Hello everyone! A few responses here...
Those power pegs are an interesting idea, I have never been a fan of multiple vias on a PCB installed underneath a chip in an attempt to promote heat flow. One thing though, with the power peg installed in the hole how do I solder the chip to the board/peg?
The pegs do not press fit. This would cause stress in the FR4. They slip-fit in a 2.5MM via.
Simply add a dab of flux, tack in place, allow to cool, and paste/reflow as usual. Action of capillarity holds the peg in place when the solder is molten.
I will try to make a video soon.
I really like the Power Pegs, I will definitely have them in mind the next time I am considering though hole TO220s or similar with a standing heat-sink.
As I understand you screw the heat-sink into the peg after everything has been soldered. But since they are tiny, how much momentum can you use on the screw? How do you prevent the screw from shaking loose (Loctite?)?
1.0 inch pounds of torque MAX. Use a clutch driver, or screw by hand.
http://tem-products.com/TCAP-4325-TR_Datasheet.pdfAs long as the screw is fully engaged in the Peg, the screw will actually break before the thread strips. 0-80 screws are delicate!
PowerPeg is made of copper, so friction is enough to hold the screw in place when fully tightened. I have never seen one come loose (and I have used them in every way imaginable
). However loctite can be used, and does not effect the thermal interface.
Additional screws from PCB to heatsink are recommended to relieve mechanical stress from the thermal connector. PowerPeg is tough, but not invincible!
Those thermal pegs are quite nice, but one thing concerns me about them: Can the solder joints withstand the mechanical stress created by those pegs? Imagine you have 6-10 transistors on a board, all connected to the same heatsink, each with its own powerpeg. The heatsink will certainly have a different thermal expansion coefficient than FR4 - something will have to give.
The effects of thermal expansion of copper are negligible over short distances. For example: with a temperature change of 100C the length of the peg will change 0.000068 inches.
PowerPeg is precision machined to have matched thickness allowing many pegs to be attached to a single heatsink.
these Thermal Connectors are nice
but they are overpriced. $1.4 each ?? too expensive.
In the past two years we have made only one batch of 1200 pegs. The small quantity is the reason for the high price.
These pegs were (partially) hand made. They are precision machined from copper alloy and plated with nickel, then 24 kt gold.
The next batch will be larger. I forsee the price under $0.80.