Update on bump bonding
• Detector– preFPIX2I – UCD, 1st detector delivered but
inner row of wire bond pad not exposed; they need a few more chips and we will send them the re-diced sensors
– preFPIX2tb – AIT; expect to get up to 6 detectors.
ATLAS Prototype 2 wafer
• 1, 5 = STlad• 2,6 = Stnod• 3,4 = STsmd
• Use 3,4 and 2 from Cis Wafers.
Layout of SINTEF wafer
GREEN• FPIX1_SIP: A,C,D,F• FPIX1_SCP: B,E,G
BLUE• FPIX1_TIP5X1: TILIPBonding instructions:Use C and D (FPIX1_SIP) andB (FPIX1_SCP).If the FPIX1 chips are still useable,
please bond them to the FPIX1_TIP%X1 and produce a module.
Dummies
• Test of dummies – long term storage, thermal cycle, and irradiation.
• Little change due to cooling and long term storage
• Saw some changes due to irradiation (C060 up to 13 Mrad)
Need to understand what’s causing this
Will receive another batch irradiated to more than 10 Mrad
• Selcuk – talk at LEB Workshop next month at Stockholm
• Dummy assembly test: glue epoxy on top of the dummy assembly; do wire bonding on a few pads, repeat connectivity test; no change observed. Next do thermal cycle test; expect all the results this week
Thinning
• We would like to thin the 8” wafer to 200 um from 750 um.
• Checking out a few vendors (together with MCNC)– QBBS ( UV release tape)– APTEK (wax)– TRUE-Si (plasma etching, not touching the
back side)
Thinning (cont)
• We will chek the flatness, uniformity of the thinning here using touch probe, optically, interferometry (ANL)
• 1st wafers received from MCNC (bumped 6” wafers)– Target thickness: 200 m– Our measurement: 190 m and 170 m (SD
about 25 m); the thick one broke into two halves
APTEK
QBBS
TRUE_SI
Summary
• A lot of work need to be done on thinning and protection of the bumps
• QBBS – look best out of the three in terms of bump protection
• Have talked to MCNC about using photoresist to protect the bumps( not easy, very thick layer)
• Have sent out to these companies 8” wafers to be thinned