The units are not airtight and some small amount of moisture is inevitable / acceptable. The linx guys got back to me and said that they use Zytel HTNFR52G30 Polyimide for thier lids. Any thoughts? Ken -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick Sent: Monday, December 10, 2012 7:20 PM To: [log in to unmask] Subject: Re: [TN] Polymer Lid Ken, Also consider that if you seek to create an enclosed cavity, the air inside that cavity will expand during heating and sometimes create blow holes in the 'seal' during heat cure of the adhesive. Similarly, during reflow, depending upon the adhesive used, you can 'pop' the lids off. I've encountered situations in the past where a small hole was left in the lid to avoid the 'over pressurization scenario' and then 'sealed' post-reflow. Can you use a deep drawn metal lid as opposed to a folded type metal lid/shield? You could use a logo on sticker to cover the vent hole afterwards... Steve Creswick Sr Associate - Balanced Enterprise Solutions http://www.linkedin.com/in/stevencreswick 616 834 1883 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Kenneth J. Wood Sent: Monday, December 10, 2012 6:58 PM To: [log in to unmask] Subject: Re: [TN] Polymer Lid Bob, I'm using a metal lid for the larger size modules now and it is a pain to say the least to solder them on manually. One of the issues in the past was liquids getting under the lid during cleaning. That's why I wanted a plastic lid with no seams that could be filled with goo and glued down. These units are supplied as a module to end uses so they have to have the lids on from us. Ken -----Original Message----- From: Robert Kondner [mailto:[log in to unmask]] Sent: Monday, December 10, 2012 6:48 PM To: 'TechNet E-Mail Forum'; 'Kenneth J. Wood' Subject: RE: [TN] Polymer Lid Kenneth, Yes, I looked at your link so now I see better. Your users will be doing a reflow. So you need a thermoset lid. Glue it on with a silicon and I think you are set except maybe for cleaning. I would imagine your customer will clean their boards which would tend to trap fluids under the lids. So then you get into the area of filling and sealing? That is a mess. It gets worse as you have SMT leads coming off the PCB. If you can place filling holes in the PCB you can get the right amount of material in the unit except for the filling of voids. I played with this once and using a vacuum fixture to removed voids can cause a mess. You need to vacuum then fill with the vacuum applied. Then reintroducing air fills voids as air pushed down through the fill holes. A mess to fixture. You might look at cavist.com as they do low temp thermoplastics, maybe they can do a low temp thermoset so you can encapsulate soldered modules. Or consider metal cans? :-) Getting the right amount of fill material to provide a filled sealed device is very difficult. Bob K. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Kenneth J. Wood Sent: Monday, December 10, 2012 6:04 PM To: [log in to unmask] Subject: Re: [TN] Polymer Lid Bob, Thanks for your help on this. Quantities are 1,000 to 50,000 per year and the lid needs to be glued on before it ships to the end users. Ken -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner Sent: Monday, December 10, 2012 5:58 PM To: [log in to unmask] Subject: Re: [TN] Polymer Lid Kenneth, I looked into this some years back and any material that "Stands Up" to reflow temps would be difficult to form. Injection molding would probably be impossible but ask, don't take my word. At all costs is there any way to add it as a last step addition to a finished PCB? How many are you talking about? I did have some plastic parts made from a thermoset. It was black material and I forgot the trade name. It was probably just a phenolic material. Not sure how well it takes reflow temps. If you need help contact me off line, I will get you a sample. I had some 2 x 4 inch boxes and cover made. Bob K. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Kenneth J. Wood Sent: Monday, December 10, 2012 5:30 PM To: [log in to unmask] Subject: [TN] Polymer Lid Hi all, I need to design a polymer lid that gets glued on top of a square PCB. The lid will be 0.66" x 0.66" by 0.20" (maybe 0.025" wall thickness) with a flat top so I can have the company logo and part number printed on it. The PCB itself is a system that gets soldered to a main board by way of castellated holes. My question is, what lid material should I use since this unit must go through a reflow over? I assume a vacuum formed CPVC lid would melt right? The unit is somewhat similar in mechanical characteristics to a Linx module like the TXM-xxx-es https://www.linxtechnologies.com/resources/data-guides/txm-xxx-es.pdf Thanks Ken _____________________________________ Kenneth J. Wood Saturn PCB Design, Inc. [log in to unmask] www.saturnpcb.com ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. 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