JPS62130590A - Formation of thick film circuit - 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 for forming a thick film circuit that can be used in radio receivers, television receivers, video tape recorders, and other various communication devices. The present invention relates to a method for forming a thick film circuit by a magnetic printing method using a magnetic toner having a magnetic toner.

Conventional technology Traditionally, thick film circuits have been formed by creating a paint in which precious metals and a small amount of low-melting glass powder are dispersed in an organic binder.
There is a high-temperature firing conductive paint method in which a metal circuit pattern is formed by firing this, and a so-called low-temperature firing conductive paint method in which a circuit pattern consisting of a mixture of metal powder and an organic binder is formed primarily on a plastic insulating substrate. be.

Both of these methods use screen printing technology. Additionally, as a method of forming circuits without using screen printing technology, a method called circuit drawing has been devised and put into practical use in some cases. In order to form a thick film circuit, this method attempts to form a circuit by sending high-temperature firing type conductive paint onto a substrate from a fine-tipped nozzle and sequentially drawing a circuit pattern.

Problems that the invention aims to solve: Since screen printing technology uses mask patterns,
It takes time to replace the mask butter 7 and to clean the mask pattern and squeegee, making it unsuitable for small-lot production or when there are many changes in product types.

The high-temperature firing conductive paint method is highly reliable and allows direct soldering, and is widely used for hybrid ICs, but it requires high-temperature treatment of around 850°C, and the ceramic thick film paste for the substrate is Aa m It is necessary to use a noble metal such as Au, which limits the material and is expensive.

On the other hand, the low-temperature firing conductive paint method does not require high-temperature treatment and is easy to use, but since it contains an organic binder, direct soldering is impossible and the circuit resistance is high.

Furthermore, with the circuit drawing method, you only need to input the route information data to be drawn as numerical values, so you can easily change the pattern, but since you have to draw the entire circuit pattern, it is difficult to form a circuit with a long overall length. Since it takes a long time to complete the process, it is suitable for producing very small quantities, but is not suitable for actual production.

Means/Function for Solving the Problems The present invention solves the drawbacks of the above-mentioned conventional methods, allows any circuit pattern to be directly soldered with the ease of handling equivalent to an office copy, and low-temperature firing, and has a low circuit resistance value. The present invention provides a method for forming a thick film conductor circuit with excellent quality.

That is, the present invention forms a magnetic latent image in a desired reverse circuit pattern on a magnetic drum using a magnetic recording head, develops it with a conductive magnetic toner that does not contain an organic binder, and then converts the magnetic toner into a prepreg. The prepreg is transferred onto a sheet and hardened by firing the prepreg at a low temperature of about 150''C to form a thick film circuit.

In other words, by using a magnetic printing technique, it is possible to uniformly and thickly adhere (develop) conductive magnetic toner to the surface of a magnetic latent image by utilizing magnetic force that is not affected by humidity or the like.

In addition, by using a B-stage prepreg sheet for the substrate, the toner can be transferred to the substrate by the adhesiveness of the prepreg sheet without adding an organic binder to the toner, so the metal parts are exposed on the surface and can be directly Soldering becomes possible.

Furthermore, since it does not contain an insulating organic binder, circuit resistance is reduced and circuit characteristics are improved. The prepreg sheet is still cured at a relatively low temperature (approximately 150'C), so
In addition to precious metals, toner materials include Cu, Al,
A wide range of materials such as NL can be arbitrarily selected depending on desired circuit characteristics.

Further, as a magnetic toner having conductivity, Ni is used.

It is possible to use comparatively more conductive metal magnetic materials such as Co and Fe alone, but their resistance is high, and A
A coated powder provided with a conductive metal layer such as q, 8u, or Cu has excellent conductivity and is suitable. In other words, Ag, Au,
By blending a conductive metal such as Cu, the resistance of the coated powder itself is lowered, and excellent conductivity can be stably obtained by bringing the conductive metal layers on the surface into contact with each other.

Embodiments In embodiments of the present invention, the following components of the conductive magnetic toner are employed.

First, the magnetic material is a necessary component for adhering to the magnetic latent image with magnetic force. Oxide magnetic materials such as ferrite can also be used, but Ni and Co do not inhibit conductivity.

A metal ferromagnetic material with relatively good conductivity such as Fe is preferable, and Ni is particularly preferably used because it is relatively difficult to oxidize. It is preferable that this magnetic material is blended in a range of 5 to 60% by weight of the thick-film magnetic toner. If it exceeds % by weight, the specific resistance is higher than that of noble metals, resulting in high circuit resistance and poor electrical properties.

Conductive materials to be coated by electroless plating with the magnetic material as a core include noble metals or platinum metals such as Au, Ag, Pt, and Pd, as well as Cu, Ni, and A.
Metal materials normally used for conductive circuits, such as I, are used as a single component or in combination. Conductive material is 50-96
Preferably, the proportions are within the range of weight %. In this case, if it is less than 50% by weight, the resistance value will be high, and if it is more than 95% by weight, the balance with other components will be lost and the function will be degraded.

Note that in order to form a high-resolution circuit pattern, it is practical for the particle size of the toner to be in the range of 0.1 to 10 μm.

In this example, the Ni content is 30 wt% and the Cu content is 70 wt%.
As magnetic toner 1, Cu-coated Ni powder having a composition of 1 μm and an average particle diameter of 1 μm was used.

A magnetic latent image is then formed in the equipment shown in FIG. Here, 2 is a hoop-shaped glass epoxy prepreg sheet, 3 is a magnetic drum, 4 is a magnetic recording head, 6 is a degaussing head, 6 is a toner applicator, 7.8.9 is a static eliminator, and 1o is a cleaning glove. , 11 is a preheater, and 12 is a transfer roller. In this case, a γF e 203 coating film is formed on the surface of the magnetic drum 3 as a magnetic recording medium.

In the equipment shown in FIG. 1, a magnetic recording head (ferrite ring head) 4 is driven in the direction of the drum axis in conjunction with main scanning by the rotation of the magnetic drum 3, that is, it is sub-traveled, and a voltage pulse is applied at a predetermined position. This generates a magnetic field, magnetizes a predetermined portion of the surface of the magnetic drum 3, and forms a magnetic latent image with a reverse pattern of the desired circuit pattern.

The magnetic latent image formed on the surface of the magnetic drum 3 is developed with the magnetic toner 1 by the toner applicator 6 section.

Subsequently, the thickness of the developing area is adjusted to a constant thickness using the suction knife 13. In addition, there is a static eliminator.

8.9 is used for the purpose of preventing magnetic toner and dust υ from adhering to unnecessary parts due to electrostatic force.

Now, the reverse pattern of the thick film circuit pattern developed on the surface of the magnetic drum 3 is preheated to 60°C by the preheater 11.
The prepreg sheet 2 heated to 160'C is transferred to a predetermined position on the substrate 2 by feeding it into the gap between the transfer roll and the magnetic drum 3 in synchronization with the rotation of the magnetic drum 3. After cutting, this substrate was heat-pressed at 150''C for 15 minutes to achieve a high resolution of 10 lines per person, a film thickness of 12 μm, and electrical properties (resistance value 50 mΩ/s).
q) A stable thick film conductor circuit was obtained.

Moreover, this conductive circuit can be directly soldered.

In the example, γ-Fθ2o3 (maghematite) was used for the magnetic drum, but other magnetic materials with a coercive force of 30,000 or more and residual magnetization of 1,200 Gauss or more, such as chromium dioxide, cobalt-based iron oxide, or metal magnetic material, may also be used. You can use it as you wish.

Further, as a fixing method, in addition to heat fixing, pressure fixing is also possible.

When switching models, the erasing head 1o demagnetizes the magnetized portion on the magnetic drum 3 while forming a new magnetic latent image, thereby making it possible to quickly respond to the production of a wide variety of products. Since a magnetic latent image is formed using the trench electrical signals, it is also possible to connect to a CAD system for thick film circuits via an interface and directly manufacture thick film circuits based on CAD information.

Effects of the Invention As is clear from the above explanation, according to the present invention, a thick film circuit is formed on a prepreg sheet by a magnetic printing method in which a magnetic latent image is developed using a conductive magnetic toner. By doing so, the following effects can be obtained.

(1) Since magnetic toner is transferred and fixed using the adhesiveness of the prepreg sheet, there is no need to use an organic binder and direct soldering is possible. Also, low temperature (15
In addition to precious metals, Cu, N
A wide range of conductive materials such as i, AI, etc. can optionally be used.

1.2) Since magnetic toner, which has less fluidity than conventional paste, is used in a dry process, high-resolution conductor circuits can be obtained without printing smear.

((2) Since a magnetic latent image is created by electrical signals, CA
It is easy to connect with the D system, etc., thick film circuits can be formed with ease of handling comparable to office copying, and circuit patterns can be changed arbitrarily and in a short time, making it possible to support multi-product production.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of the equipment configuration of the present invention, Fig. 2-
FIG. 3 is a cross-sectional view showing different structural embodiments of the thick film magnetic toner of the present invention used in printing equipment. 1...Magnetic toner (Cu coated Ni powder), 2.
...Glass epoxy prepreg sheet, 3...
・Magnetic drum, 4...Magnetic recording head, 5...
...Demagnetizing head. 6... Toner applicator, 7.8.9...
... Static eliminator, 10... Cleaning brush, 11... Preheater, 12...
Transfer rotor, 13... Suction knife, 14...
... cutter, 15 ... heat pump, 21 ...
...Ni, 22...Cu. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2

Claims (2)

[Claims] (1) A step of forming a magnetic latent image of a desired shape on an object having a magnetic layer, a step of developing this magnetic latent image with a conductive magnetic toner, and a step of transferring the magnetic toner to a prepreg sheet. and curing the prepreg sheet by heating. (2) The method for forming a thick film circuit according to claim 1, wherein the conductive magnetic toner uses coated powder in which a magnetic material is used as a core and a conductive metal layer is provided on the outer periphery.