Update on bump bonding

1
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.

2
ATLAS Prototype 2 wafer

• 1, 5 STlad
• 2,6 Stnod
• 3,4 STsmd
• Use 3,4 and 2 from Cis Wafers.

3
Layout of SINTEF wafer

• GREEN
• FPIX1_SIP A,C,D,F
• FPIX1_SCP B,E,G
• BLUE
• FPIX1_TIP5X1 TILIP
• Bonding instructions
• Use C and D (FPIX1_SIP) and
• B (FPIX1_SCP).
• If the FPIX1 chips are still useable, please bond
  them to the FPIX1_TIPX1 and produce a module.

4
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 whats 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

5
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)

6
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 mm
• Our measurement 190 mm and 170 mm (SD about 25
  mm) the thick one broke into two halves

7
APTEK
8
QBBS
9
TRUE_SI
10
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