Ingemar,
Continuing on with this thread, I went back to some of my records on InGaN, SiC, GaAs, and the flurry of other LED-type acronyms and come up with the following short list of qualified bond schedules for one bonder.
These schedules were 'Production Approved', based on DOE's, accelerated aging, etc. etc. 1T = first bond time [ms], 1P = first bond power [the machine generator's own special units], 1F = first bond force [gm].
My caveat is that no two machines are exactly identical, therefore a power setting on one machine does not necessarily correlate to the same value on another machine of the same model, etc. So, just because this works for me on one F&K 6200, does not mean that the settings were the same on the next 6200 [although they tended to be close :-)]
Here they are:
1T 80±2 40±2 40±2 45±2 30±2 40±2
1P 39±4 55+5/-0 60+5/-0 80±3 75±3 80±2
1F 70±10 40±2 40±2 55±2 55±3 55±5
The above 6 first bond schedules represent a large cross-section of chip manufactures and metallization types. All were done using the SPT UTF-51IJ-CM-1/16-16mm 15MTA capillary. All with 38µm wire. The temps were all 175±5°C. Devices plasma cleaned prior to bonding.
Specifically, the second and third parameter sets represent the difference between the cathode and anode bond schedules on the same chip. Not much, but enough to be visible over the long haul.
The first parameter set is highly unusual for me as I try to keep time below [or well below] the basic power level. In this case time was very high and power quite low. You will also note that the force was quite high for a first bond too! It was an AlInGaP chip as I recall, but was unique to that one chip... Almost like it strongly wanted a thermocompression bond ... I guess you could say that I gave it a chilly TC bond.
All this does is provide a flavor of what worked for someone else, with different chips, and different machines. I know that it is not a cookie-cutter answer to your situation...
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Monday, August 18, 2008 4:13 AM
To: [log in to unmask]
Subject: [TN] Wire bonding gurus ohoy!
Hi all,
will send a picture to Steve for getting help.
Thermosonic 25um gold balls don't stick to the thinfilm gold on a optic
chip.
2,500A Au over 400A Cr. Bad yield, many balls lift. No contaminations
found.
Despite I have the good fishbone, I can't find out why the odd pattern
under lifted bals.
A guess is that the capillary have to steep chamfer angle, so that the
U/S mechanical energy becomes concentrated in the middle. Anyone with
similar experience?
Inge
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