JPS63241981A - Thick film circuit metal 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 [Object of the Invention] (Industrial Application Field) The present invention relates to a thick film circuit metal substrate in which a thick film-like printed circuit is formed on a metal core insulating substrate.

(Prior Art) In recent years, various types of conductive pastes and dielectric pastes have been printed in the form of thick films on metal-core insulating substrates whose surfaces are coated with insulating coatings such as epoxy resin.

Thick film circuit metal substrates that form printed circuits by firing are attracting attention.

Such a thick film circuit metal substrate has a printed circuit formed on the metal substrate, so it has better heat dissipation than, for example, one using a ceramic substrate.

On the other hand, however, thick film circuit metal substrates having such a structure generally have a problem in that they are prone to conduction defects such as regular disconnections in printed circuits.

Further, in cases where electrical components electrically connected to the printed circuit are mounted on the substrate, there is a problem in that poor conduction between the electrical components and the printed circuit is likely to occur.

As a result of repeated experiments to solve these problems, the inventors of the present invention found that the above problems occur because the physical strength of the metal substrate is weak.

In other words, as metal substrates are often made of flat metal plates with a thickness of about 2" in order to reduce weight, the physical strength of this metal substrate is very weak, and if mechanical stress is applied due to vibration etc. , a small amount of distortion occurs in the substrate.

As a result of such distortion of the substrate, the printed circuit formed on the substrate develops so-called micro-cracks, and eventually becomes disconnected.

Similarly, if an electrical component that is electrically connected to the printed circuit is mounted, the connection between the electrical component and the printed circuit (usually the land part of the printed circuit and the lead terminal of the electrical component is soldered) Stress due to distortion of the substrate tends to concentrate on the parts where the substrate is attached, and as a result, the above-mentioned phenomenon occurs, resulting in a loss of conductivity.

(Problem to be solved by the invention) As mentioned above, in the conventional thick film circuit metal substrate.

It is easy to cause conduction failure in economical printed circuits.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thick film circuit metal substrate that eliminates the above-mentioned drawbacks and can significantly reduce conduction defects in printed circuits.

[Structure of the invention]

(Means and effects for solving the problems) The thick film circuit board of the present invention includes a metal core insulating substrate in which an insulating coating is applied to the surface of the metal substrate, and a thick film-like printed circuit board formed on the substrate. It has a circuit, and is constructed by forming a metal substrate into an uneven shape.

In the thick film circuit board of the present invention, since the metal substrate is formed in an uneven shape, the physical strength of the metal substrate is significantly improved. Therefore, even if stress is applied to this metal substrate, it is difficult for the printed circuit formed on the substrate to undergo minute deformations such as distortion.

Continuity defects such as disconnections in the printed circuit are significantly reduced.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of a thick film circuit metal substrate according to the present invention.

In other words, as shown in the figure, the metal core insulating substrate has nine layers (3) coated with a film thickness of about 40 μm.

Here, as can be understood from the figure, this metal substrate (2) is formed to have a gently uneven shape.

Such a metal substrate (2) is made by, for example, processing a metal flat plate in advance by pressing or the like before applying the insulating coating (3), and it is preferable that the variation value of the unevenness is set to about 1 mm.

On the surface of the metal-core insulating substrate (1) configured as described above, a thick film of various conductor pastes or dielectric pastes, for example, mainly made of copper powder, is printed and fired to form a printed circuit (4). has been done.

1 According to the observations of the present inventors, when printing various pastes on a metal core insulating substrate on which a gradual unevenness of about one step is formed as described above,9 We have confirmed that the technology can be applied.

In other words, some unevenness is formed on the metal core insulating substrate.
However, the fluidity of the printed paste is a problem.

It is presumed that a pattern substantially equivalent to the conventional pattern is formed on this substrate surface.

In addition, by changing the thickness of the insulating coating appropriately according to the unevenness of the metal substrate (2), the unevenness of the insulating coating is alleviated, and in other words, the surface of the insulating coating on which the printed circuit is formed is flattened. Afterwards, a printed circuit may be formed.

According to the thick film circuit metal substrate of this embodiment as described above, the metal substrate is processed into an uneven shape.

The physical strength of the substrate is significantly improved compared to conventional planar substrates.

Therefore, even if stress caused by, for example, vibration is applied,
This substrate is less likely to be deformed, and as a result, minute deformations such as distortion do not occur in the printed circuit formed on the substrate.

Therefore, the occurrence of so-called cracks in the printed circuit due to minute distortions of the substrate is significantly reduced, and conduction defects such as wire breakage can be prevented.

Next, another embodiment of the thick film circuit metal substrate according to the present invention is shown in FIG. 2 and will be described in detail below.

In other words, as in the previous embodiment, the metal core insulating substrate (1) is electrically insulated by being coated with a metal substrate (2) K made of aluminum, for example, which has a gently uneven shape, and an insulating coating (3). is applied.

Further, a thick film-like printed circuit (4) is formed on the surface of this metal core insulating substrate (1).

Furthermore, an electric component (5) such as a semiconductor element or a chip component is mounted on the metal core insulating substrate (11) corresponding to the protrusion (2a) of the metal substrate (2). ) The land portion (4a) of the printed circuit (4) that is electrically connected to the lead terminal (5a) of It's shaking.

In addition, the lead terminal (5a) of the electrical component (5) and the printed circuit (
4) The electrical connection to the land portion (4a) may be made by, for example, reflow soldering.

According to the thick film circuit metal board configured as described above, the portion (connection portion) where the land portion of the electrical component and the printed circuit and the lead terminal of the electrical component are connected.

Since it is provided on the metal core insulating substrate corresponding to the convex part of the metal substrate (2), stress concentration at the connection part due to minute distortion of the board is reduced, and therefore the conductivity of this connection part is reduced. Deterioration can be prevented.

In the above embodiments, the dimensions of the material and the like of the thick film circuit metal substrate of the present invention are described in detail.

The present invention is not limited to this.

In other words, for example, an aluminum substrate is selectively used as the metal substrate in the embodiment, but it is also possible to use a metal substrate such as copper.

In addition to the materials shown in the embodiments, various existing materials can be selected and applied to the insulating coating and various pastes for forming the printed circuit.

Furthermore, as shown in the example 1, for example, if the thickness of the insulating coating is changed to flatten the surface of the insulating coating that forms the printed circuit, the displacement of the unevenness can be reduced to about 1a or more in order to further increase the strength of the metal substrate. However, printed circuits can be easily formed using existing printing methods.

Furthermore, depending on the application, the casing may be formed by bending a part of the metal substrate, such as a part where a printed circuit is not formed.

〔Effect of the invention〕

As described above, according to the configuration of the present invention, it is possible to provide a thick film circuit metal substrate that can increase the strength of the metal substrate and significantly reduce conduction defects in printed circuits.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway sectional view showing an embodiment of the thick film circuit metal substrate of the present invention. FIG. 2 is a partially cutaway perspective view showing another embodiment of the present invention. It is. (1)...Metal core insulated substrate, (2)...
・Metal substrate. (3)・・・Insulating coating, (4)・・・Printed circuit 3 Insulating coating Fig. 1 5a Lead terminal Fig. 2

Claims (1)

[Claims] (1) A thick film circuit metal substrate comprising a metal core insulating substrate having an insulating coating deposited on the surface of the metal substrate, and a thick film-like printed circuit formed on the metal core insulating substrate, wherein the metal The board is
A thick film circuit metal substrate characterized by being formed in an uneven shape.