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Precision Artwork by Contact Printing and Masking

IP.com Disclosure Number: IPCOM000050136D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Edwards, JC: AUTHOR

Abstract

A major problem in creating bumped automated beam tape for bonding to n an integrated circuit chip is the precision required to generate multiple photomasks for the etching of the bumps. This is achieved by generating a single, high resolution photomask of the beam lead layout, making a contact exposure (emulsion side to emulsion side) of that master, and then re-exposing all but the tips of the beam leads using a lower resolution photomask.

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Precision Artwork by Contact Printing and Masking

A major problem in creating bumped automated beam tape for bonding to n an integrated circuit chip is the precision required to generate multiple photomasks for the etching of the bumps. This is achieved by generating a single, high resolution photomask of the beam lead layout, making a contact exposure (emulsion side to emulsion side) of that master, and then re-exposing all but the tips of the beam leads using a lower resolution photomask.

The precision for beam leads and bumps must be within 0.0001 inch. Fig. 1 shows the master beam layout mask, which is made a single time to the high precision required. In Figs. 1, 2, and 3 the dotted outline shows chip position. An emulsion side to emulsion side photographic copy is made, and that copy is also exposed to the mask of Fig. 2, which exposes all but the tip-end area. The precision of exposure of the Fig. 2 mask need not be so high.

The resulting bump lead mask is shown in Fig. 3. It is precisely registered with regard to the leads and registered with adequate precision with regard to the outer edges of the bumps. The final lead profile is shown in Fig. 4, made by standard optical and etching techniques on beam tape using the mask of Fig. 3.

The subsequent bonding process must take into account that the bumps are flat rather than conventionally round. They are symmetrical about the center of each lead and have no tendency to cause a slip to the side.

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