Soldering underneath chips

Step 6 Heat from underneath

Now turn the board over and heat the poking out bits of copper wire from underneath.

Watch the topside of the board and notice that there should be a little bit of fumes as the solder paste melts and fluxes.

When cooled, nudge the chip. It should be rock solid if the paste has melted and solidified. If there is any play....then try heating again, or else remove everything/clean and try again.

Finally solder the remaining pins and the previously tacked pins and clean up with clean braid then flux remover and test for shorts.

Congratulations you've successfully attached a chip with a heatsink underneath both thermally and electrically.

Sorry about the blurry pics, my camera only just does macro.

This technique should be useful for not only chips as shown in the pictures, but also high power LEDs and any other components with a similiar need for a good electrical and thermal connection to PCB layouts.

Comments

[wierd idiot]

I just have to ask this. Why was the name of the chip wiped?

[kllrwolf]

I have been told by many professors at school (Electrical Engineering major), that once you start making things others will use, removing chip identifiers is the best way to protect your design from people who will try to reverse engineer it.

[wierd idiot]

Sad isn't it? That people do such things like being a copy cat.:(

[Derin]

And it makes the harvester's job harder.

[rgbphil]

nothing mysterious, I just wanted to have an uncluttered picture to emphasize the process not the circuit. Its a LTC3477 switch mode controller in case you're interested.

[drewish]

"Sorry about the blurry pics, my camera only just does macro." I think you'll find that adding more light and holding the camera still will do the trick.

[andrew101]

yea ither crop the image or hold it farther away and zoom

[jridley]

And if it really is true that the camera won't focus that close, then don't get that close, just crop the image down.