True,
But if THAT was a microvia with the bottom of the hole
stopping at the pad, wouldn't the pad area STILL be in tact
and the electrical connection <surface area> still be rather
large <compared to a drilled through hole>?

<Thinking outside the squares now gang>
Groovy
-----Original Message-----
From: Alain Savard [mailto:[log in to unmask]]
Sent: Monday, October 18, 1999 12:34 PM
To: [log in to unmask]
Subject: Re: [TN] Annular ring requirement by IPC


Reliability is the answer. A more complete annular ring gives a stronger
joint
both electrically and mechanically. Vibrations may pose a problem in the
z-axis.

Alain Savard, B.Sc.
Chemical Process Analyst
CAE Electronics Ltd.
e-mail: [log in to unmask]
-----Original Message-----
From: Ken Patel [mailto:[log in to unmask]]

I have the basic question:
Why do we need annular ring on inner layers? If the answer is no then why
IPC is asking for 1 mil annular ring on Class 3 products. The problem arisen
due to microBGA application.
re,
ken patel

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