Laminate and use thereof

Abstract

A laminate having a layer structure of first inorganic layer-insulating layer-second inorganic layer or inorganic layer-insulating layer, characterized in that the insulating layer comprises two or more resin layers containing a core insulating layer and an adhesive insulating layer, and at least one layer constituting the insulating layer comprises a polyimide resin which has a recurring unit represented by the general formula (1), has a glass transition temperature of 150° C. to 360° C., and exhibits a rate of dissolution in a basic solution of 3 mu / min or more, preferably 5 ?m / min or more, most preferably 8 mu / min or more.

Description

[0001] The present invention relates to a laminate suitable for etching, by wet process, of a plurality of resin layers constituting an insulating layer in a laminate having a layer construction of first inorganic material layer (mainly metal layer) / insulating layer / second inorganic material layer (mainly metal layer) or a layer construction of inorganic material layer (mainly metal layer) / insulating layer, an insulating film, and an electronic circuit component, particularly a suspension for hard disk drives, produced by etching of the laminate by the wet process.[0002] In recent years, rapid development of semiconductor technology has led to rapid progress of a reduction in size of semiconductor packages, the adoption of multipin, the adoption of fine pitch, minimization of electronic components and the like. That is, the semiconductor field has entered the so-called "age of high density packaging." Regarding printed wiring boards, this has also led to a change from single side wi...

AI Technical Summary

Benefits of technology

[0030] The present inventors have made extensive and intensive studies on various polyimide resins which, when a multi-layer structure of two or more resin layers is adopted in an insulating layer in a laminate having a layer construction of first inorganic material layer (mainly metal layer) / insulating layer / second inorganic material layer (mainly metal layer) or a layer construction of inorganic material layer (mainly metal layer) / insulating layer, can provide a good etching shape as a resin for the insulating layer.

[0031] As a result, it has been found that, also in a thermoplastic polyimide resin having good adhesion, the presence of a specific structure within the resin skeleton can accelerate the etching rate. According to this thermoplastic polyimide resin, the etching rate can be made close to the etching rate of the low expansion polyimide which structurally has a high etching rate, and a good etching shape can be provided even in etching by the wet process.

Problems solved by technology

When wiring has been formed of such thin layer, a warpage disadvantageously takes place in wiring due to a difference in coefficient of thermal expansion between the metal layer and the polymeric insulating layer.

Since, however, the low-expansion polyimide is not generally thermoplastic, the adhesion to the metal layers is poor making it difficult to provide adhesive strength high enough to withstand practical use.

Excessively small thickness of the adhesive layer, however, is detrimental to the adhesion.

The above problem makes it very difficult to perform patterning of the insulating layer by wet etching.

For this reason, satisfying severe specifications is required of wireless suspensions using the laminate.

Therefore, disadvantageously, the productivity is low, and, in addition, sine the apparatus is expensive, the production cost is very high.

Regarding laminates for wireless suspensions required to satisfy severe specifications, however, the wet process could not have been put to practical use for the following reason.

Therefore, this resin is likely to be poor in suitability for etching by the wet process, and, thus, the etching rate is much lower than the etching rate of the core insulating layer.

Therefore, the etching of the whole insulating layer does not proceed evenly, and, thus, even etching shape cannot be disadvantageously provided.

Thus, optimizing the etching rate of the core insulating layer and the etching rate of the adhesive insulating layer in the insulating layer in the laminate for electronic circuit components, such as wireless suspensions, and, at the same time, improving the adhesion of the adhesive layer are contradictory to each other and are difficult to simultaneously realize.

Therefore, in the whole insulating layer, the etching shape is uneven.

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