Ken, there are quite a few injection moldable thermoplastics that will survive reflow temps including LCPs, high temp nylons and others. Find a good mold house that works with hi-temp plastics and they should be able to recommend the best material for cost, moldability and your application.
Jim McGrath
Strategic Marketing Manager
TE Consumer Devices
Cell: 630-244-3872
Email: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Monday, December 10, 2012 5:48 PM
To: [log in to unmask]
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
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