JPH0520366U - Printed wiring board - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Fine pitch surface mount components and TAB components,
It is also used when mounting surface mount components having small terminals on a printed wiring board. [Structure] During the manufacturing process of a printed wiring board, a solder d having an appropriate thickness is deposited on a footprint and a pattern by electrolytic solder plating, and then a solder film d is left only on the footprint, and the solder is mounted at the time of mounting the component. To use. [Effect] It is not necessary to print the solder paste, and after mounting the component, short-circuit due to solder does not occur between the fine pitches. The deposited solder film is similar to eutectic solder and is easily melted by heat.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention is used for mounting fine pitch surface mount components, TAB components, and surface mount components having small terminals on a printed wiring board.

[0002]

[Prior Art]

 Normally, when mounting surface mount components on a printed wiring board, a metal plate is used, solder paste is printed in a footprint or round, and then the solder is heated and melted to heat the surface mount component terminals and the printed wiring board footprint. Was connected. A fine-pitch footprint makes it difficult to control the solder paste thickness and align the solder print wiring board.

[0003]

[Problems to be solved by the device]

 In order to mount surface mount components on a printed wiring board, it is necessary to solder the footprints and rounds before mounting. Further, the solder thickness is important in a fine pitch footprint, and the solder paste printing method cannot control the solder thickness. Alignment of the metal plate and the printed wiring board during printing is also difficult at a fine pitch.

[0004]

[Means for solving the problem]

 Except for its drawbacks, this plan deposits a solder of appropriate thickness on the footprint and pattern by electrolytic solder plating during the printed wiring board manufacturing process, and then leaves the solder film only on the footprint. Use the solder when mounting components. In addition, it aims to develop a highly reliable printed wiring board that can be soldered with an appropriate thickness only on a fine-pitch footprint or round, and does not cause solder shorts after component mounting. Is.

[0005]

[Action]

 The solder thickness of electrolytic solder plating can be controlled in units of several microns mainly by controlling the plating bath concentration and composition, current density, plating time, and the like. Also, regarding the composition of the deposited solder, it is easy to obtain a eutectic solder film by controlling the plating bath composition, current density, bath temperature and the like. In order to leave the copper foil pattern, solder plating is performed and the copper foil is patterned using the solder film as an etching resist. Similarly, for the footprint part, the resist fabrication for electrolytic solder plating to deposit the solder film is performed using a highly accurate photographic method.

[0006]

【Example】

 The present invention will be described below with reference to the drawings. The drawing is an embodiment to which the present invention is applied. FIG. 1 is a cross-sectional view of a printed wiring board on which a solder plating resist is produced after through-hole copper plating. A is a photosensitive film such as a solder plating resist or a dry film, which is prepared by a photographic method. b is a copper base and a copper plated part, and c is a base material such as glass epoxy or glass polyimide. FIG. 2 shows a state in which the solder film d is deposited by electrolytic solder plating. FIG. 3 is a cross-sectional view in which the solder plating resist of a is peeled off, and the copper portion is etched by using the solder film as an etching resist with an ammonia-based etching solution to form a pattern. In FIG. 4, since the solder is left only on the fine pitch footprint, the photosensitive film of the dry film is used, and the resist e is left on the solder film by the photo method. In FIG. 5, the solder film is left only on the footprint with a nitric acid-based solution, and the solder film is removed from the pattern portion and the like. Solder peeling is a cross-sectional view after the process is completed. This solution dissolves solder but not copper. In FIG. 6, a copper resist in the pattern portion is coated with a solder resist f for rust prevention and for protection from solder bridges, moisture and the like.

[0007]

[Effect of the device]

 Since this printed wiring board has a solder film with an appropriate thickness only on the footprint, it is not necessary to print the solder paste before mounting, and after mounting the component, a short circuit due to solder occurs between the fine pitches. do not do. The deposited solder film is close to eutectic solder and is easily melted by heat.

[Submission date] July 3, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The drawing is an embodiment to which the present invention is applied. FIG. 1 is a cross-sectional view of a printed wiring board in which a solder plating resist is produced after through-hole copper plating. A is a photosensitive film such as a solder plating resist or a dry film, which is prepared by a photographic method. b copper matrix and the copper plating unit, c is a substrate such as glass epoxy or glass polyimide. FIG. 2 shows a state in which the solder film d is deposited by electrolytic solder plating. FIG. 3 is a cross-sectional view in which the solder plating resist of a is peeled off and the copper portion is etched by using the solder film as an etching resist with an ammonia-based etching solution to form a pattern. 4, to leave the solder only on the footprint of Fainpi pitch is obtained by making a registry e by photography on the solder layer. In this case, photosensitive film Installing tension using a vacuum Ramineta, to keep out air solder edge. Baking the film for using a resist film was slightly larger than the footprint patterns. In FIG. 5, the nitric acid-based solution leaves the solder film only on the footprint, and the pattern film and the like are removed. Solder peeling is a cross-sectional view after the process is completed. This solution dissolves solder but not copper. In FIG. 6, the copper foil in the pattern part is coated with a rust preventive and a solder resist f to protect it from solder bridges, moisture and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view after a solder resist is produced by a photographic method after copper through-hole plating.

FIG. 2 is a sectional view showing a state in which a solder film is deposited by electrolytic solder plating.

FIG. 3 is a cross-sectional view after forming a pattern by etching a copper portion using a solder film as an etching resist.

FIG. 4 is a cross-sectional view after forming a resist to leave a footprint solder.

FIG. 5 is a cross-sectional view showing a state in which the solder on the pattern portion is removed and the solder film remains only on the footprint.

FIG. 6 is a cross-sectional view in which a pattern portion is coated with a solder resist.

[Explanation of symbols]

 a is a solder plating resist b is a copper foil of the pattern part c is a substrate such as glass epoxy d is a solder film deposited by electrolytic solder plating e is a resist for leaving the solder of the footprint f is a solder coated with the pattern part Resist

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[Procedure amendment]

[Submission date] July 3, 1992

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (1)

[Scope of utility model registration request] 1. A pattern is produced by depositing a solder film having an appropriate thickness on a footprint of a printed wiring board on which surface mount components are mounted and a pattern round portion by electrolytic solder plating, and etching excess copper foil. After that, a solder peeling resist is formed on the footprint, the solder film on the pattern part is removed, and the solder film is left only on the footprint.