JPS58119695A - Method of producing multilayer printed circuit board - 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 method for manufacturing a multilayer printed wiring board, and more particularly to a method for easily and economically manufacturing a multilayer printed wiring board with excellent heat resistance reliability and wiring accommodation capacity.

Conventionally, in order to increase the number of wires that can be accommodated in printed wiring boards, multilayering using a plated through-hole method has been widely applied. Multilayer printed wiring boards using this technology can form printed circuits using multiple printed wiring boards! A laminated board having an inner layer circuit and a surface layer circuit is produced by heat-pressing bonding via Resoreg, and holes for through-holes are formed with a drill at predetermined positions on this laminated board, and the holes are plated to connect the two layers. It can be manufactured by electrically connecting the circuits.

Multilayer printed wiring boards manufactured by the above method are required to accommodate a significant increase in the number of wires to be accommodated as the degree of integration of integrated elements increases, and the number of printed wiring boards tends to increase year by year. however,
As the number of layers increases, the wiring area on the p1 plane, where the number of through holes for interlayer connections is large, decreases, so even if the number of layers is increased, the number of wires accommodated cannot be improved very much. Therefore, it is necessary to reduce the diameter of the through hole, but as the number of calendars increases, the substrate becomes thicker, resulting in disadvantages such as poor hole machinability and poor plating coverage. Therefore, as the number of wires accommodated increases, the manufacturing yield is extremely reduced, which is a major problem.

Previously, when an integrated element is changed, the printed wiring board on which it is mounted may be required to change its base turn, but in the manufacturing technology of multilayer wiring boards by drilling, this
Since it is difficult to change the meta, you have to start over from the beginning, which is extremely wasteful.

On the other hand, various types of heat-resistant energy-sensitive resin compositions have been developed in the past, but because they only dissolve in high-boiling point solvents or have low molecular weights before curing, they cannot be made into dry films. It is melted, applied to the printed circuit by spinner coating, dipping, etc., and dried.

For this reason, the workability of organic disintegration is significantly reduced due to the dangers in handling and the long drying time.

Furthermore, various types of dry films such as solder masks have a low glass transition temperature and a large coefficient of linear expansion even after curing. When used as an insulating material for this rounded printed wiring board, it has the disadvantage that it expands due to the heat generated from the mounted elements and breaks the circuit conductor.

The present invention has been made in view of the above circumstances, and its purpose is to provide a method for easily and economically manufacturing a multilayer printed wiring board that has excellent wiring accommodation capacity and high heat resistance and reliability. .

Hereinafter, the present invention will be explained in detail with reference to the drawings.

First, as shown in FIG. 1(a), a glass cloth base material is made of Liimide I! A printed circuit board 8 is manufactured by forming a printed circuit 2 on an insulating substrate 1 made of T#4 according to a conventional method. The printed wiring board used here may be a multilayer printed wiring board.

Next, a general formula [where R1 + R'1 are the same - or different and (However, Y
, z represents a bulky atom of water, a methyl group, an ethyl group, an isoglobil group, or a phenyl group, which may be the same or different from each other), and R2 and R'2 are the same or different, and U 1l -C-C-CH-V (where U and V represent a group on the hydrogen atom 19 or a phenyl group, which may be the same or different from each other), and X is a hydrogen atom, a chlorine atom or a bromine atom, where each represents a positive integer] is formed (as shown in FIG. 1(b)).

The polymer represented by the above general formula is a photosensitive phenoxy
It is known as phase-resistant, and its manufacturing method has already been proposed. (Japanese Patent Publication No. 44-16125) A typical method for producing this polymer is based on nine general formulas having a bisphenol structure (where y and z represent a hydrogen atom, a methyl group, an ethyl group, an isonoropyl group, and a phenyl group; (which may be the same or different) is reacted with epichlorohydrin to form a polymer with the general formula % (where U and V are hydrogen atoms, methyl groups, or phenyl groups). which may be the same or different] in pyridine).

In addition, when using light such as ultraviolet rays as energy rays in the energy ray irradiation described later, it is desirable to further sensitize the photoreaction by adding a sensitizer. As such sensitizers, carbonyl compounds such as acetophenone, benzophenone, dimethylaminobenzophenone, and penzoin isoglobyl ether are effective, and as spectral sensitizers, 5-nitroacenaphthene and 1-
Compounds such as nitropyrene are also effective. It is appropriate that these compounds be added in an amount of 1 to 15% by weight based on the polymer.

Additionally, in order to increase the crosslinking density, it is effective to add a crosslinking agent such as an aromatic tetrazo compound, an aromatic bisazide compound, or a polyfunctional vinyl compound, but in order not to increase the linear expansion coefficient of the insulating film, 1 to 20 weight grams of said polymer is desirable.

In forming the energy ray-sensitive polymer layer 4, for example, the polymer acid, a sensitizer and a crosslinking agent added as necessary are dissolved in an appropriate solvent, and this liquid is applied to a flexible support. Apply it on a body film, for example a polyester film, dry it, and then put it on the container? A dry film with a polyethylene structure is prepared in advance by providing a polyethylene cover sheet, the four-layer dry film sheet is peeled off, and an energy ray-sensitive polymer layer made of the above-mentioned polymer is printed on the support film. Place it so that it is in contact with the wiring board, and laminate it with a hot roll laminator. This polyester film may be left as is or may be peeled off during irradiation with the extraction energy. The thickness of the energy ray-sensitive polymer layer 4 thus formed is desirably 50 μm or more in view of the characteristic inopedance of the printed wiring board.

Next, as shown in FIG. #I1 (c), energy rays are selectively irradiated onto the energy ray-sensitive polymer layer 4 through the mask 5. In this case, as shown in FIG. 2, energy rays may be selectively irradiated directly onto the energy ray-sensitive polymer layer 4 from the energy ray source 5. Due to such selective irradiation with energy rays, the irradiated portions of the polymer layer 4 become unnecessary to the solvent 9, while the unirradiated portions remain soluble in the solvent. Examples of such energy rays include visible light-1 ultraviolet rays, X-rays, laser beams, and electron beams.

Next, by subjecting the energy ray-sensitive polymer layer 4 to 46 treatments, the east irradiated portion of the polymer layer 40 is eluted into the solvent, forming through-hole holes r (as shown in FIG. 1). Examples of the developing agent used here include organic solvents such as methylene chloride.

Next, holes 7 for through holes are provided and the dead polymer 1air is
4 is subjected to heat treatment or full-surface exposure to energy rays to flatten the insulation. Next, 1 m 4 of the highly insulating electrical composite was subjected to liquid honing or plasma etching to roughen the surface of the mosquito polymer layer 4 and improve the through holes, and then coated with organic acid, etc. Then, the plating active layer 8 is formed by exposing the area where the conductor circuit is to be formed through a photomask (not shown) and visual processing. A conductor circuit 9 is formed on the plating active layer 8, a 49-layer JO is formed in the through hole r, and a part of the conductor circuit 9 is printed back as described above, thereby manufacturing a multilayer printed wiring board having three or more layers. .

According to the method of the present invention, an energy ray-sensitive polymer layer containing a polymer represented by the general formula as a main component is provided on a printed wiring board on which a printed circuit is formed on the surface of an insulating substrate, and the layer is photosensitive. Fine holes for through holes can be easily formed through a mask or by direct energy beam irradiation and visual processing. Subsequently, the energy ray-sensitive polymer layer after the cough hole formation is subjected to heat treatment or energy ray irradiation treatment to make the layer highly insulating. It is possible to form a highly insulating polymer layer having characteristics such as superior adhesion to an insulating substrate and heat resistance, and a small coefficient of linear expansion. Next, the surface of the layer is roughened by liquid honing or plasma etching, etc., and the wettability of the layer surface and inside of the through hole is improved, and then an activation treatment is performed using an organic acid silver salt, etc. By performing electrolytic plating to form a conductor circuit, a two-layer printed wiring board can be created by electrically connecting it to a printed circuit on the board through through holes. Then, by further forming the energy ray-sensitive polymer layer on top of this and repeating the same operation as above,
A printed wiring board having a multilayer structure of three or more layers can be efficiently manufactured. In the multilayer printed wiring board produced in this way, the diameter of the through hole is smaller than in the case of conventional drilling, so the number of wires that can be accommodated can be greatly increased.

Examples Phenoxy resin synthesized from bisphenol A and epichlorohydrin (8cismtlfi@Polxm@rP
rodu@ts g ) (weight average molecular weight 3.2X1
G) 200)k It was dissolved in pyridine 11, methacryloyl chloride 200P was added dropwise thereto, and the mixture was stirred at 50° C. for 7 hours to react. This reaction solution was poured into methanol 20.J and methacryloylated to obtain a nine-phenol resin.

This phenoxy resin (Zoo) and 5 t of dimethylazonopenzophenone were dissolved in methylene chloride IJK, 1 m
The mixture was coated on a 1 ms I diester film, dried, and covered with a 4-polyethylene film to form a Santoy, H structure, thereby obtaining a dry film of 80 g Illl.

A dry film obtained by the above method is heat-pressed using a hot laminator onto a printed wiring board obtained by photoetching the surface steel foil of a steel-clad laminate (glass cloth base polyimide resin) using a conventional method. Covered in round shape. Next, a photomask in which black circles of 0.15 .phi. were formed on a 1.25 .mu. grid was closely attached to this, and exposure was performed for 10 minutes using a 3 kW ultra-high pressure mercury lamp. By developing this with methylene chloride for 3 minutes, it was printed on a printed wiring board with a grid of 1.25 mm and a diameter of 0.15 mm.
The above polymer layer with holes of -0 was obtained. Next, this substrate was heat-treated at 250°C for 1 hour to make the layer highly insulating. Next, the surface of the scissors layer and the inside of the holes were subjected to liquid honing (2 Kl/ 3) The surface is roughened and rounded. Next, add this to lO
- Apply a silver glutamic acid salt aqueous solution, dry it, and then expose it to an ultra-high pressure mercury lamp through a photomask to deposit silver, which will become the core of the steel plating, only on the parts that will become the circuit, and then leave it unexposed with a lO-weighted acetic acid aqueous solution. of silver glutamic acid was eluted. Next, it was immersed in an electroless steel plating solution (MK-450, manufactured by Muromachi Kagaku Co., Ltd.), and plated steel was deposited to a thickness of 25 μm on the silver pattern to obtain a two-layer printed wiring board. Furthermore, a five-layer printed wiring board was prepared by repeating the same operation as above three times using Mayuki dry film thereon. In addition, for comparison, a printed wiring board with through-hole holes formed using conventional drilling technology was prepared, and the circuit characteristics of both were investigated.

The results are shown in the table below.

As is clear from the table above, in the present invention, the diameter of the through hole formed is smaller than in the case of conventional drilling. A multilayer printed wiring board can be obtained.

Furthermore, the coefficient of linear expansion of the dry film after heat treatment used in the present invention is extremely low at 5×1o,'t, and therefore the dimensional stability is good, so the multilayer printed wiring board prepared according to the present invention was heated at 200°C for 2 hours. After that, even when rapidly cooled to θ°C, no abnormalities such as circuit breakage or insulation layer breakdown were observed. In addition, conventional techniques such as acrylic photocrosslinkable polymer film (manufactured by Hitachi Chemical 5R-1000, thickness 0.075-
), the linear expansion coefficient after crosslinking is 5X10
/l, and after heating to 200℃ for 30 minutes, the temperature is 0℃.
When rapidly cooled, the through hole broke.

As explained above, the method for manufacturing a multilayer printed wiring board according to the present invention has an excellent pattern accommodation capacity, so that the total number of turns t of the multilayer wiring board by drilling can be reduced to 1/'3 of the number of layers.
It is possible to accommodate CiJ in an amount of ~IA, and together with the reduction in manufacturing steps and improvement in yield, it is possible to significantly reduce manufacturing costs.

In addition, the multilayer printed wiring board obtained according to the present invention has high heat resistance and excellent dimensional stability. It is extremely reliable as it does not cause any breakage.

Furthermore, the manufacturing method of the present invention can be applied only to parts of printed wiring boards that require high-density wiring (for example, parts where highly integrated elements such as ultra-L81 are mounted), and it is possible to It is extremely economical because it can easily deal with circuit deformation caused by current.

[Brief explanation of drawings]

FIGS. 1(a) to (f) are cross-sectional views showing the manufacturing process of the multilayer printed wiring board of the present invention, and FIG. 2 is a cross-sectional view (8) showing the process of directly irradiating the energy-sensitive polymer layer with energy rays. It is. 11・i Insulating board, 2...Printed circuit, 3...Mark-U
! ! [i ray plate, 4... energy ray sensitive polymer layer,
5... Photomask, 6... Energy M source, 7.
...Through-hole hole, 9...Conductor circuit, 10...
conductor layer.

Claims (1)

[Claims] On a printed wiring board on which a printed circuit is formed, a printed wiring board of the general formula [wherein a, , R/, are the same or different and ZZ
Z
(However, Y and z represent either a hydrogen atom, a methyl group, an ethyl group, an isoglobil group, or a phenyl group, and these may be the same or different and represent a thyl group or a phenyl group, and these may be the same as each other) ), X represents a hydrogen atom, a chlorine atom, or an ionic atom, and Crow represents a positive integer]. Step of forming a layer, selectively irradiating energy rays on this polymer layer, forming holes for through-holes, and heat-treating or irradiating this polymer layer with energy rays to achieve high insulation. forming a conductor circuit by plating on the highly insulating polymer layer, and electrically connecting the conductor circuit to the printed circuit on the printed wiring board through the through-hole hole. A method for manufacturing a multilayer printed wiring board that requires waiting.