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Die Attach Paste Process in Thin Packaging Technology Using Multiple Die Attach Paste Adhesives with Different Cure Temperatures

IP.com Disclosure Number: IPCOM000101585D
Publication Date: 2005-Mar-16
Document File: 4 page(s) / 53K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that dispenses two adhesive pastes (with different curing properties), then uses a heated tip and/or heated stage to control thin die warping, reverse adhesive fillet formation and/or excessive die attach bleed-out.

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Die Attach Paste Process in Thin Packaging Technology Using Multiple Die Attach Paste Adhesives with Different Cure Temperatures

Disclosed is a method that dispenses two adhesive pastes (with different curing properties), then uses a heated tip and/or heated stage to control thin die warping, reverse adhesive fillet formation and/or excessive die attach bleed-out.

Background

There are three major issues when using die attach paste adhesives in thin packaging:

1.      Warping of the thin die

2.      Reverse adhesive fillet formation or excessive adhesive bleed-out

3.      Controlling the adhesive bond line thickness (BLT) and the tilt on die on a flex substrate
(see Figure 1). 

Currently, these problems are solved by using a heated die attach process. In this process, the paste adhesive is dispensed on the substrate, and the die is attached to the substrate while heated.  The die attach tool tip and/or the stage are heated in the process. The die attach tool tip is placed on the die while the die attach stage is holding the substrate. However, this process suffers from an incomplete adhesive fill caused by adhesive pre-curing (see Figure 2).

General Description

The disclosed method simultaneously dispenses two different adhesive pastes, then uses a heated tip and/or heated stage in die attach. The disclosed method controls the current process problems by the heat treatment of the two adhesive pastes during the die attach and post die attach cure processes.

Paste A and Paste B are used, and the temperature they are cured at are TA and TB, respectively.  Paste B cures at a lower temperature, compared with Paste A (i.e. TB is lower than TA). Typically, the paste adhesive with a higher cure temperature (Paste A) is dispensed first on the inner area of the bond-line, and the other paste adhesive (Paste B) is dispensed afterward on the outer bond-line region. The die is picked from the wafer boat and p...