DIY thermal vias

Jim Yanik · 2009-08-31T17:41:00+00:00

I'm making a doublesided PCB,1/32" thick,that the datasheet for the IC calls for 4-6 thermal vias to the ground plane,under the IC. Is there any way of making them on a home-etched PCB? Google didn't turn up anything.I was considering cutting a slot and soldering a piece of copper the same thickness as the PCB into the slot.The IC (LM3410xmy)will be soldered to the thermal pad/ground. It's a boost LED driver driving two Cree high power LEDs at 340ma.-- Jim Yanikjyanikat

Aug 31, 2009 22 Replies

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MK 16 years ago

No you haven't quite got it - if the OP uses a board in the conventional way he will need 4 layers and probably 5 thou track and gap design rules. He'll pay well over $50 for one and will need to wait a couple of weeks (or well over $200 and have it in a couple of days.). But even when he gets the board he will have trouble soldering it. If he wants just one, tomorrow, and has no cash the home brew pcb with hand crafted copper slug makes perfect sense.

I don't etch my own boards any more because it's more cost effective for a paying customer to use a pcb house rather than my time. My kids have different budgets/priorities and have etched their own - it's actually quite a lot of fun.

Michael Kellett

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Hammy 16 years ago

An 8-pin MSOP isn't that difficult to work with. If you're intimidated by the package an alternative TH CC driver is the NCV3065PG you will need a bigger inductor max switching speed is only 150kHz.Search Onsemi for the part and it will give an excel based spreadsheet for components values.

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But seeing that you already have the MSOP John already gave you good advice.

Most people use Eagle I'm not sure of the download size, I've been using a student version of Orcad for years.

The half hour time I posted assumed you already had the board layout.

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Phil Hobbs 16 years ago

Sounds like a sensible idea to me too.

To control the thermal spreading resistance where the top and bottom sheets attach to the vias, it might be worth leaving the wire sticking out a bit and putting on a fairly generous solder fillet before trimming.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net

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