JPH02303089A - Manufacture of through hole board - Google Patents

Abstract

PURPOSE:To form a copper film having excellent adhesive properties including a hole without adhesive layer at all by treating a hole opening plate formed with many through holes at desired positions of a heat resistant resin film or a thermosetting resin laminated plate in a nonoxidative atmosphere or under reduced pressure under predetermined conditions. CONSTITUTION:A hole opening polyimide sheet 10 formed with many through holes at desired positions of a heat resistant resin film or sheet or a thermosetting resin laminated board is manufactured, and introduced into a through hole circuit board continuously manufacturing apparatus having a reduced pressure plating chamber, a heater, etc. The sheet 10 is held at 165 deg.C or higher to the size variation allowable temperature of the sheet 10 in a nonoxidative atmosphere or under reduced pressure. Copper formate is continuously introduced at 130-165 deg.C at a speed of 1deg/min or more into the heater of the apparatus to raise its temperature. Both are held at an interval of 5cm or less, the sheet 10 is removed, copper of 0.1-5mum is brought into close contact within the hole to obtain a through hole board.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a multilayer printed wiring board having a perforated polyimide film, a laminate, or an inner wiring layer in which the hole walls are also plated with copper using a novel dry method. This is a manufacturing method for through-hole boards, such as , which forms a pure copper film that does not contain any corrosive elements such as halogens, and has excellent adhesion and conductivity, so it can be used as is or as needed. According to
It is plated with copper, nickel, or other metals and is suitably used as a printed wiring board.

[Conventional technology and its problems]

The most common conventional manufacturing method for double-sided boards and multilayer boards that have through-holes is to make through-holes at predetermined positions in sheets or laminates with copper foil covered on both sides, activate them as appropriate, and then release them. A method of forming a copper layer on the inner wall of the hole by electrolytic plating, increasing the thickness of copper by electrolytic plating as appropriate, forming a resist pattern, and etching to form a surface wiring network, and a double-sided copper foil. There was a method of using a material without copper foil on the surface instead of a laminate sheet or laminate.

Since these methods use an electroless plating solution, which is an unstable aqueous solution containing harmful chemicals, methods such as vapor deposition of metal or application of conductive paint are being considered in place of electroless plating. However, a process that can be put to practical use in terms of adhesion between the substrate and metal, productivity, and reliability has not been completed.

On the other hand, it is known that by applying copper formate to an article and heat-treating it in a non-oxidizing atmosphere, it is possible to obtain an article with a copper film attached, but conventionally this method has been used to form copper films for printed wiring boards. There are no examples of this happening. The reason for this is that the adhesive strength of the produced copper film is insufficient, and there is no method suitable for mass production.

[Means to solve the problem]

In view of the above circumstances, the present inventors used a simple method to
This was completed as a result of intensive research into an economical method for producing through-hole plated printed wiring board substrates with excellent adhesion strength.

That is, in the present invention, a large number of through holes are formed at desired positions in a heat-resistant resin film or sheet or a thermosetting resin laminate to produce a plate (a), and the plate (a) is non-woven. In an oxidizing atmosphere or under reduced pressure, at a temperature of 165°C or higher, the copper formate is introduced into a heating device maintained at a temperature below the allowable dimensional change of the plate (a), and copper formate is heated at a temperature of 130°C.
It was continuously introduced into the heater to raise the temperature up to ~165°C at a rate of ldeg/min or more, and the two were separated by 5 cm.
After holding for a predetermined time at the following intervals, the formic acid copper The supply amount is 0.0 per total surface area of plate (a).
01g/ClIr or more, and the above-mentioned pores are that the board (a) is a multilayer printed wiring board having a polyimide film, a laminate board, or an inner wiring layer, and that the through-hole board manufactured by the manufacturing method is This is a method for manufacturing a through-hole board in which the thickness of the copper layer is made 5p or more by electrolytic copper plating, and the electrolytic copper plating speed is set at 0.1 m/sec until the thickness of the copper layer becomes 5p or more. The speed shall be as follows.

The present invention will be explained below.

The perforated plate (a) of the present invention is formed by forming a large number of through holes at desired positions of a heat-resistant resin film or sheet or thermosetting resin laminate, that is, at desired through-hole positions of a printed wiring pattern. temperature of 165℃
Above, preferably the dimensional change is within a substantially permissible range at 180°C or higher, usually the dimensional change rate is 0.3% or less, preferably the dimensional change rate is 0.1% or less. It does not cause excessive decomposition or discoloration. In addition, the perforated plate (a) of the present invention may be annealed before being processed to improve dimensional stability, if necessary, and adhesion may be improved prior to the plating process of the present invention. Surface treatment etc. shall be carried out as appropriate.

Here, the heat-resistant resin film or sheet (hereinafter simply referred to as a sheet) includes polyimide, polybenzimidazole, polyphenylene sulfide, wholly aromatic polyamide, polyetherimide, polysulfone, polysulfone, polyether sulfone, and polyether ether. Ketone, polyphenylene ether, polyethylene-2,6
- A sheet made of a heat-resistant resin selected from the group consisting of naphthalate, polyoxybenzoyl, aromatic liquid crystal polyester, and a resin composition containing two or more of these as essential components,
Examples include sheets made of JPN and semi-IPN, as well as sheets blended with inorganic or organic fillers, or composites with the base material described below, with polyimide being particularly preferred.

In addition, laminates include phenolic resins, epoxy resins, unsaturated polyester resins, cyanato resins, and other thermosetting resins; compositions made by appropriately blending two or more of these resins:
Furthermore, these thermosetting resins, compositions made by blending two or more thereof, modified with polyvinyl butyral, acrylonitrile-butadiene rubber, polyfunctional acrylate compounds, other known resins, additives, etc.; crosslinked polyethylene, crosslinked polyethylene A cross-linked curable resin composition consisting of /epoxy resin, cross-linked polyethylene/cyanato resin, polyphenylene ether/epoxy resin, polyphenylene ether/cyanato resin, polyester carbonate/cyanato resin, and other modified thermoplastic resin (IPN or semi-IPN) as a matrix Resin, kraft paper, linter paper, glass (E, D, S, T, quartz and other various glass fibers) woven and non-woven fabrics, fully aromatic polyamide, polyphenylene sulfide, polyethernylene ketone, polyetherimide , woven fabrics, non-woven fabrics, and heat-resistant engineering plastic fibers such as polytetrafluoroethylene.
A laminate having an insulating layer composed of a porous sheet and a composite fiber/non-woven fabric made by appropriately mixing or combining these materials as a base material, and a printed wiring having a metal printed wiring network formed on the insulating layer. Examples include multilayer printed wiring boards manufactured using boards.

The copper formate of the present invention is usually cupric formate, and includes anhydrous copper formate, copper formate tetrahydrate, and mixtures thereof, with anhydrous copper formate being particularly preferred in the present invention.

In the present invention, the above-described perforated plate (a) and copper formate are introduced simultaneously or separately into a heating device maintained at a predetermined temperature of 165° C. or higher in a non-oxidizing atmosphere or under reduced pressure. Then, both are held at an interval of 5 co+ for a predetermined period of time, and metallic copper produced by thermally decomposing copper formate is deposited on the perforated plate (a) and on the inner wall surface of the holes. At this time, the temperature of the copper formate is raised from 130 to 165° C. by 1 deg/min or more.

Heating equipment uses radiation heating such as infrared rays, electron beams, and microwaves, electric furnaces, ovens, oil heating, pressurized steam heating, nichrome wire, and other means as appropriate. A continuous heating machine with an introduction section, a heating section, and a take-out section is suitable, and depending on the resin of the perforated plate (a), the heat treatment temperature and the temperature at which the dimensions of the perforated plate (a) will significantly change permanently are suitable. Since these temperatures may be close to each other, it is preferable to set the set temperature to a value with small variations. In addition, as the heating part, a heating plate system is common, and a perforated plate (a
) There are no particular limitations on the heating rate, except that care must be taken to minimize dimensional changes. On the other hand, copper formate is preferably heated at a temperature of 130 to 165°C at a heating rate of 1 to b. Initially, the perforated plate (a) and the copper formate are kept at a distance of 5 cm or less, preferably 2 cm or less, and the heating time is 3 hours or less, preferably 1 to 60 minutes. If the heating rate of copper formate is less than 1°C/min, the plated film obtained will tend to be non-uniform or have poor adhesive strength, and copper powder will be produced the most, which is undesirable. If the heating rate is high, the copper plating rate will be high, but this is not preferable because the plating film tends to be non-uniform.

A known method for creating a non-oxidizing atmosphere in the heating equipment is N2
．． By introducing a gas such as Ar, CQi, Co, +12, etc., by reducing the volume of the heating section of the perforated plate (a) and reducing the opening area of the inlet and outlet to the heating section, an inert gas can be introduced. A method of maintaining the perforated plate (a) in an atmosphere of decomposed copper formate gas without using a (a) A method of arranging a decompression chamber at the introduction part and the extraction part is exemplified,
The degree of pressure reduction is 400 Torr or less, preferably 0T.
orr or less, particularly preferably 30 Torr or less.

Further, the amount of copper formate introduced is 0.001 g/- or more, preferably 0.002 to 0.00 g/- per surface area of the perforated plate (a).
゜1g/caf (6 range) The introduction method is not particularly limited, but in the case of a continuous method, a method of introducing copper formate placed on a continuous belt is usually mentioned. A suitable method for introducing copper formate onto a continuous belt is The arrangement method involves preparing a solution in which copper formate is dissolved or powder is uniformly dispersed in a solvent with a relatively low boiling point that does not substantially react with copper formate, and applying this to a continuous belt and drying it; One side (!!!1
! One method is to use a single-sided uneven belt with many small depressions and grooves on the surface (on which the acid copper is arranged), or with a net or cloth attached, and to apply the copper formate powder to the depressions, grooves, and stitches.

When using a solvent, water, alcohol, aliphatic hydrocarbon, aromatic hydrocarbon, and other suitable solvents with a boiling point of 1
Examples include those below 10°C, and in particular, in the case of anhydrous copper formate, organic solvents that do not contain water, such as methylene chloride, heptane, hexane, cyclohexane, octane, propatool, butanol, heptatool, benzene, toluene, It is preferable to use a dispersion solution obtained by kneading xylene or the like with fine copper formate powder. Application methods include brush type,
Other coating methods such as dipping, spray coating, bar coding, roll coating, and printing are exemplified, and drying is carried out by heating or drying under reduced pressure at a temperature below the decomposition start temperature of copper formate, particularly below 110°C.

The inner wall of the hole manufactured by the above manufacturing method also has a thickness of 0.1
~5-1 A through-hole substrate with a preferably 0.2 to 3-copper film in close contact with it can be used as it is as a substrate for a printed wiring board, but usually the negative pattern of the printed wiring pattern is formed with a resist as it is. After plating copper and increasing the thickness of the copper foil, lightly etching it (flash etching method or metkiresist method), or after plating copper and increasing the thickness of the copper foil, forming a resist pattern and etching to form a printed wiring network. Depending on the forming method (etching resist method), the thickness of the printed wiring copper foil is 5P or more, usually 70A3 or less, preferably 8 to 35J.
A is a through-hole printed wiring board. Here,
Electrolytic plating is preferred from the viewpoint of productivity, and plating is preferably carried out at a plating rate of 0.1x/sec or less, particularly in the range of 0.003 to 0.051/sec, until the metal layer thickness reaches 5 mm or more. Note that it is naturally possible to perform electroless plating or electrolytic plating of nickel, gold, or other metals instead of or after copper plating, and in particular, electrolytic plating is used as appropriate. Further, after the plating, it is preferable to perform an annealing treatment to remove plating stress from the viewpoint of improving adhesion.

The present invention has been described in detail above, and in particular, the manufacturing method of the present invention will be explained by way of an example.

Figure 1 is an example of a conceptual diagram of a continuous method manufacturing device for through-hole substrates of the present invention, Figure 2 is an example of a heating method in a vacuum plating chamber, and Figure 3 is a coating of copper formate powder on an uneven belt. This is an example showing the surroundings of the reduced pressure plating chamber when the plating chamber is supplied at a reduced pressure.

This manufacturing apparatus shown in FIG. 1 is capable of reducing pressure with a vacuum roll (Vl to v4'), and is capable of handling a perforated polyimide sheet (10) as an article to be plated and a copper formate adhesion belt with a 5CffI
Reduced pressure plating room (A) where heat treatment and plating are performed at the following intervals:
, peripheral equipment for attaching copper formate to a belt (20) and supplying it to the vacuum plating chamber A, and a post-treatment tank (C) for plated perforated polyimide sheets. In FIG. 1, a long perforated polyimide sheet (10) is introduced into a vacuum plating chamber A via a vacuum roll (vl),
Here, it is heated to a predetermined temperature by a far infrared heater (H3). Further, a copper formate coated belt (21, 21') coated with a copper formate solution with a coating roll (C1, C1°) and dried with a heater (111, Hlo) is coated with a vacuum roll (V3.
Similarly, the reduced pressure plating chamber A is introduced through the heater () 12. H2°), it is moved and held at a predetermined interval together with the above-mentioned perforated polyimide sheet 10. During this time, copper formate is heated to a predetermined temperature with heater H2, 82°, evaporates, and decomposes on the polyimide sheet (10) to become copper and reducing decomposition gas, and the copper is deposited on the surface of the perforated polyimide sheet and the inner wall of the hole. A copper-plated polyimide through-hole circuit board (11) is then formed. The circuit board 11 comes out of the vacuum plating chamber 8 via a vacuum roll (v2), is processed in a post-processing tank (C), and is dried to become a target product. On the other hand, the copper formate supply belt 21.21° is a vacuum roll (V4.
It exits the vacuum plating chamber 8 via the vacuum plating chamber 8 via the copper formate coating tank (B1, Blo), where it is cleaned by properly removing copper powder adhering to the surface, and the copper formate solution from the copper formate coating tank (B1, Blo) is applied to the coating roll ( C
1, CI') and dried. In addition, the solvent vapor generated during drying is led to a cooler, cooled and turned into a liquid, and then uniformly mixed with copper formate powder (1) in a formic acid preparation tank (B), and then transferred to a copper formate coating tank B1. ．． It is circulated to Blo. Note that the vacuum pump exhaust gas is suitably subjected to catalytic combustion, etc., and converted into water and carbon dioxide gas, which are then discharged.

FIG. 2 shows an example of a case where the temperature of the perforated polyimide sheet 10 in the vacuum plating chamber is kept higher than that of the copper formate powder. It is made by inserting an insulated heating wire.

In addition, Fig. 3 shows that copper formate powder is applied to the concave surface of a single-sided uneven belt and supplied to the vacuum plating chamber A, and instead of the long perforated plate (a), a perforated plate of a predetermined size ( This figure shows a case in which double vacuum rolls (V) are provided at the inlet and outlet in consideration of the case where a) is transferred with its front and rear and both ends fixed and plated.

The continuous manufacturing method of a through-hole board according to the present invention has been explained above with reference to the drawings, but naturally the present invention includes the following steps, except that the perforated plate and the copper formate are held separately in a heating device at a predetermined interval. The present invention is not limited to the above drawings. for example,
Use a batch method instead of a continuous method; Reverse the introduction and movement direction of the copper formate supply belt; Place the equipment horizontally, and apply copper plating to the holes from one side; and post-processing. This includes adding processes such as electrolytic plating of copper or other metals, annealing treatment, etc. Further, the copper through-hole substrate manufactured as described above can be appropriately subjected to known anti-corrosion treatment, if necessary.

〔Example〕

The present invention will be explained below with reference to Examples and Comparative Examples. still,
Parts in Examples and Comparative Examples are based on weight unless otherwise specified.

Example 1 100 parts of anhydrous copper formate powder and 50 parts of butyl alcohol were kneaded to obtain a dispersion solution (hereinafter referred to as treatment liquid 1) in which the anhydrous copper formate powder was uniformly dispersed.

This was applied to one side of a predetermined aluminum film and dried to form a copper formate supply belt.

After heat-treating a long polyimide sheet (manufactured by DuPont Azuma, trade name: Kapton) with a thickness of 501.3 at a temperature of 300°C for 30 minutes, through holes with a diameter of 0.4 mm were formed at predetermined positions at intervals of 1.25 mm. With 100 pieces in a row, the distance between the rows is 1
After opening 10 rows at 2.5W intervals, the surface was treated with a caustic soda aqueous solution.

A container that can be depressurized is equipped with a part for holding, supplying, and taking out the perforated polyimide sheet and a copper formate supply belt to which copper formate powder has been attached in advance. Using a device in which a copper formate supply belt is disposed in a freely transferable manner, the polyimide sheet and the copper formate supply belt are continuously supplied between heating plates and taken out to form a through-hole board in which the inside of the hole is also copper plated.

The length of the heating area of the heating plate was 40 cm, the pressure inside the container was 0.1 to I Torr, the temperature of the heating plate was 280°C, and the speed at which the perforated polyimide sheet was introduced between the heating plates was 5 cm/min. The speed of the copper formate supply belt was 1°3 cm/min, and the amount of deposit was 0.008 g/co? The distance between the polyimide sheet and the copper formate was 20M1. The heating rate of the copper formate was 16°C/min between 130 and 165°C.

After plating a predetermined length, the container was opened, allowed to cool to room temperature, and the polyimide through-hole substrate was taken out.

The thickness of this copper film, including the inner wall of the hole, was 0.5 to 0.7 -, the surface resistance was 0.06 to 0.1 Ω/mouth, and the dimensional change rate between the holes was 0.06%. .

Next, this polyimide through-hole board was electrolytically plated with copper to give a copper film thickness of 10 J.
After annealing for a minute, the adhesive strength of the copper foil was measured to be 0.8 kg/cm, and the surface from which the copper foil was peeled was a glossy surface.

Example 2 In Example 1, the polyimide sheet was replaced with a thickness of 0.
4mm perforated glass fiber reinforced 4 cyanato resin laminate (
Manufactured by Mitsubishi Gas Chemical ■, product name: Nitrite CCL IIL
Using a laminate (without copper foil for 810), I fixed both ends with polyimide fasteners to make 10 sheets in a row, preheated at 230℃ for 30 minutes, and set the plating hot plate temperature to 2.
A through-hole substrate was obtained in the same manner except that the temperature was 30°C.

The thickness of this copper film, including the inner wall of the hole, was 0.5 to 0.7 -, the surface resistance was 0.06 to 0.1 Ω/mouth, and the dimensional change rate between the holes was 0.02%. .

Next, the adhesive strength of the copper foil was measured in the same manner as in Example 1 with a copper film thickness of 10 ccm, and it was found to be 0.8 kg/cm.
Met.

[Operation and effects of the invention]

According to the manufacturing method of the present invention as described above, a copper film with excellent adhesion, including inside the holes, is formed without any adhesive layer (in the case of polyimide film, copper film is formed without any adhesive layer). The foil adhesion surface becomes a glossy double-sided copper-clad through-hole polyimide film.) A through-hole board is obtained which has excellent dimensional accuracy and can be applied to everything from flexible to rigid boards.

This through-hole board can be used as is, but since the adhesion strength after plating is extremely high, it is extremely easy to plate it and manufacture ultra-thin copper foil-clad through-hole printed wiring boards with a copper foil thickness of 5 to 12 A3. Because it can be done, its industrial significance is extremely high.

[Brief explanation of drawings]

Fig. 1 is an example of a conceptual diagram of a manufacturing apparatus for through-hole circuit boards according to the present invention using a continuous method, Fig. 2 is an example of a heating method in a vacuum plating chamber, and Fig. 3 is a diagram showing an example of a heating method in a vacuum plating chamber. This is an example showing the area around the reduced pressure plating chamber when the plating is coated and supplied. Patent applicant Mitsubishi Gas Chemical Co., Ltd. agent (9070) Patent attorney Sadafumi Kobori No. 1 Figure 1 O°Perforated L Reimi F sheet ↓ C0'& Processing tank Figure 2 Figure 3

Claims (1)

[Claims] 1. A perforated plate (
a), and the perforated plate (a) is kept in a heating device in a non-oxidizing atmosphere or under reduced pressure at a temperature of 165°C or higher and below the permissible temperature for dimensional change of the perforated plate (a). At the same time, copper formate was introduced at a temperature of 130°C to 165°C at 1 degree. The perforated plate (a) is continuously introduced into the heater so as to raise the temperature at a rate of 1/min or more, and after holding both at an interval of 5 cm or less for a predetermined period of time, the perforated plate (a) is taken out. This is a method for manufacturing a through-hole board with a thickness of 0.1 to 5 μm in which copper is adhered. 2. The method for manufacturing a through-hole substrate according to claim 1, wherein the amount of copper formate supplied is 0.001 g/cm^2 or more per total surface area of the perforated plate (a). 3. The method for manufacturing a through-hole substrate according to claim 1, wherein the perforated plate (a) is a polyimide film. 4. The method for manufacturing a through-hole board according to claim 1, wherein the perforated plate (a) is a laminated board or a multilayer printed wiring board having an inner wiring layer. 5. A method for manufacturing a through-hole substrate, which comprises subsequently electrolytically plating the through-hole substrate according to claim 1 to give a copper layer thickness of 5 μm or more. 6. The method for manufacturing a through-hole board according to claim 5, wherein the electrolytic copper plating is performed at a rate of 0.1 μm/sec or less until the copper layer thickness becomes 5 μm or more.