DD276760A1 - COVERING COVER FOR THE PROTECTION OF UNCONTACTED SEMICONDUCTOR BODIES - Google Patents

Abstract

The invention relates to a Abdeckueberzug for the protection of uncontacted semiconductor bodies which are provided for a flux-free inert gas Loetverfahren with the task to protect noble metal layers from atmospheric influences. According to the invention, the metal layers are covered with a self-adhesive film.

Description

Field of application of the invention

The invention relates to a cover coating for the Srhutr of uncontacted semiconductor bodies, in particular of Si chips or slices, which are provided for a Flcßmittelfreies inert gas soldering.

Characteristic of the known technical solutions

Semiconductor bodies in the form of chips or slices will provide for complete devices or hybrid circuits on their contact surfaces with metal layers prior to assembly. These layers generally consist of a sequence of layers, wherein the last applied layer is often a layer of noble metal. It causes the good wettability of the solder during the soldering process.

For l.ötvorgänge. which are free from molten flux and under an inert gas atmosphere, it is customary to use gold as the last layer.

However, such solutions are very expensive. Further, by night, the provision of gold is limited.

There are also known metallization technologies, which as a last layer less expensive metals, eg. As silver use. Refer to Poor / Semi-conductor Technologies Dand 2, page 240ff.

Over time, however, these less noble layers are subject to atmospheric influences due to the formation of compounds with components present in the air, eg. As oxygen, carbon or sulfur compounds. The latter show an upward trend.

Now, if such chips are not directly contacted with less noble layers, so is a constant reduction of the solderability up to the complete passivation in flußmittelfreien inert gas soldering the result.

To remedy this situation, it is known by the WP 102664 to use for storage and transport of Si-slices containers that are hermetically sealed. It is also possible to use this container. B. to fill with inert gas, so that the hermetically sealed by dor outside atmosphere slices can be stored longer time without loss of quality; However, it is disadvantageous that the production is complicated and the cost is considerable.

Object of the invention

It is the object of the invention for Si wafers and chips to improve the storage stability, to reduce the cost of storage and rejects, as well as to make the manufacturing process economical.

Explanation of the essence of the invention

The invention is based on the object for Si wafers and chips, whose outer metal layer is less noble than gold on the contact surfaces, for the period until further processing to ensure the Weichlötfähigkeit after longer storage times. According to the invention this object is achieved in that for an airtight completion of the surface to be soldered whose last metal layer is less noble than gold, an easily removable, not interacting with the surface conformable material is used.

After completion of the metallization process are in a period of max. 12 hours, the metallized contact surfaces brought into contact with a tight-fitting tight at least 30pm thick self-adhesive plastic film. The adhesive side is rolled up at room temperature on the contact surfaces to avoid trapped air. The material used can be polyethylene, PVC, Teflon or similar plastic.

Claims (3)

1. Abdäcküberzug for the protection of uncontacted semiconductor bodies, in particular Si chips or discs, dio are provided for a Flußmittelfreies Inertgaslöiverfahren, characterized o'aß as cover a plastically deformable, air-impermeable adhesive coated on one side smooth material with at least a thickness of 30 μιη is used. 2. cover cover according to claim 1, characterized in that the material is a seibstklebende foil verwondat. 3. Abdecküberüug, according to claim 1, characterized in that the film consists of polyethylene, PVC, Teflon or similar plastic.