Overmolding PCB
Overmolding PCB
(OP)
I want to overmold a PCB.
This is really hard because the components upon the PCB need to survive the high temperatures and high injection pressure.
Any material suggestions?
Suggestions?
This is really hard because the components upon the PCB need to survive the high temperatures and high injection pressure.
Any material suggestions?
- SAN (Styrene Acrylonitrile)
- PS (Polystyrene)
- PETG (Glycol-modified Polyethylene terephthalate)
- PA12 (Polyamide 12)
Suggestions?






RE: Overmolding PCB
Cheers,
Marc
RE: Overmolding PCB
Why not hollow out the design you have, add some supports and turn it into a housing?
www.nxjournaling.com
RE: Overmolding PCB
We want to protect the PCB from:
- Mechanical loads
- Electro static discharge
- Thermal loads(There are some plastics with decent thermal properties)
- Water
- Maybe a light guide
Its not about functionality in the first place, its more about pushing the process limits.RE: Overmolding PCB
- I assume the edge running around the perimeter of the part is the parting line. If so, it will need to move up to the centerline of the 3 round connectors otherwise the part will be trapped in the mold.
- The 3 round connectors may be distorted/destroyed by the pressure the mold exerts on them.
- The 3 round connectors appear to have a nut on them, which leads me to believe the bodies are threaded. Shutting off against a threaded surface will be next to impossible.
- The PCB will need to be supported in the mold, which will lead to portions of it being exposed.
- The rectangular connector in the middle of the board needs to have mold steel around it, which means the mold will have to shut off on the board face. There will need to be a support on the backside. The pressure of shutting off on the board may destroy nearby connections, traces, and/or the board itself.
- The resulting plastic piece has a very thick section that transitions sharply to a thinner section. This will result in warping as the piece cools. This will also result in sink marks and possibly voids.
- If it works, you'll end up with a part that has a near 0 chance of being recycled.
Also, you may want to check with approval agencies such as UL, CEC, etc to see what rules they have, if any, for such a design.RE: Overmolding PCB
Thanks for your reaction.
I modelled those issues on purpose.
because I want to check if moldex3D can spot those issues. We have a workshop this friday, and we are considering buying it.
This isnt a part we going to produce, this is just to test the moldex software.
Sorry for the confusion.
RE: Overmolding PCB
RE: Overmolding PCB
We overmold a particular PC board with reasonably good results (but no electrolytics which appear to be on your pc board?). Do consider a parylene coating first if moisture permeability is a concern.
RE: Overmolding PCB
RE: Overmolding PCB
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Overmolding PCB
RE: Overmolding PCB
They also have very high viscosity, even at that temperature, so pressures in the vicinity of 9000 psi are required to make them flow through a typical mold. The heat and the stress from the mold flow will likely displace or destroy any preattached components.
That's why epoxy, or anything else that can be gravity cast, is preferred for encapsulating electronics.
Mike Halloran
Pembroke Pines, FL, USA
RE: Overmolding PCB
The pressure will be a problem, but I think with smart gate choices I can overcome that problem
RE: Overmolding PCB
I am designing a mold as we speak, so I should have result in 1.5 months.
RE: Overmolding PCB
Melts at 60C or 140F much lower than polyethylene.
Chris DeArmitt - PhD FRSC
My Plastics & Materials Consulting Site: www.phantomplastics.com
Consultant to the Fortune 500
My Plastic Training Site: www.plastictraining.com
Where you can buy recorded training webinars on plastics, filled plastics, impact modification and more
RE: Overmolding PCB
Generally that's not the way manufacturing works. Unless you're simply doing pure research.
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Overmolding PCB
Demon3 thank you for your useful suggestion, I will certainly take a look at that!
Ornerynorsk, It is research oriented. I thought mechanical engineering was about making the impossible possible??
Cheers.
Marc
RE: Overmolding PCB
The research side is interesting and fun, I'll grant you that
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.