JPS5814725B2 - Denshikairosouchino Seizouhouhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing an electronic circuit device.

In particular, the present invention relates to a manufacturing method for improving the stability of the resistance value of a resistor formed on a substrate of an electronic circuit device.

Low-temperature firing resistors are formed on the surface of plastic substrates using methods such as printing, which are used in hybrid integrated circuits, etc., to reduce size and save labor in the assembly process.

An example is shown in FIG. 1 and FIG. 2.

That is, copper foil conductor electrodes 2 and 3 are formed on a printed circuit board 1 in a prescribed manner, an undercoat 4 is formed on the substrate between the conductors 2 and 3, and a resistor 5 is printed on this in a prescribed manner. let

Next, silver electrodes 6, 7 of resistors are directly attached to the conductor electrodes 2, 3.
Print and connect the conductor and resistor, respectively.

However, when formed in this way, an oxide film is formed on the surface of the copper electrode of the conductor, so if it is not removed before printing and contacting the silver electrode, the contact resistance will increase and the characteristics will change. Since it becomes defective, it is removed by polishing or etching, and immediately after that, silver electrodes are printed.

Even if it is removed, if it is left for a long time, an oxide film will be formed again and the contact will become unstable.

Furthermore, even after forming the silver electrode, a film may be formed on the surface of the copper electrode, making it difficult to stabilize the resistance value over a long period of time.

The present invention prevents the formation of an oxide film that causes such poor characteristics, improves the contact between the silver electrode of the resistor and the conductor, and improves the stability of the resistance value by soldering the electrode surface of the conductor. The present invention provides an improved method of manufacturing an electronic circuit device coated with a polyurethane.

The method of the present invention will be explained below with reference to the drawings.

As shown in FIG. 3, a phenolic resin copper-clad laminate 11
A necessary conductor pattern 12 is formed on the copper foil by a predetermined method.

After this pattern is formed, solder plating is applied to necessary portions of the conductor to form a thin solder film 13, for example, a film with a thickness of 3 to 5 μm.

The composition of the solder used at this time was 3% Ag and 6.1% Sn.
5%, Pb35.5%, Sn63%, Pb37
% etc.

Next, undercoat 1 is applied to a predetermined portion of the laminate between the conductors 12 with a heat-resistant and moisture-resistant epoxy solder resist.
4.

The resistor 15 is formed by overlapping and printing carbon in a predetermined manner, and is temporarily dried at 120°C.

After forming the conductor and resistor in this way, silver electrodes 16 are connected to the resistor and the conductors on both sides.
The resistor and silver electrode are printed and formed at the same time.
Dry at 50°C.

By coating the conductor with solder in this way, there is no formation of an oxide film, and the contact between the silver electrode of the resistor and the solder surface formed by coating the conductor is stable. There is no change in resistance value, and no characteristic defects occur.

It is particularly stable when left at high temperatures or during high temperature and high humidity tests, and the solder treatment applied to the conductor attachment part to improve solderability with the attached parts is fully effective. It is something.

In addition to solder plating as described above, the conductor can be coated with solder by various solder treatments such as forming a thin film of solder on the conductor using roll solder, and exhibiting the same stabilizing effect as described above. It is something that can be done.

It goes without saying that it is more preferable to coat the resistor with a heat-resistant and moisture-resistant resin after forming the resistor in order to prevent changes in resistance.

[Brief explanation of drawings]

Figure 1 is a plan view of essential parts showing resistors, conductors, etc. formed on the substrate of an electronic circuit device, Figure 2 is a vertical cross-sectional view of Figure 1,
FIG. 3 is a longitudinal cross-sectional view of a main part of a board mounted on the electronic circuit device of the present invention. 11...Substrate, 12...Conductor, 13.
...Solder film, 15...Resistor, 16...
...Silver electrode.

Claims (1)

[Claims] 1. When manufacturing an electronic circuit device comprising the steps of forming a conductor and a resistor for low-temperature firing on a plastic substrate, and then connecting the resistor and conductor with a silver electrode, the surface of the conductor is coated with a silver electrode. 1. A method of manufacturing an electronic circuit device, which comprises coating the electronic circuit device with solder before connecting it to a resistor.