[SI-LIST] Re: How to solve short circuit issues in high dense pcbs
- From: Gene Glick <gglick@xxxxxxxxxxxx>
- To: rskiruban <rskiruban@xxxxxxxxxxxxxxxxxx>
- Date: Mon, 31 Oct 2011 09:59:12 -0400
On 10/31/2011 4:01 AM, rskiruban wrote:
> Hi All,
> One of my board having a short circuit (Zero Ohms) across a power supply
> (That supply connects to thousands of decoupling capacitors and 44 BGAs) and
> Ground. Is there any method to identify the route cause for the short
> without removing any components?
>
> Note:
> ####
> 1. The board is not yet powered on.
> 2. It was verified that the PCB doesn't contains any short across supplies
> before board assembly.
>
>
1) Use a milli-ohm meter may help. Place the ground lead to one corner
of the board. Probe the board at various places using the positive
lead. As you get closer to the short, the milli-Ohm meter will read lower.
2) Get a thermal imaging camera. Apply power to the board using a bench
supply. Setup the supply to limit the current at a very low value so
you don't blow up any parts. You could setup a lower voltage as well.
Now, with power supplied to the board, view the board through the
thermal imaging camera. The short will show up very clearly as a hot-spot.
Method 2 has proven to be *very* effective!
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