JPS5934696A - Many circuit boardsand method of producing same - 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 The present invention relates to a multilayer wiring board that can be made without a through-hole plating process, and a method for manufacturing the same.

Conventionally, when forming a circuit in layers using a double-sided copper clad board or a copper clad board for multilayer circuits, the connection between each layer was perforated by drilling or punching, and then a force jT% was applied to the connection between each layer.
Circuits were removed and continued by so-called through-hole plating, which is a combination of deplating or electroless plating and electrolytic plating.

However, when through-hole plating is used, for example, when the quality of the substrate material is low, insulation deterioration of the hole wall due to moisture absorption,
There are many factors that reduce circuit reliability, such as deterioration of plating due to expansion and contraction in the thickness direction due to humidity, drying, heating and cooling, and deterioration of the quality of attached plating due to unsuitable drilling conditions such as so-called smear and nail head. In order to highly eliminate the factors of
Currently, IJ1 boards are extremely expensive.

On the other hand, as a multi-M board without through-hole plating, a conductive paste can be printed on a pre-formed circuit layer through an insulating layer, and by repeating this process, a second layer can be created. , a third layer, etc., to form a multilayer wiring board is known.

However, with conductive paste alone, the conductivity of the circuit is lower than that of copper.
Inferior to metal circuits such as nickel.

In order to improve this point, a method has been devised in which circuits are printed using resin to which copper powder is added as a conductive paste, and metal plating is deposited using the copper powder exposed in an electroless plating bath as a catalyst. . However, even if this method is used, the deposited plating is non-uniform, has weak adhesion, and tends to be easily disconnected, so that a conductive circuit with sufficient reliability still cannot be obtained.

In addition, a method is commonly used in which the parts of a single-sided board where the circuits intersect three-dimensionally are connected using metal wires called jumper wires, but since this method is not a wiring that is tightly fixed to the board, stray capacitance etc. are likely to fluctuate. Signal circuits tend to pick up noise.

The present invention provides a multilayer wiring board that does not have these drawbacks and a method for manufacturing the same, which eliminates the hassle of drilling.
The circuits in each layer and the connections between the layers are made using highly reliable metal plating, so that the insulating layer and the circuit layer are integrated without any gaps. The present invention relates to a multilayer wiring board with high lubricating properties and a PJ manufacturing method thereof.

EMBODIMENT OF THE INVENTION Hereinafter, specific embodiments of a multilayer "J" wiring board and a method of manufacturing the same according to the present invention will be described in detail.

First, in the present invention, the base layer of gold, the solid conductor circuit, and the second metal conductor circuit are composed of WR*j circuits formed on one side of the substrate. Among the circuits, the circuit on the inner layer side was used as the base layer, the circuit on the outer layer side was used as the second metal conductor circuit. Gold Fη)
(There are no particular restrictions on the material for the scale, but it is preferable to use copper because it has excellent circuit conductivity and is easy to process.The technology for forming the circuit into a pattern is the conventional foil etching method. Alternatively, an additive plating method may be applied. In other words, in the case of a base layer circuit, etching resist ink is printed on a single-sided copper clad plate by screen printing, hardened, and etched to obtain a metal conductor circuit in the desired pattern. Furthermore, the base layer circuit itself may be multi-layered.

Furthermore, the present invention is characterized in that the electrically insulating resin layer and the metal conductor circuit formed thereon are attached to each other without floating.

The peeling strength of the circuit is not particularly limited, but it is preferably 0'' to more than 1.0k19/crr, more preferably 1.0k19/crr.
It is better to be L or higher. The internal and external circuits sandwiching the resin layer are integrally connected using metal-to-metal plating in the required areas of the resin layer, so electrical contact resistance is low and mechanically strong. Connection is made.

Therefore, even though the substrate material is usually a relatively general-purpose material that causes many concerns about reliability when used for through-hole plating, it is still as good as through-hole plating using glass cloth epoxy resin copper clad board. Continuity and continuity can be achieved.

The resin layer may include thermosetting resin, thermoplastic resin, rubber or synthetic rubber, and mixtures thereof, such as phenol resin, phenol resin, melamine 41W resin, polyvinyl butyral resin, and polybutylene resin. Gen rubber, acrylonitrile rubber, etc. may be used alone or in combination or modified.

Nl printing properties in the resin! Various additives, inorganic fillers, etc. for conditioning may be uniformly mixed and dispersed. On the other hand, the resin layer can also be used as an integrated layer in which several layers are brought into close contact with each other. In this case, when at least the outermost layer is made of a modified thermosetting resin or mixed resin containing 5% or more of rubber or synthetic rubber, the peel strength of the second metal conductor circuit is particularly increased. There is a need for wholesalers to improve the reliability of connections in multilayer circuits.
One fruit is remarkable.

Next, in order to open a window in only the portion of the resin layer that is desired to be exposed above the circuit of the base layer, an appropriate method can be selected from among various known methods. For example, the resin layer may be made into a semi-cured film and only the window holes removed by punching, which is then aligned on the circuit of the base layer, heat-sealed, and then cured. When forming a pattern using a paste-like layer and using a screen printing method, for example, it is preferable to use a plate in which the resin ink is not applied to the window areas.

As the second metal conductor circuit, a metal plating circuit can be deposited by means such as a seven-mia day tape method or a one day tape method. When depositing metal plating circuits using these methods, it is recommended to mechanically or chemically roughen the surface of the area where the plating is to be deposited in a fine and homogeneous manner in order to improve the adhesion of the plating. It is valid. In this case, if the entire insulating layer or the surface layer is made of a modified thermosetting resin or mixed resin containing 5% or more of rubber or synthetic rubber, chromic acid.
It is convenient to form a preferable roughened surface by chemical agitation such as a sulfuric acid mixture. 1. Example L Paper base epoxy resin single-sided laminated board Sumilite Kita who
4152 (manufactured by Juju Bakelite) by etching the circuit shown in FIG. On top of this, as an electrically insulating resin layer, epoxy ≦ liquid solder resist ink,
Using Tamura's SR-γQG/MX-5, the entire surface was coated to a thickness of about 50 μm with a pattern shown in FIG. 2 in which only the pad portions were opened, and then cured. The surface of this substrate was evenly and finely roughened over the entire surface with 320 abrasive grains (Tosa Emery). Subsequently, electroless button 1 plating is deposited to a thickness of about % μm over the entire surface through hydrochloric acid treatment, catalyst treatment, and accelerator treatment according to a normal electroless plating process. Furthermore, about 20 μm of electrolytic plating was deposited on the entire surface in a copper sulfate plating bath. Print a resist on this and print the third
The circuit shown in the figure was created using the etching method. The circuit of the two-layer (multilayer) wiring board obtained as a result is shown in FIG. After removing the resist, by covering the surface with a solder resist with the pattern shown in Figure 2 again as an electrically insulating resin layer, it is possible to process the circuit to prevent thermal and mechanical shock during processing. be.

Example 2゜Paper base phenolic resin single-sided copper clad laminate SUMILITE LC!
The circuit shown in FIG. 1 was created on LO-2321 (manufactured by Juju Bakelite) by etching. On top of this, ultraviolet curable resist ink H Engineering R (Chuo Meiban Kogyo) is used as an electrically insulating resin, and as shown in Figure 2, the entire surface is turned after opening only the butt part. was coated to a thickness of about 30 μm and cured. On top of this coating film, apply nitrile rubber Nitsuball 1001 (Nippon Zeon) in the pattern shown in Figure 2.
40 parts epoxy resin Epicor N0O1 (shell>
20 parts P,P-diaminodiphenylmethane
Part 2 Aerosil
2 parts benzyl alcohol
Appropriate amounts of the rubber-modified thermosetting resin ink were mixed and dissolved and printed in the same pattern as in the case of H-KoR, and sufficiently dried to form a rough patch of about 20 μm.

Then, it was immersed for 5 minutes in a chemical roughening solution at 55° C. prepared by pre-mixing 0r03 100g a2so43QQmJ water 6001nl. After thoroughly rinsing this with water, the same normal electroless plating and electrolytic plating process as described in the example was carried out, followed by the salt treatment and subsequent steps to deposit about 20 μm of electrolytic plated steel. . Furthermore, the circuit shown in FIG. 3 was created by an etching method. As a result, a two-layer wiring board corresponding to that shown in FIG. 4 was obtained.

On the surface of the two-layer wiring board obtained in Example Z, the insulating ink used in Example Z, that is, ■Product R + rubber-modified thermosetting resin ink, was printed as in the pattern shown in Figure 2, and the entire surface was printed. Chemically roughened waste, hydrochloric acid, palladium chloride-stannic chloride hydrochloric acid solution, accelerator treatment. This was once dried, and the pattern shown in FIG. 5 was printed using UV-curable solder/metsukiresist ink, and then immersed in an electroless nickel plating bath Nyco S (Kizai). As a result of treatment at 30°C for 3 hours, nickel plating was applied thickly to the areas not covered by the printing of the pattern shown in Figure 5, and the entire board consisted of three layers of circuits as shown in Figure 6. Formed without using through-hole plating.

Comparative example L Paper phenolic single-sided copper clad board PLo-2321 board thickness 1.6
1 diameter at each window opening corresponding to Fig. 2.
A hole was drilled with my drill, and the next step was plating of a 20 μm thick φ-hole using the usual copper through-hole plating process, resulting in a double-sided copper-plated square. The surface of this was tented with a dry film resist in the pattern shown in Figure 1, and then in the pattern shown in Figure 3.Then, the resist was etched to leave the circuitry intact and exposed. If the resist on the surface is removed, a two-layer (double-sided) wiring board equivalent to the circuit shown in FIG. 4 can be obtained by through-hole plating.

Comparative example 2 Glass cloth base epoxy resin single-sided silk clad board Sumira Ito EI
+0-4756 (Jumikata Heckley)
The circuit shown in the figure was created using the etching method. On the surface of this, actual fffii example 2. In the same manner as in the case of 2, H-work R was formed to a thickness of about 30 μm in the pattern shown in FIG. 2 and hardened.

On this surface, a phenolic resin conductive paste containing copper powder was printed and baked in the pattern shown in the third step.

When this surface is roughened by liquid honing and placed in an electroless steel plating bath, copper plating is deposited on the circuit section due to the catalytic action of the copper powder exposed on the surface of the paste film. Approximately 10μ of plating was deposited. A wiring board with a two-layer circuit equivalent to the circuit shown in FIG. 4 was obtained.

Table I shows the evaluation results for these Examples and Comparative Examples.
Shown below.

The continuity reliability in the table represents the number of cycles in which the continuity resistance value remains within 20% of the initial value after treatment under conditions that promote continuity deterioration, with one cycle of 30 minutes at -60°C to 30 minutes at 125°C.

Looking at Table ■, the total weight in the example is 0.4 kgf/
However, the adhesion strength of the plating in the comparative example is extremely small. Moreover, the precipitated particles are coarse, and therefore the continuity reliability is also poor.

Also, Comparative Example 1. We created a double-sided through-hole plating circuit using a paper-based phenolic resin double-sided copper-clad laminate, but the continuity reliability could only be maintained up to 20 cycles, and the through-hole section had a resistance of 511. A communication failure has occurred.

On the other hand, in each example, fine particle plating is formed on the circuits of the second and third layers, and is connected to the base layer and to the insulating ink or the rubber compound ink layer coated thereon. Adhesion is strong. In particular, the plating in Example 26 was firmly adhered. It is clear that the conduction reliability is extremely good even though the same braided copper clad plate as in [Comparative Example] is used.

The method for the evaluation items in Table ■ will be explained.

"Peeling Strength" The force required to peel off the circuit in the 90 direction from the circuit surface at the 1≦2th floor where the circuit of the corresponding layer is formed is divided by the circuit. @3JN (Ni plating) of Example 3 and the second layer of Comparative Example B (
Since both the furnace electrolytic Ou plating (with thick furnace electrolysis) had poor spreadability as a plated metal, cellophane adhesive tape was attached to the plated metal surface for reinforcement for evaluation.

1 Solder Heat Resistance After the circuit was formed, the board was floated on the surface of the solder bath, and the time until blistering occurred was measured.

"Dielectric strength voltage" Measurement was made between terminals 1 and 7 in No. 41 and 1 in FIG.

"Continuity reliability" Terminal 1-2.3-4.5-6.7-8.9-IC1tf
→1 (However, for the third layer of Example U, terminal 1B-
It is expressed as the number of cycles until the change in conduction resistance (between 19 and 19) exceeds +20% of the initial value.

Table 1 shows the characteristics evaluation results for the wiring boards obtained in each example and comparative example.

Table I Characteristic evaluation results

[Brief explanation of drawings]

Figures 1 to 6 are test patterns used in Examples and Comparative Examples to explain the circuit configuration. Figure 1 is the base layer circuit pattern, Figure 2 is the resin covering pattern, and Figure 3 is the test pattern. 2
FIG. 4 shows a layout diagram of a two-layer wiring circuit, FIG. 5 shows a third-layer circuit pattern, and FIG. 6 shows a wiring diagram of a three-layer wiring circuit pattern. 1...Copper foil etching circuit 2...Board adhesive surface 3*...Window brightness is at point 4...Electrical insulating resin layer 5...Copper plating circuit 6...Resin coating surface 7...Φ Base layer circuit pattern 8 fist...2nd fV41 curve pattern 9...Circuit absent area 10...φ window light is at location 11@...Resin shield surface 12...Base layer (b) road pattern 13...・Second layer circuit pattern 14・Life・Third layer circuit pattern 15...Circuit absent part Sumitomo Bakelite Co., Ltd.

Claims (4)

[Claims] (1) In a multilayer wiring board in which 2M or more circuits are formed per board, a resin layer having electrical insulation properties is applied on the metal conductor circuit of the base layer, and the resin layer is adhered to the resin layer. A second metal conductor circuit is formed, and the resin layer has portions with windows at required locations, and the second circuit and the base layer circuit are electrically connected at those portions. A multi-Jfff wiring board, characterized in that it is constructed by connecting metals together by bonding, and connecting metals by plating. (2) Does the resin layer itself consist of multiple insulating resin pieces? At least the outermost layer is made up of 5
% or more of rubber or synthetic rubber.
'f ft17 The multilayer wiring board according to item 1. (3) There is a base layer circuit made of metal on one or both sides of the board. Open windows only in the parts that you want to expose on the surface, and apply and harden an electrically insulating resin layer to the other parts. , a multilayer wiring board characterized in that the coating photocured portions and the window coating of the resin of the thus obtained substrate include a step of forming a circuit by metal plating the entire surface or the −e=+: portion thereof. Production method. (4) The coating and curing process of the resin layer consists of repeating the coating and curing operations multiple times, and the resin used in at least the last coating and curing operation is a modified rubber or synthetic rubber compounded in an amount of 5% or more. 4. The method of manufacturing a multilayer wiring board according to claim 3, wherein the multilayer wiring board is made of a thermosetting resin or a mixed resin.