Dear Chong,
our ENIG process in being runned at 25-30 min. in electroless nickel at 82 deg. C to plate 5-6 microns (um).
Exposure time in immersion gold is 7 min. at 88 deg. C to plate 0,08 to 0,10 microns.

If the problem is locally, eg. corner of tracks with milky white areas of delamination, I would look at predry and/or coverage. 
If more overall I would look at exposure and/or final curing cycles.

From your test with Taiyo I would expect it to be the first mentioned.

Hope this helps
________________________________________________________
Jan Thuesen
Process Engineer
Chemitalic A/S
Egebjergvej 128
DK-8700 Horsens

Tlf.: ++45 76 28 70 00
Fax:++45 76 28 70 95

Mailto: [log in to unmask]

http://www.chemitalic.dk/

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of CHONG,CHEE-LEONG (A-Malaysia,ex1)
Sent: Saturday, July 01, 2000 3:29 AM
To: [log in to unmask]
Subject: [TN] Solder Mask & ENIG
Importance: High

Hi, All

We got a PCB shop to fabricate our new designed board. All issues are solved
except the solder mask. The SM appeared to be milky white after went through
electroless Ni immersion Au process. Usually delamination would occurred and
SM materials looks kind of soft. We suspect SM materials (coat Brothers)
giving problem, so we try another SM materials (Taiyo Ink). Trial run with
full Cu panel without pattern yield positive result. However when real etch
panel is tested, the same issue occurred.

After I went through their process flow and found something strange. The
electroless Ni took 40 - 60 minutes to achieve 130 u" and 20 -30 minutes for
Immersion Au. The bath is having 16g/l Ni and operate at 89 deg. C.

At this stage , we think the long exposure time that cause the SM failure.
I have a question that I would like to know is whether there is something
wrong with the bath and what is the typical time to achieve the same Ni/Au
thickness.

could someone shed some light over this issue. Any comments is truly
welcome.

Chong Chee-leong
Agilent Technologies

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