Dear Technet users,


We are facing solderablity problem with 6Layers, 0.78mm, 0.3mm(10mil)
finish hole size(BGA HOLES) with ELECTROLESS NICKEL/IMMERSSION GOLD.

01. The board when passed through the assembly line without pre baking,
have Blow holes problems in the BGA holes.

2. The boards after pre baking at 120 degree centigrade for 3 hrs had no
blow holes in BGA holes but the colour of GOLD changed to Reddish-Brown.

Will anyone can highlight on....

a) Why this colour change?
b) What are the standard pre-solderability activities to be followed for
above type of boards?
c) What is the recommanded Gold and Nickel thickness required for boards
with BGA?
d) What are the possible reasons for failure of solderability in BGA holes?

Thanks in advance.

Harsha Adya.

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