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Week 1: Die Attach
Equipment used for the die attach procedure.
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Dual Inline Hybrid Package and Die. (Package Labeling also shown.)
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Eye protection and gloves. (We are using adhesive
under pressure and would like to prevent skin sensitizing to the epoxy.)
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Acetone and tissues (swabs not shown).
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EFD 1500DV air powered adhesive dispenser with vacuum pickup pen.
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Die attach adhesive cartridge (Honeywell EC1030).
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Glass slides and spacers for application of bonding pressure.
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Clean die and package bond surfaces prior to bonding with acetone and
swabs/tissues.
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Practice dispensing the die attach "X".
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Dispense adhesive "X" on package surface.
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Pick up die using the vacuum pickup pen.
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Place die in package on the adhesive "X" using the pen.
(Carefully align top edge of die with the proper leads.)
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Die positioned correctly on top of adhesive X with spacers and slides ready.
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Apply gentle pressure to die by placing one of the provided spacers on the
die using the pickup pen and then carefully placing ~6 glass slides on top.
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Students' package assemblies ready for curing.
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Cure in oven at 150°C for 1 hour.
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Package with cured adhesive. (Leads clipped for resistance measurement.)
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All of the student packages are then placed in the dessicator to await wire
bonding in week 2.
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Week 2-3:
Wire Bonding and Encapsulation
Clean die surface with acetone prior to wire bonding.
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Attach package to the pre-heated work holder for the Westbond 7700C wire
bonder.
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Thermosonic wire bond from the pads on the die to the leads on the package as
designated in the lab handout. (Note: Ball bonds are on the die
and wedge bonds are on the leads.)
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Die mounted in Dual Inline Hybrid Package with completed wire bonds.
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Encapsulant cartridge (Thermoset ME-455).
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Fill Cavity with the ME-455 Encapsulant. (Note:
The end connector on the leads has been removed prior to this point.
This was necessary to allow measurement of the resistances through the
leads.)
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Student Packages in glass petri dishes ready to be cured. (Dishes allow
safe handling of packages with uncured encapsulant and will contain spills.)
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Cure in oven at 150°C for 30 minutes.
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Our completed first level package.
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Week 3:
Soldering to PCB
Tools required for soldering first level package to PCB.
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First level package and PCB.
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Measure resistance to verify intact wire bonds.
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Bend numbered
leads on the package to insert through holes in PCB.
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Clip remaining leads.
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Package on PCB with leads bent outward. (Note: proper position of leads
in the proper holes as noted in the lab manual.)
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Heatsink clipped to a lead before soldering. (The heat sink will
protect the die and the package from being damaged by heat during soldering.)
NOTE: The heat sink must be attached to the lead
being soldered and then moved each time.
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Solder the leads individually. Remember that
proper soldering technique requires that the tip of the soldering iron touch
both the lead and the pad on thc PCB. The solder is then applied to the
joint AFTER it is hot. This will insure a good solder bond to
both the lead and the pad. (A good bond can be checked by insuring that
the solder has "wetted" both the lead and the pad.)
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After clipping the soldered leads, the resistance is measured between the
copper pads on the PCB (this measures the entire circuit including soldering,
wire bonds and the traces on the die). This is
the resistance we will track during further testing.
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Our completed 2nd Level Package is now ready for environmental testing in Lab
3.
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