JP3780535B2 - Method for manufacturing printed wiring board - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing a printed wiring board used in various electronic devices such as a video tape recorder.
[0002]
[Prior art]
In recent years, various electronic devices such as video tape recorders have become increasingly complex electronic circuits due to the trend toward multi-functionality and simplified operation, and printed wiring boards used in these electronic devices have a wiring capacity or surface mounting density. Therefore, the conventional single-sided printed wiring board cannot process the circuit, and the use of the printed wiring board in which through holes for front and back conduction are formed using plating or conductive paste is increasing.
[0003]
A conventional printed wiring board and a manufacturing method thereof will be described below.
FIG. 3 shows a conventional printed wiring board in which through holes are formed and a method for manufacturing the same. In FIG. 3, 1 is a printed wiring board, 1a is an insulating substrate, 1b is copper foil, 1c is a copper plating layer, 2a is an etching resist, 2b is a conductor pattern, 3 is a through hole, 3a is a through hole, and 3b is conductive. It is a sex paste.
[0004]
About the printed wiring board comprised as mentioned above and its manufacturing method, the operation | movement is demonstrated below.
[0005]
First, as shown in FIG. 3 (a), through holes 3a are formed on a double-sided copper-clad laminate in which copper foil 1b is laminated on both sides of a paper base phenolic resin laminate constituting the insulating substrate 1a. Form.
[0006]
Next, as shown in FIG. 3B, in the through hole 3a for the through hole of the insulating substrate 1a and the copper foil 1b, the conductive paste 3b is applied by a pin having a conductive paste attached to the tip or screen printing. After being filled and applied, heat treatment is performed at a predetermined temperature and time, and the conductive paste 3b protruding from the copper foil 1b is removed by mechanical means such as polishing.
[0007]
Next, as shown in FIG. 3C, a copper plating layer 1c is formed on the surface of the copper foil 1b or the exposed surface of the conductive paste 3b by an electroless plating method or an electrolytic plating method.
[0008]
Next, as shown in FIG. 3D, an etching resist 2a is formed on the copper plating layer 1c by means of a screen printing method or a photographic development method, and the copper plating layer 1c on which the non-etching resist 2a formation surface is exposed is formed. The copper foil 1b is removed by etching, the etching resist 2a is peeled off, a conductor pattern 2b is formed on the insulating substrate 1a as shown in FIG. 3E, and the conductive patterns 2b on the front and back of the insulating substrate 1a are electrically connected. A printed wiring board 1 is obtained.
[0009]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, after the through hole 3a is formed, the conductive paste 3b is filled and applied to the through hole 3a, and the conductive paste 3b is cured or excessively cured conductive paste 3b is polished and removed. There has been a problem that the process becomes extremely complicated, such as a process of forming the copper plating layer 1c by an electroless plating method or an electrolytic plating method.
[0010]
In addition, in the filling / coating process of the conductive paste 3b, depending on the diameter of the through hole 3a, as shown in FIG. The polished copper plating layer 1c is in a depressed state at the through hole 3a portion for the through hole 3, which causes a problem in inducing soldering and mounting of electronic components.
[0011]
The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a method for manufacturing a printed wiring board that realizes excellent solderability by a simplified manufacturing process.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the printed wiring board manufacturing method of the present invention includes a step of laminating an adhesive sheet formed on a film together with the film on both sides of the insulating substrate, and the insulating substrate, the adhesive sheet, and the film. A step of forming a through hole with a laser, a step of press-fitting a through-hole conductor into the through-hole, a step of peeling the film, and an adhesive sheet formed on the insulating substrate and the through-hole conductor are press-fitted And a step of forming a copper-clad insulating substrate by heating and pressing to form a copper-clad insulating substrate, and a step of forming a conductor pattern by etching the copper-clad substrate of the copper-clad insulating substrate. It is a configuration.
[0014]
[Action]
With this configuration, it is possible to omit the process of applying and polishing the conductive paste and the copper plating process, and the conductor for the through hole is filled while being crushed in the through hole in the heating and pressure bonding of the conductor foil to the insulating substrate. The through hole and the through hole conductor can be maintained in a filled state without a gap by the flow of the softened resin constituting the insulating substrate, and the conductor foil or the smooth state in the through hole portion can be realized.
[0015]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 shows a printed wiring board in an embodiment of the present invention, and FIG. 2 shows a method for manufacturing a printed wiring board in an embodiment of the present invention. 1 and 2, 11 is a printed wiring board, 11a is an insulating substrate, 11b is an adhesive sheet, 11c is a film, 11d is a through hole, 12 is a conductor for a through hole, and 13a is a conductor made of copper foil. 13b is a conductor pattern and 13c is an etching resist.
[0017]
About the printed wiring board comprised as mentioned above and its manufacturing method, the operation | movement is demonstrated using FIG.1 and FIG.2.
[0018]
First, a paper base material is impregnated with a phenolic resin, and a predetermined number of prepregs obtained by polymerizing the phenolic resin in a semi-cured state are stacked, then set in a vacuum hot press machine, molded at a predetermined temperature and pressure, and an insulating substrate 11a is obtained.
[0019]
Next, the adhesive sheet 11b composed of phenol butyral resin and the film 11c composed of polyester resin are overlapped, then set in a vacuum hot press or laminator, laminated at a predetermined temperature and pressure, and FIG. 2 (a). As shown, an insulating substrate 11a with a film 11c and an adhesive sheet 11b is obtained.
[0020]
Next, through holes 11d for through holes having a predetermined diameter are formed in the insulating substrate 11a with the film 11c and the adhesive sheet 11b by means of an NC drill and drill or a carbon dioxide laser beam as shown in FIG.
[0021]
The through hole 11d formed for the through hole has a hole diameter of 0.35 mm and a height of 0.6 mm, and a spherical solder having a melting point of 183 ° C. or higher is used as the through hole conductor 12 in FIG. ). At this time, the volume of the solder is set to 100 to 110% of the volume of the through hole 11d.
[0022]
After press-fitting the through-hole conductor 12, the film 11c is peeled off, the adhesive sheet 11b is exposed, and conductor foils 13a made of copper foil having a thickness of 35 μm are disposed on both surfaces of the insulating substrate 11a. Thereafter, the through-hole conductor 12 is softened by heating and pressurizing with a vacuum hot press machine under conditions of a pressure of about 2 to 4 × 10 ⁴ Pa, a temperature of 180 to 190 ° C., and a heating and pressurizing holding time of 60 to 100 minutes. Then, the through-hole 11d is filled, and a copper / solder alloy layer is formed at the interface between the through-hole conductor 12 and the copper foil constituting the conductor foil 13a, and the smoothness as shown in FIG. A copper-clad insulating substrate with a surface is obtained.
[0023]
Next, after forming an etching resist 13c on the surface of the conductive foil 13a of the copper-clad insulating substrate 13a using a screen printing method or a photo developing method as shown in FIG. 2E, a solution such as cupric chloride is used. The conductor foil 13a composed of the exposed copper foil on the non-formed surface of the etching resist 13c is removed by etching.
[0024]
The etching resist 13c is peeled off to obtain the printed wiring board 11 in which the solder resist is formed on the conductive pattern 13b and the insulating substrate 11a as shown in FIG. 1 or FIG. Transport to solder mounting process.
[0025]
The printed wiring board 11 conveyed to the soldering and mounting process is mounted with electronic components after cream solder is printed and applied at a predetermined position.
[0026]
Next, the printed wiring board 11 on which the electronic component is mounted is heated at an ambient temperature of 210 to 230 ° C., and the solder pattern is melted and solidified after cooling, so that the conductor pattern 13b of the electronic component and the printed wiring board 11 is soldered. Be joined.
[0027]
When soldering the electronic component and the printed wiring board 11, the solder constituting the through-hole conductor 12 and filling the through-hole 11 d rises in temperature to about 150 to 165 ° C., but exceeds its melting point. Therefore, stable soldering, the conductive pattern, and the bonding state of the through-hole conductor 12 can be maintained.
[0028]
As described above, according to the present embodiment, the through-hole conductor is press-fitted so as to penetrate the insulating substrate, and the conductive foil is heated and pressed and bonded to both surfaces of the insulating substrate, and then formed into a predetermined pattern. Thus, the application of the conductive paste to the polishing step and the copper plating step can be omitted, and the depressed state of the conductor pattern in the through hole 11d portion for the through hole can be eliminated.
[0029]
In the embodiment, the insulating substrate 11a was impregnated with a phenolic resin on a paper base material, and a predetermined number of layers were laminated and laminated. However, the insulating substrate 11a was laminated by impregnating a glass fiber cloth or an aramid fiber with an epoxy resin. It is good also as what you did. The adhesive sheet 11b is made of a phenol butyral resin. However, the adhesive sheet 11b may be an epoxy resin, and a glass fiber cloth or an aramid fiber impregnated with an epoxy resin as the insulating substrate 11a. When used, the adhesive sheet 11b is not necessary. Furthermore, although the conductor foil 13a has a thickness of 35 μm, a conductor foil having a thickness of 9 to 70 μm may be used.
[0030]
Further, the solder used as the through-hole conductor 12 is spherical, but it may be rod-shaped or cylindrical.
[0031]
Since the through-hole conductor 12 is a metal, the volume is constant during the manufacturing process, and the through-hole volume can be filled easily without insufficient filling.
[0032]
Furthermore, by using solder as the through-hole conductor 12, the handling is simple and the joining force with the conductor pattern 13b can be easily increased.
[0033]
Since the insulating substrate 11a is formed by laminating sheets made of a plurality of resins, when the conductor foil 13a is heated and pressurized and bonded to the insulating substrate, the through-hole conductors 12 are formed in the through holes by the flow of the softened resin. Can be filled without gaps.
[0034]
【The invention's effect】
As described above, according to the present invention, insufficient filling of the through-hole conductors and variations in the filling state are unlikely to occur, the electronic component is excellent in soldering and mounting, and the manufacturing process can be simplified.
[0035]
Further, since the through-hole conductor is a metal, the volume is constant during the manufacturing process, and the volume of the through-hole can be filled easily without insufficient filling.
[0036]
Furthermore, by using solder as the through-hole conductor, the handling is simple and the bonding force with the conductor pattern can be easily increased.
[0037]
And since the insulating substrate is laminated with a plurality of resin sheets, when the conductor foil is heated and pressurized and bonded to the insulating substrate, the through hole conductor is filled in the through hole without gaps by the flow of the softened resin. It is possible to provide a method of manufacturing a printed wiring board that can be used.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a printed wiring board in an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a method for manufacturing a printed wiring board in an embodiment of the present invention. Sectional view shown [Explanation of symbols]
11 Printed wiring board 11a Insulating substrate 11b Adhesive sheet 11c Film 11d Through hole 12 Through hole conductor 13a Conductive foil 13b Conductive pattern 13c Etching resist

Claims (3)

  Laminating an adhesive sheet formed on a film on both sides of the insulating substrate together with the film, forming a through hole in the insulating substrate, the adhesive sheet, and the film with a laser, and forming a through hole in the through hole A step of press-fitting a conductor, a step of peeling the film, a copper foil is placed on the adhesive sheet formed on the insulating substrate and the through-hole into which the conductor for through-hole is press-fitted, and heated and pressed to form a copper A method of manufacturing a printed wiring board, comprising: a step of forming a tension insulating substrate; and a step of etching the copper tension of the copper tension insulating substrate to form a conductor pattern.   The method for manufacturing a printed wiring board according to claim 1, wherein the volume of the through-hole conductor is 100 to 110% of the volume of the through-hole.   The printed wiring board manufacturing method according to claim 1, wherein the through-hole conductor has a spherical shape, a rod shape, or a cylindrical shape, and is made of metal.

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