JPS6378742A - Manufacture of high thermal conductive copper-stuck substrate - 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 (Field of Industrial Application) The present invention relates to a method for manufacturing a highly thermally conductive copper-clad substrate used as a printed circuit board for internal wiring of electronic devices and the like.

(Prior Art) In general, if an insulating substrate with good thermal conductivity is used in the construction of a circuit board, it is possible to use a high-output circuit board despite its small size. Insulating substrate materials include BeO (17+7 oxide) and BN (Ron nitride), but Boo has the problem of being toxic, and BN is said to be difficult to supply stably in Japan. There's a problem. Therefore, AtN (
Aluminum nitride) has been attracting attention and importance. However, since AjN has the disadvantage of poor wettability with metals such as thin copper plates, a method is used in which the metals are bonded after pretreatment with AtN. The method is to form an oxide film on the surface of AtN or coat it with a metal oxide film.

Furthermore, as a highly thermally conductive insulating substrate, the Telefunken method, in which a paste of a high melting point metal such as W or Mo is applied to the surface of an AtN substrate and then fired, or the T t + Cr method is used.
*There is also a method in which a thin layer of metal is provided on the surface of the substrate by an active metal method using an active metal such as Zr or a plating method, and then a thin copper plate is closely attached to the surface.

However, in all of these methods, the AtN substrate is pretreated, but since AtN is inert, the treatment takes a long time and the operations are complicated. Met.

(Problems to be Solved by the Invention) The present invention has developed a method for firmly adhering a thin copper plate to an AtN substrate in a simple manner and in a short time.

(Means for Solving the Problems) The method of the present invention is characterized in that a copper foil, on which an oxide film has been previously provided on the surface, is heat-pressed onto a non-oxide ceramic substrate, so that the two are brought into direct contact with each other. It is something.

Since the method of the present invention only needs to oxidize the surface of the copper thin plate, it can be oxidized at a much lower temperature than the process of oxidizing an AtN substrate, and since copper oxide has a lower melting point than copper, the AtN substrate When adhering to a substrate, it is possible to use a material that easily follows the undulations of the substrate, becomes integrated with the substrate, and has good adhesion. In addition, a thin copper plate has the characteristic that it can be oxidized in a short period of time. Note that the oxidation temperature of the copper thin plate is not particularly specified.

Also, for the AtN substrate, only Affl may be used, but A
tN is a rare earth oxide such as Y2O3, At205, 5
in2. It may also contain 10 vt% of CaO or the like.

Also, the conditions for adhering the LtN substrate and thin copper plate are as follows: The bonding temperature is 800-1083℃, 0-160kg.
The bonding process is normally carried out in a nitrogen atmosphere under a pressure of /M2, but if the thin copper plate is to be oxidized during the bonding process, a small amount of oxygen may be used. Although it is not necessarily necessary to apply pressure, the adhesion between the two can be significantly improved by applying pressure.

(Example) Example (1) A copper foil having a thickness of 300 μm was heated in the air at about 500° for 5 minutes to perform surface oxidation treatment. This surface oxidized copper foil is
It was laminated on a tN substrate and bonded by applying a pressure of 50 kg/m while heating at 1070° C. for 30 minutes in a nitrogen atmosphere.

After the adhesion treatment, the copper foil was subjected to a reduction treatment (hydrogen ring radical) to remove the oxide film on the copper foil, thereby obtaining a highly thermally conductive copper-clad substrate according to the method of the present invention. The adhesion strength of the lead foil on this copper-clad board was measured and was found to be 3 kg7m2.

Comparative example (1) AtN substrate was heated to 75'C3 with 20% sodium hydroxide.
After etching for 0 minutes, it was heated at 1250° C. in the air for 1 hour to form an At203 film on the surface of the AtN substrate. A copper foil having a thickness of 300 .mu.m was laminated on this substrate and bonded by applying a pressure of 50 kg/c1n2 while heating at 1070.degree. C. for 30 minutes in a nitrogen atmosphere to obtain a highly thermally conductive galvanized substrate according to the method of the present invention.

The adhesion strength of the copper foil on this copper-clad board was measured and the result was 3kg/
It was m2.

(Effects) As detailed above, according to the method of the present invention, the pretreatment process for bonding a non-oxide ceramic substrate and copper foil can be performed extremely easily and in a short time. The present invention is extremely useful industrially, as it provides a highly thermally conductive steel-clad substrate with extremely good adhesion between the substrate and the copper foil.

Claims (1)

[Claims] A method for producing a highly thermally conductive copper-clad substrate, which comprises heating a thin copper plate on which an oxide film has been previously provided on the surface of a non-oxide ceramic substrate, and directly bonding the two.