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