[sdiy] JH goes PCB - Copper ring size for PCBs?

[JH.]

Thank you Seb!

Meanwhile I've goot feedback from Olimex (much faster than I expected), and 
they also say it's ok.

So I'll go for this.

Thanks again,

JH.


----- Original Message ----- 
From: "Seb Francis" <seb at burnit.co.uk>
To: "JH." <jhaible at debitel.net>
Cc: "diy" <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, May 17, 2007 2:03 PM
Subject: Re: [sdiy] JH goes PCB - Copper ring size for PCBs?


A couple of things:

Normally manufacturers assume the size you specify is the finished hole
size, not the actual drill size.  So you shouldn't need to think about
the thickness of the plating through the hole, only about what size
component legs you want to push through the finished hole.

However just be confusing, the manufacturers I know spec the minimum
annular ring width with regard to the Production Hole Diameter (the
drill size itself).  The actual minimum annular ring width will vary
from manufacturer to manufacturer, but a typical value is 0.15mm.  Thus
your pad diameter must be 0.3mm larger than the Production Hole Diameter
(drill size), or 0.4mm larger than the finished hole size.

So Hole = 0.9mm, Pad = 1.5mm sounds easily ok (but do check the minimum
annular ring specs of your manufacturer)

Seb


JH. wrote:
> I'm editing some library elements of my Rimu PCB layout tool for the use
> with Olimex:
>
> Olimex web site says that final hole diameter will be 0.1mm smaller than
> drilled because of plating of the holes, and consequently offer "odd" 
> drill
> diameters as a standard, like 0.9mm and 0.7mm, to get the "standard" holes
> of 0.8mm and 0.9mm.
>
> So, ist it ok to increase the hole size in the library without also
> increasing the pad diameter?
> Specifically, is the combiantion
>
> Hole = 0.9mm, Pad = 1.5mm ok ?
>
> (Talking of double sided boards - I know it's probably not large enough 
> for
> single sided ...)
>
>
> Hmmm, yes ... I think I'm going to make pcbs again after many years of
> Veroboard-only.
> And I hope it will be for the benefit of the DIY comunity, too! :)
>
> And I just found that I *might* get the whole lot of filterbanks and
> envelope detectors of a Sennheiser vocoder
> on a single 320 x 200 mm board, when I completely redesign the circuit
> topology ...
>
> JH.
>
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