JPH05114668A - Aluminum substrate for semiconductor - Google Patents

Abstract

PURPOSE:To provide an anodized film with favorable insulating property in addition to aluminum's excellency in heat radiation by drilling holes in an aluminum substrate, and forming an anodized film of a specific barrier layer thickness on the surface thereof and the inside faces of the holes. CONSTITUTION:After drilling holes in an aluminum board 1, burrs are removed and pretreatment is performed. A phosphate anodic oxide film is formed on the surface of the aluminum board 1 and the inside faces of the holes using a phosphoric acid solution as electrolyte solution. Then a required film thickness is obtained using an organic acid solution as electrolyte solution. This forms a two layer anodized film of an organic acid film 2 and a phosphoric acid film 3 laminated in this order on the aluminum board 1. The anodized film is of a barrier layer thickness of 500Angstrom or more. This improves the insulating property of the anodized film itself, making it suitable for a substrate for pin grid array.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum substrate for semiconductors, especially for through-hole type pin grid arrays.

[0002]

2. Description of the Related Art Recent electronic parts (IC packages, multilayer wiring boards, etc.) are required to be highly integrated, downsized, and speeded up with the development of LSI / VLSI. Ceramics such as Al ₂ O ₃ and AlN are used as conventional pin grid array type materials. The ceramic material has excellent properties such as insulation and reliability, but has problems in terms of thermal conductivity (heat dissipation), weight (lightening), price, and the like. For example, in terms of thermal conductivity, it is necessary to use a high heat dissipation material in order to cope with an increase in the amount of heat generated due to the speedup of LSIs in the future, but conventional ceramic materials can always ensure sufficient heat dissipation. Was not.

Therefore, an anodized film is formed on the surface of the substrate and the hole made of aluminum or an aluminum alloy (hereinafter, simply referred to as aluminum) which is a high heat dissipation material that meets the above requirements as a material of the pin grid array type, and thereafter, The present inventors have previously proposed to coat the whole with a resin (Japanese Patent Application No. 3-181614).

In the above case, the anodized film formed on the aluminum surface and the hole is mainly made of alumite phosphate in consideration of the adhesiveness to aluminum, but the alumite phosphate has a relatively thick film thickness. The thickness could not be increased, and sufficient insulation was not obtained.

The present invention can meet demands for high integration, downsizing, speeding up, etc., and particularly for semiconductors in which good insulating properties are imparted to the anodized film itself when aluminum having excellent heat dissipation is used. In particular, it is an object to provide an aluminum substrate for a through-hole type pin grid array.

[0006]

SUMMARY OF THE INVENTION The present invention provides a substrate for a pin grid array in which an insulating film is formed on a surface of a substrate and a hole, which have been predrilled, and a copper film is formed on the surface of the insulating film. The pre-drilled substrate is composed of an aluminum plate having an anodized film on its surface and holes, and the barrier layer thickness of the anodized film is 500 Å or more. In the present invention as described above, the anodized film may have a two-layer structure of phosphoric acid alumite and organic acid alumite.

According to the present invention, the insulating property of the anodic oxide film is determined by the barrier layer thickness of the film, and the barrier layer thickness is required to be at least 500Å for use as a substrate for a pin grid array. This is based on the findings of the present inventors.

The barrier film thickness of the anodic oxide film formed on the aluminum plate is proportional to the electrolytic voltage during the anodizing process. Therefore, for example, even with sulfuric acid alumite, the required insulating performance can be obtained by increasing the electrolytic voltage. Generally, a thick barrier film can be easily obtained by electrolysis using an organic acid solution such as oxalic acid or sulfonic acid. Also, in order to improve the adhesion of the film,
It is preferable to have a two-layer structure having a surface of about 1 μm of alumite phosphate.

The present invention will be described below with reference to FIG. 1. In FIG. 1, reference numeral 1 denotes an aluminum plate, which may be made of aluminum or an alloy thereof regardless of its material. A relatively hard material such as A5052P-H34 is preferable in terms of prevention of sagging at dawn and strength. After this aluminum plate 1 is perforated, deburring is performed, pretreatment is performed according to a conventional method, and a phosphoric acid solution is used as an electrolytic solution.
A phosphoric acid alumite film having a thickness of about 0.3 to 0.5 μm is formed in the hole. Then, an organic acid solution (oxalic acid, sulfosalicylic acid, etc.) is used as an electrolytic solution to generate a predetermined film thickness (5 to 20 μm). As a result, a two-layer anodic oxide film in which the organic acid film 2 and the phosphoric acid film 3 are sequentially laminated is formed on the aluminum plate 1.

[0010]

EXAMPLE An insulating aluminum plate having a thickness of 1.0 mmt and a thickness of 1050-H24 was subjected to alumite phosphate treatment and further subjected to various alumite treatments to form a two-layer structure, and insulation properties were compared. The results are shown in Table 1.

[0011] In the insulation performance shown in the table above, in the circuit of FIG. 2, the leakage current when the applied voltage of DC50V is maintained for 100 hours is 1 /
When it was 10 ⁷ A or less, it was determined to be OK, and when it exceeded it, it was determined to be NG.

From the above table, No. 2 and No. In No. 3, the insulation performance was kept almost constant (1/10 ⁸ A) throughout the holding time. 1 and No. 1 In No. 4, a short circuit occurred in a short time. This insulating property is determined by the thickness of the barrier film, and when the applied voltage is 50 V, the thickness of the barrier film is 5
It turns out that more than 00Å is required.

[0013]

As described above, according to the present invention, the insulating performance of the anodized film itself is improved, and therefore, in combination with aluminum having a good heat dissipation property, the substrate for semiconductors, especially for the pin grid array. Will be the optimal one.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of an aluminum substrate according to the present invention.

FIG. 2 is a circuit diagram of insulation performance tested in an example.

[Explanation of symbols]

 1 Aluminum plate 2 Organic acid film 3 Phosphoric acid film

Claims (2)

[Claims] 1. A pin grid array substrate comprising a pre-drilled substrate surface and holes with an insulating coating, and a copper coating on the surface of the insulating coating, wherein the pre-drilled substrate is An aluminum substrate for a semiconductor, comprising an aluminum plate having an anodized film on the surface and holes, and the barrier layer thickness of the anodized film is 500 Å or more. 2. The aluminum substrate for a semiconductor according to claim 1, wherein the anodized film has a two-layer structure of phosphoric acid alumite and organic acid alumite.