JPH03266494A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To enable a required fine pattern to be easily formed by a method wherein a solder resist film pattern is deposited on a laminated board which is formed by laminating base materials into one piece, and a chemical plating layer is deposited on a prescribed circuit pattern region. CONSTITUTION:A copper foil is plated on the primary surface of, for instance, a prepreg layer where resin deposited by dipping is semi-cured or partially uncured to form a base board 7, a required through-hole 4 is bored in the board 7, and a photoetching treatment is carried out to form a required circuit pattern 1 on the board 7. The base board 7 is cured into one piece by thermocompression forming to enable the circuit pattern 1 to be buried in the surface of the base board 7, consequently a laminated board 3' whose surface is flattened can be obtained, and a required solder resist film pattern 2 is selectively formed on the surface of the laminated board 3'. The laminated board 3' is subjected to a chemical copper plating treatment, whereby a chemical plating layer 5 is deposited on circuit pattern regions 1a and 4a not covered with the solder resist film 2 to form a required printed wiring board 3. By this setup, a fine patterning can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a printed wiring board, and particularly to a method for manufacturing a printed wiring board suitable for the configuration of a mounted circuit unit.

(Prior Art) In response to the miniaturization of electronic devices and the improvement of circuit functions, so-called hybrid function circuit units have been developed and are now widely put into practical use. In other words, in electronic equipment, for the purpose of simplifying and compacting the configuration, a printed wiring board is used for the wiring part, and a memory IC element, a resistor, etc. are mounted and mounted on the printed wiring board surface. Functional circuit units are known.

However, in the configuration of the above-mentioned hybrid functional circuit unit, there is a third
A printed wiring board is used, the main part of which is shown in cross section in the figure. That is, while it has an inner circuit pattern layer (not shown), a required circuit pattern 1 is provided on the outer surface, and the surface other than the required connection pads 1a and through hole lands 4a is covered with a solder resist film 2. A printed wiring board with a similar structure is used.

Further, the front 86 printed wiring board is generally manufactured as follows. That is, a prepreg layer is interposed between inner layer substrates (base materials) provided with a predetermined circuit pattern, and a copper foil-clad base material is laminated as an outer layer via the prepreg layer, and after being cured and integrated by heating and pressurizing, A desired outer layer circuit pattern 1 is formed by selectively photo-etching the outer layer copper foil. Therefore, the outer layer circuit pattern 1 protrudes from the surface of the printed wiring board 3 by the thickness of the copper foil, or is substantially flattened by the solder resist film 2 being deposited thereon.

(Problem to be Solved by the Invention) However, the printed wiring board 3 with the above configuration is for surface mounting,
In other words, when used for a hybrid function circuit unit, there are the following disadvantages. In other words, in order to improve the surface mounting density of electronic components and to make hybrid functional circuit units more compact, it is necessary to reduce the width of the outer layer circuit pattern 1 of the printed wiring board 3 and the interval between the outer layer circuit patterns 1. will be done. For this reason, not only are adjacent outer layer circuit patterns 1 exposed on the surface easily short-circuited, but also it is difficult to mount and mount the leads 6 of required electronic components such as memory IC elements at predetermined positions without misalignment. However, there are problems such as requiring careful attention and advanced technology, and making the configuration of the hybrid functional circuit unit complicated.

The present invention has been made in response to the above circumstances, and provides a manufacturing method for obtaining a printed wiring board that allows easy formation of a desired fine pattern and does not require complicated positioning of electronic components to be surface mounted. With the goal.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a main surface provided with a required circuit pattern, and
A step of laminating base materials in which the impregnated resin is semi-cured or partially uncured so that at least the circuit pattern is located on the outer surface, and curing and integrating them by pressurizing and heating; a step of selectively depositing a desired solder resist film pattern on the surface of the laminated board; and a step of depositing a chemical plating layer on a predetermined circuit pattern area not covered with the solder resist film. It is characterized by being

(Function) According to the present invention, at least the circuit pattern is located on the outer surface of a base material in which a required circuit pattern is provided on the main surface and the impregnated resin is semi-cured or partially uncured. Since the outer layer circuit patterns are laminated and cured and integrated by heating and pressing, the outer layer circuit patterns are embedded in the base material while being separated from each other, and the surface is flattened. In addition, a solder resist film pattern is selectively deposited on the laminate surface, for example by exposing the connection pad surface, and a chemical plating layer is selectively deposited on the exposed surface, so soldering is easy. etc. will also be reinforced.

On the other hand, since the chemical plating layer formed is thinner than the thickness of the solder resist film, the solder resist film acts as a dam and also contributes to short circuit prevention and positioning.

(Example) The present invention will be described in detail below with reference to FIGS. 1 and 2.

FIGS. 1(a) to (d) are cross-sectional views schematically showing aspects of the manufacturing process of a printed wiring board according to the present invention, and FIG. FIG. 2 is a cross-sectional view schematically showing how the leads of an electronic component mounted and mounted on a printed wiring board are soldered.

First, a blank plate 7 is prepared by laminating copper foil on the main surface of a prepreg layer in which the impregnated resin is semi-cured or partially uncured.
Prepare. Next, after drilling the required through holes 4 in the blank plate 7, the copper foil is subjected to a so-called photo-etching process to form a required circuit pattern 1 (see FIG. 1).
a)).

Thereafter, the base plate (base material) in which the required circuit pattern 1 has been formed and the impregnated resin is semi-cured or partially uncured is cured and integrated by heating and pressure molding to form the circuit pattern. A laminated plate 3' having a flattened surface is obtained by embedding No. 1 into the 7 sides of the blank (base material) (FIG. 1(b)). For example, a photocurable solder resist film 2 is deposited on the surface of the thus obtained laminate 3', and is exposed and developed to selectively form a desired solder resist film pattern 2. That is, in the formed circuit pattern 1, the portions forming the connection pads la and through-hole lands 4a are exposed, and other areas are selectively masked with a required solder resist film 2 (see FIG. 1). C)).

Next, the laminated plate 3' which has been masked as described above
After performing the required plating pre-treatment, a chemical copper plating process is performed to form a chemical plating layer 5 on the circuit pattern areas 1a and 4a not covered with the solder resist film 2, thereby forming the desired print. Wiring board 3
is obtained (Fig. 1(d)).

In the printed wiring board 3 obtained as described above, a part of the patterns 1 on the outer surface that are electrically isolated from each other (embedded in the base material) are covered with a solder resist film 2, while this solder resist film 2 is exposed. As shown in FIG. 2, for example, a memory IC element glue 6 is connected to the connecting pad 1a by soldering. In this case, the risk of short circuits between adjacent connection pads 13 due to solder leakage is completely avoided.

In addition, although the example of the manufacturing method of a double-sided printed wiring board was shown above, it can of course be applied to the manufacturing of a single-sided printed wiring board and a multilayer printed wiring board.

[Effects of the Invention] As explained above, according to the method for manufacturing a printed wiring board according to the present invention, the mounting density is high and the positioning during mounting and mounting of electronic components can be easily performed. A printed wiring board suitable for this configuration can be easily obtained.

That is, since the outer layer circuit pattern and the like can be formed using relatively thin copper foil as a starting material, fine patterning becomes possible. Moreover, since the outer layer circuit patterns and the like are embedded in the support base material, and adjacent circuit patterns are electrically isolated from each other, there is no risk of short circuiting even if the pitch is narrowed. In addition, the solder resist film used in selective chemical plating to reinforce soldering properties helps with positioning and prevents solder flow, making it easier to mount and mount required electronic components.

[Brief explanation of drawings]

FIGS. 1(a), (b), (c) and (d) are sectional views of essential parts schematically showing an embodiment of the method for manufacturing a printed wiring board according to the present invention, and FIG. FIG. 3 is a cross-sectional view of a main part of a conventional printed wiring board for a hybrid functional circuit unit. 1...Outer layer circuit pattern 1a...Connection pad 2...Solder resist film 3...Printed wiring board 3'...Laminated board 4... ...Through hole 4a...Through hole land 5...Chemical plating layer 6...Lead of electronic parts

Claims (1)

[Claims] Base materials each having a required circuit pattern on the main surface and semi-cured or partially uncured resin impregnated with the resin are laminated so that at least the circuit pattern is located on the outer surface. a step of curing and integrating by pressurizing and heating; a step of selectively forming a desired solder resist film pattern on the surface of the laminate obtained by the integration; 1. A method for manufacturing a printed wiring board, comprising the step of depositing a chemical plating layer on a circuit pattern area.