Browse Prior Art Database

Minimize Stress of Detaping C4 Wafers Using Temperature

IP.com Disclosure Number: IPCOM000022340D
Original Publication Date: 2004-Mar-09
Included in the Prior Art Database: 2004-Mar-09
Document File: 2 page(s) / 802K

Publishing Venue

IBM

Abstract

To thin C4 wafers it is industry standard to tape the frontsideof the wafers with UV curable tape. The UV tape manufacturers require only that the tape be properly UV exposed to detape. We have found that this is not the case. We have noticed detaping issues as the bump density increased.Heating the UV tape was necessary to remove the tape from wafer.

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Minimize Stress of Detaping C4 Wafers Using Temperature

Main Idea

Disclosed is a process : when thinning C4 wafers it is industry standard to tape the frontside of the wafers with UV curable tape. The UV tape manufacturers require only that the tape be properly UV exposed to detape. A study found that this is not the case. IBM has noticed detaping issues as the bump density increased. UV tape manufacturers suggested we level a flap of tape to grab (this method did not help). Our study shows the tape once cured still surrounds the C4 ball by 70-80 um. Post cure the UV adhesive hardens, so now the 120 um C4 bump is surrounded by 70um of harder plastic. This creates stress during the detaping process. See chart #1 , force in grams during detape of UV cured tape on C4 wafer.

The invention comprises heating the tape up to 30-50 degrees celsius post UV curing which removes the stress so that the force of detape equals a wirebond product. See chart #2 (UV cured tape on C4 wafer detaped at 40 C). See chart # 3 (UV cured wirebond wafer ).

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