CN111112495A

CN111112495A - Flexible forming method and forming die for pins of SOT integrated circuit packaging products

Info

Publication number: CN111112495A
Application number: CN201911217361.0A
Authority: CN
Inventors: 付小青; 李庆生; 贡喜; 刘文涛; 赵康
Original assignee: Tongling Sanjia Shantian Technology Co ltd
Current assignee: Tongling Sanjia Shantian Technology Co ltd
Priority date: 2019-12-03
Filing date: 2019-12-03
Publication date: 2020-05-08

Abstract

The invention discloses a flexible molding method and a molding die for pins of SOT integrated circuit packaging products, which solve the problems that the inner pins are easy to pull out from packaging colloid in the existing rigid molding, tin layers on the pins in an imprinting area are peeled and accumulated, and copper exposure phenomenon or short circuit caused by peeling of the tin layers is easy to occur. The method comprises the following steps: (1) fixing the SOT integrated circuit packaging product on a forming concave die; (2) and the cutting edge of the forming male die matched with the forming female die vertically moves downwards and transversely and gradually approaches to the pins of the SOT integrated circuit packaging product, and the pins are extruded to the forming female die to realize flexible forming. The invention reduces the pulling force on the pin during molding, and meanwhile, because the molding male die and the pin hardly have relative displacement during molding, only a bending area can generate short impression marks after the pin is molded, and the problem of short circuit caused by copper exposure or tin layer falling is not easy to occur.

Description

Flexible forming method and forming die for pins of SOT integrated circuit packaging products

Technical Field

The invention relates to a method for forming pins of SOT integrated circuit packaging products and a forming die for realizing the method.

Background

The SOT type integrated circuit package product is a surface mount package form, and generally has a small-outline transistor with 5 or less pins. With the rapid development of electronic complete machine products towards miniaturization and portability and the development of integrated circuit packaging products towards miniaturization, high density, large base island and the like, the market demand of SOT type integrated circuit packaging products will be larger and larger. As the plastic package body of the product is continuously developed to be small and exquisite, the requirements on the forming size and the appearance of the product are continuously improved. For the manufacture of surface mount products, the punching and molding of the leads also becomes a more critical process in the whole packaging industry. In the pin forming process of the prior SOT product, pins are bent into gull-wing shapes at one time by adopting the rigidity of a mould, and then the separation process is completed to cut the product from a frame. The SOT products are small and thin, and the typical SOT products are shown in figure 1, and the external dimension is 2.9 mmX2.9mmX1.15mm. Because the pins of the product are very small in forming, the pins are bent into the required shape at one time by adopting a rigid forming mode, the running track of the cutting edge of the forming male die is shown as part A in figure 2, and the track of the cutting edge of the forming male die is vertical. Chinese patent application No. CN201810941756.4 discloses a die for punching and molding high-density package SOT lead frame and a method for using the same, and chinese patent application No. CN201720394352.9 discloses a die for separating semiconductor products on SOT89 series lead frames, which are all formed rigidly. In order to be suitable for mounting larger wafers, the base island of the SOT product is larger and larger at present, but the appearance is smaller and smaller, so that the bonding force between the packaged pins and the packaging colloid is smaller and smaller, and when the pins are rigidly molded, the inner pins are easy to pull out from the packaging colloid, so that the product yield is reduced. Meanwhile, a large section of stamping area is left on the pins in the rigid forming mode, as shown in part B in fig. 2, in a severe case, a tin layer on the pins in the stamping area is stripped and accumulated, and a copper exposure phenomenon or a short circuit caused by the stripping of the tin layer is easy to occur.

Disclosure of Invention

The invention aims to solve the problems that the pins of the SOT integrated circuit packaging product are rigidly formed, so that the inner pins are easy to pull out from a packaging colloid, a large stamping area is left on the pins, and a tin layer on the pins in the stamping area is stripped and accumulated when the stamping area is serious, so that the copper exposure phenomenon or the short circuit of a circuit caused by the stripping of the tin layer is easy to occur, and provides a flexible forming method and a forming die for the pins of the SOT integrated circuit packaging product.

In order to solve the problems, the invention adopts the technical scheme that: the soft forming method of the SOT integrated circuit packaging product pins comprises the following steps:

(1) fixing the SOT integrated circuit packaging product on a forming concave die;

(2) the cutting edge of the forming male die matched with the forming female die moves downwards to extrude the pins to the forming female die for forming;

the method is characterized in that the downward movement of the male die cutting edge in the step 2 is that the male die cutting edge vertically moves downward from two sides of the upper part of the pin and horizontally and gradually approaches to the pin of the SOT integrated circuit packaging product, and the pin is extruded to a forming female die, so that flexible forming is realized.

By adopting the technical scheme, the forming male die moves downwards from the two sides of the upper part of the pin to approach the running track to form a curve in the pin forming process, the forming male die is always pressed in the bending area for forming the pin, the pulling force on the pin during forming is reduced to the maximum extent, and meanwhile, because the forming male die and the pin hardly have relative displacement during forming, short impression marks can be generated only in the bending area after the pin is formed, and the defects caused by the tin accumulation of the pin during forming are completely eradicated.

Preferably, the cutting edge of the forming male die vertically moves downwards from two sides of the upper part of the pin and horizontally and gradually approaches the pin of the SOT integrated circuit packaging product downwards along an arc line. The forming convex die moves downwards along an arc line to extrude the pins to achieve flexible forming, so that the quality of SOT integrated circuit packaging products is further guaranteed.

A flexible forming die for realizing the SOT type integrated circuit packaging product pin comprises a forming female die, forming male dies matched with the forming female die and a cam for fixing the SOT type integrated circuit packaging product, and is characterized in that the number of the forming male dies is two, the bottom of each forming male die is provided with a punching cutting edge, the back of each forming male die is provided with a through hole for hinging, the upper part of each forming male die is provided with an extrusion boss, the two forming male dies are connected together in a back-to-back mode through a fixing shaft penetrating through the back through hole, and a return spring for mutual extrusion is arranged between the backs of the two forming male; the cam is positioned on one side of the forming male die, and the side wall of the upper part of the cam is provided with a continuously-heightened guide block matched with the extrusion boss.

By adopting the forming die, during forming, the forming male die descends, the SOT type integrated circuit packaging product limits the position of the cam, and in the descending process of the forming male die, the curved surface formed by the guide block of the cam simultaneously pushes the boss to drive the whole forming male die to move along the designed forming track, so that the forming male die is always pressed on a forming bending area in the forming process of pins of the product, and the whole pin male die is always pressed on the bending area formed by the pins, thereby better ensuring the quality and yield of the product.

In a further improvement, a boss at the upper part of the forming convex die is provided with a roller which is movably connected. Through the contact extrusion of gyro wheel and cam guide block, reduced the friction, increased the reliability of operation.

In a further improvement, the side wall of the upper part of the cam is provided with a continuous height increasing line of the continuous height increasing guide block, and the continuous height increasing line is an arc surface line. The adoption of the arc surface line is more favorable for the contact of the roller and the guide block, and the stability is increased.

Preferably, the back of the single-piece forming male die is provided with a countersunk groove, and the end part of the return spring is positioned in the countersunk groove. The countersunk head groove further limits the spring.

In conclusion, the beneficial effects of the invention are as follows: according to the invention, the forming male die moves downwards along the arc line to approach, the male die is always pressed in the bending area for forming the pin, so that the pulling force on the pin during forming is reduced to the maximum extent, and meanwhile, because the forming male die and the pin are almost not relatively displaced during forming, only the bending area can generate short impression marks after the pin is formed, the problem of circuit short circuit caused by copper exposure or tin layer falling is not easy to occur, and the defect caused by tin accumulation of the pin during forming is completely eradicated, so that the integrated circuit product produced by the invention has the advantage of high quality product rate.

Drawings

FIG. 1 is a front and top view of a typical SOT-like integrated circuit package product;

FIG. 2 is a schematic view of prior art rigid forming;

FIG. 3 is a schematic view of flexible forming;

FIG. 4 is a schematic view of the forming punch of the present invention;

FIG. 5 is an exploded view of FIG. 4;

FIG. 6 is a schematic diagram of operation;

fig. 7 is an enlarged view of a portion a of fig. 6.

In the drawing, the moving track of the cutting edge of the rigid forming male die is A, the stamping area of rigid forming pins is B, the moving track of the cutting edge of the flexible forming male die is C, the stamping area of the flexible forming pins is D, the stamping area of the flexible forming pins is 1, the fixed shaft is 2, the forming male die is 3, the roller is 4, the mandrel is 5, the reset spring is 6, the cam is 7, the SOT type integrated circuit packaging product is 8, the forming female die is 9 and the guide block.

Detailed Description

The present invention will be described in detail with reference to the following description of the drawings.

The soft forming method of the SOT integrated circuit packaging product pins comprises the following steps:

(2) and the cutting edge of the forming male die matched with the forming female die vertically moves downwards and transversely and gradually approaches to the pins of the SOT integrated circuit packaging product, and the pins are extruded to the forming female die to realize flexible forming. As shown in fig. 3, the moving track of the cutting edge of the flexible forming punch is that the cutting edge of the forming punch vertically moves down from two sides of the upper part of the pin and horizontally and gradually approaches to the pins of the SOT integrated circuit packaging product, and the pins move down along an arc line and approach to each other, and are extruded, bent and formed.

As shown in fig. 4 and 5, the flexible forming die for realizing the pins of the SOT integrated circuit packaging product comprises a forming female die 8, a forming male die 2 matched with the forming female die 8 and a cam 6 for fixing the SOT integrated circuit packaging product, wherein the forming male dies 2 are two, the bottom of each forming male die 2 is provided with a punching cutting edge, the punching cutting edges are matched with the pins of the integrated circuit packaging product in position, the cutting edges extend outwards, the back of the forming male dies is provided with through holes for hinging, the through holes on the two forming male dies are staggered, and the apertures of the through holes are consistent. The upper part of the forming male die 2 is provided with an extrusion boss extending to the outer side surface, the middle part of the boss is provided with a movably connected roller 3, and the movable roller 3 is movably connected on the boss through a mandrel 4. The two forming male dies are connected together in a back-to-back mode through a through hole which penetrates through the fixed shaft 1 and is staggered at the back, and two reset springs 5 which are extruded mutually are arranged between the backs of the two forming male dies; the back of the single-piece forming convex 2 die is provided with two countersunk grooves, and the end parts of the two reset springs 5 are positioned in the countersunk grooves. The cam 6 is positioned at one side of the forming male die 2, and the side wall of the upper part of the cam 6 is provided with a continuously-heightened guide block 9 matched with the extrusion boss. As shown in fig. 6, the continuously rising lines of the continuously rising guide blocks provided on both side walls of the upper portion of the cam 6 are arcuate lines.

As shown in fig. 6, the cam 6 first contacts the upper surface of the glue of the SOT type integrated circuit package product 7 during the downward movement of the molding punch 2 during the molding process, as shown in fig. 7. The forming male die 2 continues to move downwards, the SOT type integrated circuit packaging product 7 limits the position of the cam 6, and in the descending process of the forming male die 2, the curved surface formed by the guide block 9 of the cam 6 simultaneously pushes the roller 3 to drive the whole forming male die 2 to move along the designed forming track, so that the forming male die 2 is always pressed on the forming area bending area in the process of forming pins of the product. In the flexible forming mode of the invention, the moving track of the forming male die 2 in the pin forming process is a curve, such as the moving track of the cutting edge of the flexible forming male die shown as C in figure 3. The forming male die 2 is always pressed in a bending area for forming the pins, such as an area D shown in fig. 3, so that the pulling force on the pins during forming is reduced to the maximum extent, and meanwhile, because the male die and the pins are almost not displaced relatively during forming, only the bending area can generate impression marks after the pins are formed, and the defects caused by tin accumulation of the pins during forming are completely eradicated.

Claims

The soft forming method of the pins of the SOT integrated circuit packaging product comprises the following steps:

(1) fixing the SOT integrated circuit packaging product on a forming concave die;

(2) the cutting edge of the forming male die matched with the forming female die moves downwards to extrude the pins to the forming female die for forming;

the method is characterized in that the downward movement of the male die cutting edge in the step 2 is that the male die cutting edge vertically moves downward from two sides of the upper part of the pin and horizontally and gradually approaches to the pin of the SOT integrated circuit packaging product, and the pin is extruded to a forming female die, so that flexible forming is realized.
2. The method of claim 1, wherein the edge of the forming punch moves vertically downward from both sides of the upper portion of the lead and gradually moves laterally toward the lead of the SOT IC package along an arc.
3. The flexible forming die for the pins of the SOT type integrated circuit packaging product comprises a forming female die (8), a forming male die (2) matched with the forming female die (8) and a cam (6) for fixing the SOT type integrated circuit packaging product (7), and is characterized in that the number of the forming male dies (2) is two, the bottom of each forming male die is provided with a punching cutting edge, the back of each forming male die is provided with a through hole for hinging, the upper part of each forming male die is provided with an extrusion boss, the two forming male dies are connected together in a back-to-back mode through the through hole in the back by a fixed shaft (1), and a reset spring (5) for mutual extrusion is arranged between the backs of the two forming male dies; the cam (6) is positioned on one side of the forming male die, and a continuously-heightened guide block (9) matched with the extrusion boss is arranged on the side wall of the upper part of the cam.
4. The SOT type integrated circuit package product pin flexible molding die according to claim 3, characterized in that a movably connected roller (3) is arranged on a boss at the upper part of the molding male die (2).
5. The SOT type IC package product pin flexible molding die according to claim 3 or 4, characterized in that the continuously increasing line of the continuously increasing guide block (9) on the upper side wall of the cam (6) is a curved line.
6. The SOT type IC package product pin flexible molding die according to claim 5, wherein the back of the single-piece molding male die is provided with a countersunk groove, and the end of the return spring (5) is positioned in the countersunk groove.