Victor, Sorry, I glazed over on the moisture resistance. It depends - used to be in hybrids that we would apply the overcoat/glaze/glass before resistor trimming. This would leave only the walls of the laser trim kerf exposed to anything. One could apply the overcoat AFTER laser trimming, but then the resistor is subject to some degree of drift. Don't know exactly what the chip resistor suppliers are doing nowadays. If you look at some under a scope and you can clearly see nothing in the kerf, then you know they cut through the glass. If you see a depression in the glass where the kerf is, then you know they applied afterwards. It is glass. I forget exactly what composition. Can moisture get through it? Yes, slowly, but can also get at the resistive material via the laser trim kerf faster. The resistive composition is normally a fritted, ruthenium oxide based compound. Low ohmic values will normally be affected faster. As I recall, the fired thickness is about 1/2-3/4 mil thick [~50-75 µm] Steve Creswick http://www.linkedin.com/in/stevencreswick 616 834 1883 -----Original Message----- From: [log in to unmask] [mailto:[log in to unmask]] Sent: Thursday, June 23, 2011 2:10 PM To: [log in to unmask]; [log in to unmask] Cc: [log in to unmask] Subject: RE: [TN] Ceramic resistor coating Steve, Thank you for sharing. You did not comment on the moisture inquiry. I heard that moisture can penetrate to the conductive ink and cause corrosion. By the way how thick is this coating or min requirement. Victor, -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick Sent: Thursday, June 23, 2011 1:05 PM To: [log in to unmask] Subject: Re: [TN] Ceramic resistor coating Victor, Chip resistors normally have a low temp firing glass over the resistive element, or sometimes an organic, epoxy based material. You would ultimately have to check with your supplier to determine which. .... or dig at it [destructively] under a microscope to estimate for yourself. The glass resistor covercoat normally fires at 500-525°C, so it will not be bothered by much of anything which you can do to it. The organic covercoat would act like a standard epoxy and could discolor, change color, crack, peel, etc with excess temps, or could have issues with solvents, etc. Hope this helps Steve Creswick http://www.linkedin.com/in/stevencreswick 616 834 1883 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez Sent: Thursday, June 23, 2011 12:16 PM To: [log in to unmask] Subject: [TN] Ceramic resistor coating Fellow TechNetters: What are some typical ceramic resistor coating? Are these coating moistures proof/resistance? Can the coating deteriorate with temperature? 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