[sdiy] My frustration as a technician..

[Martin Klang]

I use 0603 footprints for most SMT resistors and caps: 1.6 mm × 0.8 mm, on one side.

Compare that to 7.5 or 10mm grid for through hole, on both sides -
how could you fit the same components with dual footprints without completely changing the size and layout of the board?
And what do you do with ic's?

I don't think you can ever arrive at an easy metric of 'x pence per hole, per board'.

If you want to make a comparison, I suggest you take some existing smt layouts that you are interested in and re-do them with dual footprints in the different ways that you propose.
Compare board fabbing costs, and add in the extra design time. Then you can get an idea of the real overhead.

Then take into consideration what the different layouts does to the performance of the board.
Are the tracks longer or shorter, digital and analog sections better or worse isolated, are the decoupling caps further removed; what is the effect of parasitic elements?

If you were to do this I'd look forward to hearing the results.

best,

/m


On 10 May 2013, at 23:01, cheater00 . wrote:

> John,
> 
> On Fri, May 10, 2013 at 11:33 PM, John Speth <jspeth at avnera.com> wrote:
>>> Rob, Dave, John, what do you guys say: does it really cost that much
>> more to
>>> put holes in your PCBs? Serious question.
>> 
>> Yes, it really does.  Every little thing contributes to cost.  Generally,
>> the smaller the better (lower product weight, less material, lower
>> shipping cost, etc).  Pennies count in a world where customers demand low
>> prices and capitalists demand high return on investment.
>> 
>> If the maker of a product could see a higher profit in making products
>> with thru hole, it'd be on the street in no time.  It'll probably never
>> happen though.
>> 
>> JJS
> 
> Not really the answer I had been hoping for. Given 100 holes, how much
> does it cost to do:
> 
> a) a hole, through-plated
> b) a hole, non-plated
> c) a pad which is a space for a hole
> 
> at amounts of 100 PCBs, 10 000 PCBs, 100 000 PCBs?
> 
> That's 10 000 holes, 1 000 000 holes, 10 000 000 holes.
> 
> Cheers,
> D.