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Conformal Coat Thickness

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MGL

#51152

Conformal Coat Thickness | 20 July, 2007

Does anyone have any experience with DeFelsko Corporation thickness measuring equipment for conformal coat? I am looking for a quicker more accurate way of checking our coating process.

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#51153

Conformal Coat Thickness | 23 July, 2007

From NASA document: Conformal coating thickness shall be determined using a wet film thickness gauge,.......

Wet Thickness Gauges can be obtained: Wet film Thickness Gauge P/N 790010 Nordson Corp, Amherst, OH

or

http://www.nordson.com/cgi-bin/MsmGo.exe?grab_id=73&page_id=8461312&query=thickness+gauge&hiword=GAUGES+GAUGING+THICKNESSES+gauge+thickness+

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#51158

Conformal Coat Thickness | 23 July, 2007

NASA-STD-8739.1, 10.2.3 Thickness Measurements. Thickness measurements shall be made on coupons processed at the same time and under the same conditions as the PWA. The coupon substrate may be any compatible rigid material with a smooth flat surface. Thickness measurements shall be made with a wet film thickness gauge or equivalent tool. See Table 10-1. TABLE 10-1. Conformal Coating Thickness Type of Coating||Cured Coating (MIL) Acrylic||0.001 To 0.005 Urethane||0.001 To 0.005 Epoxy||0.001 To 0.005 Silicone||0.002 To 0.008 Paraxylene||0.0005 To 0.002

Gage suppliers are: * Nordson [Amherst, OH nordson.com/cgi-bin/MsmGo.exe?grab_id=73&page_id=8461312&query=thickness+gauge&hiword=GAUGES+GAUGING+THICKNESSES+gauge+thickness+] * Paul N. Gardner Co; 800-762-2478 F954-946-9309 gardco.com/wet_film.html * Elcometer; elcometer.com/international%20index%20pages/international/product%20pages%20-%20English/section%20index/wet%20film.htm * Erichsen GmbH; 1340 E. Home Ave, Akron, OH 44310; 330-633-3644 erichsen-usa.com/film_thickness.htm

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#51160

Conformal Coat Thickness | 23 July, 2007

We run a small piece of FR4 with a "thickness test" pattern before production and measure it after with a digital micrometer. Then we save the coupon with the W/O # written on it.

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#51165

Conformal Coat Thickness | 23 July, 2007

It's it curious that NASA requires 'Thickness measurements shall be made with a wet film thickness gauge or equivalent tool' yet specifies 'cured thickness' as a measure. Why do you recon they do that?

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#51166

Conformal Coat Thickness | 23 July, 2007

Josh: Do you measure the thickness of the coupon prior to coating or do you peal the coating and measure that?

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MGL

#51167

Conformal Coat Thickness | 23 July, 2007

We have not had the best of luck with wet film. I agree on your statement. Depending on the mix and amount of solvent your results will vary. We were looking for something easy, accurate and foolproof.

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MGL

#51168

Conformal Coat Thickness | 23 July, 2007

We have used many ways of measuring but all are either messy, inconsistent or time consuming. We have done wet, glass slide dry, etc. We are currently using a kapton tape dot system. Spray the board, remove the dot and measure it, subtract the thickness of your dot for your thickness.

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#51171

Conformal Coat Thickness | 23 July, 2007

We know nothing of DeFelsko, but do understand how they distinguish between the solder mask and the conformal coat.

DeFelsko manufactures hand-held, non-destructive coating thickness gages that are ideal for measuring the dry film thickness of conformal coatings on appropriate PCB. * PosiTector 6000 Eddy-current gages are ideal for measuring conformal coating thickness on printed circuit boards with copper ground planes. * PosiTector 200 gages are ideal for measuring the conformal coating thickness applied to printed circuit boards without a copper ground plane.

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#51187

Conformal Coat Thickness | 24 July, 2007

We just measure the coupon before and after. We are always btw .002" - .003" acrylic. No auditor will say a word if you are doing this much control. Unless its NASA I suppose..... we've never had a problem with any of the avionics guys doing this though.

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