Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, April 07, 2006 11:21 AM
Subject: Re: [Homebrew_PCBs] Photo-etch PCB with DF12 connector


> On Fri, 07 Apr 2006 12:10:59 +0200, Leon Heller
> <leon.heller@...> wrote:
>
>> Those DF12 sockets are made with metal tabs, but those are the only ones
>>
>> stocked by my modem supplier. There is a general shortage of those Hirose
>>
>> connectors, especially the ones with tabs, in the UK. Probably something
>> to
>>
>> do with ROHS.
>
> It seems there is sometimes a shortage of components of some kind or the
> other here in europe, ROHS or not, in low quantities anyway. Some just
> don't "seem to make it over the pond" to distributors.
>
>>> BTW those throughhole pads in places seem VERY small with that size of
>>
>>> hole in them, compared to the trace the rings are tiny. I don't think
>>> that
>>
>>> is such a good thing with non-PTH boards.
>>
>>
>> They are the standard PTH size I use, I keep meaning to change them. I
>> use
>>
>> thin wire for the links and don't have problems. I should have added
>>
>> teardrops which would help.
>>
>
> Thought so. You can always fold the end of the wires over along the trace,
> but it isn't really that desireable.

That's what I do, so that the joint is nice and strong. I don't get any
problems.

>
>> I didn't want to waste ink and solid areas seem to smear sometimes. They
>> also take a long time to dry.
>
>
> I see. I just couldn't figure out why you'd do it with a inkjet, i see why
> it is sometimes required with a laser but didn't know about the smearing
> or drying. Do you happen to know if there is any significant disadvantage
> with crosshached ground planes? i mean the area resistance is probably
> higher, but is shielding affected at all with that small size of gaps?

I'd be OK if I didn't cut out pieces of the JetStar film I use a bit larger
then the PCB and stick them to ordinary paper with a piece of masking tape.
The film is expensive and I don't like wasting it.

At the frequencies I'm using a crosshatched plane doesn't make any
difference. All the very fast stuff is in the GSM module.

>
>
>> I'm just about to get my microscope out and start assembling that
>> connector.
>
> Is that a plastic case component? could be tricky to reflow then, how are
> you going to solder it?

My usual way - drag soldering with a Metcal mini-hoof tip after tacking down
the corners, with plenty of flux. They are designed for reflow soldering, of
course.

Leon
--
Leon Heller, G1HSM
leon.heller@...
http://www.geocities.com/leon_heller

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