JPS63119294A - Manufacture of multilayer board and metal through-hole board by panel plating anchoring method - 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 This invention involves pressing metal fine particles onto an insulating layer formed using a resin resist ink or adhesive on a first layer pattern obtained by a conventional method, and then electroless plating the metal particles. The present invention relates to a multilayer substrate characterized in that a second layer pattern is produced by electrolytic plating, and a method for manufacturing a metal through-hole substrate.

(A) Prior Art A conventional multilayer board is made by stacking and pressing several sheets of prepreg. To briefly explain the manufacturing method of a four-layer board using the drawings, FIG. 2 is a cross-sectional view of each step, and the thick lines indicate the copper foil layer. FIG. 2(a) shows a 0.5% prepreg having a copper foil 2 as an insulating material 1.

First, as shown in (B), the first layer patterns (usually earth patterns) 4 and 5 are formed on the prepreg with double-sided copper foil (A) using the photographic method and printing method, and then the surface is roughened with chemicals. A prepreg with copper foil on one side (A) is pressed onto the front and back sides to form (C). (c) Drill a through hole in the center of 4 and 5. D)-4
'.5', and 4' becomes a hole with no ground.

The through hole 5' becomes a hole having ground. This is then electrolytically plated through electroless plating (E) 4'/5''
The conductive connection between each layer is completed, and the second layer pattern can be fabricated. After removing etching (
) and is completed.

For metal through-hole boards, either a through-hole larger than the actual size is punched in the metal plate and copper-clad prepreg is pasted on one side, or copper foil is pasted on both sides and a through-hole of the actual size is punched, followed by panel plating. The pattern is created using

(b) Problems to be Solved by the Invention This conventional four-layer substrate and metal through-hole substrate manufacturing method requires three plates. Expensive press equipment is required.

- Advanced technology is required to align the holes with the layers. Since a stem hole is required, more material than the actual external size is required. Therefore, material collection is very poor. The through hole 5' in Figure 2 (E) has one conductive contact point on the first layer ground pattern.
It is very small at 8 microns. Therefore, you have to be careful about dust and dirt when wide opening, so the drilling cost is high. Due to the smear problem, a special electroless plating pretreatment process is required.

Due to these factors, the current situation is that we still rely on some major circuit board factories. In order to compensate for these drawbacks, an insulating layer is formed on the first layer pattern using a single sheet of material, and a pattern is formed using silver paste, copper paste, the Aditeep method, etc.

However, it is still not widely used due to cost, adhesion strength, and pattern density problems.

Purpose of the Invention This invention was made to solve these problems, and its objectives are to reduce costs by half, shorten delivery time, and make it possible to operate the product in small-scale manufacturing plants as it does not require press equipment. .

In the future, by converting components into chips, through-hole boards and four-layer boards without component holes will become possible. The present invention also relates to a method for manufacturing a four-layer board, which has the advantage that if a metal plate is completely coated with resin, a metal through-hole board or a four-layer metal board can be produced. The present invention will now be described in detail based on examples.

Structure of the Invention FIG. 1 shows cross-sectional views of each process, and thick lines indicate copper foil. 1st
As shown in Figure (A), double-sided copper-clad laminate material shown as 2 is used as the insulating material 1. As shown in Figure 1 (B), through-holes A-B are drilled at the required locations, and a pattern is created using photography or printing to match the holes, and as shown in Figure 1 (C). First layer patterns A' and Bo are produced. As shown in ), the entire surface is coated with solder resist ink for the first time, leaving only the la and bond areas of A' and Bo, and the solder resist ink is applied to the entire surface at 160 degrees.
After drying for 0 minutes, apply a second coat of liquid, two-component solder resist ink or two-component resin adhesive to the entire surface, leaving the land areas of A' and Bo (e) 3 and 4. A second insulating layer is formed as shown in . Burn this to B stage.

Make money. After this is crimped to help the adhesion of the metal particles, it is rapidly baked and dried at a high temperature of 150 degrees for 40 minutes, pickled, and then subjected to crucible polishing to roughen the surface and then plated in a conventional manner.

As shown in FIG. 1 (g) 6, the inside of the hole becomes a through hole due to copper plating. After that, a secondary pattern is created using a photographic method, a printing method, or a solder plating method, followed by etching. A through-hole pattern without a ``B'' can be a pattern with a ground.If the first layer pattern 2 is made symmetrical on the front and back as shown in Figure 1 (force), all patterns can be grounded. It will be completed as a figure (nu).

Measures to solve the problem: (1) Ethanol cleaning, (2) Metal powder sorting method, (6) Timing of spraying. The process characterizing this invention is shown in (to) in Figure 1.
A metal fine particle layer shown in 5 is created to increase the adhesion of electroless plating, and then electrolytic plating is performed.

FIG. 3 shows the method of selecting fine metal particles and the timing of spraying used in an embodiment of the method for manufacturing a multilayer board according to the present invention.

J/■/S standards for metal powder are aluminum powder (J/■/5K-5
906), but since it does not exist in brass powder or copper powder, copper powder (427
4-44 micron 325 methane (3% residue) was used. Copper powder also contains copper metal, iron powder, and stearic acid powder as impurities, and these impurities are the cause of disconnections, short circuits, and poor adhesion. It is necessary to remove these impurities to obtain a uniform wire copper powder.

The company says that it is not possible due to cost and technical considerations to produce balanced fishing wire copper powder, so first the copper powder is washed with ethanol.

For the purpose of ethanol cleaning, stearic acid is used in the stamp mill during the copper powder manufacturing process. Therefore, there is a stearic acid coating on the copper particles)
It interferes with the adhesion of electroless copper. Further, when removing copper other than the pattern formed on the copper plating layer and copper particles under the copper plating layer by etching, it is necessary to react well with the etching solution. Furthermore, since stearic acid powder is mixed in, it is necessary to remove this, so the step of washing the copper powder with ethanol is important.

Sorting method: Next, the copper ingot, iron powder and relatively large copper powder are sprayed into the primary copper powder tank (1) without adjusting the air pressure. The powder that flies up is sent to secondary tank 2. Since the secondary tank is larger than the primary tank, the air flow is gentle and only light particles and fine particles are blown out.

Spraying timing (SL) (Next, as shown in Book Temple Street (B), the resin solder resist ink or adhesive hardens in the order of A stage, B stage, and C stage.The curing time is determined by each company. It varies depending on the product.In a successful experiment, Taiyo Ink Co., Ltd. S-
40-liquid, S-222 two-liquid, Asahi Scientific CR
-20G two-component, Konishi Bond Co., Ltd. E-36, E-4
0-Liquid.

At the A stage, a sufficient amount of solvent is contained, and when heated, the solvent begins to melt and evaporate. If the surface of the secondary insulating layer is covered with copper powder, the solvent attempting to evaporate will break through the copper powder layer and evaporate. At this time, the copper powder penetrates into the resin and is hardened, so it cannot be removed by etching and remains copper. In the B stage at high temperatures, the material hardens while the solvent is trapped inside, so sufficient hardness cannot be obtained and the adhesion of the copper powder is poor. For this reason, the adhesion of copper plating is very poor.

At the C stage, the surface of the insulating layer has begun to harden, so the adhesion of the copper powder may vary or may not adhere at all. Therefore, the time of implanting copper powder must be when the B stage has been entered. 4 Table 1 shows the stable B stage time with the best workability. In the experiment, a hot air heating type baking kiln was used as the baking kiln for bringing the material to the B stage. In this type of kiln, which is commercially available, hot air is uniformly blown from the bottom to the top of the left and right walls of the firing chamber. A board that is baked while standing on a rack begins to harden from both left and right ends and the top end, and when the center of the board is in the B stage, the end is in the C stage. Such curing variations are most noticeable on large-area substrates. Improvements in baking ovens are required to obtain consistent B-stage hardening. For this reason, all but the hot air holes at the bottom left and right in the baking chamber are crushed. The hot air from the lower tier serves to carry the evaporating solvent outside, so strong hot air is not necessary.

The B stage time obtained based on the improved kiln conditions as described above varies somewhat depending on the kiln capacity. After spraying separated pure copper fine particles evenly onto the second insulating layer of the B stage obtained uniformly, apply slight roll pressure to planarize the particles, and increase adhesion by blending them onto the insulating layer. .

Next, it is necessary to bake at a high temperature of 150 degrees for 40 minutes. Low-temperature baking has a high rate of residual copper. Next, after pickling, both sides are thoroughly polished.

This is because even if the copper powder is washed with ethanol, the stearic acid coating on the copper particles cannot be completely removed, so the remaining coating is removed by polishing, and the surface of the insulating layer is roughened to make it more resistant to electroless plating. help. Next, electrolytic plating is applied to form a pattern, and after removal by etching, the process of manufacturing a multilayer board as shown in FIG. 1(a) is completed.

Effects of the invention An insulating layer is created using resist ink on the four-layer board manufactured according to this process and the insulating layer board (glass epoxy cloth material) from which copper foil has been removed on both sides, and a metal particle layer is created using this manufacturing method, and panel plating is performed. A normal through-hole substrate was manufactured using the following steps. Leave this as a bare board with a solder leveler.
Wait for a minute and check the adhesion of the plating. Since there was no swelling or disconnection, the electrical characteristics were tested at the Tokyo Metropolitan Industrial Technology Center for 15 years, and the results were as shown in Table 2.

Later, a board with a high pattern of 0.15% between two pins was fabricated, and solder leveling was performed in the same manner with the solder remaining bare. There was no abnormality in this result pattern.

The manufacturing method of metal substrates using this panel plating anchor method is the difference between the hole-drilling procedure performed on the metal plate and the coating with resin, in which a layer of metal particles is created by simply drilling, and then the panel is plated to create a pattern. is the same process.

In the experiments described based on the examples, an aluminum plate with a thickness of 1.5% was used. First, prepare three washer-shaped copper tubes or brass tubes with a thickness of 1.5% that have the same inner diameter as the stack pin.

As shown in Fig. 4(a) 1 (the dotted part is a metal material), two stack pin holes and one eyelet hole are drilled in accordance with the outer diameter of the copper tube. As shown by 2 in FIG. 4(b) A, the prepared copper tubes are inserted into the six through holes to form stack pin holes. If a primary through hole is drilled with a size twice the actual diameter based on this, it will become B in FIG. 2 (C).

Next, as shown by A3 in Fig. 3), put tape on both sides of the stack pin hole and mark hole so that the outside diameter of the copper tube does not protrude.
Make sure that the adhesive does not get into the hole.

As shown in Figure 2 (Ho 1) 4, the entire surface of the aluminum plate is coated with resin. In the experiment, 1.
A workpiece with a thickness of 6% is made, a two-component adhesive is applied to the entire surface of the aluminum plate, it is placed inside the workpiece, and a film is placed on top. Remove the adhesive and make it flat 990
After primary drying at low temperature for 40 minutes, remove the film and dry at high temperature for 40 minutes.
Secondary drying was performed at 0 degrees Celsius for 60 minutes. FIG. 2 (Ho 2) is a plan view.

As shown in Figure 2 (see 5), apply solder resist ink or adhesive to the entire surface of the chipped resin.B
Burn it onto the stage.

As shown in Figure 6, the separated metal particles are
= Spray on the staged surface and after drying Figure 4 (G) B
As shown in o, remove the tape applied to the stack pin hole A, and using this as a reference, drill a hole of the actual size using the same NC tape as the primary hole. The thickness of the insulation layer of the metal plate hole is equal to the radius of the actual hole diameter. After this, when pickling is performed, abnormalities in the insulating layer can be found.

After crucible polishing as shown in Fig. 4 (7), panel plating is performed, a conventional pattern is created as a through hole, and etching is removed to complete the process as shown in Fig. 4 (N). This is done by drilling, but in the case of mass production, punching is used.

~'+A- (a) (b)(
Table 1)

[Brief explanation of the drawing]

FIGS. 1A to 1C are cross-sectional views of each manufacturing process of a four-layer board by the panel plating anchor method. 1... Diagonal lines indicate insulating material 2... Thick solid lines indicate copper foil portion 6... 4... Insulating layer 5... Metal particle layer 6...・The intersecting diagonal lines indicate the electrolytic plating layer (panel plating) A...B...Hole A...
・B'...Land portion of created pattern FIG. 2 is a cross-sectional view of each process of a four-layer board made by a conventional bonding method. a...b...Prepreg material 1...Insulating material 2...Copper foil 3...Cross diagonal lines indicate electrolytic plating layer (panel plating) 4...5 ...-Land part 4' of layer pattern
...5'...Through hole Figure 2 Each process of manufacturing a metal substrate to which this invention is applied is shown in a plan view and a sectional view. 1... Point part, plan view of metal material 2...
・Washer-shaped copper tube or brass tube 3... Tape to prevent resin from entering the hole 4... Resin coating layer Ho 2... Flat surface of coated metal material Figure 5...Resin adhesive layer 6...Metal particle layer 7...Cross diagonal lines, electrolytic plating layer A...
Stack pin hole B in which the pipe is embedded...Primary hole B, which is twice the actual size diameter...Secondary hole and through hole land area, which are drilled to the actual size diameter

Claims (1)

[Claims] A through hole is drilled in an insulating substrate that has copper foil on both sides, and two or more insulating layers are applied over the entire surface using resin resist ink or adhesive, leaving the land part of the primary pattern created to fit the hole. A process of baking this insulating layer to the B stage (semi-dry state, hereinafter referred to as B stage), a process of washing the metal powder with ethanol, a process of separating the metal powder washed with ethanol into impurities and fine metal particles, and a process of separation. There is a process of spraying the metal fine particles that have been prepared over the entire surface of the insulating layer that has entered the B stage to form a metal fine particle layer, a process of applying roll pressure to increase the degree of adhesion, and a process of thoroughly baking and polishing it. When manufacturing a metal board by applying the conventional method of manufacturing a four-layer board with through-holes by plating the surface after roughening the surface by applying the conventional panel plating process, and applying the features of this invention, copper or brass pipes are stacked with stack pins. The step of embedding the stack pin in the hole, and using the stack pin hole as a reference, using an Nc hole drilling machine or
A process of punching a primary through hole twice the actual diameter, a process of applying resin adhesive to the entire surface of the metal plate (front and back ends of the hole), and a process of creating a primary insulating layer on the front and back after drying.
After baking on the stage and creating a metal particle layer, a secondary through hole with the same center axis as the primary through hole is drilled with the actual size, and then conventional panel plating is applied to create a metal core. This is a method for manufacturing a printed circuit board having through holes.