阅读说明：本技术 一种squid芯片压焊装置与压焊方法 (SQUID chip pressure welding device and pressure welding method ) 是由 王海 朱浩波 李子豪 孔祥燕 于 2021-08-20 设计创作，主要内容包括：提供一种SQUID芯片压焊装置与压焊方法,压焊装置包括PCB固定装置及其面接触式的压力传感器(7),与其位置对应,设置有由驱动装置(5)驱动可作直线滑动的推进杆(6),推进杆(6)包括位于其顶部的芯片推头(8),芯片推头(8)的顶端设置有芯片容纳槽(9)；压焊方法包括将芯片(1)的电引出端与PCB板(2)的电接入端设置为数量相同的对应的焊接盘(3)；选用各项异性的导电胶(18)加热至100至200度,将芯片(1)压焊至PCB板(2)的对应位置,使对应焊接盘(3)之间的导电胶(18)达到设定的压缩程度而电连通；本发明使用导电胶压焊的方式,消除了现有技术焊盘留有引线的问题,提高了作业效率。(The SQUID chip pressure welding device comprises a PCB fixing device and a surface contact type pressure sensor (7), a push rod (6) which corresponds to the position of the pressure sensor and is driven by a driving device (5) to slide linearly is arranged on the pressure sensor, the push rod (6) comprises a chip push head (8) positioned at the top of the push rod, and a chip accommodating groove (9) is arranged at the top end of the chip push head (8); the pressure welding method comprises the steps that the electric leading-out end of the chip (1) and the electric connecting end of the PCB (2) are arranged into corresponding welding discs (3) with the same number; heating conductive adhesive (18) with various characteristics to 100-200 ℃, and pressure-welding the chip (1) to the corresponding position of the PCB (2) to ensure that the conductive adhesive (18) between the corresponding welding discs (3) achieves the set compression degree and is electrically communicated; the invention adopts the conductive adhesive pressure welding mode, eliminates the problem that the bonding pad in the prior art is provided with a lead, and improves the working efficiency.)

1. The SQUID chip pressure welding device is used for welding a SQUID chip (1) on an object, and enabling at least 2 welding discs (3) of the SQUID chip (1) to be electrically communicated with corresponding conductive elements with the same number as the object; the SQUID chip pressure welding device is characterized by comprising an object fixing device for fixing an object, wherein the object fixing device is fixedly arranged on a fixing support (4), a pushing rod (6) which is driven by a driving device (5) to linearly slide is arranged corresponding to the position of the object fixing device, the pushing rod (6) comprises a chip pushing head (8) positioned at the top of the pushing rod, and a chip accommodating groove (9) corresponding to the SQUID chip (1) is arranged at the top end of the chip pushing head (8); the object fixing device is provided with a surface contact type pressure sensor (7), or a thin film pressure sensor is attached to the surface of the chip accommodating groove (9).

2. The SQUID chip bonding apparatus according to claim 1, for bonding the SQUID chip (1) on the PCB board (2) and bringing at least 2 of the bonding pads (3) provided on the SQUID chip (1) into electrical communication with the corresponding bonding pads (3) of the same number as the PCB board (2); the SQUID chip pressure welding device is characterized by comprising a PCB fixing device for fixing a PCB (2), wherein the PCB fixing device is fixedly arranged on a fixing support (4), the pushing rod (6) is arranged corresponding to the position of the PCB fixing device, and the pushing rod (6) comprises a chip pushing head (8) positioned at the top of the pushing rod; the PCB fixing device is provided with a surface contact type pressure sensor (7).

3. The SQUID chip bonding device according to claim 2, wherein the PCB fixing device comprises a PCB limiting clamping seat (10) symmetrically installed on the fixing support (4) in two sides, and each side of the PCB limiting clamping seat (10) is provided with a protruding part (11) protruding oppositely; the pressure sensor (7) is a PVDF film pressure sensor and is directly stuck on the fixed support (4) between the PCB limiting clamping seats (10) at the two sides by using a strong glue (19); or the PVDF film pressure sensor comprises a bearing sheet and a PVDF pressure sensing film stuck on the bearing sheet, and the PVDF film pressure sensor is stuck on the fixed support (4) between the PCB limiting clamping seats (10) at the two sides by using a strong glue (19); a space for loading the PCB (2) is formed between the PCB limiting clamping seats (10) on the two sides and the pressure sensor (7).

4. The SQUID chip bonding device according to claim 2, wherein the PCB fixing device is an integrated PCB fixing device fixedly mounted on the fixing support (4), and comprises a base frame (12), through holes (21) are formed in two ends of the base frame (12), and the base frame is fixedly mounted on the fixing support (4) through bolts; the PCB limiting clamping seat comprises a base frame (12), wherein protruding strips (13) are symmetrically arranged on two sides of the base frame (12), PCB limiting clamping seats (10) are symmetrically and fixedly arranged on two sides of the base frame (12), each PCB limiting clamping seat (10) is provided with a protruding part (11) which extends out in opposite directions, each PCB limiting clamping seat (10) comprises a sliding block (14), a sliding groove (15) for the sliding block (14) to be embedded into is formed in the base frame (12), and a compression spring (16) is arranged between each PCB limiting clamping seat (10) and each protruding strip (13); the pressure sensor (7) is a film pressure sensor, comprises a bearing sheet and a pressure sensing film stuck on the bearing sheet, and is stuck in the middle of the base frame (12) by a strong glue (19); a space for loading the PCB (2) is formed between the PCB limiting clamping seats (10) on the two sides and the pressure sensor (7).

5. The SQUID chip bonding device according to claim 4, wherein the bump bar (13) and the PCB limiting cassette (10) are respectively provided with a section of protruding rod (17), and two ends of the compression spring (16) are respectively sleeved on the bump bar (13) and the protruding rod (17) of the PCB limiting cassette (10).

6. The SQUID chip bonding apparatus according to claim 1, wherein a detachable chip pusher (8) is provided on the top of the pushing rod (6), and a chip receiving groove (9) corresponding to the SQUID chip (1) is provided on the top end of the chip pusher (8); the chip pushing head (8) is provided with an external thread (20), and the top end of the pushing rod (6) is provided with a corresponding threaded hole.

7. A SQUID chip pressure welding method is used for welding a SQUID chip (1) on an object, and enabling at least 2 welding discs (3) of the SQUID chip (1) to be electrically communicated with corresponding conductive elements with the same number as the object; characterized in that anisotropic conductive adhesive (18) is selected and heated to 100 to 200 ℃ and then is kept warm for standby, the heated conductive adhesive (18) is pasted on the area of the object corresponding to the conductive element, the SQUID chip pressure welding device according to any one of claims 1 to 6 is used for fixing the object pasted with the conductive adhesive (18) on the object fixing device, and the SQUID chip (1) is placed in the chip accommodating groove (9) of the pushing head of the pushing rod (6); a surface contact type pressure sensor (7) for closely attaching the object piece to the object fixing device, or a thin film pressure sensor for closely attaching the SQUID chip (1) to the surface of the chip accommodating groove (9); the driving device (5) drives the push rod (6) to bond the SQUID chip (1) to the corresponding position of the object, so that the conductive adhesive (18) between the bonding pad (3) of the SQUID chip (1) and the corresponding conductive element of the object reaches the set pressure and bonding time, and the bonding pad (3) of the SQUID chip (1) is electrically communicated with the corresponding conductive element of the object.

8. The SQUID chip bonding method of claim 7, for bonding the SQUID chip (1) on the PCB board (2) and bringing at least 2 pads (3) of the SQUID chip (1) into electrical communication with the same number of corresponding pads (3) of the PCB board (2); the SQUID chip soldering device is characterized in that the heated conductive adhesive (18) is pasted on the area where the soldering disk (3) of the PCB (2) is located, the PCB (2) pasted with the conductive adhesive (18) is fixed on a PCB fixing device and tightly attached to a pressure sensor (7), a driving device (5) drives a push rod (6) to press and weld the SQUID chip (1) to the corresponding position of the PCB (2), the conductive adhesive (18) between the soldering disk (3) of the SQUID chip (1) and the soldering disk (3) of the PCB (2) reaches set pressure and pressure welding time, and the soldering disk (3) of the SQUID chip (1) is electrically communicated with the soldering disk (3) of the PCB (2).

9. The SQUID chip bonding method of claim 7, wherein the bonding process comprises the following steps: starting a driving device (5), wherein a pushing rod (6) pushes a SQUID chip (1) to advance, a surface-contact pressure sensor (7) arranged on an object fixing device or a film pressure sensor attached to the surface of a chip accommodating groove (9) senses the pressure from the pushing rod (6), when the pressure reaches a limited pressure value X, the driving device (5) stops running, and a set time Y is waited to solidify a conductive adhesive (18); after the waiting time is over, the driving device (5) automatically runs in a reverse direction and returns to the original position; and opening the object fixing device, and taking down the object after the pressure welding is finished.

10. The SQUID chip bonding method according to claim 8, wherein the bonding pad (3) of the SQUID chip (1) is not larger than the bonding pad (3) of the PCB (2), and after the SQUID chip (1) and the PCB (2) are attached to each other, the bonding pad (3) of the SQUID chip (1) is completely covered by the bonding pad (3) of the PCB (2).

The technical field is as follows:

the invention relates to a SQUID (Superconducting Quantum Interference Device for short) chip bonding Device and a bonding method.

Background art:

magnetic microscopes, also known as scanning SQUID microscopes. Among the current magnetic detection instruments, the magnetic microscope is the most sensitive due to its higher spatial resolution and magnetic field resolution; the welding mode of the SQUID chip and the design precision of the magnetic microscope probe have very high requirements. The SQUID chip comprises a substrate layer, an insulating layer and a Josephson junction layer which is clamped between the substrate layer and the insulating layer and is used as a core magnetic flux induction area of the SQUID chip, and a sensitive source of the magnetic microscope is the Josephson junction layer which is used as the core magnetic flux induction area of the SQUID chip. During detection, the magnetic microscope spatial resolution and the magnetic field resolution between the SQUID chip Josephson junction layer and a sample to be detected have obvious influence, so that the magnetic microscope spatial resolution and the magnetic field resolution depend on the distance between the SQUID chip Josephson junction layer and the sample to be detected to a great extent, and the closer the two distances, the higher the magnetic microscope spatial resolution and the magnetic field resolution.

The Josephson junction layer of the prior SQUID chip is punched from the insulating layer to lead out a conductive connecting wire, so that a bonding pad is arranged on the insulating layer of the chip. The conventional welding method of the SQUID chip is to bond a conductive connecting wire (an aluminum wire or a gold wire) to a SQUID chip bonding pad by using a bonding machine through ultrasonic vibration or hot pressing. And the conductive connecting wire is led out from the SQUID chip bonding pad and is used for external connection. The mode applied to the scanning SQUID microscope chip has the following defects: mainly, 1) a conductive connecting line (an aluminum wire or a gold wire) led out from a chip bonding pad can form a bending height of dozens of micrometers, which influences the spatial resolution of a subsequent scanning SQUID microscope; the detailed reasons for this can be found in the background section of the specification of the patent application entitled "a SQUID chip and magnetic microscope probe and packaging method therefor" filed on the same date as the present application by the applicant. Secondly, 2) the conductive connecting wire is very thin and has high operation difficulty, and a wire outlet is easy to block when a hard material is bound; 3) the binding machine is manually operated to carry out binding operation, so that the requirement on the proficiency of an operator is high; 4) the bonding machine can only complete bonding of one bonding pad in one operation.

The invention content is as follows:

the invention aims to provide a SQUID chip pressure welding device and a pressure welding method, in particular to a pressure welding device and a pressure welding method of a SQUID chip used as a magnetic microscope probe.

In order to solve the technical problems, the SQUID chip pressure welding device has the technical scheme that:

the device comprises a SQUID chip, a plurality of conductive elements and a plurality of conductive pads, wherein the SQUID chip is welded on an object, and at least 2 welding pads of the SQUID chip are electrically communicated with the corresponding conductive elements with the same number as the object; the SQUID chip pressure welding device is characterized by comprising an object fixing device for fixing an object piece, wherein the object fixing device is fixedly arranged on a fixing support, a pushing rod which is driven by a driving device and can linearly slide is arranged corresponding to the position of the object fixing device, the pushing rod comprises a chip pushing head positioned at the top of the pushing rod, and a chip accommodating groove corresponding to the SQUID chip is arranged at the top end of the chip pushing head; the object fixing device is provided with a surface contact type pressure sensor, or a film pressure sensor is attached to the surface of the chip accommodating groove.

The following is a further scheme of the SQUID chip pressure welding device of the invention:

the SQUID chip pressure welding device is used for welding the SQUID chip on the PCB and electrically connecting at least 2 welding discs arranged on the SQUID chip with corresponding welding discs with the same number as the PCB; the SQUID chip pressure welding device comprises a PCB fixing device for fixing a PCB, the PCB fixing device is fixedly arranged on a fixing support, the position of the PCB fixing device corresponds to that of the PCB fixing device, the pushing rod is arranged, and the pushing rod comprises a chip pushing head positioned at the top of the pushing rod; the PCB fixing device is provided with a surface contact type pressure sensor.

The PCB fixing device comprises PCB limiting clamping seats which are symmetrically arranged on the fixing support in two sides, and each PCB limiting clamping seat is provided with a protruding part which extends out in opposite directions; the pressure sensor is a PVDF film pressure sensor and is directly stuck on the fixed support between the PCB limiting clamping seats at the two sides by strong glue; or the PVDF film pressure sensor comprises a bearing sheet and a PVDF pressure sensing film pasted on the bearing sheet, and the PVDF film pressure sensor is pasted on the fixed support between the PCB limiting clamping seats on the two sides by using a strong adhesive; a space for loading the PCB is formed between the PCB limiting clamping seats on the two sides and the pressure sensor.

The PCB fixing device is an integrated PCB fixing device fixedly arranged on the fixing support and comprises a base frame, through holes are formed in two ends of the base frame, and the base frame is fixedly arranged on the fixing support through bolts; the PCB limiting clamping seat comprises a sliding block, a sliding groove for the sliding block to be embedded into is formed in the base frame, and a compression spring is arranged between the PCB limiting clamping seat and the protruding strip; the pressure sensor is a film pressure sensor, comprises a bearing sheet and a pressure sensing film adhered on the bearing sheet, and is adhered to the middle of the base frame by a strong adhesive; and a space for loading the PCB is formed between the PCB limiting clamping seats on the two sides and the pressure sensor.

The protruding strip and the PCB limiting clamping seat are respectively provided with a section of extension bar, and two ends of the compression spring are respectively sleeved on the extension bars of the protruding strip and the PCB limiting clamping seat.

The top of the pushing rod is provided with a detachable chip pushing head, and the top end of the chip pushing head is provided with a chip accommodating groove corresponding to the SQUID chip; the chip pushing head is provided with an external thread, and the top end of the pushing rod is provided with a corresponding threaded hole.

Any one of the SQUID chip pressure welding devices is characterized in that a control circuit is arranged between the driving device and the pressure sensor, and the control circuit is sequentially provided with a driving device driving module, a main control module and a pressure sensor reading module.

In order to solve the technical problems, the technical scheme of the SQUID chip bonding method is as follows:

the SQUID chip pressure welding method is used for welding the SQUID chip on an object, and at least 2 welding discs of the SQUID chip are electrically communicated with corresponding conductive elements with the same number as the object; the SQUID chip pressure welding device is used for fixing the object piece attached with the conductive adhesive on an object fixing device, and the SQUID chip is placed in a chip accommodating groove of a pushing head of a pushing rod; attaching an object piece to a surface contact type pressure sensor arranged on the object fixing device, or attaching a SQUID chip to a thin film pressure sensor attached to the surface of the chip accommodating groove; the driving device drives the pushing rod to press and weld the SQUID chip to the corresponding position of the object piece, so that the conductive adhesive between the welding disc of the SQUID chip and the corresponding conductive element of the object piece reaches the set pressure and the set press and weld time, and the welding disc of the SQUID chip is electrically communicated with the corresponding conductive element of the object piece.

The following is a further scheme of the SQUID chip pressure welding method of the invention:

the SQUID chip pressure welding method is used for welding the SQUID chip on the PCB, and at least 2 welding discs of the SQUID chip are electrically communicated with corresponding welding discs with the same number as the PCB; the SQUID chip soldering device is characterized in that the heated conductive adhesive is pasted on the area where the welding disc of the PCB is located, the PCB which is pasted with the conductive adhesive is fixed on the PCB fixing device and is tightly attached to the pressure sensor, the driving device drives the pushing rod to press and weld the SQUID chip to the corresponding position of the PCB, the conductive adhesive between the welding disc of the SQUID chip and the welding disc of the PCB reaches the set pressure and the press and weld time, and the welding disc of the SQUID chip is electrically communicated with the welding disc of the PCB.

The pressure welding process comprises the following steps: starting a driving device, pushing a SQUID chip to advance by a pushing rod, sensing the pressure from the pushing rod by a surface contact type pressure sensor arranged on an object fixing device or a film pressure sensor attached to the surface of the chip accommodating groove, stopping the driving device when the pressure reaches a limited pressure value X, and waiting for a set time Y to solidify the conductive adhesive; after the waiting time is over, the driving device automatically runs reversely and returns to the original position; and opening the object fixing device, and taking down the object after the pressure welding is finished.

The welding disk of the SQUID chip is not larger than that of the PCB, and after the SQUID chip and the PCB are attached, the welding disk of the SQUID chip is completely covered by the welding disk of the PCB.

Heating the conductive adhesive to 175-200 ℃, and then preserving heat for later use; the defined pressure value X is 30-40 newtons; the set time Y is 25 seconds to 35 seconds.

The invention provides a SQUID chip pressure welding device and a pressure welding method, in particular to a pressure welding device and a pressure welding method of a SQUID chip used as a magnetic microscope probe. Compared with the existing mode that a bonding machine is used for bonding a conductive connecting wire to a SQUID chip bonding pad through ultrasonic vibration or hot pressing, and the conductive connecting wire is led out from the SQUID chip bonding pad and used for being connected externally, the distance from a lead bending part to a SQUID chip sensitive source is thoroughly eliminated, and the distance from a magnetic microscope probe to a Dewar sapphire glass window from the SQUID chip is shortened. The shortened distance is about several tens of um, and the distance can be shortened by about 10% relative to the distance (several hundreds of um) between the SQUID chip and the sample. Therefore, the spatial resolution and the magnetic field resolution of the magnetic microscope can be greatly improved, and the detection sensitivity of the magnetic microscope can be greatly improved. This also gives a lifting rate of about 10% for spatial resolution.

In addition, the SQUID chip pressure welding device and the pressure welding method provided by the invention can be used for pressure welding a plurality of bonding pads at one time, so that the welding efficiency is improved, and the welding cost is reduced. And (3) heating the conductive adhesive to nearly 200 ℃, then performing pressure welding, and setting the pressure threshold of the film pressure sensor to be 35 newtons and the pressure welding time to be 30 seconds, wherein the chip and the PCB have good conductivity. The device is provided with limiting grooves with different specifications so as to be suitable for pressure welding of SQUID chips with different specifications. The invention is a technology worth popularizing in the technical field of chip detection. In addition, the invention provides a SQUID chip pressure welding device and a pressure welding method, which can be widely applied to magnetic detection systems based on SQUID, including but not limited to heart magnetism, brain magnetism, lung magnetism, muscle magnetism, geophysical, low-field nuclear magnetic resonance and nondestructive detection systems, and are particularly suitable for scanning SQUID microscope systems for detecting semiconductor chip current magnetic anomaly.

Drawings

FIG. 1 is a schematic diagram of a SQUID chip bonding apparatus according to the present invention;

FIG. 2 is a schematic top view of a SQUID chip and a PCB;

FIG. 3 is a schematic view of the bonding process of the SQUID chip bonding device of the present invention;

FIG. 4 is a schematic view of an integrated PCB fixture;

FIG. 5 is a schematic view of the hidden right side compression spring state of the integrated PCB fixture;

FIG. 6 is a schematic view of a detachable chip pusher of the pusher bar;

FIG. 7 is a schematic view showing a state in which the conductive paste is deformed by pressure between the SQUID chip and the PCB during pressure welding;

FIG. 8 is a schematic view of the operation of the bonding process;

FIG. 9 is a schematic cross-sectional view of a prior art SQUID chip;

figure 10 is a cross-sectional schematic view of a SQUID chip in accordance with the present invention;

FIG. 11 is a schematic view of a cold finger as a bonding object according to the second embodiment;

FIG. 12 is a schematic view of a square copper pin;

FIG. 13 is a schematic view showing a state where a square copper pin is embedded in a non-through groove of a cold finger;

FIG. 14 is a schematic view of the conductive gel attached to the tip of the cold finger;

FIG. 15 is a perspective view of the SQUID chip pressure-bonded on the top of the cold finger after the pressure-bonding of the second embodiment is completed;

FIG. 16 is a schematic top view of the SQUID chip pressure-bonded on the cold finger tip after the pressure-bonding of the second embodiment is completed;

figure 17 is a schematic side view of the SQUID chip pressure bonded on the cold finger tip after the pressure bonding of the second embodiment.

The figures are schematic and do not correspond to actual proportions.

The parts indicated by the reference numerals in the figures are: 1. a SQUID chip; 2. a PCB board; 3. welding a disc; 4. fixing a bracket; 5. a drive device; 6. a push rod; 7. a pressure sensor; 8. a chip pushing head; 9. a chip accommodating groove; 10. a PCB limiting card seat; 11. a protruding portion; 12. a base frame; 13. a raised strip; 14. a slider; 15. a slider; 16. a compression spring; 17. an extension bar; 18. a conductive adhesive; 19. strong glue; 20. an external thread; 21. a through hole; 22. a substrate layer; 23. an insulating layer; 24. a josephson junction region layer; 25. a conductive connection line; 26. cold fingers; 27. a non-through groove; 28. a square copper pin; 29. a conductive surface; 30. an insulating surface; 31. conductive particles.

Detailed Description

The present invention is described in further detail below with reference to the attached drawings.

A conventional SQUID chip is generally shown in fig. 9, and includes a substrate layer 22, an insulating layer 23, and a josephson junction layer 24 sandwiched between the substrate layer 22 and the insulating layer 23 as a core flux induction region of the SQUID chip, a bonding pad 3 is disposed on an outer surface of the insulating layer 23, the insulating layer 23 is perforated, and a conductive connection line 25 is led from the josephson junction layer 24 and electrically connected to the bonding pad 3 through the hole of the insulating layer 23.

Generally, as shown in fig. 10, the SQUID chip 1 according to the present invention includes a substrate layer 22, an insulating layer 23, and a josephson junction layer 24 sandwiched between the substrate layer 22 and the insulating layer 23 as a core flux induction region of the SQUID chip 1, wherein a bonding pad 3 is provided on an outer surface of the substrate layer 22, the substrate layer 22 is perforated, and a conductive connection line 25 is led out from the josephson junction layer 24 and electrically connected to the bonding pad 3 through the hole of the substrate layer 22.

The SQUID chip pressure welding device is used for welding the SQUID chip 1 on an object, and at least 2 welding discs 3 of the SQUID chip 1 are electrically communicated with corresponding conductive elements with the same number as the object; the SQUID chip pressure welding device comprises an object fixing device for fixing an object piece, the object fixing device is fixedly arranged on a fixing support 4, a pushing rod 6 which is driven by a driving device 5 and can slide linearly is arranged corresponding to the position of the object fixing device, the pushing rod 6 comprises a chip pushing head 8 positioned at the top of the pushing rod, and a chip accommodating groove 9 corresponding to the SQUID chip 1 is arranged at the top end of the chip pushing head 8; the object fixing device is provided with a surface contact type pressure sensor 7, or a film pressure sensor is attached to the surface of the chip accommodating groove 9.

During pressure welding, anisotropic conductive adhesive 18 is selected and heated to 100-200 ℃ and then is kept warm for standby, the heated conductive adhesive 18 is attached to the area of the object corresponding to the conductive element, the SQUID chip pressure welding device is used for fixing the object attached with the conductive adhesive 18 on the object fixing device, and the SQUID chip 1 is placed in the chip accommodating groove 9 of the pushing head of the pushing rod 6; the object piece is tightly attached to a surface contact type pressure sensor 7 arranged on the object fixing device, or the SQUID chip 1 is tightly attached to a thin film pressure sensor attached to the surface of a chip accommodating groove 9; the driving device 5 drives the pushing rod 6 to press and weld the SQUID chip 1 to the corresponding position of the object, so that the conductive adhesive 18 between the welding disc 3 of the SQUID chip 1 and the corresponding conductive element of the object reaches the set pressure and the press and weld time, and the welding disc 3 of the SQUID chip 1 is electrically communicated with the corresponding conductive element of the object.

Example one

Fig. 1 shows a SQUID chip bonding apparatus according to an embodiment of the present invention, which is used for bonding a SQUID chip 1 shown in fig. 2 to a PCB 2, and electrically connecting a bonding pad 3 of the SQUID chip 1 to a bonding pad 3 of the PCB 2. As shown in fig. 1, the SQUID chip pressure welding device comprises a PCB fixing device for fixing a PCB board 2, the PCB fixing device is fixedly installed on a fixing support 4, the PCB fixing device corresponds to the PCB fixing device in position and is provided with a push rod 6 driven by a driving device 5 to slide linearly, the PCB fixing device is provided with a surface contact type pressure sensor 7, the push rod 6 comprises a chip push head 8 positioned at the top of the push rod, and the top end of the chip push head 8 is provided with a chip accommodating groove 9 corresponding to the SQUID chip 1. The driving means 5 generally comprise a motor and a slide driven by it; or a cylinder or a gas cylinder.

As shown in fig. 1, the PCB fixing device with a simpler structure comprises PCB limit card seats 10 symmetrically installed on a fixing support 4 at two sides, wherein each PCB limit card seat 10 is provided with a protrusion part 11 extending in opposite direction; the pressure sensor 7 is a PVDF film pressure sensor and is directly stuck on the fixed support 4 between the PCB limiting clamping seats 10 at the two sides by the strong glue 19; or, the PVDF film pressure sensor comprises a bearing sheet and a PVDF pressure sensing film stuck on the bearing sheet, and the PVDF film pressure sensor is stuck on the fixed support 4 between the PCB limiting clamping seats 10 at the two sides by using a strong glue 19; a space for loading the PCB 2 is formed between the PCB limiting clamping seat 10 on the two sides and the pressure sensor 7.

As shown in fig. 4 and 5, the PCB fixing device with a better effect is an integrated PCB fixing device fixedly installed on a fixing support 4, and includes a base frame 12, wherein through holes 21 are formed at two ends of the base frame 12 and fixedly installed on the fixing support 4 through bolts; the two sides of the base frame 12 are symmetrically provided with the protruding strips 13, the two sides of the base frame 12 are symmetrically and fixedly provided with the PCB limiting clamping seat 10, the PCB limiting clamping seat 10 on each side is provided with a protruding part 11 which extends in opposite directions, the PCB limiting clamping seat 10 comprises a sliding block 14, the base frame 12 is provided with a sliding groove 15 for the sliding block 14 to be embedded in, and a compression spring 16 is arranged between the PCB limiting clamping seat 10 and the protruding strips 13; the pressure sensor 7 is a PVDF film pressure sensor, comprises a bearing sheet and a PVDF pressure sensing film stuck on the bearing sheet, and is stuck in the middle of the base frame 12 by a strong glue 19; a space for loading the PCB 2 is formed between the PCB limiting clamping seat 10 on the two sides and the pressure sensor 7. The protruding strip 13 and the PCB limiting clamping seat 10 are respectively provided with a section of extension bar 17, and two ends of the compression spring 16 are respectively sleeved on the protruding strip 13 and the extension bar 17 of the PCB limiting clamping seat 10. As shown in fig. 4 and 5, according to the size of the PCB 2, the PCB limit card seat 10, the sliding groove 15 and the compression spring 16 can be arranged in parallel, and due to the action of the compression spring 16, the PCB 2 can be subjected to a proper clamping force and can also adapt to more PCBs 2 with different specifications and sizes.

As shown in fig. 6, a detachable chip pusher 8 is arranged at the top of the pushing rod 6, and a chip accommodating groove 9 corresponding to the SQUID chip 1 is arranged at the top end of the chip pusher 8; the chip pushing head 8 is provided with an external thread 20, and the top end of the pushing rod 6 is provided with a corresponding threaded hole.

In any SQUID chip pressure welding device, a control circuit is arranged between the driving device 5 and the pressure sensor 7, and the control circuit is sequentially provided with a driving device driving module, a main control module and a pressure sensor reading module.

The SQUID chip pressure welding method is used for welding the SQUID chip 1 shown in figure 2 on the PCB 2 and enabling the welding disc 3 of the SQUID chip 1 to be electrically communicated with the welding disc 3 of the corresponding PCB 2. The electrical leading-out terminal of the SQUID chip 1 is set to more than 1 soldering lands 3, and correspondingly, the electrical connecting terminal of the PCB 2 is set to the corresponding soldering lands 3 with the same number. As shown in fig. 2, the SQUID chip 1 electrical terminals and the PCB board 2 electrical terminals are arranged as 4 pads 3 distributed symmetrically. Heating conductive adhesive 18 with anisotropy to 100-200 ℃ for heat preservation and standby application, attaching the heated conductive adhesive 18 to the area where the welding disc 3 of the PCB 2 is located, using the SQUID chip pressure welding device, fixing the PCB 2 attached with the conductive adhesive 18 on a PCB fixing device and clinging to a pressure sensor 7, placing the SQUID chip 1 in a chip accommodating groove 9 of a pushing head of a pushing rod 6, driving the pushing rod 6 by a driving device 5 to pressure-weld the SQUID chip 1 to the corresponding position of the PCB 2, enabling the conductive adhesive 18 between the welding disc 3 of the SQUID chip 1 and the welding disc 3 of the PCB 2 to reach a set compression degree, and enabling the welding disc 3 of the SQUID chip 1 to be electrically communicated with the welding disc 3 of the PCB 2.

The anisotropic conductive adhesive 18, which is a special bonding consumable for the bonding apparatus of the present invention, is commercially available. The anisotropic conductive adhesive contains discrete conductive particles 31 inside, and has no conductivity without being compressed; the conductive particles 31 are electrically conductive only when the conductive particles 31 are brought into contact with each other in the compression direction by gathering the conductive particles 31 in a discrete state at the pressed portion through a certain degree of heat compression. The conductive principle of the conductive adhesive is as follows: the contact of the conductive particles 31 can be improved by compressing the heated conductive paste by pressure, thereby forming a conductive path. Anisotropic conductive adhesives are adhesives that are only conductive in one direction, such as the Z direction, and only non-conductive in the X and Y directions.

The pressure welding process comprises the following steps: as shown in fig. 3, the SQUID chip bonding apparatus is in an initial state as shown in fig. 3-1, and is a PCB fixing apparatus having a simpler structure as shown in fig. 1, or a PCB fixing apparatus having a better effect as shown in fig. 4 and 5. The PCB 2 pasted with the heated conductive adhesive 18 is fixed in a space formed between the PCB limiting clamping seat 10 and the pressure sensor 7 on the two sides; the SQUID chip 1 is housed in a chip housing groove 9 of the pusher 6. The driving device 5 is started, and the pushing rod 6 pushes the SQUID chip 1 to ascend, as shown in figure 3-2. When the SQUID chip 1 is about to touch the PCB 2, as shown in fig. 3-3, the conductive adhesive 18 is squeezed and deformed by the SQUID chip 1, and after the bonding process is completed, as shown in fig. 7, the conductive adhesive 18 still remaining between the bonding pad 3 of the SQUID chip 1 and the bonding pad 3 of the PCB 2 reaches a set degree of compression, so that the upper and lower bonding pads can be electrically connected. And the conductive adhesive 18 which is not positioned between the soldering land 3 of the SQUID chip 1 and the soldering land 3 of the PCB 2 is not sufficiently compressed and is not conductive. At this time, the film pressure sensor tightly attached to the back of the PCB 2 senses the pressure from the push rod 6, when the pressure reaches a limited pressure value X, the driving device 5 stops running, and waits for a set time Y to solidify the conductive adhesive 18; after the waiting time is over, the driving device 5 automatically rotates reversely to return to the original position; and opening the PCB limiting device, and taking down the PCB 2 after the pressure welding is finished.

The welding disc 3 of the SQUID chip 1 is not larger than the welding disc 3 of the PCB 2, and after the SQUID chip and the PCB are attached, the welding disc 3 of the SQUID chip 1 is completely covered by the welding disc 3 of the PCB 2. The following modes or related parameters are suitable: 1. as shown in fig. 2, the land 3 of the PCB 2 is slightly larger than the land 3 of the SQUID chip 1. 2. The conductive adhesive 18 is heated to 175-200 deg.C and then kept warm for standby, with the optimal value being 200 deg.C. 3. Limiting the pressure value X to be 30-40N, and optimally 35N; the time Y is set to 25 seconds to 35 seconds, and the optimum value is 30 seconds.

If a motor and a slider driven by the motor are selected as the driving device 5, the driving device 5 shown in fig. 1 includes the motor and the slider driven by the motor; the pressure welding process comprises the following operation steps:

1) the PCB pad is attached with anisotropic conductive adhesive which is heated to 200 degrees (pressure welding is carried out at the temperature, and the adhesive and the conductivity are better).

2) And fixing the glued PCB on the limiting device and clinging to the film pressure sensor.

3) And the SQUID chip is arranged on the push rod and push head clamping groove.

4) And starting a motor, and pushing the SQUID chip to ascend by the aid of the pushing rod.

5) And a film pressure sensor behind the PCB senses the pressure of the push rod.

6) When the pressure reaches the limit requirement 35 Newton, the motor is turned off and stops rotating.

7) Waiting for 30 seconds, and solidifying the conductive adhesive.

8) And when the waiting time is over, the motor automatically rotates reversely and returns to the original position.

9) And opening the PCB limiting device switch, and taking down the PCB 2 after the pressure welding is finished.

The drive device driving module, the main control module and the pressure sensor reading module are sequentially arranged in a control circuit between the SQUID chip pressure welding device and the pressure sensor 7 from the drive device 5, and can be set according to the functional target requirements as shown in figure 8: as shown in fig. 8, when the pressure welding starts, the motor rotates forward, and at the same time, the pressure applied to the pressure sensor is continuously detected, and whether the pressure is greater than the set value is determined, if not, the motor continues to rotate forward, if so, the motor stops rotating, waits for 30 seconds, the motor rotates backward, and at the same time, the pushing rod 6 reaches the origin, if not, the motor continues to rotate backward, if so, the motor stops rotating, and the program ends.

After the SQUID chip 1 is welded on the PCB 2, the welding disk 3 of the SQUID chip 1 is electrically communicated with the welding disk 3 of the corresponding PCB 2.

After the bonding is completed, as shown in fig. 7, the conductive paste 18 still remaining between the bonding pad 3 of the SQUID chip 1 and the bonding pad 3 of the PCB 2 reaches a set degree of compression, the conductive particles 31 are gathered at the pressed portion in a discrete state, and the conductive particles 31 are brought into contact with each other in the compression direction to have conductivity, so that the upper and lower bonding pads 3 are electrically connected. And the conductive adhesive 18 which is not positioned between the soldering land 3 of the SQUID chip 1 and the soldering land 3 of the PCB 2 is not sufficiently compressed and is not conductive. And no conductive connecting wire led out from the soldering pad 3 for external connection is arranged on the soldering pad 3 of the SQUID chip 1 after the pressure welding is finished. The influence on the spatial resolution and the magnetic field resolution of the magnetic microscope due to the fact that the conducting connecting line led out from the chip bonding pad forms the bending height of dozens of micrometers is naturally eliminated, and the spatial resolution and the magnetic field resolution of the magnetic microscope can be greatly improved.

Example two

As shown in fig. 11 to 17, the main difference between the second embodiment and the first embodiment is that the object is directly the cold finger 26, which is an important component of the magnetic microscope probe.

As shown in fig. 11, the top of the cold finger 26 is square, and the top ends of the cold fingers 26 are provided with non-penetrating grooves 27 inwards from the left side of 4 side surfaces of the cold finger, or the top ends of the cold fingers 26 are provided with non-penetrating grooves 27 inwards from the right side of 4 side surfaces of the cold finger. The non-through grooves 27 are not communicated with each other, and each non-through groove 27 is provided with 1 square copper pin 28 with a rectangular cross section. As shown in fig. 12, 1 of the 4 surfaces of the square copper pin 28 in the length direction is a conductive surface 29, the other 3 surfaces are insulating surfaces 30, and 3 insulating surfaces 30 are coated with insulating glue. As shown in fig. 13, the copper pins 28 are respectively inserted into the non-through grooves 27 with the conductive surfaces 29 thereof facing upward, and each copper pin 28 is mostly inserted into the non-through groove 27 at the top end of the cold finger 26 and a small portion thereof is exposed. The outer end of the copper pin 28 is provided with a conductive connecting wire 25 for connecting with the extension pin of the magnetic microscope probe. The SQUID chip 1 is placed on top of the cold finger 26 with its pads 5 facing downwards, each pad 5 of the SQUID chip 1 corresponding to a conductive surface of one of the 1 copper pins 28, respectively.

The anisotropic conductive adhesive 18 is selected in advance, heated to 100 to 200 ℃ and then kept warm for standby, and as shown in fig. 14, the anisotropic conductive adhesive 18 which is heated and pressure welded to enable the conductive adhesive to have conductivity is attached to the top end of the cold finger 26. The SQUID chip 1 is pressure-welded at the corresponding position of the top end of the cold finger 26 in a mode that the welding pads 5 of the SQUID chip 1 face the top end of the cold finger 26, so that the welding pads 5 of the SQUID chip 1 respectively correspond to the conductive surfaces of 1 copper pin 28, the conductive adhesive 18 between the welding disc of the SQUID chip 1 and the conductive surface of the copper pin 28 reaches the set pressure and the pressure-welding time, and the welding disc of the SQUID chip 1 is electrically communicated with the copper pin 28. Others may be followed by embodiment one.

Fig. 15, 16, and 17 show the second embodiment after the bonding. After the bonding process is completed, as shown in fig. 17, the conductive paste 18 still remaining between the bonding pad 3 of the SQUID chip 1 and the conductive surface of the copper pin 28 reaches a set degree of compression, the discrete conductive particles 31 are gathered at the pressed portion, and the conductive particles 31 are in contact with each other in the compression direction to have conductivity, so that the upper and lower pads are electrically connected. And the conductive adhesive 18 which is not positioned between the welding disk 3 of the SQUID chip 1 and the conductive surface of the copper pin 28 is not enough compressed and is not conductive.

The SQUID chip 1 after the pressure welding is placed at the top end of the cold finger 9 in a mode that the bonding pad 5 faces downwards, and no conductive connecting wire 6 which is led out from the bonding pad 5 and is used for external connection is arranged on the bonding pad 5 of the SQUID chip 1. The influence on the spatial resolution and the magnetic field resolution of the magnetic microscope due to the fact that the conducting connecting line led out from the chip bonding pad forms the bending height of dozens of micrometers is naturally eliminated, so that the spatial resolution and the magnetic field resolution of the magnetic microscope can be greatly improved, and the detection sensitivity of the magnetic microscope can be further greatly improved. For more details, refer to the patent application entitled "SQUID chip and magnetic microscope probe and packaging method thereof" filed on the same date as the present application by the applicant.