Transcript No Slide Title

TEC/TOB bias bonds
Susanne Kyre
University of California, Santa Barbara
Tracker week, October 2005
Susanne Kyre
Slide 1
TEC/TOB bias bonds
• Wirebonds will be added to the back of all TEC
and TOB modules to add redundancy to the bias
connection
• On TOB modules a bondable tab needs to be
added to the module frame
•
•
New modules
Existing modules are retrofitted (~2600 modules)
• TEC modules already have a gold plated area on
the module frame, where wirebonds can be placed
• All bias bonds get encapsulated to protect them
from damage during handling
Tracker week, October 2005
Susanne Kyre
Slide 2
New TOB modules
• Two small tabs (gold plated
kapton) are soldered to the
module frame
• During module assembly the
tabs are glued to the back side
of the sensor
Tracker week, October 2005
Susanne Kyre
Slide 3
Existing TOB modules I
• For modules that have
little or no silver epoxy
under the the gold plated
hole in the kapton of the
module frame, a small tab
(gold plated kapton) gets
glued with silver epoxy to
the gold
• The tab is also glued to the
sensor
• Most of the 1200 modules
at UCSB will be
retrofitted using this
method
Tracker week, October 2005
Susanne Kyre
Slide 4
Existing TOB modules II
• For modules that have a lot of
silver epoxy under the gold
plated hole in the kapton of the
module frame, a wire is
soldered to the resistor on front
side of the module
• The wire gets looped around the
edge of the frame to the back
side
• A small tab (gold plated
kapton), which has previously
been soldered to the wire, gets
glued to the sensors straddling
the gap between the sensors
• All 1400 FNAL modules and
about 80 UCSB modules will
be retrofitted using this method
Tracker week, October 2005
Susanne Kyre
Slide 5
Bias wirebonding
• Height requirement: Maximum
encapsulant height must be
below the highest point on the
module frame
•
•
Wirebond loop height is kept
to 280 microns
Encapsulant height is kept
below 630 microns
• After the front side of the
module is wirebonded, the
module gets removed from the
module carrier, turned over and
placed on a special vacuum
fixture
• 15 wire bonds are placed on
each of the 2 bias bond areas on
the backside of the modules
Tracker week, October 2005
Susanne Kyre
Slide 6
Bias bond encapsulation
• For the detailed procedure see:
http://hep.ucsb.edu/cms/cms_procedures/tec-encapsulation-procedure.pdf
• For the drawings of UCSB designed tools see:
http://hep.ucsb.edu/cms/mechanical.html
Tracker week, October 2005
Susanne Kyre
Slide 7
Material and Preparation
• Sylgard 186 Silicone
Elastomer, 2 part kit, 10:1
mixing ratio
(manufacturer: DowCorning)
• Mixing cups
• Mixing sticks
• Digital bench scale
• Small vacuum chamber or
centrifuge for degassing
Tracker week, October 2005
Susanne Kyre
Slide 8
Dispensing Equipment
• Pneumatic glue dispenser
with foot pedal and timed
pulse option
(manufacturer: EFD
model: Ultra 1400)
www.efd-inc.com
• 3ccm syringe barrel and
piston (EFD)
• Smooth-flow tapered tips,
gage 20 (EFD)
Tracker week, October 2005
Susanne Kyre
Slide 9
Set up Equipment
• Base plate (UCSB design),
to hold the module on a
module carrier upside
down
• Plastic trowel (UCSB
design), to spread the
encapsulant over the
wirebonds and to keep the
height of the encapsulant
below the maximum
height
• Stereo microscope
(optional)
Tracker week, October 2005
Susanne Kyre
Slide 10
Procedure I
• Mix encapsulant, degas
the mixture and fill
syringe
• Set pneumatic dispenser to
15 psi and 1 second
dispense time
• Set module in carrier
upside down onto base
plate
• Dispense a line of
encapsulant across the
width of the wirebonds
Tracker week, October 2005
Susanne Kyre
Slide 11
Procedure II
• Position the trowel with
one leg on the sensor, one
leg on the kapton
• Spread the encapsulant
over all 15 wirebonds by
sliding the trowel across
the bonds
• Once the trowel is past the
wirebonds, lift it up and
clean it off with a dry
tissue paper
Tracker week, October 2005
Susanne Kyre
Slide 12
Procedure III
• Check that all wirebonds
are covered completely
with the encapsulant (this
can be done with or
without a stereo
microscope)
• If necessary apply more
silicone and repeat the
troweling procedure
• Cure for 24 hours with the
backside of the module
facing up to avoid beading
up of the encapsulant
Tracker week, October 2005
Susanne Kyre
Slide 13