hi,

i assume that you are talking about measuring the coating thickness on pwa's.  if that's the case,  i know of no way other than microsectioning the assembly.  the reason is that (other than with parylene) it is impossible to get a uniform thickness.  the problem has to do with surface tension.  sharp points, corners and edges probably have no coating on them.  fillets between components and the laminate surface have relatively high thicknesses to them.  the usual way to control thickness (and it is essentially meaningless) is to coat a 'witness' panel alongside the part you are coating.  thickness is determined by measuring the thickness of the panel before and after coating.

phil

-----Original Message-----
From: Bissonnette, Jean-Francois [mailto:[log in to unmask]]
Sent: Thursday, March 14, 2002 6:58 AM
To: [log in to unmask]
Subject: [TN] Coating thickness


Hi All,

Does anyone now of a technique or system to check conformal coating
thickness after it's dry on production units?  We have a positector to 
measure paint thickness on our enclosures but they're not design to
work on materials like PCB.

Jean-François Bissonnette
Vérificateur, Contrôle de la Qualité
Électronique
Produits et Procédés
Vapor Rail Inc.
10655 Henri-Bourassa O.
St-Laurent, Qc
H4S 1A1

(514) 335-4200 x2021
(514) 335-4231 fax

 <<Bissonnette, Jean-Francois.vcf>> 


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