Homebrew PCBs

I'm pondering making a homebrew S100 card or two.  Does anyone here have
experience in making cards with connection fingers?  Is tinplating as
applied by, say, solder paste, okay?  I know there are gold-plating kits
for this purpose out there, but it's prohibitively expensive.

-- 
David Griffith
dgriffi@...

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

> David wrote:
> 
> I'm pondering making a homebrew S100 card or
> two.  Does anyone here have experience in
> making cards with connection fingers?  Is
> tinplating as applied by, say, solder paste,
> okay?  I know there are gold-plating kits
> for this purpose out there, but it's
> prohibitively expensive.

Have not done S100 cards but do make edge
connectors for other things.

I tin with real solder (not paste) and then
use wick to remove the layer of solder I put
down.  I tried my vacuum pump desoldering
station - but it does not do as good a job
as wick.

Any thick layer of solder is not good for
edge conectors.

Solder paste should work as well as real
solder as long as you also wick it up
afterwards.

On Thu, 15 Jun 2006, Andrew wrote:

> > David wrote:
> >
> > I'm pondering making a homebrew S100 card or
> > two.  Does anyone here have experience in
> > making cards with connection fingers?  Is
> > tinplating as applied by, say, solder paste,
> > okay?  I know there are gold-plating kits
> > for this purpose out there, but it's
> > prohibitively expensive.
>
> Have not done S100 cards but do make edge
> connectors for other things.
>
> I tin with real solder (not paste) and then
> use wick to remove the layer of solder I put
> down.  I tried my vacuum pump desoldering
> station - but it does not do as good a job
> as wick.

Have you considered blowing the melted solder away instead of sucking it
up?

Actually, I'm considering building a D16 and/or a Magic-1 computer.  See
http://www.timefracture.org and http://www.homebrewcpu.org.  Ideally I'd
like to use VME backplanes.  A 12-slot backplane with both J1 and J2
connectors is what I'd prefer, but I can't seem to find them on Ebay.


-- 
David Griffith
dgriffi@...

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

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

From: "David Griffith" <dgriffi@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, June 15, 2006 3:37 AM
Subject: [Homebrew_PCBs] cards with fingers


>
> I'm pondering making a homebrew S100 card or two.  Does anyone here have
> experience in making cards with connection fingers?  Is tinplating as
> applied by, say, solder paste, okay?  I know there are gold-plating kits
> for this purpose out there, but it's prohibitively expensive.

Tandy used tin plating on the TRS-80 Model 1 expansion connector, it was 
rather unreliable and some people soldered gold-plated connectors onto their 
units. I never bothered and just unplugged and replaced the connector each 
time I used the computer, or kept the power on all the time. The current 
through the connector kept it conducting properly.

Leon

--- In Homebrew_PCBs@yahoogroups.com, David Griffith <dgriffi@...> wrote:
>
> 
> I'm pondering making a homebrew S100 card or two.  Does anyone here have
> experience in making cards with connection fingers?  Is tinplating as
> applied by, say, solder paste, okay?  I know there are gold-plating kits
> for this purpose out there, but it's prohibitively expensive.

If you use lead solder, that isn't technically tinning, is it?

I know from experience (I was manager of an arcade for a few years and
repaired a lot of games) that solder is a terrible thing on edge
connectors. The lead surface oxidizes very fast and causes terrible
connection problems.

We had one game that in the past had been "repaired" first by an
eraser on -gold- contacts, then solder on the edge connector, then
more and more solder in an attempt to make harder contact with the
spring contacts. The game would work for a little bit, then a bump
would reset it.

I removed -all- the solder right down to the bare copper, then used
that electroless tin plate. Cleaned the lead oxide off of the spring
contacts in the connector, and the game was golden after that.

Steve Greenfield

Q: What's the most annoying thing on a newsgroup?
A: Self-righteous self-appointed list-cops.

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

From: "Steve" <alienrelics@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, June 15, 2006 4:15 PM
Subject: [Homebrew_PCBs] Re: cards with fingers


> --- In Homebrew_PCBs@yahoogroups.com, David Griffith <dgriffi@...> wrote:
>>
>> 
>> I'm pondering making a homebrew S100 card or two.  Does anyone here have
>> experience in making cards with connection fingers?  Is tinplating as
>> applied by, say, solder paste, okay?  I know there are gold-plating kits
>> for this purpose out there, but it's prohibitively expensive.
> 
> If you use lead solder, that isn't technically tinning, is it?

Of course it is! One 'tins' wire or a terminal using a soldering iron.

Leon

--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" <leon.heller@...>
wrote:
>
> ----- Original Message ----- 
> From: "Steve" <alienrelics@...>

> > If you use lead solder, that isn't technically tinning, is it?
> 
> Of course it is! One 'tins' wire or a terminal using a soldering iron.

I know that people -call- it "tinning" when they are really applying a
coat of lead/tin solder. I mean you aren't really applying a coat of
just tin.

Did you read the rest of the message about using lead based solder on
edge connectors?

Steve Greenfield

On Thu, 15 Jun 2006 17:15:57 +0200, Steve <alienrelics@...> wrote:

>
> I removed -all- the solder right down to the bare copper, then used
> that electroless tin plate. Cleaned the lead oxide off of the spring
> contacts in the connector, and the game was golden after that.
> Steve Greenfield


I reckon you can use tin-only solder these days or tin-only plumbing  
solder paste. You'd need to make a thin coat but it should not have the  
problems you saw with the lead.

You are right tinning is not a good word, but what would you call it?  
soldering? solder plating? tin/lead plating? not really.

In a few years when they have taken all lead solder away and we have run  
out of our stocks the problem will solve itself ;-)

ST

> Steve wrote:

> <snip>
> I removed -all- the solder right down
> to the bare copper, then used that
> electroless tin plate. Cleaned the
> lead oxide off of the spring contacts
> in the connector, and the game was
> golden after that.

Steve - Was the electro-less tin plate
a particular brand ?  The generic stuff
I used from out big yellow and black
woolworths stores over here (DSE) was
shocking for corrosion.  It would turn
grey almost straight away and then
sometimes almost go black.

> <snip and out of order>
> that solder is a terrible thing on edge
> connectors. The lead surface oxidizes
> very fast and causes terrible connection
> problems.

Agree - any thickness of solder is very 
bad for connectors.  Thats why I advocate
wicking the solder up.  I suspect that it
only leaves what tin/lead has alloyed with
copper when doing a good wicking.  Though
I may be speaking carp here and it might
leave a much thicker layer of tin/lead
that has not alloyed with copper.  In any
case it is more reliable than a thick
layer.

When I tried to use my desolderer it left
too thick a film on the connector and it
was extra unreliable (as opposed to just
the standard unreliable the wicked version
gave)

Either way the solder version is probably
not reliable enough for an arcade or any
other comercial installation.  Maybe good
enough for a home made S100 bus - but if
a better quality tin plate works then that
is easier than solder.

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
>
> I reckon you can use tin-only solder these days or tin-only plumbing  
> solder paste. You'd need to make a thin coat but it should not have
the  
> problems you saw with the lead.

There you go.

> You are right tinning is not a good word, but what would you call it?  
> soldering? solder plating? tin/lead plating? not really.

I call it solder plating. Short, accurate. But is that 60/40, or
63/37, or 61/37/2, etc.... oh, my head!

> In a few years when they have taken all lead solder away and we have
run  
> out of our stocks the problem will solve itself ;-)

Very true. Let's hope the solder doesn't suck then.

Steve Greenfield

--- In Homebrew_PCBs@yahoogroups.com, "Andrew" <andrewm1973@...> wrote:
>
> > Steve wrote:
> 
> > <snip>
> > I removed -all- the solder right down
> > to the bare copper, then used that
> > electroless tin plate. Cleaned the
> > lead oxide off of the spring contacts
> > in the connector, and the game was
> > golden after that.
> 
> Steve - Was the electro-less tin plate
> a particular brand ?  The generic stuff
> I used from out big yellow and black
> woolworths stores over here (DSE) was
> shocking for corrosion.  It would turn
> grey almost straight away and then
> sometimes almost go black.

I don't recall. I don't even remember where I got it. For fun I plated
several pennies, many years later they look as bright as when I plated
them.

> > <snip and out of order>
> > that solder is a terrible thing on edge
> > connectors. The lead surface oxidizes
> > very fast and causes terrible connection
> > problems.
> 
> Agree - any thickness of solder is very 
> bad for connectors.  Thats why I advocate
> wicking the solder up.  I suspect that it
> only leaves what tin/lead has alloyed with
> copper when doing a good wicking.  Though
> I may be speaking carp here and it might
> leave a much thicker layer of tin/lead
> that has not alloyed with copper.  In any
> case it is more reliable than a thick
> layer.

No idea. Perhaps when the lead is in alloy with the copper it doesn't
oxidize, but then again it will oxidize when alloyed with tin. Maybe
there is so little lead left, it leaves very little oxidized lead left.

Steve Greenfield

On Thu, 15 Jun 2006 23:59:25 +0200, Andrew <andrewm1973@...> wrote:

>
> Either way the solder version is probably
> not reliable enough for an arcade or any
> other comercial installation.  Maybe good
> enough for a home made S100 bus - but if
> a better quality tin plate works then that
> is easier than solder.


You may also try rub-on silver. Either cool-amp or a cheaper homemade  
recepie.
It will oxidize but silver oxide should be conductive, right?

ST

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
>
> On Thu, 15 Jun 2006 23:59:25 +0200, Andrew <andrewm1973@...> wrote:
> 
> >
> > Either way the solder version is probably
> > not reliable enough for an arcade or any
> > other comercial installation.  Maybe good
> > enough for a home made S100 bus - but if
> > a better quality tin plate works then that
> > is easier than solder.
> 
> 
> You may also try rub-on silver. Either cool-amp or a cheaper homemade  
> recepie.
> It will oxidize but silver oxide should be conductive, right?

Yes, to both. However, I'm thinking there are reasons it isn't used on
edge connectors, which all seem to be either true tin plated, or gold
plated. While silver oxide is a conductor, I seem to recall that it is
not a very good one.

Steve Greenfield

On Fri, 16 Jun 2006 00:56:34 +0200, Steve <alienrelics@...> wrote:

> Yes, to both. However, I'm thinking there are reasons it isn't used on
> edge connectors, which all seem to be either true tin plated, or gold
> plated. While silver oxide is a conductor, I seem to recall that it is
> not a very good one.
> Steve Greenfield


I think i may have seen some, in TVs. Certainly rotary switches that have  
the same sliding/wiping action.

ST

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
>
> On Fri, 16 Jun 2006 00:56:34 +0200, Steve <alienrelics@...> wrote:
> 
> > Yes, to both. However, I'm thinking there are reasons it isn't used on
> > edge connectors, which all seem to be either true tin plated, or gold
> > plated. While silver oxide is a conductor, I seem to recall that it is
> > not a very good one.
> > Steve Greenfield
> 
> 
> I think i may have seen some, in TVs. Certainly rotary switches that
have  
> the same sliding/wiping action.

Doh! I should have remembered that.

The difference: those are self-cleaning because they get turned
constantly. There is grease/oil on them that tends to keep oxygen away
from the silver, plus rotating it scrapes off the relatively soft
silver oxide.

I've seen TVs get bad reception when left on one channel for a long
time, the fix is to change channels a few times.

Steve Greenfield

In a message dated 6/15/2006 11:40:17 A.M. Central Daylight Time,  
alienrelics@... writes:

I mean  you aren't really applying a coat of
just tin.



That would be "tin-plating", a whole-nuther process than  "soldering"


[Non-text portions of this message have been removed]

At 15:33 06/06/16, Stefan Trethan wrote:
>It [silver] will oxidize but silver oxide should be conductive, right?

Resistivity
Copper: 1.7E-8 Ohm-m
Silver: 1.6E-8 Ohm-m
Gold:   2.4E-8 Ohm-m
Silver Sulphide: 1.5E-3 to 2.0E-3 Ohm-m
Silver Oxide: 1.0E9 Ohm-m

So that's a 1.6E17 ratio - not my idea of a conductor.
(Numbers from an unauthoritative but well-argued Internet source)

However, in my locale, silver tarnishes to a brown/black, which
is probably silver sulphide (silver oxide is white or greyish).

This is only about 5 decades worse than the metal.

Still enough to cause unreliability in my college computer room's
old 10Base2 network with its many silver-plated BNC connectors.

To locate the bad ones, I used to terminate a section with a
shorted terminator and impose a small test current and
listen for the AF noise across the current limiting resistor as the
cable was handled. Usually, some contact cleaner and several
re-insertions would restore service for a few months.


Regards, LenW