Shirley,

have you verified your drilling process isn't 'punching' and causing
initiation of your delam issue? It'd a fairly common cause for the drilling
process to be overstressed and actually punch through the panels rather than
complete the drilling action, with the results you describe. It's a
combination of drill bit sharpness, rotational speed, the downward drill
feed and the number of panels up being drilled. Basically the drill is
driven faster than it can cut and ends up 'punching rather than drilling. It
creates an intermittent fault.

If you've checked this already - my apologies.

Andrew Hoggan
BBA Associates
www.bba-associates.com

----- Original Message -----
From: "Shirley Xiao" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, June 27, 2001 1:22 AM
Subject: [TN] Multiple Thermal Stress


> After drilling, PTH and etch we take samples for 3
> times solder floating test (288 C 10 seconds each
> time). We do find some board will delam. Is there
> anyone have the experience that laminate produced by a
> certain laminate supplier is easy to pass this test?
> How about the thermal stress performance of major
> laminate suppliers such as Isola, Polyclad & Nelco?
>
> Any input will be greatful.
>
> Shirley
>
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