JPS5939094A - Method of producing printed 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 Object of the Invention The present invention relates to a method of manufacturing a printed circuit board, and more particularly to a method of forming a component mounting pattern of a printed circuit board in If\.

BACKGROUND OF THE INVENTION With the recent development of electronic devices, the density of printed circuit boards and circuit boards has been increasing. In particular, axial components have traditionally been the mainstream for components mounted on printed circuit boards, but with the increasing density of printed circuit boards, the use of flannel back components has increased, and recently axial components and fugit back components have been mounted on the same printed circuit board. Mixed products are becoming mainstream. Here, a conventionally known method for manufacturing a printed circuit board will be explained with reference to the drawings. Note that the printed circuit board referred to herein also includes a copper-clad laminate.

First, a method for manufacturing a normal solder-plated through-hole printed circuit board will be explained. FIG. 1 is a sectional view of a printed circuit board showing how the printed circuit board is manufactured by this method.

A necessary hole 3, that is, a through hole, is drilled in a predetermined position in the printed circuit board 1, and an activation process is performed on it. By performing I plating and further performing electrolytic copper plating 4, the copper foils 2 on both sides are electrically connected through the conductive layer 5 inside the hole 3. Next, a predetermined pattern is left by a silk screen method, a photoprint method, etc., and other parts are covered with a resist 6. Furthermore, solder plating 7 is applied to the parts not covered by the resist 6, and after peeling off the resist 6, an etching process is performed to melt and remove unnecessary steel parts. Overhang is removed to form a predetermined pattern.

The printed circuit board produced using this method has the following drawbacks.

(1) Recent high-density printed circuit boards have very small through-pole diameters, and the above-mentioned overhang removal process after solder plating causes solder clogging in the through-holes, making it impossible to detect defects in the through-holes.

(II) Due to the solder hole υ of the through-hole described above, mounting of axial parts becomes 1t in Japanese language.

(Ill) The solder wire υ inside the through-hole makes it difficult to conduct wiring for repairs or the like through the through-hole.

OV) Removal of solder overhang adds heat load to the printed circuit board.

Next, a method for manufacturing a copper-plated through-hole printed circuit board will be explained. FIG. 2 is a cross-sectional view of a p-printed board showing how it is manufactured by this method.

'it fR Hole plating process and steps are the same as those for solder plated printed circuit boards. Next, a photoresist film 8 is pasted on the surface of the printed circuit board, the predetermined wiring pattern and the surface of the hole 5 are covered by photoprinting, etc., and unnecessary fr and copper parts are removed by etching, and the predetermined pattern is formed. make.

There is also a method of coating the inside and surface of the hole with a dipping or roller method @Kyoyoshi sensitizer film, and after drying, forming a predetermined pattern using the shahei-yakikin method or the like.

The /C printed board thus produced has the following drawbacks.

(I) Since there is no solder on the pattern, it is necessary to print the solder base 1 in a predetermined pattern in order to mount flat pack components, which requires a large number of man-hours. As a result of various studies, we have discovered a method that combines only the advantages of conventional methods, and have arrived at the present invention.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for manufacturing a printed circuit board that allows selective formation of a solder plating pattern portion and a copper plating pattern portion.

In the present invention, after copper plating is applied to the copper parts on both sides of a printed circuit board so that the copper parts are electrically conductive through through-holes, solder plating parts, copper plating parts, and parts not having solder plating or copper plating are selected on the printed circuit board. The method is characterized by a method for manufacturing a printed circuit board.

Embodiment of the Invention An embodiment of the invention will be described with reference to FIGS. 3 and 4. FIG.

FIG. 3 is a sectional view of a printed circuit board showing how the printed circuit board is manufactured by the method of the present invention. A hole 3 is made at a predetermined position on a printed circuit board 1 having copper foils 2 on both sides, and is subjected to activation treatment and electroless copper plating, and further electrolytic copper plating 4 is performed.

By electrolytic copper plating, a conductive layer 5 is formed, and the copper foils 2 on both sides are electrically conductive. Next, using a photoprinting method or the like, the flat pack component mounting portion is left and the other portions are covered with a resist 6, followed by solder plating. Solder plating 7 is solder plating applied to the flat pack component mounting area. After that, the resist 6 is removed, and then the solder-plated part and the hole 3 are covered with a resist 6 using a photoprinting method, screen method, etc., and then etched with an eraking solution such as ferric chloride. Dissolves and removes only copper.

After that, by removing the resist on the circuit, a printed board is completed in which only the flat pack component mounting pattern is formed by solder plating 7, and the hole 3, which is the axial component mounting portion, is formed by copper plating 4. If anti-corrosion treatment of the circuit is particularly required, for example, snow-free and detinning plating 9 is performed.

Furthermore, a solder mask 10 made of epoxy resin or the like is applied as a solder bridge prevention treatment during soldering.

Next, other embodiments of the present invention will be described.

FIG. 4 is a cross-sectional view of a printed circuit board showing the process of manufacturing the printed circuit board by this method. Holes 3 are made at predetermined 18'r positions on a printed circuit board 1 having copper foils 2 on both sides, and subjected to field activation treatment and electroless copper plating, and further electrolytic copper plating 4.

A conductive layer 5 is formed by this electrolytic steel plating, and the copper foils 2 on both sides are electrically conductive. Next, after covering the holes 3, component mounting areas, and other circuit patterns with a resist 6 using a photoprinting method or the like,
All patterns are formed by etching using an etching solution such as ferric chloride. Thereafter, fludge plating 12 is performed on the entire surface by chemical copper plating. Next, by photo-printing or the like again, the flat pack mounting pattern is left and other parts are covered with the resist 6, and after Hirata plating 7 is applied, the resist 6 is removed.

Next, flash etching is performed using an alkaline type etching solution to dissolve and remove unnecessary copper, thereby forming a pattern. After that, by carrying out the above-mentioned rust prevention treatment and solder bridge prevention treatment, only the flat back component AF mounting pattern was formed with solder plating 7, and the rust prevention treatment was applied to the hole 3f which is the open/kill component mounting part. A printed circuit board formed with a copper plated pattern is obtained.

The printed circuit board produced by the method of the present invention has the following advantages: (11) There is no need to remove the overhang of the solder plating pattern, and no through-hole jamming occurs. easily discovered.

(11) Since the through-hole jam described above does not occur, it is easy to mount axial components.

(Town: Because the through-hole clogging mentioned above does not occur,
It is easy to wire for repairs, etc. inside or through the through-holes.

(1v) Since the flat pack component mounting pattern is solder-plated, it is possible to easily mount the flat pack component, and the conventional solder paste printing work can be abolished.

(V) Since there is no overhang removal of the solder plating pattern, there is no heat load on the printed circuit board.

As described in detail, according to the present invention, a solder plating pattern and a copper plating pattern can be selectively mixed and formed on the same printed circuit board, and a printed circuit board without through-pole clogging can be obtained. .

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a printed circuit board showing the process of manufacturing the printed circuit board by a conventional method, and FIGS. 3 and 4 show a printed circuit board manufactured by a method according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of the substrate showing the process in which it is removed. 1... Printed circuit board 2... Copper foil 3... Hole
4...Copper plated 5/Conducting layer
6.Resist 7.Solder milling 8.Sensitive C film 9.Electroless tin plating 10.Solder mask 12.Flash plating copper 3 ports

Claims (1)

[Scope of Claims] A printed circuit board manufacturing method characterized by selectively forming plated portions and portions that are neither solder plated nor copper plated. 2. After performing the copper plating, a second half solder plating process is performed in which the parts to be solder plated on the printed circuit board are left and the other parts are covered with a first resist, and after the first resist is removed, the Leaving the areas where the copper plating should be removed, cover the other areas with a second resist and perform an etching process,
2. The printed circuit board manufacturing method according to claim 1, further comprising removing the second resist. 3 After applying the copper plating, leave the part on the printed circuit board where the copper plating should be removed and cover the other part with the first resist, and then perform an etching process to remove the first resist. The entire surface of the removed hindlimb printed circuit board is plated, leaving the parts that should be solder plated and covering the other parts with a second resist, performing a second half solder plating process, and removing the second resist. 2. The printed circuit board manufacturing method as set forth in claim 1, wherein the plated parts other than the second half solder plated part are removed by 4'fK'.