Chris, Many thanks...I'll see if Hexel or Cytec happen to have a very thin epoxy pre-preg with an insulative (sufficient di-electric circa 2000+Vac) core and reasonable thermal conductivity....maybe a field they've looked into?
IRstuff..sure... or a thermo-set....for my application all I need...
Chris; Yes your solution with epoxy/carrier/epoxy is practically the same as what I'm looking for with a phase change material. Where I have a concern is that for such a long and thin PCB in a production environment the consistent application of the epoxy would need to be very well managed (and...
lumenharold; Thanks very much, you're right this would work, unfortunately we're looking at 5000+ examples so hoping there's a solution that's free of variables.
I was hoping there would be a heat activated phase change material that would double as a strong adhesive. I just cannot find one...
Right I see, with some practice and the right epoxy and conductive plastic this would work...however the annual volume is going to be up to 5000, so I'd really prefer a solution that can be assembled and work without any fitting skills.Although this pcb is 150mm long, we're also looking at one...
IR Stuff: I need the adhesion between the PCB and Heatsink to hold them together, in assembly I can use a longitudinal clamp to fix their location but this would be a temporary measure as the adhesion cures....
Compositepro:I need to rely on the adhesion, the application is using the heatsink...
Jimbo...thanks, I hadn't considered this soldering idea....maybe a practical problem given length of pcb.
IRStuff....You're mostly right, the fixture of the PCB to the heatsink is a problem...what should resolve this is if I can achieve adequate adhesion between the insulating material and the...
Hi,I have also posted this enquiry to the Polymers forum because they may be equally able to assist....there may be a better way of doing this?
My issue is that I have an application that requires an electrically insulating (breakdown voltage better than 2000 vac)material with excellent thermal...
Unfortunately we don't have the controls for ensuring an even distribution of a paste or spray nor the health and safety measures required for management of them. Also because the PCB will take European main voltage, both sides are exposed to this so there must be no risk or bridging and the...
Hi,
I have an application that requires an electrically insulating (breakdown voltage better than 2000 vac)material with excellent thermal conduction (better than 0.5 C-in2/W)to be used between a long pcb 150mm x 25mm and it's heat sink (has same mating area).
I have looked at the usual options...
Hi Harold, thanks very much for the information on the grades of PC from Bayer that look suitable for this application. I'll contact them and see if they can send a tech sheet. And...I recollect the author JPDonlevy would start a new sentence with "And" ....many thanks to Pat for spotting my...
Thanks HDS, If you take a standard Opal incandescent lamp, tulip or bulb shape, break the glass and check it out you'll most likely find it to be clear glass (sub 1mm thick) with a painted coating on the inner face.
I have considered using a clear PC and doing something similar because this is...
Hi H,
Thanks for the suggestion, I'll try one out (and check for the markings on the base first!), however difficulty is knowing whether I'll get discolouration of an opal coloured one after a couple of years use?
I'll see if the suppliers do them in a translucent off white for 1mm thick...
Pat,
The cover has to comply with “Luminaires – BS-EN 60588 – 1 , to amendment A11” this is because the cover would be within 30mm of a potential heat source. i.e the electrics of the Compact Fluorescent. So the risk is not the normal running temperature (a contact thermo-couple gave 65C peak...
Hello Pud; I need opalescent, as for the usual practice with conventional light-bulbs, so it's translucent but not transparent. It's a good point that with a low % GF the 1mm section with PC may have sufficient light transmission. Thanks for your advice.
Pat, as you note, my expectation is that the opalescent pigment along with the base polymer (PC) both needs UV stability and with FR additive may be time limited. At least PC is nominally FR. Where these then affect translucency and it's repeatability I have no idea. Many thanks for your...
Chris, thanks, I'll check out the ASA....I think it is a styrene alloy? so not surprised there's just the one FR....also need to see how it is for light transmission, hopefully not Milky opaque!
Trueblood..interesting comment re: UV and IR..the lightbulb type I'm working with is the low-energy...
Just read this off Wikipedia;
""Plastic" (polycarbonate) lenses can become cloudy and discoloured. This is due to oxidation of the painted-on lens hardcoat by ultraviolet light from the sun and the headlamp bulbs. If it is minor, it can be polished out using a reputable brand of a car polish...
I'll check out the polymers used for the head and tail lights for flammability, if they're PC based alloy then should be reasonable. Similarly I'll check up on Kynar.
Domestic use is usually heavier than the automotive, ie. taking the 4000 hrs target then for an average 30mph that gives 120K...
Thanks,I believe they tend towards PC-ABS, would this be OK in a translucent opal and given the adjacency to the light source it's a big ask on the UV stability?