably, if the force exerted by the contact probe 4 on the guide exceeds a predetermined value, a step of correcting the control instructions CI and therefore the trajectory of the support 6 is provided, or the movement of the support 6 is interrupted and assembly is again attempted for a predetermined number of times using the same trajectory.

Obviously, for each set of concentric guide holes 3 of the guide 2, all the steps described above are repeated in a determined sequence. Then, each contact probe 4 is picked up from the housing element 14 and placed in a predetermined position at the support 6, the support 6 being suitably moved so that the contact probe 4 is housed in the guide hole 3 associated therewith. In this way, each guide hole 3 follows a specific trajectory that is different from the trajectories of the other holes and is calculated each time according to the profile of the contact probe to be housed therein and the coordinates of the hole itself, the centre of each hole following said profile, so that the guide 2 can be fitted to said contact probe 4 in a very precise and efficient manner. In other words, the center of the guide hole 3 follows a trajectory substantially conforming to the profile P of the contact probe 4.

It is finally pointed out that the contact probes are always supported at the same predetermined position at the support 6 by the retaining means 7a and 7b, the support 6 being placed on a movement element XY (not shown in the figures) which moves said support 6 in the plane X-Y so as to bring the correct guide holes close to the contact probes to be housed therein. In other words, the movement element X-Y provides a first rough displacement of the support 6, and then the support 6 will be moved in a fine manner towards the touch probe by its actuator.

In summary, the present invention provides a device for the automatic assembly of a probe head, in which, instead of moving the holding means (and therefore the contact probe) towards the guide hole of the guide of the probe head to be assembled, the contact probe is held in a predetermined position by suitable holding means, the contact probe is moved on a support on which the guide is arranged, the support having a plurality of degrees of freedom of movement and being able to follow a suitable trajectory calculated from the profile of the contact probe in order to fit the guide onto the probe, the probe being held in a predetermined position by the holding means.

Advantageously, according to the invention, the support of the moving guide, instead of the holding means of the contact probe, allows to select with greater freedom the trajectory to be provided to said support, allowing to form complex trajectories in a very precise manner.

Furthermore, simply holding the contact probe without movement reduces the risk of deformation or breakage thereof.

Moreover, the choice of the trajectory of the support according to the contour of the contact probe to be assembled makes the assembly process of the invention no longer limited by the shape of the contact probe and the coordinates of the centre of the guide hole to follow the contour properly, thus producing a significant advance compared to known solutions.

Furthermore, knowing the coordinates of the guide holes (and therefore the relative misalignment of the holes) and subsequently adjusting the trajectory of the supports according to the coordinates allows the assembly process to be no longer limited by the possible excessive misalignment of the holes, a phenomenon that is present in the known solutions.

Furthermore, it is observed that the apparatus described in the present disclosure allows a fully automated and efficient assembly process, thereby reducing the intervention of the operator to a minimum.

The preliminary evaluation of the profile of the contact probe by means of the camera system also makes it possible to discard those probes whose profile is too far from the nominal profile, thus avoiding interruption of the alignment process in the case of probes with very irregular profiles, and avoiding possible accidental breakage of the probe itself, thus increasing productivity and therefore bringing economic advantages and time savings.

The use of a robotic support with six degrees of freedom also allows extremely precise trajectories to be set to accurately fit the guide onto the touch probe without assembly errors.

Finally, the integration of the sensor makes it possible to detect the force exerted by the contact probe on the guide, so that the variations of the probe that occur during the movement of the support can be observed with precision, thus allowing an extremely precise and complete control of the assembly process.

In essence, the apparatus and method shown in the present disclosure effectively solve the technical problem of the present invention, since the support of the guide of the probe head to be assembled can be moved according to the profile of the contact probe to be received in a specific set of concentric guide holes.

It is clear that a man skilled in the art, in order to satisfy contingent and specific requirements, may apply to the device and to the method described above many modifications and variants, all of which are included within the scope of the invention as defined by the following claims.