Anil,
except foro IPC and other standards, the used bonding technology and wire
dimension plays a role. 0.8 micrometer is a very smooth and fine pad, but
we don't have such a tough requirement if it ain't necessary. So, bonding
ball and gold 17um is equal to 0.5 micrometer, while bonding ball and gold
50 um has 1.5 um. If we are bonding on nickel plated pads using 250um
aluminium wedge, the pads can look like anything. So, it's a whole range of
values depending on metal finish, metal finish thickness, wire material,
substrate properties etc. That's the practical side, which does not always
coincide with standards.
Let me finish by adding that far more important than roughness value is
CLEANLINESS! And pad finish hardness vs. the wire.
Best way to check is, of course, wire pull test. Harman's book is excellent
for all working with wire bonding. Get that, Anil. Worth its weight in gold!
(no,no...not IAu)
Inge
Dear all wire bond experts
Is 0.8 micron RMS roughness value achievable on wire bond pad area? as
per
IPC 6012B - 3.5.4.3. Do users regularly sample lots under 1000X or an
SEM?
How do you judge it ?
What is normally acceptable at low end bonding of 10 to 50 wbps?
thanks
Anil
micro interconnexion pvt. ltd
D3-12A, Corlim Industrial Estate
Corlim, Ilhas , Goa , India 403110
tel: 91-832-2284209/337. fax 2284209/2285271
e mail: HYPERLINK "mailto:[log in to unmask]"[log in to unmask]
Leaders in Gold plated PCBs - selective/ cob
an ISO 9001-2000 Company
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