阅读说明：本技术 一种内引脚粗化工艺 (Inner pin coarsening process ) 是由 马文龙 康亮 康小明 孙飞鹏 于 2021-07-12 设计创作，主要内容包括：本发明,公开了一种内引脚粗化工艺,属于引线框架粗化技术领域,其工艺步骤如下：(1)除油；(2)三级水洗；(3)酸洗；(4)三级水洗；(5)风切；(6)上干膜；(7)曝光；(8)斩板；(9)显影；(10)蚀刻；(11)三级水洗；(12)粗化；(13)三级水洗；(14)酸洗；(15)三级水洗；(16)退膜；(17)三级水洗；(18)酸洗；(19)三级水洗；(20)吸干；(21)烘干；蚀刻完成后进行粗化,可以在不借助任何其他元素的条件下实现内引脚粗化,且内引脚的尺寸不会发生变化,整条框架经过蚀刻药水的腐蚀,再次粗化时减少粗化面积,从而降低生产成本。(The invention discloses an inner pin coarsening process, belonging to the technical field of coarsening of lead frames, which comprises the following process steps: (1) removing oil; (2) washing with water in a third stage; (3) acid washing; (4) washing with water in a third stage; (5) wind cutting; (6) applying a dry film; (7) exposing; (8) chopping the plate; (9) developing; (10) etching; (11) washing with water in a third stage; (12) coarsening; (13) washing with water in a third stage; (14) acid washing; (15) washing with water in a third stage; (16) removing the film; (17) washing with water in a third stage; (18) acid washing; (19) washing with water in a third stage; (20) sucking to dry; (21) drying; coarsening is carried out after etching is finished, coarsening of the inner pins can be realized without any other elements, the size of the inner pins cannot be changed, and the coarsening area is reduced when the whole frame is coarsened again through corrosion of etching liquid medicine, so that the production cost is reduced.)

1. An inner pin coarsening process is characterized in that: the process comprises the following steps: (1) removing oil; (2) washing with water in a third stage; (3) acid washing; (4) washing with water in a third stage; (5) wind cutting; (6) applying a dry film; (7) exposing; (8) chopping the plate; (9) developing; (10) etching; (11) washing with water in a third stage; (12) coarsening; (13) washing with water in a third stage; (14) acid washing; (15) washing with water in a third stage; (16) removing the film; (17) washing with water in a third stage; (18) acid washing; (19) washing with water in a third stage; (20) sucking to dry; (21) and (5) drying.

2. The inner lead roughening process according to claim 1, wherein: and (3) soaking the lead frame by using an acid-washing coarsening liquid in the coarsening process of the step (12), wherein the main components of the acid-washing coarsening liquid comprise formic acid, copper chloride, sodium chloride, ammonium chloride, ethylenediamine, citrate and tartrate.

3. The inner lead roughening process according to claim 2, wherein: the acid washing coarsening liquid medicine measuring mode adopts an EDTA titration method.

4. The inner lead roughening process according to claim 1, wherein: and (3) in the coarsening process of the step (12), the cylinder body equipment is made of titanium metal.

5. The inner lead roughening process according to claim 4, wherein: the cylinder equipment pressure can be adjusted according to the frame size.

Technical Field

The invention belongs to the technical field of coarsening of lead frames, and particularly relates to an inner pin coarsening process.

Background

An IC lead frame is used as a chip carrier, and the internal circuit of a chip is connected to an external PCB circuit through leads on the lead frame by using lead bonds (bonding gold wires or copper wires), which is an important component of a semiconductor package. In a complete IC package, the lead frame functions to secure the chip, transmit circuit signals, provide a heat dissipation path, and protect the chip circuit structure. Because the reliability level of an integrated circuit is often determined by a plurality of factors, the requirements of the packaging process of an integrated circuit chip on a lead frame are high, and the performance of the lead frame plays a leading role in improving the MSL reliability level. In recent years, more and more semiconductor package customers have required that the reliability of integrated circuit chips must meet the MSL1 level requirement, with a key improvement being in increasing the bond strength of the lead frame to the encapsulation resin. The method for improving the reliability of the chip is to increase the roughness of the surface of the lead frame, enhance the bonding force between the lead frame substrate and the packaging resin through a mechanical interlocking principle, and avoid a failure mode that the lead frame and the packaging resin are layered due to a popcorn effect in an MSL 1-level reliability test.

The method is characterized in that after etching of a lead frame is completed, roughening treatment is needed, inner pins can be roughened after roughening treatment, packaging reliability is improved after roughening, the surface concave-convex shape is mainly realized by the current process based on surface roughening, rough copper plating and browning processes to improve the packaging reliability, and as the packaging technical requirements are higher, more and more layered frames are required, the roughening process of the inner pins of the lead frame needs to be optimized in order to change the current situation.

Disclosure of Invention

In order to solve the problems in the background art, the invention provides an inner pin coarsening process, which can reduce the coarsening area when the whole frame is coarsened again by corroding the whole frame by etching liquid medicine, thereby reducing the production cost.

In order to achieve the purpose, the invention provides the following technical scheme: an inner pin coarsening process comprises the following process steps: (1) removing oil; (2) washing with water in a third stage; (3) acid washing; (4) washing with water in a third stage; (5) wind cutting; (6) applying a dry film; (7) exposing; (8) chopping the plate; (9) developing; (10) etching; (11) washing with water in a third stage; (12) coarsening; (13) washing with water in a third stage; (14) acid washing; (15) washing with water in a third stage; (16) removing the film; (17) washing with water in a third stage; (18) acid washing; (19) washing with water in a third stage; (20) sucking to dry; (21) and (5) drying.

In order to maintain the stability of the etching solution during the roughening process, it is preferable that in the roughening process of the step (12), the lead frame is soaked in an acid-washing roughening solution during the roughening process, wherein the acid-washing roughening solution mainly comprises formic acid, copper chloride, sodium chloride, ammonium chloride, ethylenediamine, citrate and tartrate.

In order to improve the accuracy of the measurement of the coarsening liquid medicine, the preferable coarsening process of the inner pin is that the acid-washing coarsening liquid medicine measurement mode adopts an EDTA titration method.

In order to prolong the service life of the cylinder roughening equipment, the preferable inner pin roughening process is that the cylinder roughening equipment used in the roughening process in the step (12) is made of titanium metal.

In order to facilitate the cylinder body equipment pressure to be suitable for frames with different sizes to carry out coarsening work, the cylinder body equipment pressure can be adjusted according to the size of the frame as the preferable inner pin coarsening process.

Compared with the prior art, the invention has the following beneficial effects:

1) in the production process, the inner pins are completely exposed after the lead frame is etched, the whole lead frame is soaked in the pickling roughening solution for roughening, so that the inner pins are roughened without any other elements, and the roughening effect is the same after the inner pins and the surface of the lead frame are roughened simultaneously, so that the phenomenon of size change of the inner pins is avoided;

2) the roughening step is arranged after the etching step, the whole frame is corroded by etching liquid medicine, and the roughening area of the lead frame can be reduced when the whole frame is roughened again, so that the waste of acid washing roughening liquid is reduced, and the production cost is reduced.

Drawings

Fig. 1 is a process flow diagram of the lead frame inner pin roughening process of the invention.

Fig. 2 is a flowchart of a conventional leadframe roughening process.

Detailed Description

The invention will be described in detail with reference to the drawings and specific embodiments, which are illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Referring to fig. 1-2, the present invention provides the following technical solutions: an inner pin coarsening process comprises the following process steps: (1) removing oil; (2) washing with water in a third stage; (3) acid washing; (4) washing with water in a third stage; (5) wind cutting; (6) applying a dry film; (7) exposing; (8) chopping the plate; (9) developing; (10) etching; (11) washing with water in a third stage; (12) coarsening; (13) washing with water in a third stage; (14) acid washing; (15) washing with water in a third stage; (16) removing the film; (17) washing with water in a third stage; (18) acid washing; (19) washing with water in a third stage; (20) sucking to dry; (21) and (5) drying.

In this embodiment: in the production process, the inner pins are completely exposed after the etching of the lead frame is finished, the whole lead frame is soaked in the pickling roughening liquid for roughening, then the inner pins are roughened without any other elements, the roughening effect is the same after the inner pins and the surface of the lead frame are simultaneously roughened, the phenomenon that the sizes of the inner pins are changed is avoided, the roughening step is arranged after the etching step, the roughening area of the lead frame can be reduced, and the waste of the pickling roughening liquid is reduced.

As a technical optimization scheme of the invention, in the roughening process in the step (12), the lead frame is soaked by using an acid-washing roughening solution, the main components of the acid-washing roughening solution comprise formic acid, copper chloride, sodium chloride, ammonium chloride, ethylenediamine, citrate and tartrate, and the acid-washing roughening solution is measured by adopting an EDTA titration method.

In this embodiment: EDTA titration method is also called as 'EDTA titration method', EDTA is a strong complexing agent, can form stable complex with a plurality of metal ions, utilizes the complexing reaction of the EDTA and the metal ions as the basis, adopts the color change of a metal indicator or an electrical and optical method to determine the titration end point, and calculates the content of the substance to be measured according to the dosage of the standard solution; after acid-washing coarsening liquid medicine is measured, the etched lead frame is placed into acid-washing coarsening liquid to be soaked for 35 minutes, ethylenediamine is used for complexing with copper ions or cuprous ions to form a complex to participate in corrosion reaction and keep the stability of the etching solution, when no copper ions exist in the coarsening liquid, the microetching speed is very low, the microetching depth is shallow, copper chloride dihydrate enables the microetching speed to tend to be stable, and sodium chloride and ammonium chloride are used for controlling the etching speed and improving the etching efficiency.

As a technical optimization scheme of the invention, in the coarsening process in the step (12), the cylinder body equipment is made of titanium metal, and the pressure of the cylinder body equipment can be adjusted according to the size of the frame.

In this embodiment: the appearance of titanium metal is similar to that of steel, titanium has the characteristics of high strength, small density, high hardness and high melting point, meanwhile, the titanium has very strong acid-base corrosion resistance, can not be corroded in seawater after being soaked for 5 years, and the service life of equipment can be prolonged by arranging the cylinder body equipment made of the titanium metal.

The technical solutions provided by the embodiments of the present invention are described in detail above, and the principles and embodiments of the present invention are explained herein by using specific examples, and the descriptions of the embodiments are only used to help understanding the principles of the embodiments of the present invention; meanwhile, for a person skilled in the art, according to the embodiments of the present invention, there may be variations in the specific implementation manners and application ranges, and in summary, the content of the present description should not be construed as a limitation to the present invention.