"The absolute last thing they should be doing is asking an assembly house to specify a potting material in an RF design and then ask the vendor of the material if it is going to be an issue...." May be they should fork over part of designer's salary as well? When the design give away the selection of the materials, it smells big trouble. Run, like hell. . -------------------------- Sent using BlackBerry ----- Original Message ----- From: John Burke [mailto:[log in to unmask]] Sent: Sunday, August 15, 2010 06:13 PM To: [log in to unmask] <[log in to unmask]> Subject: Re: [TN] Is Calcined alumina in Epoxy resist tramission signal..? Hi hetal, Maybe they should be asking why they are potting at all? (maybe a conformal coating with parylene?) Honestly from your mail the design team seem to be disconnected with reality. Used to be that they would take the RF properties of their proposed design into account and arrange materials/ RF power output (for transmission)/front end amplification (for receivers) into account. The absolute last thing they should be doing is asking an assembly house to specify a potting material in an RF design and then ask the vendor of the material if it is going to be an issue..... Suggest that the assembly house might want to push back on this and ask what exactly the attenuation limits of the materials should be in order for the design to pass DVT/PVT testing. On the mechanical issue I have seen assemblies use a 2 part potting process, the first as a semi-compliant coating, the second as an epoxy coating over the top of the first. I am sure others here on TechNet will be able to help on the mechanical questions. On the RF performance the designer will need data sheets on the materials and a mechanical estimation of the depth of potting materials over the board/transmission component surfaces - he will need data on dielectric constant of the materials - and to be honest to avoid problems of the assembly house facing "failed on test yield" issues I would recommend a full pilot run with DVT and PVT testing on the pilot units. Unless they have a master plan for re-working potted assemblies?...............8-) Best regards, John Burke -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Hetal Shah Sent: Thursday, August 12, 2010 10:08 AM To: [log in to unmask] Subject: [TN] Is Calcined alumina in Epoxy resist tramission signal..? Our customer have an RF Transmitter on the PCB. they have a couple of concerns. One that the potting material will damage the components and the other that the potting material will shield the RF Transmissions of their transmitter. Their assembly house was going to use our 2 parts Epoxy (which conatains Calcined alumina) as the potting material. Will this create any of the problems mentioned? Any insight into this matter would greatly be appreciated. Thank you Hetal Shah R & D Chemist MG Chemicals ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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