Homebrew PCBs

I've just uploaded my latest PCB. It's a prototyping board for the
Siemens MC55 GSM modem module. The tricky part about it is the Hirose
DF12 50 way socket for the MC55, it's tiny with 0.5 mm lead spacing.
I've used that sort of spacing with ICs like the Philips LPC2016 ARM,
but it took some time to get the transparency right - I had to reduce
the pad widths slightly to get adequate clearance between them.

Hirose makes even smaller sockets with 0.4 mm lead spacing, I doubt if
I'll be able to manage those, unless I get the artwork printed on a
really high-res printer.

The pic is here:

http://groups.yahoo.com/group/Homebrew_PCBs/files/PhotoEtching/Leon/

Leon

My worry with that would not so much be the spacing, that should be fine,  
but i would be afraid the socket would come off if pulled on ;-)
0.4mm should still be possible with TT, that's just under 8/8mil rules i  
think. The problem is with those metric spacings the printer must "round"  
to the next full pixel, and i have found it is required to make the pads  
rather narrower than the spaces, to avoid problems.

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.

Also, i notice you cross-hatched the ground plane. Why?

ST

On Fri, 07 Apr 2006 11:16:16 +0200, leon_heller  
<leon.heller@...> wrote:

> I've just uploaded my latest PCB. It's a prototyping board for the
>
> Siemens MC55 GSM modem module. The tricky part about it is the Hirose
>
> DF12 50 way socket for the MC55, it's tiny with 0.5 mm lead spacing.
>
> I've used that sort of spacing with ICs like the Philips LPC2016 ARM,
>
> but it took some time to get the transparency right - I had to reduce
>
> the pad widths slightly to get adequate clearance between them.
>
>
> Hirose makes even smaller sockets with 0.4 mm lead spacing, I doubt if
>
> I'll be able to manage those, unless I get the artwork printed on a
>
> really high-res printer.
>
>
> The pic is here:
>
>
> http://groups.yahoo.com/group/Homebrew_PCBs/files/PhotoEtching/Leon/
>
>
> Leon
>

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, April 07, 2006 10:34 AM
Subject: Re: [Homebrew_PCBs] Photo-etch PCB with DF12 connector


> My worry with that would not so much be the spacing, that should be fine,
> but i would be afraid the socket would come off if pulled on ;-)
> 0.4mm should still be possible with TT, that's just under 8/8mil rules i
> think. The problem is with those metric spacings the printer must "round"
> to the next full pixel, and i have found it is required to make the pads
> rather narrower than the spaces, to avoid problems.

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.

>
> 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.

>
> Also, i notice you cross-hatched the ground plane. Why?

I didn't want to waste ink and solid areas seem to smear sometimes. They 
also take a long time to dry.

I'm just about to get my microscope out and start assembling that connector.

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

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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.

> 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'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?

ST

----- 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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On Fri, 07 Apr 2006 12:36:52 +0200, Leon Heller  
<leon.heller@...> wrote:

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

I found a great increase in my satisfaction with the finished product once  
i made larger pads, which is why i suggest it to everyone.

> 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.

I tried to find something similar for my ersa iron, it seems the power  
well or solder well tips are equivalent to the mini hoof. What outside  
diameter has this mini hoof approximately? The smaller solder well is  
2.5mm wide and i think that could be a bit much?

ST

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, April 07, 2006 12:09 PM
Subject: Re: [Homebrew_PCBs] Photo-etch PCB with DF12 connector


> On Fri, 07 Apr 2006 12:36:52 +0200, Leon Heller
> <leon.heller@...> wrote:
>
>> That's what I do, so that the joint is nice and strong. I don't get any
>> problems.
>>
>
> I found a great increase in my satisfaction with the finished product once
> i made larger pads, which is why i suggest it to everyone.
>
>> 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.
>
> I tried to find something similar for my ersa iron, it seems the power
> well or solder well tips are equivalent to the mini hoof. What outside
> diameter has this mini hoof approximately? The smaller solder well is
> 2.5mm wide and i think that could be a bit much?

Yes, they sound similar similar. PACE makes them, as well. The mini-hoof is 
here:

http://www.okinternational.com/product_soldering/mx500smtc

so the solder well is probably closest.

I've got a micro-hoof as well, but that is for very fine leads.

The X is for the different temperature ranges.

Leon


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On Fri, 07 Apr 2006 13:49:44 +0200, Leon Heller  
<leon.heller@...> wrote:

> Yes, they sound similar similar. PACE makes them, as well. The mini-hoof  
> is
>
> here:
>
>
> http://www.okinternational.com/product_soldering/mx500smtc
>
>
> so the solder well is probably closest.
>
>
> I've got a micro-hoof as well, but that is for very fine leads.
>
>
> The X is for the different temperature ranges.
>
>
> Leon


Well ersa shows pictures and a description that is identical to what you  
say about the hoof.
I might get one. Only drawback is the tip costs about 20eur, if you  
consider one of my stations only cost 12eur or so...

ST

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, April 07, 2006 12:57 PM
Subject: Re: [Homebrew_PCBs] Photo-etch PCB with DF12 connector


> On Fri, 07 Apr 2006 13:49:44 +0200, Leon Heller
> <leon.heller@...> wrote:
>
>> Yes, they sound similar similar. PACE makes them, as well. The mini-hoof
>> is
>>
>> here:
>>
>>
>> http://www.okinternational.com/product_soldering/mx500smtc
>>
>>
>> so the solder well is probably closest.
>>
>>
>> I've got a micro-hoof as well, but that is for very fine leads.
>>
>>
>> The X is for the different temperature ranges.
>>
>>
>> Leon
>
>
> Well ersa shows pictures and a description that is identical to what you
> say about the hoof.
> I might get one. Only drawback is the tip costs about 20eur, if you
> consider one of my stations only cost 12eur or so...

The Metcal tips are even more expensive; they are often available quite 
cheaply on Ebay, though.

Leon 

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On Fri, 07 Apr 2006 14:09:54 +0200, Leon Heller  
<leon.heller@...> wrote:

>
> The Metcal tips are even more expensive; they are often available quite
>
> cheaply on Ebay, though.
>
>
> Leon
>


I keep a permanent eye out on ebay for all ersa things, for tips and  
replacement irons and stuff, but so far none of these special tips has  
even made an appearance. Also, recently prices on ebay are getting quite  
silly. I mean i'm not paying like half of shop price with high shipping  
and no warranty, but some people seem prepared to do that these days. The  
days when i bought at ebay around 1/10th of shop prices seem over, for  
some reason i do not understand.

ST

That's 'cause some people live in the middle of nowhere and have no
alternative source.

There are still deals on EBay, you just have to be lucky and keep an eye
out.  It took me a while, but I got Visual Basic 6 at an excellent price.
You just have to be patient, something that just kills me.

Robert
:)


-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Stefan Trethan
Envoyé : avril 7 2006 08:24
À : Homebrew_PCBs@yahoogroups.com
Objet : Re: [Homebrew_PCBs] Photo-etch PCB with DF12 connector


I keep a permanent eye out on ebay for all ersa things, for tips and  
replacement irons and stuff, but so far none of these special tips has  
even made an appearance. Also, recently prices on ebay are getting quite  
silly. I mean i'm not paying like half of shop price with high shipping  
and no warranty, but some people seem prepared to do that these days. The  
days when i bought at ebay around 1/10th of shop prices seem over, for  
some reason i do not understand.

ST


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On Fri, 07 Apr 2006 14:31:52 +0200, Robert Hedan  
<robert.hedan@...> wrote:

> That's 'cause some people live in the middle of nowhere and have no
>
> alternative source.
>
>
> There are still deals on EBay, you just have to be lucky and keep an eye
>
> out.  It took me a while, but I got Visual Basic 6 at an excellent price.
>
> You just have to be patient, something that just kills me.
>
>
> Robert


That's true, but in general the prices here have gone up.
When i started with ebay not many even knew about it, now everybody buys  
there, that has driven prices up.

Also, the ebay market here (Austria and Germany) is much smaller than  
ebay.com so things are much rarer, and shipping makes import impossible in  
many cases, or the seller doesn't deal internationally, or the items were  
just never sold in significant numbers outside europe, like ersa soldering  
tips, so they don't come up on ebay.com anyway.

One can still get OK deals, after all i won't buy it if it isn't a ok  
deal, but a really great deal (something that is worth several hundred eur  
for 1eur, or at least something for 10% shop price or less) i haven't had  
for quite a while, and many more things i look at reach quite unreasonable  
prices often 10 times more than i had bought an identical item a few years  
ago and now want another. Also, i often want quite rare things, that maybe  
come up two or three times a year, if that. Many people are just not  
prepared to let something like that get away - well i am not prepared to  
pay unreasonable prices. I would expect VB6 to be fairly frequently coming  
up so that you can stand back and wait for a great deal.

ST