Following is quoted from IPC-A-610C which was recently approved by industry consensus ballot and is being prepared for publication.  (DON'T CALL TO ORDER IT YET--IT WON'T BE IN STOCK FROM THE PRINTER UNTIL MID-JANUARY AT LEAST).

9.1.3 Conformal Coating Thickness
Table 9-1 Coating Thickness (exactly the same is the coating thickness table in J-STD-001.)

Table 9-1 provides coating thickness requirements. The thickness is to be measured on a flat, unencumbered, cured surface of the printed wiring assembly or a coupon that has been processed with the assembly. Coupons may be of the same type of material as the printed board or may be of a non-porous material such as metal or glass. As an alternative, a wet film thickness mea-surement may be used to establish the coating thickness provided there is documentation that correlates the wet and dry film thickness. Conformal coating on tip of the lead is not required.

Acceptable - Class 1,2,3
* Coating meets the thickness requirements of Table 9-1.
Defect - Class 1,2,3
* Coating does not meet thickness requirements of Table 9-1.

Hope this helps.  Jack

> -----Original Message-----
> From: Jean-Francois Bissonnette [SMTP:[log in to unmask]] 
> Sent: Thursday, December 09, 1999 08:06
> To:   [log in to unmask] 
> Subject:      [TN] Conformal coating thickness
>
> Hello again!
>
> In IPC-A-610, they specify a 0.05mm thickness for silicon coatings. they
> dont say if it is nonconforming defect if it is not respected.  Can a
> board
> be rejected if the thickness is not as required?
>
> Thank You!
>
> JF


==========================================
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Manufacturing, March 12-16, 2000, Long Beach, California.
More information on website www.ipc.org/html/apex.htm 
-----------
Jack Crawford, IPC Director of Assembly Standards and Technology
2215 Sanders Road, Northbrook IL  60062-6135
[log in to unmask] 
847-790-5393
fax 847-509-9798

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