JPH0576557B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a mask jig for partial plating used to ensure adhesive strength between a plate-shaped plated object and a resin package.

``Prior Art'' Conventionally, as a mask jig for partial plating to plate a plate-shaped plated object such as an IC lead frame, a mask jig for partial plating, as shown in the lower part of Fig. 6, has been used. 1 in which the opening 2 has a simple shape such as a rectangle is used and is on the market (for example, Japanese Utility Model Application Publication No. 105658/1983). In recent years, with the increase in the number of pins and thinner ICs, resin packages (not shown) and
Since it was necessary to ensure adhesive strength with the IC lead frame 4 and improve moisture resistance, we added a lock hole 5 to the IC lead frame 4 as shown in the upper part of Fig. 6 and Fig. 7 a. The number of items has been increasing. However, in the conventional mask jig for partial plating, since the mask jig opening 2 has a simple shape such as a rectangle corresponding to the plating target area 4a of the lead frame 4, the silver is applied to the inner wall surface 5a of the lock hole 5. We discovered a problem in which the plating solution was not sufficiently supplied, resulting in an incomplete plating finish on the inner wall surface of the lock hole, which affected the adhesive strength with the resin package. Therefore,
If the area of the mask jig opening 2 is made narrower than the lock hole 5 in order to eliminate incomplete plating finish, the required portion of the tip of the inner lead 6 will not be plated. Furthermore, as shown by the two-dot chain line in FIG. 7b, if the mask jig opening 2 is made wider than the lock hole 5, the area to be plated will be
There is a problem in that it spreads to the external area of the dam 7 that is not included in the plating target area 4a, and a large amount of expensive silver plating liquid is required. Furthermore, the enlargement of the mask jig opening 2 increases the leakage of the plating liquid to the end face of the inner lead 6 other than the mold area 4b of the IC lead frame 4, which increases the leakage of the expensive plating liquid. . Moreover,
This plating leakage causes a leakage failure due to electrophoresis in a humid environment, which poses a problem of lowering reliability.

The mask plate described in Japanese Patent Application Laid-Open No. 60-39193 defines a mask plate having a shape in which only the part of the lead frame surface (target surface) that is required for plating is opened, and the resin plate 20 is It is nothing more than a mask plate into which the shape of the object 2 is transferred and recessed, and a small diameter plating liquid supply hole 28 is formed in the recess 22 at a position corresponding to the plating area X of the object 2 to be plated. Since the object 2 does not have a lock hole, the mask plate disclosed in the above-mentioned publication has the disadvantage that the adhesive strength between the object 2 to be plated (IC lead frame) and the resin package cannot be ensured.

The mask plate for partial plating described in Japanese Utility Model Application Publication No. 57-48265 defines a mask plate having a shape in which only the part of the lead frame surface (target surface) that requires plating is opened, similar to the above publication. The mask has an island mask portion 4 corresponding to the island 2 for adhering a semiconductor element of the semiconductor lead frame 1, and openings 6, 6' around the island mask portion 4 which can be processed so that the tips of the inner leads 3 of the lead frame 1 can be seen. It is only a mask plate 7 for partial plating made by applying a coating rubber layer 9 to a resin substrate, and no lock holes are formed in the inner leads 3 of the IC lead frame, so it is difficult to bond the IC lead frame 1 and the resin package. The disadvantage is that strength is not ensured.

In addition, Utility Model Application No. 58-128980 (hereinafter simply referred to as No. 3)
The surface treatment mask described in the reference) is
This relates to the cross-sectional shape of a mask aimed at improving the accuracy of the plating area when masking. This is just a surface treatment mask that projects inward from the opening 2 at an angle of 20°, and no lock hole is formed in the IC lead frame 4, so the adhesive strength between the IC lead frame 4 and the resin package is limited. The disadvantage is that it is not guaranteed.

"Problems to be Solved by the Invention" Therefore, the present invention was made to solve the above problems, and it is possible to ensure adhesive strength between a plated object such as an IC lead frame and a resin package. At the same time, we have provided a mask jig for partial plating that can adequately plate the parts to be plated that require precious metal plating, and that does not increase the leakage of expensive precious metal plating solution. The purpose is to provide.

``Means for Solving the Problems'' Therefore, the present invention is a mask jig for partial plating used for plate-shaped plated objects with lock holes in order to ensure adhesive strength with the resin package. , on the support surface of the plating object in the mask jig for partial plating, a mask jig opening corresponding to the plating target area is bored, and a mask jig opening corresponding to the plating target area adjacent to the plating target area is bored. To provide a mask jig for partial plating, characterized in that a groove is bored in an inner wall surface of an opening of the mask jig.

"Operation" According to the above configuration, when supplying the precious metal plating solution to the plating target area of the plated object through the mask jig opening in the mask jig for partial plating, the hole is drilled in the inner wall surface of the mask jig opening. The precious metal plating liquid is supplied to the inner wall surface of the Rock Hall through the groove, and sufficient precious metal plating is applied not only to the plating target area of the IC lead frame but also to the inner wall surface of the Rock Hall, thereby preventing the adhesion between the plated object and the resin package. Strength is ensured. Furthermore, since the opening of the mask jig is not enlarged much, leakage of the plating solution is minimized.

"Example" Next, an example of the present invention will be described based on FIGS. 1 to 5.

As shown in FIGS. 1 and 2, in the mask jig 1 of the first embodiment, mask jig openings 2 are bored at intervals of 4L corresponding to the plating target portions 4a in the IC lead frame 4. There is. The mask jig opening 2 has a substantially rectangular shape corresponding to the part 4a to be fitted, and several rows of semicircular grooves 21 corresponding to the lock holes 5 are bored in the mask jig opening inner wall surface 2a. . Depth 21a of groove 21
is approximately 1/ of the lock hole diameter 5b of the lock hole 5.
3 or more (Figure 3). The material of the mask jig 1 is silicone rubber, which has flexible elasticity and chemical resistance, and has a seal. A mask jig support stand 3 is used to support the mask jig 1 made of silicone rubber (FIGS. 1 and 4). The mask jig support base 3 has mask jig support base openings 3a at intervals of 4L corresponding to the plating target portions 4a. The material of the mask jig support stand 3 is hard polyvinyl chloride. Then, the mask jig 1 is inserted into the mask jig support opening 3a of the mask jig support base 3.
The mask jig 1 is connected to the support surface 3 of the mask jig support base 3 by matching the mask jig opening 2 in
It is assembled to b.

The IC lead frame 4 has inner leads 6 forming terminals and semiconductor element mounting islands 8 formed by punching (FIG. 2). moreover,
The inner lead 6 has a lock hole 5 (a hole adjacent to the plating target area at the tip of the inner lead 6) and a dam 7 to ensure sufficient bonding strength and improve moisture resistance when bonding with the resin package. It is provided inside the mold area 4b. (FIG. 2) As shown in FIG. 4, the plating process involves a pressing means (not shown) that presses the IC lead frame 4 against the mask jig 1 via the upper pressing sponge 11, and
This is performed using the nozzle 9 inserted from the opposite support surface 3c of the mask jig support stand 3. An anode 10 is provided at the tip of the nozzle 9.

In the mask jig 1 of the second embodiment, as shown in FIG. has been done. The depth 21a of the groove 21 is approximately 1/3 or more of the lock hole diameter 5b. The groove 21 may have any shape as long as it allows the plating liquid to sufficiently spread over the inner wall surface 5a of the lock hole 5. The mask jig support stand 3 has the same shape as the mask jig support stand 3 used in the first embodiment.

In the mask jig 1 of the third embodiment, as shown in FIG. is being used.

In the mask jig 1 of the fourth embodiment, as shown in FIG. I am doing it.

"Operation" Next, the operation of the first to fourth embodiments will be explained. The IC lead frame 4 is mounted on the mask jig 1 with the plating target portion 4a corresponding to the mask jig opening 2 of the mask jig 1 assembled on the mask jig support stand 3 (the first Figure 1, 4th
figure). The lead frame 4 mounted on the mask jig 1 is pressed against the upper presser sponge 1 by a pressing means (not shown).
A pressure of 2 to 5 kg/cm ² is applied through the mask jig 1 and the IC lead frame 4 is pressed against the mask jig 1.
Sealing performance is maintained between the mask jig 1 and the mask jig 1. Furthermore, a voltage is applied to the IC lead frame 4 to make it a cathode, and a current is passed between it and the anode 10. The silver plating liquid sprayed from the nozzle 9 passes through the opening 3 a of the mask support 3 and the mask jig opening 2 of the mask jig 1 to the IC lead frame 4 .
Then, the IC lead frame 4 is silver-plated on the semiconductor element mounting island 8 and the tips of the inner leads 6. Since the mask jig opening 2 of the mask jig 1 has the groove 21 corresponding to the inner wall surface of the lock hole 5, the inner wall surface 5a of the lock hole 5 is also sufficiently silvered. Furthermore, because the mask jig opening 2 is enlarged to correspond to the lock hole 5, there is no leakage of the plating liquid to areas other than the mold area 4b of the IC lead frame 4, and the plating liquid is expanded only to the area corresponding to the lock hole 5. Therefore, there is no problem comparable to that of the conventional mask jig 1.

"Other Embodiments" The present invention is not limited to the details of the above-mentioned embodiments. For example, the material of the mask jig 1 may be an elastic material having flexible elasticity and chemical resistance; It may be rubber, ethylene propylene rubber, etc. Further, the shape of the groove 21 formed in the mask jig opening inner wall surface 2a of the mask jig opening 2 in the mask jig 1 may be a shape that allows the plating liquid to sufficiently spread over the lock hole inner wall surface 5a of the lock hole 5. Alternatively, the grooves 21 may be formed only in areas where it is difficult for the plating liquid to spread.

"Effects" As described above, when the mask jig for partial plating of the present invention supplies the noble metal plating solution to the plating target area of the plating object through the mask jig opening, the inner wall surface of the mask jig opening The precious metal plating liquid is supplied to the inner wall surface of the lock hole through the groove drilled in the mold, and it is possible to sufficiently plate the target area without increasing plating leakage to the outside of the mold area.

In addition, sufficient plating liquid can be supplied to the lock hole portion through the groove, and the entire inner wall surface of the lock hole portion can be reliably plated. It is possible to solve the problem of poor adhesive strength between the plated object and the resin package through the lock hole portion.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view showing a mask jig according to a first embodiment of the present invention assembled on a mask jig support stand, and shows the combination with an IC lead frame, and Fig. 2 is a mask jig according to a first embodiment of the present invention. 3 is an enlarged plan view of the mask jig opening of the mask jig with the IC lead frame placed in the mask jig of the first embodiment, and FIG. 3 is an enlarged plan view of the lock hole corresponding portion with the IC lead frame placed in the mask jig of the first embodiment. , FIG. 4 shows the state in which the IC lead frame is placed on the mask jig of the first embodiment, and the direction indicated by the arrow - - shown in FIG.
FIG. 5a is an enlarged plan view of the lock hole corresponding portion in the mask jig of the second embodiment, and FIG. 5b is an enlarged plan view of the lock hole corresponding portion of the mask jig of the third embodiment. , FIG. 5c is an enlarged plan view of the lock hole corresponding part in the mask jig of the fourth embodiment, FIG. 6 is a schematic perspective view showing a combination of a conventional mask jig and an IC lead frame, and FIG. 7a is a conventional mask jig.
An enlarged plan view of the opening of the mask jig with the IC lead frame placed in it, and Figure 7b shows the state of the IC lead frame placed in the mask jig with the opening of the mask jig simply enlarged to include the lock hole. FIG. 3 is an enlarged plan view of the mask jig opening in FIG. 1...Mask jig, 2...Mask jig opening,
2a...mask jig opening inner wall surface, 3...mask jig support stand, 3b...support surface, 4...IC lead frame, 4a...part to be plated, 5...lock hole, 6...inner lead , 7... dam, 21... ditch.

Claims (1)

[Scope of Claims] 1. A mask jig for partial plating used for a plate-shaped plated object having lock holes in order to ensure adhesive strength with a resin package, comprising: A mask jig opening is drilled in the supporting surface of the plating object in the tool, corresponding to the part to be plated, and a groove is bored corresponding to the lock hole part adjacent to the part to be plated; A mask jig for partial plating, characterized in that the groove is formed in the inner wall surface of an opening of the mask jig.