JPH03267377A - Surface treatment of aluminum - Google Patents

Abstract

PURPOSE:To partially deposit an electroless plating without damaging a plating resist and to obtain a dense pattern in a minute range at the time of applying an electroless Ni plating on the surface of an Al thin film by conducting neutral greasing when a substrate is cleaned. CONSTITUTION:A novolac resin is usually used for the positive photoresist material, and hence any problem related to the adhesion, material strength, etc., is not caused in the region ranging from acidic to neutral. However, the resin is easily dissolved in an alkaline soln., and this property is conventionally used for development and to remove the photoresist. Accordingly, a sulfate is added to an alkaline degreasing agent in the degreasing stage in this invention to adjust the pH to neutral, activation is further applied by palladium chloride, and electroless Ni plating is carried out. As a result, even a positive photoresist poor in alkali resistance can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of surface treatment of electrodes of electronic circuit boards using aluminum electrodes.

[Summary of the invention]

The present invention utilizes a plating process for an aluminum thin film pattern formed on an insulating substrate, and performs neutral degreasing to partially deposit electroless plating without damaging the plating resist, resulting in precise plating in a minute range. This is to obtain a pattern.

[Conventional technology]

Conventionally, partial electroless nickel plating on aluminum thin films has been carried out by screen printing an aluminum-resistant plating resist, degreasing with a strong alkaline pH of 13 or higher, performing zincate treatment or treatment with palladium chloride, and then applying nickel-phosphorus. A method of precipitation was used.

[Problem to be solved by the invention]

In recent years, electronic components have been required to be smaller and more dense, and there has been a demand for smaller ML patterns.However, the printing accuracy of the resist produced by screen printing cannot meet the required quality. . Therefore, highly accurate resist pattern formation by photoprocessing and plating is applied, and photoresists are widely used there. In the above-mentioned plating process, the degreasing process and the zincate process are strongly alkaline, which causes the positive type resist to dissolve, and therefore has the disadvantage that fine patterning cannot be achieved using a fluoride resist.

[Means to solve the problem]

In order to solve the above problems, in the present invention, sulfate is added to a strong alkaline degreasing agent in the degreasing process to adjust the pH to neutrality, and after activation treatment with palladium chloride, electroless nickel The plating method made it possible to use positive-type photoresists, which have poor alkali resistance.

[Effect]

Positive type photoresist materials usually use novolac resin, and there are no problems with adhesion or material strength in the acidic to neutral range, but the resin easily dissolves in alkaline solutions, so this property can be used to Development and resist removal are then performed. Here, by adding sulfate to the degreasing agent and adjusting the pH to neutral as described above, it is possible to prevent the resist from dissolving due to the action of 10H.

〔Example〕

This invention will be explained in detail below.

Example 1 A 0.8-layer aluminum layer is formed on an alumina ceramic substrate by sputtering using 4μCI as a target material. Subsequently, a positive type photoresist of novolac resin is applied at a thickness of 0°9111111 using a spinner. Further, exposure with a high-pressure mercury lamp and development with 0.5% NaOH are performed to form a resist pattern on the substrate.

The plating process is carried out as shown in FIG. 1. First, 30 g/l of NG-30 manufactured by Kisa 4 Co., Ltd. is used as a neutral degreasing agent in an aqueous solution and immersed at 35 DEG C. for 1 minute and 25 seconds. Next, it was immersed in an aqueous solution of ammonium fluoride 0.5 g/l for 18 to 45 seconds, and then immersed in an aqueous solution of palladium chloride 0.1 g/f for 18 seconds. Tonopnicolone 50 at 200 g/l, 80℃
, after depositing 3 nodes of N1-P film in a 5-minute treatment,
The resist was removed with an organic alcicarine solution, and finally, heat treatment was performed in the air at 200°C for 30°C to improve adhesion.
I went for a minute.

The N1-P partial plating thus formed had a uniform appearance without cloudy appearance or stripes, and exhibited sufficient adhesion with no peeling in the cellophane tape test.

Example 2 After forming a 1.2-inch aluminum film on an alumina ceramic substrate by vacuum deposition, a wire bonding butt and a wiring pattern are formed using photolithography. Next, a resist pattern is formed using a positive type resist so that only the aluminum surface of the bonding butt is exposed. N1-P plating was formed on the butt part under the same plating conditions as in Example 1, and then electroless gold plating was performed at g/190°C for 5 minutes to form a gold plating layer of 0.1 dc. . Next, after removing the resist, heat treatment was performed at 250° C. for 30 minutes.

25 pieces of gold wire were bonded to the bonding bat formed as above, sealed with silicone resin, stored in an environment of 80°C and 85% for 1000 hours, and tested for reliability. No corrosion was observed in any part.

〔Effect of the invention〕

As explained above, the present invention has the effect of increasing the reliability of aluminum electrodes having a minute area by enabling the use of photoresists with neutral degreasing agents.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing the flow of the plating process according to the present invention. that's all

Claims (1)

[Claims] An aluminum surface treatment method comprising performing electroless nickel plating on the surface of an aluminum thin film, which comprises performing neutral degreasing in a substrate cleaning step.