JPH0483878A - Two-shot plastic molding - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic molded product which is used as a circuit board, a circuit component, a connector, etc. by plating its surface. This invention relates to a plastic two-shot molded product made of different materials.

[Prior Art] In recent years, in order to rationalize electrical wiring and improve the degree of freedom in the shape of wiring boards, etc., MC has been used as a base material for wiring boards, etc.
B (Molded C1rcuit Board),
MW B (Molded Wiring Boa)
rd), MID (MoldedInter
The use of plastic molded products such as connection devices is being considered.

As such a plastic substrate, for example, the use of a two-shot molded product made of two types of materials has been proposed (see Japanese Patent Application Laid-Open No. 63-50482), and the manufacturing process is shown in Figure 8 (A). ~(D). To explain this manufacturing process, first, as shown in FIG. 8(A), a primary molded product 11 is molded using a resin to which metal plating easily adheres, and the part 11b to be metal plated protrudes, and then the secondary molded product As shown in Figure (B), the primary molded product 1
The recess 11a of 1 is filled with a plating-resistant resin 12 to which metal plating is difficult to adhere, and thereby a basic molded product 13 is formed. As the easily plated resin for forming the primary molded product 11, a resin containing a noble metal such as palladium as a catalyst for electroless plating is generally used in the hard to plate resin 12.

Thereafter, electroless plating is performed on the roughened surface 14 as shown in Figure (C), and metal plating 16 is formed only on the surface of the easily plated resin 11b as shown in Figure (D). This is used to form various circuits.

(Problem to be solved by the invention) However, the plastic 2 manufactured as described above
In the shot board 10, since a large amount of expensive and easily plated resin is required to mold the primary molded product 11, the manufactured plastic board 10 (basic molded product 13)
This in itself becomes extremely expensive.

Furthermore, since the surface 11b of the easily plated resin 11 to which the metal plating 16 is applied is flat, there is a problem in increasing the density of the circuit pattern. That is, when the width of the circuit pattern formed by the plating 16 is narrowed, the cross-sectional area of the conductor portion (the plating 16) becomes smaller and the current capacity decreases. In such a case, increasing the thickness of the plating 16 may be considered, but there is a limit in terms of productivity and the like.

In addition, in the plastic two-shot board 10 as described above, the adhesion between the primary molded product (easily plated resin) 11 and the secondary molded product (difficult to plate resin) 12 is poor, and the gaps between the two resins 11 and 12 are poor. There is a risk that the plating may penetrate into the circuit and cause a short circuit when electricity is applied to the circuit.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and a first object thereof is to provide a plastic two-shot molded product that can achieve high density circuit patterns at low cost. In addition, the second purpose is to improve insulation performance.

[Means to solve the problem]

In order to achieve the above object, the present invention has a primary molded product molded from a material to which metal plating does not easily adhere and has a recess formed at the location where metal plating is to be performed; Filling the recesses and forming a base molded product by integrally molding a raised part on the surface of the primary molded product using the first material; performing metal plating treatment on the surface of this base molded product; That's what I do.

Furthermore, in addition to this, a large diameter portion is provided inside the recess, or the recess is used as a through hole and the raised portions are formed on both sides of the primary molded product.

[Effect]

As described above, in the present invention, the primary molded product is molded using a hard-to-plate resin, and the easy-to-plate resin is used only in the areas where plating is required, so the amount of easy-to-plate resin used is minimized. It can be suppressed.

Furthermore, since the easily plated resin forms a raised portion on the surface of the primary molded product, the surface area of the plated portion increases compared to the conventional case where the easily plated resin surface is flat. Therefore, it is possible to increase the cross-sectional area of the metal plating (conductor portion), that is, the current capacity, without increasing the planar area.

Furthermore, if a large diameter part is provided inside the recess, or if the recess is used as a through hole and raised parts made of easily plated resin are formed on both sides of the primary molded product, the large diameter part or raised part will Molded products (resin that is difficult to plate) and secondary molded products (
The adhesion and retention with the easily plated resin is ensured.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. This embodiment will be explained using a plastic two-shot substrate 20 as an example.

FIG. 1 shows a plastic two-shot board 2 according to an embodiment.
0 viewed from above, and the manufacturing process of the substrate 20 is shown in FIGS. 2(A) to 2(D), respectively. In addition, the second
Figure (D) corresponds to a cross section taken along the line A-A in Figure 1.

The plastic two-shot board 20 is made of an easily plated resin 26 that allows metal plating to easily adhere to the filling hole 24 of a primary molded product 22 that is molded from a hard to plate resin that is not plated with metal.
, and a metal plating 28 is applied to the surface thereof.

As shown in FIG. 2(A), the primary molded product 22 has filling holes 24 formed at regular intervals to be filled with the easily plated resin 26. The filling hole 24 is formed into a tapered shape such that the inner diameter thereof increases downward. In this embodiment, the filling hole 2 penetrating the primary molded product 22 is used as the filling area for the easily plated resin 26.
4 is used, however, a simple groove may be formed at the filling position of the easily plated resin 26, and filling holes 24 as in the embodiment may be formed in a part of this groove at predetermined intervals.

The hard-to-plate resin used to form the primary molded product 22 is -
Although all plastic resins can be used, thermoplastic resins called engineering plastics, which have excellent rigidity, dimensional stability, electrical properties, thermal properties, chemical resistance, etc., such as polycarbonate, polyamide, polysulfone, Polyetherimide, polyether sulfone, polyphenylene sulfide, liquid crystal polymers (product names: Nohaculate, Vectra, etc.), and phenolic resins.

Thermosetting resins such as epoxy resins and cyatulphthalate resins, or mixtures of these resins with fillers such as glass fibers, potassium titanate fibers, and calcium carbonate, are used.

On the other hand, as the easily plated resin 26, among the above-mentioned hard-to-plate resins, resins that are immature or have a low molecular weight and whose surface is easily roughened by solvents and chemicals, as well as noble metals such as palladium, gold, and silver, are used. A product mixed with an electroless plating catalyst is used.

In this example, polyphenylene sulfide mixed with glass fiber 40-tX is used as the hard-to-plate resin, and this hard-to-plate resin (
Polyphenylene sulfide (polyphenylene sulfide mixed with 20 wtX of glass fiber) mixed with 0.02 wtχ of palladium is used.

Next, the plastic two-shot substrate 20 according to this embodiment
The manufacturing process will be explained with reference to FIG.

First, fill the hole 2 with a hard-to-plate resin as shown in (A).
A basic molded product 23 is obtained by molding a primary molded product 22 having a shape of 4, and filling the filling hole 24 with an easily plated resin 26 as a secondary molded product as shown in FIG. At this time, a protrusion 26a made of the easily plated resin 26 is formed on the surface of the primary molded product 22.

Next, dirt such as oil and fat bones, dust, mold release agent, etc. adhering to the basic molded product 23 is removed using an alkali cleaner, a surfactant, an organic solvent, or the like. Thereafter, after immersing the basic molded product 23 in N,N' dimethylformamide for 2 minutes,
0″C chromic acid/sulfuric acid or calcium hydroxide,
Etching is performed by immersion in an etching solution such as hydrofluoric acid/nitric acid or acidic ammonium fluoride/nitric acid for 4 minutes to form a roughened surface 3o as shown in (C).
Manufacturing of the plastic two-shot substrate 20 is completed by depositing electroless copper plating to a predetermined thickness (about 30 μm).

As a plating method, in addition to the electroless plating described above, chemical copper plating, chemical nickel plating, or chemical nickel plating or gold plating on top of chemical copper plating may be used.

Further, when the plating pattern is used as direct wiring, the chemical copper plating described above is used, and if necessary, chemical nickel plating, gold plating, electroless solder plating, etc. are overlaid singly or in combination.

Then, various wirings are formed using the metal plating 28 of the plastic two-shot board 20 manufactured as described above. At this time, since the filling hole 24 of the primary molded product 22 is formed into a tapered shape, the primary molded product 22 and the secondary molded product 26 are reliably fitted.

This ensures close contact and prevents the plating from entering into these gaps.

Note that the present invention is not limited to the above embodiments (
As the basic molded product, those shown in FIGS. 3 to 7 may be used.

In the molded product shown in FIG. 3, the primary molded product 22 is the same as that of the above embodiment, and the raised portion 32a of the secondary molded product 32 is made higher than that of the above embodiment.

The molded products shown in FIGS. 4 and 5 are obtained by changing the shape of the filling hole of the above embodiment, and in the molded product shown in FIG. However, in the one shown in FIG. 5, a large diameter portion is formed at the lower end of the filling hole 36a formed by the primary molded product 36.

In the molded product shown in FIG. 6, a straight filling hole 42a is formed in the primary molded product 42, and raised portions 40a made of easily plated resin 40 are formed on both sides of the primary molded product 42.

40b, respectively.

The molded product shown in FIG. 7 is a mixture of the method shown in FIG. 6 and the method shown in FIG. 1, and protrusions are appropriately formed on both sides of the primary molded product 42.

Next, a performance test of the plastic two-shot board according to the present invention will be explained. Materials for these exams include:
A substrate 20 (No. 1) shown in FIGS. 1 and 2,
A substrate (
No. 2) and the conventional substrate 10 (No. 3) shown in FIG. 8 are used as comparison materials.

The first test was a current capacity comparison test, in which the plating pitch of each material was standardized to 1.0 mm and the plating thickness was 30 μm, and the allowable current flowing through each board was measured. The results are shown in Table 1.

As is clear from this table, the higher the height of the protuberance of the easily plated resin, the higher the allowable current value. This is the raised portion 26
This is because the area to which the plating 28 adheres becomes larger due to the portions a and 32a.

The second test in Table 1 and Table 2 was to measure the minimum pitch between metal-plated conductors when the plating thickness was 30 mm and the current value was constant. are shown in Table 2.

As is clear from this table, the higher the height of the protuberance of the easily plated resin, the narrower the line pitch can be. This correlates with the first test described above, and even if the line pitch is narrowed, the raised portions 26a.

This is because the area to which the plating 28 adheres does not decrease due to 32a.

In the third test, the minimum plating thickness and plating work time were measured when the pitch between the plating conductive wires and the current value were kept constant, and the results are shown in Table 3.

As is clear from this table, the higher the height of the protrusion of the easily plated resin, the thinner the plating can be made, and therefore the working time can be shortened accordingly.

Table 3 [Effects of the Invention] As explained above, the present invention molds a primary molded product using a hard-to-plate resin, and arranges an easy-to-plate resin as a secondary molded product only in areas where plating is required. This has the effect of reducing overall costs.

Further, since the protrusions are formed on the surface of the primary molded product using the easily plated resin, it is possible to satisfactorily increase the density of the circuit pattern.

Furthermore, in addition to this, insulation performance can be improved by providing a large-diameter portion inside the surface of the primary molded product, or by forming raised portions made of easily plated resin on both sides of the primary molded product, using the recessed portions as through holes. There is an advantage to doing so.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the structure of a two-piece plastic molded product according to an embodiment. Figures 2 (A) to (D) are
FIG. 2 is a cross-sectional view showing the manufacturing process of the plastic two-shot molded product according to the example, and FIG. 3 to 7 are sectional views showing the structure of other embodiments of the present invention. Figures 8 (A) to (D) are
FIG. 2 is a cross-sectional view showing a manufacturing process of a plastic two-shot molded product according to the prior art. Explanation of symbols 20 ----------...Plastic two-shot molded product 22----- Primary molded product (resin that is difficult to plate) 24-・・・−・−−−−−1−−Filling hole 26・−・−・−−−1−−−−・−Secondary molded product (easily plated resin) 26a−・−−−−− −・−
・−・・Rising portion 2 B−−−−−−−−−−−−−−
Monometal plating 30 ---------- Roughened surface

Claims (3)

[Claims] (1) In a plastic two-shot molded product formed by performing metal plating treatment on the surface of a basic molded product formed from a first material to which metal plating easily adheres and a second material to which metal plating does not easily adhere, the above-mentioned A primary molded product molded from a second material and having a recess formed at the location where the metal plating treatment is to be performed, and a primary molded product by filling the recess of the primary molded product with the first material. A plastic two-shot molded product, characterized in that the basic molded product is constituted by a secondary molded product formed by integrally molding a raised portion on the surface of the base molded product. (2) The recessed portion has a large diameter portion extending inward from the surface of the primary molded product.
Plastic two-shot molded product as described in section. (3) The plastic two-shot molding according to claim 1, wherein the recess is a through hole passing through the primary molded product, and the raised portion is formed at both ends of the through hole. Goods.