JPH0453100B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an element part for a printed circuit board, particularly an element part whose base material is glass fiber reinforced plastic, and a method for manufacturing the same.

"Conventional technology" Conventionally, alumina PGA made from alumina was the mainstream for printed circuit board element parts (hereinafter referred to as PGA), but recently plastic PGA made from glass fiber reinforced plastic has been increasingly used. It's summery. This is alumina
Plastic PGA costs 1/3 compared to PGA.
This is because it can reduce mechanical shock to ~1/4, and is also superior in terms of mechanical impact, fine circuit formation, circuit pattern accuracy, external dimension accuracy, package design changeability, and additional changeability of specifications.

Conventional plastic PGA has a rectangular recess in the center of the upper surface of a glass fiber reinforced plastic substrate with gold plating applied to the entire bottom and side surfaces, and gold plating around the recess to avoid contact with the gold plating of the recess. The semiconductor device has a large number of microcircuits with a large number of microcircuits and a large number of lead pins that pass through the board and have one end connected to each of the microcircuits and the other end protruding from the bottom surface of the board, and an IC is mounted in the recess. It is used by connecting each of the IC lead wires to the inner end of each microcircuit.

``Problems to be Solved by the Invention'' In the conventional plastic PGA described above, the lead wires of the IC connected to the microcircuit tend to come into contact with the upper edge of the gold-plated recess wall, and as a result, the IC does not work properly. The defect of not working often occurs.

"Means for Solving the Problem" In order to eliminate the defects of the conventional plastic PGA, the present invention removes the gold plating applied to the recess where an IC is to be mounted from the upper edge of the side of the recess at least slightly below the upper edge of the side surface of the recess. It is characterized by being

The present invention further provides that when forming the copper plating part which becomes the base of the part to be gold plated by a photographic process in order to manufacture the plastic PGA having the above structure, a photosensitive resin film to be pasted on the copper plating is exposed and developed. The opening for plating the recess formed in the portion overlapping the recess is made smaller than the actual size of the recess by an amount corresponding to the portion from which the gold plating is removed from the side surface of the recess, and extends from the four corners of this opening toward the four corners of the recess. A feature is that a slit is formed.

"Function" The plastic PGA according to the present invention has no gold plating on the adjacent parts of the upper edges of the two orthogonal sides of the side surfaces of the recess where the IC is to be mounted.
Even if the lead wire comes into contact with the upper edge, it will not shoot out.

Further, according to the method for manufacturing plastic PGA of the present invention, the above-mentioned recess plating openings and slits are formed in the photosensitive resin film by exposure and development, and at the same time, the portions protruding inward from the recesses around the openings are formed into the photosensitive resin film. Due to the internal tension acting on the recess, it can be bent downward to cover the upper part of the side surface of the recess and prevent this part from being gilded.

"Embodiment" FIGS. 1 and 2 show a cross-sectional view and a perspective view of an embodiment of a plastic PGA according to the present invention,
A rectangular shallow recess 2 is formed in the center of the upper surface of a rectangular substrate 1 made of glass fiber reinforced plastic, and the inner surface of the recess 2 is plated with gold on the entire bottom surface 3 and four side surfaces 4 to a position slightly below the upper edge 5. 6 has been applied. Further, as in the past, a large number of gold-plated microcircuits 7 are formed on the upper surface of the substrate 1 surrounding the recess 2 from positions slightly spaced apart from the upper edge 5 of the recess 2, and each microcircuit 7 is It is connected to the upper ends of a number of lead pins 8 that penetrate through the substrate 1 and protrude below the substrate. The portions of the microcircuit 7 that are not plated with gold are protected by a coating 10 of epoxy resist ink. The lower surface of the substrate 1 also has a rectangular copper-plated portion 9 in the center, which is further protected by a coating 10 of epoxy resist ink, as is conventional.

The plastic PGA having the above structure is used by mounting an IC (not shown) in the recess 2 and welding the lead wire of the IC to the inner end of the microcircuit 7. In conventional plastic PGAs, where the gold plating on the side surface 4 of the recess 2 extends all the way to the top edge 5, the lead wires tend to contact the gold plating on the side surface, making the IC work well. The problem of not working often arose. As mentioned above, in the plastic PGA of the present invention, the gold plating 6 on the inner surface of the recess is applied to a position slightly below the upper edge 5 of the side surface 4 of the recess 2, and is perpendicular to the upper edge 5 as shown in an enlarged view in FIG. Since there is no gold plating on the adjacent parts of the upper edges 5 of the two sides, even if the lead wires of the IC come into contact with the upper edges 5, they will not be shot.

The plastic PGA of the present invention having the above structure can be manufactured by the following method. First, as shown in FIG. 4, a plurality of recesses 2 are counterbored on the upper surface of a glass fiber-reinforced plastic laminate 1 coated with copper on both sides, and a large number of pin insertion holes are formed through the laminate 1 at predetermined locations around each recess 2. 11 is formed.
Next, the top and bottom surfaces of the laminate are coated with electroless copper plating to a thickness of about 0.2μ, and then electrolytically plated with copper to a thickness of 20μ. In this way, the recess 2 and the pin insertion hole 1
After copper plating 41 is applied to the entire upper and lower surfaces including the inner surface of the laminate 1, a photosensitive resin film 12 is pasted on both the upper and lower surfaces of the laminate 1, and a photomask film 13 on which a predetermined pattern is printed is superimposed on the photosensitive resin film 12. FIG. 5 shows this state only in the vicinity of the recess 2 on the top surface, and 40 is the copper foil of the copper-clad laminate 1. Next, exposure and development is performed to leave only a portion corresponding to a predetermined pattern on the photosensitive resin film 12. At this time, the photosensitive resin film 12 left on the upper surface of the laminate 1 has pores 17 and recesses 2 (the outline of the upper edge 5 is shown by broken lines) corresponding to each microcircuit, as shown in FIG. A rectangular opening 1 with a similar shape slightly smaller than the recess 2 on the top
4 are formed, and slits 15 extending diagonally from the four corners of the opening 14 and cut to the four corners of the upper edge 5 of the recess 2 are formed. The opening 14 thus formed in the photosensitive resin film 12
is surrounded by four shelf-like portions 16 that protrude inwardly by, for example, 50 μm from the upper edge 5 of the recess 2. Since the photosensitive resin film 12 is affixed under tension to these shelf-like portions 16, they are opened during development. 14 and slit 1
5 is formed and simultaneously bends downward under the action of internal tension to cover the upper part of the side surface 4 of the recess 2 as shown in FIG.

Following exposure and development, solder plating 42 with a thickness of 8 microns is applied to the copper plating 41 except for the portion covered with the photosensitive resin film 12, as shown in FIG. Next, when the photosensitive resin film 12 is peeled off and treated with an etching solution, the copper in the unsolder-plated area and some of the copper in the lower layer of the solder-plated area in the vicinity are melted, as shown in FIG. 9, and only the solder-plated part 42 is melted. As shown in Figure 10, the copper part that was covered under the solder plating appears. This corresponds to the microcircuit 7, the lower part of the bottom surface 3 and side surface 4 of the recess 2, and the slit 15 formed in the photosensitive resin film 12. Next, cover the parts except the melted copper part and the inner end of the microcircuit 7 with an epoxy ink resist, apply copper plating to the exposed parts of the copper as needed, and then apply nickel plating to a thickness of 10μ. When electrolytic gold plating is applied to the copper, as shown in FIG. 11, gold plating 43 is formed on the copper that was left in the step of FIG. 10. The thickness of the gold plating 43 is, for example,
It is 0.5μ.

As shown in FIG. 1, a rectangular copper plating layer 9 is formed on the lower surface of the substrate 1 at the center using the same process as described above with reference to FIGS. Cover and protect. Finally, the lead pin 8 is driven into the insertion hole 11 of the substrate 1 and the die is cut out to form the plastic of the present invention.
PGA will be completed.

"Effects of the Invention" Since the plastic PGA according to the present invention has the above-described structure, when connecting the IC lead wire and the microcircuit, the lead wire never touches the gold plating layer on the side surface of the recess, making it easy to assemble in mass production. Suitable for the process.

In addition, in the manufacturing method according to the present invention, the height of the unplated portion at the upper part of the side surface can be determined by simply changing the area of the rectangle printed on the photomask film 13 in order to develop and form the opening 14 for plating the recesses on the photosensitive resin film 12. Since it can be adjusted freely, it is extremely easy to manufacture, and the reliability of the plastic PGA equipped with the IC is greatly improved.

Note that in the above embodiment, only the gold plating near the upper edge 5 of the side surface 4 is removed, but in some cases, the same effect can be obtained by removing the gold plating entirely on the side surface and applying gold plating only to the bottom surface. It is obvious that there is.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of a plastic PGA according to the present invention in a sectional view taken along line I--I in FIG. Figure 2 shows the plastic PGA shown in Figure 1.
FIG. FIG. 3 is an enlarged sectional view of a portion of FIG. 1. Figure 4 shows the plastic of the present invention.
FIG. 2 is a perspective view showing a state in which recesses and lead pin insertion holes are formed in a copper-clad laminate at the first stage of PGA manufacturing. FIG. 5 is a cross-sectional view of the vicinity of the concave portion on the upper surface of the laminate, showing the stage where the laminate is plated with copper and a photosensitive resin film and a photomask film are layered thereon. FIG. 6 is a partial plan view showing the pattern of the photosensitive resin film in the vicinity of the recesses after exposure and development following the step shown in FIG. FIG. 7 is a cross-sectional view showing a state in which the photosensitive resin film having the pattern shown in FIG. 6 is formed, and at the same time, the portion protruding from the recess around the opening is bent downward to cover the upper part of the side surface of the recess. . Figures 8 to 11 show the stages after solder plating following the stage in Figure 7,
FIG. 3 is a cross-sectional view showing a stage after performing an etching process, a stage after removing solder plating, and a stage after performing a gold plating process. 1...Glass fiber reinforced plastic substrate, 2...
... recess, 3 ... bottom of recess, 4 ... side surface of recess, 5 ...
Upper edge of side surface, 6... Gold plating, 7... Fine circuit, 8
...Lead pin, 11 ...Lead pin insertion hole, 1
2... Photosensitive resin film, 13... Photo mask film, 14... Opening for plating recesses, 15...
...Slit, 40...Copper foil, 41...Copper plating,
42...Solder plating, 43...Gold plating.

Claims (1)

[Scope of Claims] 1. A rectangular recess plated with gold in the center of the upper surface of a glass fiber reinforced plastic substrate, and a rectangular recess plated with gold plated around the recess part in a non-connected relationship with the gold plating of the recess part. In an element component for a printed circuit board, which forms a large number of microcircuits, and further has a large number of lead pins that penetrate the substrate and connect to each of the microcircuits at one end and protrude from the bottom surface of the substrate at the other end, An element part for a printed circuit board, characterized in that the applied gold plating is removed from the upper edge of the side surface of the recessed portion at least slightly below the upper edge. 2 A rectangular recess is formed in the center of the upper surface of a glass fiber reinforced plastic laminate plate coated with copper on both sides, and a large number of pin insertion holes are formed around the recess to penetrate the laminate plate, and a number of pin insertion holes are formed in the upper and lower surfaces of the laminate plate. After applying copper plating, a photosensitive resin film is pasted onto it, a photomask film printed with a predetermined pattern including at least fine circuits and concave portions is placed on top of it, exposed and developed, and then both top and bottom surfaces are soldered and then exposed to the photosensitive resin film. After peeling off the adhesive resin film, the unsolder-plated copper part is dissolved and removed, and then only the solder-plated part is dissolved and removed to expose the copper-plated part having the predetermined pattern.Finally, the copper-plated part left on the upper surface is removed. In a method for manufacturing an element component for a printed circuit board having a gold-plated recess and a fine circuit on the upper surface, the photosensitive resin film on the upper surface is exposed and developed. In addition to the pores corresponding to the microcircuits in the film, there is a recess plating that overlaps the recess, has a similar shape to the bottom of the recess, and is reduced inwardly from the upper edge of the recess by a length that is at least smaller than the height of the side surface of the recess. manufacturing an element component for a printed circuit board, characterized in that a pattern is formed in the photomask film such that apertures for the purpose and slits extending diagonally from the four corners of the aperture toward the four corners of the recess are formed. Method.