JPS5999787A - Thick film printed circuit board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a thick film wiring board, and more particularly to the shape of a wiring connection pad that facilitates modification of the printed wiring connection. ′□ (bl Technology background ・ ・：
'□In recent years, with the practical application of semiconductor integrated circuits (■c) and large-scale semiconductor integrated circuits (・r,,5lt), □Electronic equipment and other areas have been rapidly hiring, and wide A bE ( However, as high-density packaging of B-line products is required, printed B-line boards are becoming more and more common.
It is becoming more frequent and multi-layered.

(C), Prior art and problems.

A conventional multilayer printed wiring board is formed by laminating a plurality of printed laminates each having a printed circuit formed by selectively etching the copper and cladding of a laminate made of a copper-clad glass fiber-containing epoxy board.

On the other hand, electronic devices and appliances that are used under harsh environmental conditions, such as high temperatures and severe mechanical vibrations, 2. For example, printed board circuits used in automobile electronic equipment and appliances can be made of ceramic or enamel plates made of iron plates treated with glue instead of general synthetic or resin-printed laminates. used as a substrate.

A single layer or multilayer circuit formed by a thick film method is disposed on the substrate.

FIG. 1 is a partially cross-sectional perspective view conceptually showing an example of the structure of a part of the thick film wiring board.

A wiring 2 is formed on the surface of a ceramic substrate 1 using a conductive paste such as copper or silver palladium by a thick film method, and a wiring connection pad 3 is connected to the tip of the wiring 2. These wirings are screen printed on a ceramic substrate using the above conductive paste according to the thick film method, and then baked at about 900 DEG C. in an electric or nitrogen furnace. Thereafter, an insulating layer 4 formed by baking glass powder or the like is used to cover the entire surface of the board 1, leaving the wiring connection pads 3, to cover the wiring and passive components (not shown in the figure) that are simultaneously formed using a thick film method. protect.

The above has been described with respect to the surface layer or single layer structure, but if it is necessary to perform multilayer printed wiring to increase the packaging density, the second wiring 5 and its A second insulating layer 6 is formed thereon. This method of forming multilayer printed wiring in layers one on top of the other as required is called an additive method. Wiring connections between the eyebrows do not involve through-hole plating as is the case with general printed board circuits, but the necessary circuit connections are made between circuit wires on different layers each time the wires are formed.

The electronic component 9, for example, the resistor chip 7, is connected to the wiring connection pad 3 by soldering to the external terminal 8 of the resistor chip 7. 9 is a resistor.

On the other hand, electronic devices such as computers are constantly being improved.
Also, user requirements are changing rapidly.

It often happens that the circuit wiring connections of the above-mentioned thick film wiring board are modified or changed. At this time, when connecting a new circuit, use polyurethane-coated copper wire 10, etc., as shown in Figure 1.
- This is done by soldering to the wiring connection pad 3 or the terminal portion 8 of the electronic component. This soldering process is troublesome and reduces reliability. In particular, when trying to cut wiring formed in the inner layer, it is difficult to cut the wiring formed in the inner layer.

There has been a long-awaited desire for some kind of means that would facilitate the modification of wiring connections as described above.

(d) Purpose of the Invention The present invention has been made in view of the above-mentioned points.It is an object of the present invention to improve the shape of wiring connection pads formed on the surface layer of a thick film wiring board to facilitate changing the wiring connections of the board. That is.

tel Structure of the Invention The object of the above invention is to provide a thick film wiring board having an inorganic material such as ceramic or enamel as a substrate, and a first extension portion coated with solder on a predetermined wiring connection pad of the thick film wiring board. This can be easily achieved by providing a second extension part through the narrow part to form a modified wiring connection pad and an inner layer wiring connection pad, respectively.

(fl Embodiments of the Invention Examples of the present invention will be described below with reference to the drawings. FIGS. FIG. 2 is a partial plan view and a partial cross-sectional view.

As shown in the figure, the conventional wiring connection pad 3 is extended to form a modified wiring connection pad 3a and an inner layer wiring connection pad 3b. This is not attached to all wiring connection pads 3, but to pads 3 where wiring connection changes or modifications are expected in advance.
It is attached to.

In addition, as seen in FIG. 2 (al), a notch is provided in the inner layer wiring connection pad 3b at the connection part with the original pad 3 so that the wiring connection can be easily disconnected, and a narrow part 3c is formed. has been done.

Furthermore, the insulating layer 4 shown by dotted lines in FIG.

The bands 3.3a, 3b are covered with solder by screen printing a solder paste thereon and heating it.

Alternatively, the board is coated with solder by dipping the board into a solder bath to prevent the band from oxidizing during storage, and
When making a modified wiring connection, it is convenient to place the connection electrode of the mounted component, which is similarly solder-plated, on the pad and heat it in an electric furnace to make the connection by the so-called reflow method.

(g+ Effects of the Invention As is clear from the above explanation, the modified wiring connection pad 3a and the inner layer wiring connection pad 3b based on the present invention are obtained by extending the wiring connection pad provided on the surface layer of the thick film wiring board. If necessary, if modification wiring is required after completing the thick film wiring board, the modification wiring work becomes extremely easy.

By removing the narrow portion 3c, wiring can be easily cut, and the finish is beautiful and reliability can be improved.

In addition, when connecting modified wiring to wire connection pads or component terminals that have already been soldered, use a soldering iron tip because the soldering surface is not flat due to the existing solder. When the connection wiring is held down, the wiring tends to move laterally, making it difficult to mechanize the modification wiring work.5 However, since the modification wiring connection pad and the inner layer wiring connection pad according to the present invention are flat, the modification wiring work can be easily carried out. The advantage is that automation is easy.

[Brief explanation of the drawing]

FIG. 1 is a perspective view with a partial cross section conceptually showing an example of the structure of a part of a conventional thick film wiring board, and FIG. 2 is an implementation of a thick film wiring board with an improved structure based on the present invention. f showing example
FIG. 3 is a) a partial plan view and (b) a partial cross-sectional view. In the figure, 1 is a ceramic wiring board, 2.5 is a printed wiring, 3 is a wiring connection pad, 3a is a narrow part of the wiring connection pad, 4.6 is an insulating layer, 7 is a chip resistor, 8 is an external terminal, and 9 is an external terminal. A resistor and 10 indicate @ wires for modified wiring, respectively. Figure 2

Claims (1)

[Scope of Claims] A thick film wiring board having an inorganic material such as ceramic, enamel, or the like as a substrate, and a first extension portion in which a predetermined wiring connection bar of the thick film wiring board is coated with solder. □ A thick film wiring board characterized in that a second extension part is provided through the narrow part.・ ′ □：