Atul, I would guess that the flux is causing a non conductive oxide to develop on your socket contact surfaces. Multiple insertions are scuffing off the oxide layer allowing the Pentium pins to make contact, at least for now. Check with your socket manufacturer to verify the quality of the contact plating and compatibility with your flux process. Norm Dill ---------- From: TechNet-request To: TechNet Subject: Flux contamination in Pentium Socket Date: Tuesday, May 07, 1996 1:21AM Date : 7/5/96 9:06 Msg From: ATUL RASTOGI We are a contract manufacturer , doing mfg for a large PC company.Recently we have been facing a problem of flux residue coming on the contact area of ZIF socket used for Pentium.Due to this residue when Pentium is inserted in the socket and the mother board is powered on , it doesn't work.This happens due to the insulative nature of the flux residue.After multiple insertions of the Pentium it starts working. Our process is a no clean process and our mother boards are Entek CU 106 coated.We are using spray as well as wave fluxer on our wave soldering machines. Does somebody has an answer or suggestions to this problem? Thanks Atul Rastogi Atul Rastogi