JPS59117293A - Method of producing electronic circuit 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 Field of Industrial Application The present invention relates to a method of manufacturing an electronic circuit board used in industrial electronic equipment, consumer electronic equipment, and the like.

Conventional array configuration and its problems In recent years, the demand for smaller and lighter electronic devices has been increasing, and the trend toward high-mix, low-volume production has also become stronger. Therefore, in order to meet the above-mentioned demands, the electronic circuits that make these devices function are becoming more and more densely packaged.

For example, to form a conductor circuit, the desired circuit is formed by etching the copper foil of the copper clad laminate according to a pattern specified by the circuit design information. On the other hand, for resistors, capacitors, etc., a method is adopted in which so-called chip resistors and chip capacitors with a size of several η frame angles are supplied to a chip mounter at °C and fixedly connected to a conductor circuit by soldering. Furthermore, when forming an electronic circuit similar to the above on a substrate made of phenol, etc., a conductor paint is screen printed, this is cured at high temperature to form a conductor circuit, and a carbon resistance paint is screen printed between the conductor circuits. However, methods such as curing the material at high temperatures to form a resistor have also been adopted.

These manufacturing methods are typically used to form a conductive circuit on the surface of a board, such as printing photoresist ink on copper foil using a mesh screen or screen printing conductive paste. It is indirectly formed through a screen or negative pattern having a pattern of . However, such a method requires a pre-process of forming a negative pattern on a screen in advance. In addition, although the above method is suitable for mass production of conductor circuits with the same pattern, changing the pattern requires changing the negative pattern on the screen, similar to the trend in electronic devices mentioned above. , it is not possible to respond quickly to the trend of high-variety, low-volume production of electronic circuits.

For this purpose, a manufacturing method for electronic circuit boards has been developed in which a conductive paint is applied directly to the surface of the board according to circuit design information, and a predetermined circuit pattern is drawn and constructed. A method of spraying the paint onto the board in the form of droplets can be adopted, but generally this type of paint has a viscosity of 15,000 to 200 at 25°C.
00 centipoise, making it difficult to spray in the form of droplets. Therefore, electronic circuit forming paints for jetting and drawing have been developed whose viscosity is in the range of 10 to 200 centipoise. Furthermore, when spraying paint, it is common practice to raise the temperature of the paint to 30 to 60°C to lower the viscosity and make it possible to draw circuit patterns by spraying. The paint tends to flow easily, making it difficult to maintain the thickness and pattern of the paint with good precision.
It is difficult to obtain a satisfactory electronic circuit board.

OBJECTS OF THE INVENTION An object of the present invention is to prevent a low viscosity paint from flowing on a substrate in a manufacturing method of manufacturing an electronic circuit board by directly drawing an electronic circuit forming paint on a substrate.

An object of the present invention is to provide a method for applying and drawing paint onto a substrate with high accuracy.

Structure of the Invention The present invention is a method of spraying a paint made by dispersing powder and resin for forming circuit elements in a solvent in a droplet form directly onto a cooled electrically insulating substrate that becomes a base for forming circuit elements. Put it on,
Hereinafter, the manufacturing method of the present invention will be specifically described with reference to examples of predetermined circuit elements.

The electronic circuit board based on the present invention will be explained using one drawing. An electrically insulating substrate 6 is cooled by a cooling plate 14,
The paint sprayed onto the substrate 6 is maintained so that the shape, width, and thickness of the drawn circuit element satisfy the desired performance. In relation to the temperature-based viscosity characteristics of the electronic circuit forming paint, it is necessary to cool the paint by 10°C or more relative to the temperature of the paint. Here, as a cooling method, we used an electronic cooling method that cools the cooling plate using a Bertier element, which is a thermoelectric element, but there are other methods for cooling the cooling plate.
A method of cooling by flowing cooling water or a substance serving as a refrigerant may also be used.

Here, a paint injection head used in an embodiment of the present invention will be described.

The drawings show the configuration of the ink jet recording head and the state of the substrate. In the same figure, 1 is the base container of the injection head,
A piezoelectric element 2 is pasted on its upper surface. 3,4
, 5, 6.7 are respectively a power source for driving the piezoelectric element, a discharge port, a pressure chamber, and an electrically insulating substrate.

It's a pipe. Reference numerals 8, 9, and 10 are a control valve, a paint delivery pump, and a paint reservoir, respectively. moreover.

12 is a head heater, 13 is a head temperature controller,
14 is a cooling plate.

To explain the function of the paint jet drawing head, an electrical pulse is applied to the piezoelectric element 2 from the piezoelectric element driving power source 3, and when the upper surface of the base container 1 is deformed convexly toward the pressure chamber 5, the pressure is The internal volume of the chamber 5 is reduced and the pressure is increased, and the paint 11 is ejected from the discharge port 4 in the form of droplets and is directly applied onto the substrate 6 to write a circuit pattern. Paint is supplied to the head from a paint reservoir 10 by applying pressure with a delivery pump 9 and through a pipe 7 with its flow distribution controlled by a delivery control valve 8.

Naturally, the ejection drawing head can relatively move the positional relationship between the ejection port 4 and the substrate 6 within a two-dimensional plane according to the circuit pattern information.

Furthermore, the amount of movement is controlled so that the paint that is to become each circuit element, including the conductor lines, is applied on the board in a linear manner rather than in a dotted manner.

Regarding the heads described above, specific conditions for each head are as follows.

Piezoelectric element drive frequency: 30 to 40 curves Piezoelectric element diameter: 15m/η2 Coating delivery pressure
・・・・・・3.514/cm Discharge port diameter
---0, 15-0, 30m/m head movement amount
・・・・・・300-500m15/Sec Some of these conditions of the head were taken into consideration from the recent demand for high-density packaging, manufacturing man-hours, etc. in the manufacturing method of the circuit board of the present invention. This is seen as the most needed level.

It was then used in the present invention. The electronic circuit forming paint will be specifically explained. The electronic circuit forming paint used here must be one that can be sprayed and drawn sufficiently at the level of the above head conditions, and the circuit elements drawn on the board must satisfy the desired performance. .

Generally, an electronic circuit forming paint contains at least a circuit element forming powder, a resin component, and a solvent. As the circuit element forming powder, if the circuit element is a conductor, conductive powder,
For example, silver powder, copper powder, etc. are used. If the circuit element is a resistor, carbon powder can be used. As resin components, acrylic resin, polyester resin, xylene resin,
Epoxy resin or the like can be used. As the solvent, any suitable solvent that can dilute the resin component may be selected. The electronic circuit forming paint made of these various components is sprayed in the form of droplets onto an electrically insulating substrate, which serves as a base for forming circuit elements, to draw a circuit pattern.

As mentioned earlier, in order to comply with the recent trend of high-density packaging, for example, if the circuit pattern is a simple straight conductor circuit, the line width must be at least 0.5 m/m or less. Preferably O,;II'-0.3m/m 7b'=
request. Therefore, the above paint has such a line rj
Characteristics that can be drawn with J are not desirable. These paints generally have much lower viscosity at temperatures of 30°C to 70°C than at temperatures of around 26°C or lower, provided the firing temperature is around 100'C to 16Q'C.

Conversely, if the temperature is lowered, the viscosity becomes higher.

Next, the temperature and viscosity of the electronic circuit forming paint used here will be specifically explained.

Silver powder with an average particle size of 1.5μ771 is used as a powder for forming circuit elements, acrylic resin (methyl methacrylate, e.g. Fujikura Kasei MM2002/1) is used as a resin component, and butyl cellosolve is used as a solvent. Conductor lines were drawn on a phenol substrate using the jet drawing head shown. As a result, the crosstalk composition ratio, viscosity at 30'C, and sheet resistance are shown in Table 1. Furthermore, Table 2 shows the viscosity values when the temperature of the sample was changed for the I61°2.3 and 6.7 samples shown in Table 1. Note that the first
table.

The test conditions are the same for both tables, and the paint curing conditions after drawing are 100°C for 1 hour.

Sample 58 in Table 1 (see the margin below) has a circuit pattern that is drawn and has been drawn, and it is difficult to maintain the thickness of the paint due to the large amount of solvent in the paint. Circuit element characteristics cannot be obtained.This is because it is impossible to draw in a line shape at the time of jet drawing, so the low viscosity region is determined to be 10 centipoise.
Ru. In addition, the sample with a flatness of 4.5 is a case in which the desired circuit element characteristics are not obtained even though the paint viscosity is within the desired range, and this is due to the fact that the circuit element forming powder and resin components This is caused by an inappropriate ratio of

Usually, this ratio is 80 to 90 times the object for forming one circuit element.

A resin content of 20 to 10 pieces is appropriate. It is desirable that the paint used complies with these conditions from the viewpoint of resistance value.

As seen in the above examples, the temperature and viscosity of the paint, as well as the injection conditions, shape retention, and viscosity will be described next. If the viscosity of the paint exceeds 200 centipoise, it becomes almost impossible to spray. At this paint viscosity, even if a maximum of 200 Vpp is applied to the piezoelectric element of the drawing head and the piezoelectric element is driven, it will not be possible to draw. However, as shown in Table 2, even with a highly viscous paint, if the head temperature is raised, the paint humidity is adjusted, and the viscosity is lowered, spraying becomes possible. When sprayed and drawn under these conditions, the viscosity of the curd is maintained on a substrate at normal temperature, and it is extremely fluid, with a width and thickness of 1 as a line. It is difficult to maintain the shape as a circuit element. However, as can be seen from Table 2, if the temperature of the paint is lowered by at least 10'C from the temperature of the paint that can be jetted, the viscosity will definitely become impossible to jet, and the formation of circuit elements on an electrically insulating substrate will become impossible. The fluidity of the paint is considerably reduced. Therefore,
Cooling the electrically insulating substrate according to the present invention by 10'C or more relative to the temperature of the paint lowers the temperature of the circuit forming paint directly onto the board by spraying to be lower than the temperature at the time of spraying. It will be cooled by 10°C or more. -10°C is the minimum temperature difference range in which a certain degree of viscosity difference can be obtained.

By using the effect method of the invention, it is possible to prevent the flow and sagging of the circuit element forming paint drawn on the electrically insulating substrate by the jet drawing method, and to accurately form the lines, thickness, and shape of the drawn circuit elements. It enables holding and sintering, and has great industrial value.

[Brief explanation of the drawing]

The drawing is an overall configuration diagram for explaining the method of manufacturing an electronic circuit board according to the present invention. 1...Base container, 2...Piezoelectric element, 3...
...Piezoelectric element drive power supply, 4...Discharge port,
5...pressure chamber, 6...electrically insulating substrate,
7... Pipe, 8... Control valve, 9...
...Paint delivery pump, 10...-Paint reservoir. 11...Sprayed paint, 12...Heater, 13...Temperature controller, 14...
cooling plate.

Claims (2)

[Claims] (1) Droplets of paint made by dispersing circuit element forming powder and resin in a solvent are applied directly to a cooled electrically insulating substrate that will serve as a base for forming circuit elements, and A method for manufacturing an electronic circuit board, comprising forming circuit elements on the substrate. (2) Manufacture of an electronic circuit board according to claim 11, wherein the temperature of the electrically insulating substrate serving as a base for forming circuit elements is lowered by 10'C or more relative to the temperature of the paint. Method.