Hi, Mary,
If the missing solder mask is not meant to be missing, I would definitely
class it as a defect. What you have to ask yourself, though, (as one of our
TN gurus said to me not long ago) is "What do you want the Solder Mask to
do?" In this case, if you have concluded that the missing solder mask does
not constitute a defect, then why was it there in the first place?
Solder Masks are used to serve several purposes - to protect copper traces
and planes from the ravages of the environment, to prevent solder from
attaching to the copper, to act as a dielectric or as an insulator, to act
as a base for further coating, etc. What purpose does yours serve?
Do you know what caused the solder mask to be missing? Was it physical or
chemical or simply an omission from the requirement? If it was chemical, it
could still be active, and you might find more mask coming off in the
future. Apart from making the board look unsightly, you will be
progressively loosing the protection that the mask layer provides.
Pete Duncan
Mary Jane
Chism To: [log in to unmask]
<mchism@KIMBA cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
LL.COM> Subject: [TN] Exposed copper
Sent by:
TechNet
<[log in to unmask]
ORG>
06/02/01
12:31 AM
Please
respond to
"TechNet
E-Mail
Forum.";
Please
respond to
Mary Jane
Chism
I have a question concerning the subject matter of "exposed copper" on
conductors and/or ground planes due to missing solder mask. I have reviewed
the IPC-A-600 and SM-840 and have came to a conclusion on this. I want to
hear from the experts, which includes all of you, the interpretation of
this condition. I want to know if this is a defective condition or not,
what makes it defective, or if it is acceptable; anything you all want to
tell me. Thanks much.
Mary Jane Chism
Technical Trainer/ Learning Center
Kimball Electronics Group
Phone: (812) 634-4462
Fax: (812) 634-4501
email: [log in to unmask]
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