JPH0575261A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To apply and form a solder resist layer simultaneously in the manufacturing process of a multilayer printed wiring board body. CONSTITUTION:Circuit blank boards, in which required conductor patterns 3a, 3b, 3c are applied and formed on the main surfaces of thermoplastic resin insulator layers 1a, 1b, 1c, to which through-holes 2a, 2b, 2c for connection among conductor pattern 3a, 3b, 3c layers are bored, are laminated and unified through heating and pressure molding. Accordingly, the circuit blank boards using a thermoplastic resin as the insulating layers are aligned and laminated, and unified through heating and pressure molding while solder resist layers are unified, thus forming the required solder resist layers, then displaying an excellent liquid-tight state, in which mutual adhesive properties or welding properties are also improved and there is no interface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for manufacturing a multilayer printed wiring board having a thermoplastic resin film as an insulating layer.

[0002]

2. Description of the Related Art In recent years, as one type of multilayer printed wiring board for the purpose of increasing the density of wiring or downsizing of circuit components, a film of thermoplastic resin such as polycarbonate resin or polysulfone resin is used as an insulator. Multilayer printed wiring boards with layers are known. That is, for example, a copper foil is attached to at least one main surface of a thermoplastic resin film having through holes for connection between required conductor pattern layers through an adhesive layer, and a desired conductor is formed by photoetching treatment ( There is known a means for obtaining a required multilayer printed wiring board by forming a (circuit) pattern and then laminating a plurality of the circuit base plates and integrating them by heating and pressure molding.

In the method for manufacturing a multilayer printed wiring board of this type, a so-called solder resist layer is deposited and formed on both exposed main surfaces except the conductive pattern connecting portions in the final step. Provides insulation or surface protection. For example, screen print solder resist,
This is cured by heat or ultraviolet rays, or a photosensitive resin layer is applied / formed on the entire surface (such as film sticking or ink application), and this is exposed / developed to obtain the required solder resist layer. Is formed and equipped.

[0004]

However, the following inconveniences are recognized in the above-mentioned manufacturing method of the multilayer printed wiring board, particularly in the deposition / formation of the solder resist.

First of all, an interface unavoidably exists between the main surface of the printed wiring board and the solder resist layer to be deposited / formed. In other words, for the printed wiring board body surface,
Due to the poor adhesion of the solder resist layer deposited / formed on the surface, the surface protection function such as moisture proof cannot be sufficiently fulfilled (water penetrates through the interface). There is a problem that the migration of the conductive pattern and the deterioration of the surface resistance are caused and the reliability is lowered.

Secondly, in the case of depositing / forming the solder resist layer, there is a problem in that the resolution of screen printing is limited and it cannot be applied to fine patterning of high density wiring. Moreover, when the screen printing means is applied, a screen printing machine and a curing means (for example, an oven) are required in addition to the manufacturing apparatus for the main body of the multilayer printed wiring board, which is not only a large scale in terms of equipment, but also in each use. Since the screen plate is washed with an organic solvent, there is also a problem in the working environment. On the other hand, when a photosensitive resin layer is deposited / formed (film sticking or ink application) and exposed / developed to form a required solder resist layer, compared to the case of the screen printing described above. Although the problem of resolution is solved, it requires equipment for exposure and development, and especially in exposure equipment, there is a problem that equipment investment will be large, such as cutting off light of a specific wavelength in the work environment. is there. Further, in the development process after exposure, there is a problem that a dedicated facility corresponding to the problem of treating the waste liquid is required regardless of whether an organic solvent or an aqueous solution of acid or alkali is used as the developer.

The present invention has been made to solve the above-mentioned problems, and a large scale is achieved by simultaneously applying and forming a so-called solder resist layer in the manufacturing process of the multilayer printed wiring board body, that is, in the process of stacking and integrating. It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board by a simple process while eliminating the need for special equipment.

[0008]

A method of manufacturing a multilayer printed wiring board according to the present invention provides a required conductor pattern on a main surface of a thermoplastic resin-based insulator layer having through holes for connection between conductor pattern layers. In a method for manufacturing a multilayer printed wiring board, in which circuit substrate plates formed by deposition are laminated and integrated by heating and pressure molding, a connecting portion is provided on the exposed conductor pattern surface side of the laminated circuit substrate. It is characterized in that a thermoplastic resin layer of the same kind as the above-mentioned insulating layer, in which a portion corresponding to the formed conductor pattern area is selectively cut off, is further laminated and integrated by heating and pressure molding.

[0009]

In the method for manufacturing a multilayer printed wiring board according to the present invention, the thermoplastic resin film substantially forming the solder resist layer is fused and integrated with the exposed main surface in the heat and pressure molding step. That is, a circuit board having a thermoplastic resin as an insulating layer is aligned / laminated and integrated by heating / pressure molding, and at the same time, a solder resist layer is integrated to provide a multi-layer having a required solder resist layer. A printed wiring board is obtained. Moreover, since the thermoplastic resin layer forming the solder resist layer is of the same kind as the thermoplastic resin forming the insulating layer of the circuit board, mutual adhesion or welding is good and there is no interface. A liquid-tight state is exhibited.

[0010]

Embodiments of the present invention will be described below with reference to FIGS.

First, as the thermoplastic resin film, three polysulfone resin films 1a, 1b and 1c having a thickness of 100 μm and cut to the required dimensions are prepared, and the required polysulfone resin films 1a, 1b and 1c are prepared. Holes 2a, 2b, and 2c penetrating in the thickness direction were drilled at the positions. Then, on one or both sides of the polysulfone resin film 1a, 1b, 1c, a conductive paste such as Ag paste is screen-printed to a thickness of 10 μm.
Required conductive pattern (circuit pattern) 3a, 3b of about m
Each of 3c was deposited / formed and heated / dried.

On the other hand, two sheets of 10 μm thick polysulfone resin films 4a and 4b cut into the same size as described above are prepared, and predetermined positions of these polysulfone resin films 4a and 4b, in other words, a print finally formed. Holes 5a and 5b penetrating in the thickness direction are formed by pressing in regions corresponding to the connecting portions 3a 'and 3b' of the conductive patterns 3a and 3b exposed on the wiring board surface, for example, the connecting portions of the electronic components to be mounted and mounted. Drilled.

Thereafter, a circuit base plate having the polysulfone resin films 1a, 1b and 1c as an insulating layer and polysulfone resin films 4a and 4b having through holes 5a and 5b at predetermined positions are shown in FIG. Position and stack as shown in cross section. Set the above-mentioned laminated laminate on a predetermined press machine, for example, temperature 140-160 ℃, pressure 2kg / cm
Integrate by heating and pressure molding at ^{2 to} 10 kg / cm ² . In the integration stage by this heat / pressure molding, the through holes 2a, 2b of the polysulfone resin films 1a, 1b, 1c forming the circuit board are formed.
In the portion 2c, the conductive pattern (circuit pattern) 3a,
While the required electrical connection between 3b and 3c is achieved,
The facing surfaces of the polysulfone resin films 1a, 1b, 1c, 4a, 4b are also fused and easily integrated. That is, FIG.
Thus, a multilayer printed wiring board is manufactured in which solder resist layers are integrally adhered and formed on both main surfaces of which the principal part is shown in cross section.

In the above, when the conductive patterns 3a, 3b, 3c are formed of a conductive paste using a thermoplastic resin as a binder, both the thermoplastic resin layer and the thermoplastic resin layer are thermoplastic in the heating and pressure molding process. Effectively works, and the connection between the conductive patterns 3a, 3b, 3c is made easier. Further, as described above, by setting the thickness of the outer polysulfone resin film 4a, 4b that substantially functions as a solder resist layer to be relatively thin, the outer conductive patterns 3a, 3b, etc. may be broken or damaged. Easily resolved or avoided.

In the above description, a polysulfone resin film is used as the thermoplastic resin film forming the main insulating layer (insulating base material) and the solder resist layer, but the thermoplastic resin film is not limited to this. , For example, polysulfone resin, polycarbonate resin, polystyrene resin, polyethersulfone resin, polyacetal resin, polyetherketone resin, polyetherimide resin, polyphenylene sulfide resin, polyphenylene oxide resin, acrylic resin, polyethylene resin, ABS resin, polyamide resin, Films of polyvinyl chloride resin, fluororesin, polyetheretherketone resin and the like can be used. Also, the thickness and the number of layers to be multilayered can be appropriately selected and set according to the application of the multilayer circuit board to be manufactured.

On the other hand, the conductive paste is not limited to the above-exemplified silver paste. For example, gold, copper, nickel, tungsten, or the like may be used with the above-mentioned thermoplastic resin as a binder.
Metal powder such as tin, molybdenum, aluminum and platinum,
It is also possible to use one in which a semiconductive powder such as carbon powder, silicon carbide powder, vanadium pentoxide powder, etc. is contained and dispersed. Furthermore, the deposition / application of the conductive paste (formation of the conductive pattern) is performed by screen printing. Alternatively, a method such as offset printing can be adopted. Further, the conductive pattern may be formed not by the conductive paste but by etching, for example, a laminated copper foil.

[0017]

As described above, according to the present invention, a multilayer printed wiring board in which a solder resist layer is densely integrated with a main surface of the multilayer printed wiring board can be easily manufactured by simultaneous molding. That is, since a thermoplastic resin layer of the same type as the thermoplastic resin that constitutes the insulating layer of the multilayer printed wiring board body is laminated, and because they are heat-sealed and densely integrated, there is no room for forming an interface, Completely eliminates the risk of water intrusion. Therefore, in the multilayer printed wiring board, problems such as migration of conductive patterns and deterioration of electric resistance are avoided, and a highly reliable function is always exhibited. On the other hand, complicated operations in the manufacturing process have been largely eliminated, and the manufacturing equipment has been simplified, which can be said to greatly contribute to cost reduction.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an embodiment example of a method for manufacturing a multilayer printed wiring board according to the present invention.

FIG. 2 is a sectional view showing a structural example of a main part of a multilayer printed wiring board obtained by a manufacturing method according to the present invention.

[Explanation of symbols]

1a, 1b, 1c, 4a, 4b ... Thermoplastic resin insulator layer (polysulfone resin film) 2a, 2b, 2c, 5a, 5b ... Through hole
3a, 3b, 3c ... Conductive pattern 3a ', 3b' ... Surface connection part

Claims (1)

[Claims] 1. A thermoplastic resin in which through holes for connection between conductor pattern layers are formed is laminated on a circuit board having a required conductor pattern formed on a main surface of an insulating layer, and heating and pressing are performed. In a method for manufacturing a multilayer printed wiring board integrated by molding, on the exposed conductor pattern surface side of the laminated circuit element boards, a portion corresponding to a conductor pattern region forming a connection portion is selectively cut off. A method for manufacturing a multilayer printed wiring board, which comprises further laminating a thermoplastic resin layer of the same kind as the insulating layer and integrating them by heat / pressure molding.