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'[EE]:PCB etching: gravity method works'
2003\11\22@011954 by Colin Constant

picon face
I just tried the gravity method for etching boards and it really works!

Normally I just chuck the board in the tupperware and come back in half an
hour, for the first check.  But lately I noticed that the boards were coming
out with little granules of copper all over them.  Which led me to suspect
that maybe the bottom of the FeCl was getting a little loaded up.

So I suspended a board with masking tape, copper side down, just under the
surface, and it was done in like 15 minutes.

Thanks to the guy that came up with that idea.

Colin

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2003\11\22@020313 by Jinx

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> So I suspended a board with masking tape, copper side down,
> just under the surface, and it was done in like 15 minutes

You can do it even simpler - just float it

http://home.clear.net.nz/pages/joecolquitt/0makepcb.html

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2003\11\22@030442 by Luis Moreira

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Hi All
Since I joined the PICLIST I seen a lot of ways of producing PCB's but
because there are so many I am getting a bit apprehensive... I need to
produce PCB's with a good quality for surface mount components like, 44 pin
PQFP to 208 pin PQFP,as I am working with FPGA's.
So what I am asking is with out using outside manufacturers  is it possible
to do it and what method shall I use ?
regards
               Luis

{Original Message removed}

2003\11\22@033628 by Russell McMahon

face
flavicon
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> Since I joined the PICLIST I seen a lot of ways of producing PCB's but
> because there are so many I am getting a bit apprehensive... I need to
> produce PCB's with a good quality for surface mount components like, 44
pin
> PQFP to 208 pin PQFP,as I am working with FPGA's.
> So what I am asking is with out using outside manufacturers  is it
possible
> to do it and what method shall I use ?
> regards

Definitely doable yourself.

Single sided is easy.
Double sided is OK with care.
Never heard of an amateur pth capability although it would be possible.

Cinch through or links or whatever in place of pth is vvv annoying but can
be done.

Fine detail boards suggest avoiding amateurish methods.ie
- use a photo process.
- use presebsitised pcb material
- use decent etchant and etch tank eg use at least air bubbling.

Depending on circumstance you could consider using a local photo house to
produce negatives for you. You CAN do this yourself with a printer but a
proper photographic negative is a joy and may well not be overly dear.
Where I am there are (or were) people who do quick turnaround negatives
(same day) with internet submission.

Tinning can be a pain.
Others may comment on this.
You can get "electroless tin:" material sbut I always found them marginal.
Soldering tracks is a hard way to go :-)
if you clean a bare copper board well just before soldering and coat it with
some spray (polyurethane or better) as soon as soldered it will work well
enough.

Lack of solder mask makes very fine track seperations and eg TSOP pkgs hard
to do but not impossible.
You could do your own solder mask photographicvally too BUT somewhere about
there a cheap prototype house starts to look VERY attractive

       Russell McMahon



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2003\11\22@051817 by Philip Pemberton

face picon face
In message <003101c3b0c5$cdafc400$7223fea9@jc2>
         Jinx <.....joecolquittKILLspamspam.....CLEAR.NET.NZ> wrote:

> You can do it even simpler - just float it
> home.clear.net.nz/pages/joecolquitt/0makepcb.html
That's how I used to do it - fill a tray with etchant and float the board on
top. The trick is to tilt the tray so that most of the etchant is at one end,
with the end facing you almost dry - a section of the bottom of the tray
should be visible. Put the board onto the bare base of the tray and start
tilting the tray back down again. Agitate slightly to dislodge any air
bubbles.
What I do now is float the board vertically in the bottle of etchant (it's a
big Tupperware drinks container - one litre IIRC). That's good enough for
small boards, but for the big stuff I just pour the etchant into the tray.
I'd like to know how you managed to etch a board in 10 minutes - mine usually
take about half an hour. I did dilute the etchant in a 1:1 ratio when I got
it, as per the instructions on the bottle ("can be used neat, but should be
mixed 1:1 with water to prevent track undercutting"). I would have replaced
it by now, except I can't find a decent way to dispose of it - the best
option I've found so far involves mixing the etchant with Plaster of Paris.
Theoretically, the plaster would not only neutralise the etchant, it should
also immobilise the copper and iron left in the solution. Then again, IANAC
(I Am Not A Chemist).

Later.
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2003\11\22@053927 by Jinx

face picon face
> I'd like to know how you managed to etch a board in 10 minutes
> - mine usually take about half an hour. I did dilute the etchant in
> a 1:1 ratio when I got it, as per the instructions on the bottle ("can
> be used neat, but should be mixed 1:1 with water to prevent track
> undercutting")

I make my own super-saturated solution from crystals and never
dilute it. Fresh solution and a hot water bath will etch in less than
10 minutes. If you keep an eye on it there should be no significant
under-cutting and good clean edges. In fact I've found that old
solution gives poorer results in that regard

As for disposal, the subject has come up quite a few times and the
responsible way is to do it through a local council or, if they're willing,
ask any company that routinely has to dispose of their own nasties
to add your little bit of waste to theirs

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2003\11\22@054341 by Luis Moreira

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Hi Jinx
how small have you gone with track width ?

       Luis

-----Original Message-----
From: Jinx [KILLspamjoecolquittKILLspamspamCLEAR.NET.NZ]
Sent: 22 November 2003 10:38
To: RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU
Subject: Re: [EE]:PCB etching: gravity method works


> I'd like to know how you managed to etch a board in 10 minutes
> - mine usually take about half an hour. I did dilute the etchant in
> a 1:1 ratio when I got it, as per the instructions on the bottle ("can
> be used neat, but should be mixed 1:1 with water to prevent track
> undercutting")

I make my own super-saturated solution from crystals and never
dilute it. Fresh solution and a hot water bath will etch in less than
10 minutes. If you keep an eye on it there should be no significant
under-cutting and good clean edges. In fact I've found that old
solution gives poorer results in that regard

As for disposal, the subject has come up quite a few times and the
responsible way is to do it through a local council or, if they're willing,
ask any company that routinely has to dispose of their own nasties
to add your little bit of waste to theirs

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2003\11\22@055832 by Jinx

face picon face
> how small have you gone with track width ?

10 mil quite easily, and SMT like TSOP etc is no problem

The picture at the bottom of my page shows a recent
experiment with a Sharpie marker pen (as suggested by
Picdude) rather than the etch-resist pen I'd normally use

The fine lines are actually thinner than they appear there
because of the shine. Having the "needle-pen" and a
magnifier is a great help when tidying up resist edges
before etching and removing any bridges after etching,
not that I get very many of them at all

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2003\11\22@070201 by Luis Moreira

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face
Jinx
did you ever use the photoresist method ?

 Luis

-----Original Message-----
From: Jinx [joecolquittEraseMEspam.....CLEAR.NET.NZ]
Sent: 22 November 2003 10:58
To: EraseMEPICLISTspamMITVMA.MIT.EDU
Subject: Re: [EE]:PCB etching: gravity method works


> how small have you gone with track width ?

10 mil quite easily, and SMT like TSOP etc is no problem

The picture at the bottom of my page shows a recent
experiment with a Sharpie marker pen (as suggested by
Picdude) rather than the etch-resist pen I'd normally use

The fine lines are actually thinner than they appear there
because of the shine. Having the "needle-pen" and a
magnifier is a great help when tidying up resist edges
before etching and removing any bridges after etching,
not that I get very many of them at all

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2003\11\22@070822 by Rick C.

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You can etch and make lines as small as you can lay out the board.
Etching with copper side down will speed up your process as noted in
paragraph 6 on my website http://www.pic101.com/pcb

Negative photoresist method I find is very successful with quality
results. However, my supplier of sensitized boards, Kepro, is out of
business so I'm back to sensitizing my own boards now.
Rick C.

Luis Moreira wrote:

> Jinx
> did you ever use the photoresist method ?
>
>   Luis
>
> -----

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2003\11\22@071238 by Russell McMahon

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>.... so I'm back to sensitizing my own boards now.

Using which sensitisation method?
(spray, film, other ...)

I'm sure that people would be interested in hearing about successful home
sensitisation methods as it can be something of a black art.


   RM

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2003\11\22@072236 by Rick C.

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Paragraph 4 on my page has the instructions in detail on sensitizing your own
boards. The problem now is obtaining the KPR. It is probably harder to get
now especially with the "so-called" hazardous materials used. Although it
just smells like fingernail polish. I've googled for KPR with limited
results. I believe this is the same footrests used in making silk screens, so
it may be available under another name.

There is another company that may pick up the line of sensitized copper clad
that has a phone number on the Kepro web site. Keeping my fingers crossed.
Rick

Russell McMahon wrote:

> >.... so I'm back to sensitizing my own boards now.
>
> Using which sensitisation method?
> (spray, film, other ...)
>
> I'm sure that people would be interested in hearing about successful home
> sensitisation methods as it can be something of a black art.
>
>     RM

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2003\11\22@072858 by Rick C.

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Oops! forgot the link: http://www.pic101.com/pcb

"Rick C." wrote:

{Quote hidden}

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2003\11\22@074143 by Rick C.

flavicon
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P.S. If you use a casserole dish, the bottom is not flat, but slightly
rounded. Thus, the resist does not make contact with the glass. Only the
very corners of the board touch the glass and leave enough etch solution
to work on the board. Providing heat will circulate the etchant
sufficiently. Occasionally, lifting the board and exposing it to air
will also speed up the etching.
Rick C.

"Rick C." wrote:

{Quote hidden}

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2003\11\22@080052 by Jinx

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> did you ever use the photoresist method ?

No - always FeCl and etch-resist pen. My self-made boards
will be for my own use (eg experimental, special shape), a
prototype or a one-off for a customer.

For small quantities it's a bit of a coin toss whether to draw it
up with Eagle and get them made professionally. Depending
on the size, the time spent drawing could just as well be spent
actually making a couple. Cost, time and convenience are
factors too, so I've no hard and fast rules

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2003\11\22@081127 by Luis Moreira

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Hi Rick
because I whant to try to do some PCB's for 44 pin PQFP to 208 pin PQFP,I am
not sure about exposure time and etching times, how would you solve this?
               Luis

{Original Message removed}

2003\11\22@095723 by Charles Rogers

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----- Original Message -----
From: Russell McMahon <EraseMEapptechspamEraseMEPARADISE.NET.NZ>
To: <@spam@PICLIST@spam@spamspam_OUTMITVMA.MIT.EDU>
Sent: Saturday, November 22, 2003 2:36 AM
Subject: Re: [EE]:PCB etching: gravity method works


{Quote hidden}

Russell:

While I agree with your reply, but it might be a bit confussing.   Wouldn't
a POSITIVE
from the local photo house be easier to work with as opposed to a negative.

CR

In two years of monitioring the PICLIST this is only my  second reply.  I
was severly
chastised the first time for asking a simple question.

>
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2003\11\22@100137 by Rick C.

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The size and width of the tracks have nothing to do with exposure and etching
times. You do have to make sure on your artwork, when you have the negative (or
positive depending on your process) created the emulsion of the film is in
contact with the resist when exposing the board. Otherwise you will get creeping
of light under the film more noticeable with fine pads and traces.

Rick.

Luis Moreira wrote:

> Hi Rick
> because I whant to try to do some PCB's for 44 pin PQFP to 208 pin PQFP,I am
> not sure about exposure time and etching times, how would you solve this?
>                 Luis
>
> {Original Message removed}

2003\11\22@104205 by Rafael Fraga

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To get the best exposure time, do a test:
Use a strip of sensitized board, cover almost all of it with something
non-transparent *to UV* light, and do an exposure longer than expected. As
the time goes, say each minute, uncover a little part of the board. At the
end, develop and process as usual. This way, you will get under and over
exposures in the same board, so if you took notes of the times, you will get
the optimum exposure.
I use a 500W mercury vapor lamp (standard lightning lamp), getting around 18
minutes at a distance of 20cm.
I use the gravity method, with saturated ferric chloride solution. As the
specific gravity of the solution is higher than the board, it floats easily.
Sadly, this is not so easy with ammonium perchlorate.
Photoresist:  Kontakt Chemie Positiv 20, positive action, spray applied and
oven cured.
Anyway, craftsmanship and luck are essential

Rafael Fraga


----- Original Message -----
From: Luis Moreira <TakeThisOuTLuis.Moreira.....spamTakeThisOuTJET.EFDA.ORG>
To: <TakeThisOuTPICLISTKILLspamspamspamMITVMA.MIT.EDU>
Sent: Saturday, November 22, 2003 10:09 AM
Subject: Re: [EE]:PCB etching: gravity method works


> Hi Rick
> because I whant to try to do some PCB's for 44 pin PQFP to 208 pin PQFP,I
am
> not sure about exposure time and etching times, how would you solve this?
>                 Luis
>
> {Original Message removed}

2003\11\22@165701 by Hopkins

flavicon
face
Ahh - Russell - I also live in NZ

1. In what form do you submit your artwork JPG, BMP etc
2. What is the name of the photo house you use?
3 Were do you get your presensitised pcb's from?

I guess most photo developers would be able to create a negative.

Regards Roy

{Quote hidden}

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2003\11\23@011612 by Russell McMahon

face
flavicon
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> Ahh - Russell - I also live in NZ
>

It's been a while since I did any PCB making myself so my asnwers don't
nevessarily reflect current status BUT should be a good guide. I tend to use
the Circuit Graphics protoype service in Auckland. Not as cheap as doing it
yourself but reasonable value for money - especially if you can combine  a
number of designs onto an A3 panel. A3 is better value than A4 overall but
both are dear for single one offs.

> 1. In what form do you submit your artwork JPG, BMP etc

Depends on the photo house.
The best ones will accept Gerber which many PCB packages produce. If you are
producing artwork from an "art" or drawing package or scanning it in then
they will certainly accept one or more standard image formats. TIF is
arguably the most unoiversal due to its lossless storage. Ask who you use
what they want - converting from what you produce to anything else can
usually be done with a free utility. (The marvellous free Irfanview will
handle most http://www.irfanview.com).

> 2. What is the name of the photo house you use?

I used Compucolour in auckland (357 6234) who were excellent but I think
they may no longer offer this service. They charged $10 for an A4 sheet with
internet submission and a 4 hour turn around (sometimes as little as 2). I
have also used a company in Lansford Crescent in Avondale when I got some
PCB work done by Advanced Circuits. They would probably be happy to tell you
who they use.

> 3 Were do you get your presensitised pcb's from?

I got Riston coated board from a local PCB supplier (probably Circuit
Graphic afair). Cut to size and on single or double sided board. I was
surprised that they were happy to do this as it was in competition with
their prototype service but they didn't seem to mind at all. Prices were
good compared to small volume PCB material sourcing elsewhere. They don't
make any great money on prototypes I imagine so others may also be happy to
do this.

> I guess most photo developers would be able to create a negative.

There are many photographic companies who serve industrial needs (advertsing
and other) and thgey are probably your best targets - yellow pages.


       Russell McMahon

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2003\11\23@023657 by Jinx

face picon face
> have also used a company in Lansford Crescent in Avondale
> when I got some PCB work done by Advanced Circuits. They
> would probably be happy to tell you who they use

AC are in Avondale, and I believe they still use Hanwall Graphics
in Grey Lynn (?) The last job I put through AC was a run of boards
that had to be made from a scan of an existing board (for which
the original art/Gerber/whatever was lost). I digitised it to a sharp
b/w image and Hanwall was able to produce artwork for AC from
a 2X print-out. The whole process was around NZ$40, but there
were steps over and above normal (as well as my time to get it
to the usable graphic stage)

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2003\11\24@003706 by ahid Sheikh

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face
> Double sided is OK with care.

If you are looking for thru-hole plating, check out the
http://www.lpkf.com website. The EasyContac
(http://www.lpkf.com/others/1/233-rp_chapter_easycontac.pdf) is a manual
thru-hole plating process in which you basically flare open the ends of
a copper barrel after instering it thru the hole. That kit unlike the
rest of their products wasn't overly expensive either.
For free time browsing, the LPKF site is definitely one to visit. They
make a lot of neat prototyping stuff though most of it is very
expensive.

Shahid

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2003\11\24@021602 by William Chops Westfield

face picon face
On Sunday, Nov 23, 2003, at 21:30 US/Pacific, Shahid Sheikh wrote:
>
> For free time browsing, the LPKF site is definitely one to visit. They
> make a lot of neat prototyping stuff though most of it is very
> expensive.
>
Available cheaper, occasionally, on eBay and similar sites.   :-) :-)

Not having plated through holes (or even contemplatng manually
inserting those copper eyelets in any significant number) causes one to
make certain changes in the style of their PCB layouts :-(

BillW

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2003\11\24@061341 by Luis Moreira

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face
Hi Rafael
would it be possible to use an 80W bulb insted ? Is just for the fact that I
already have the complete thing.
thanks
               Luis

{Original Message removed}

2003\11\24@073308 by Alan B. Pearce

face picon face
> 3 Were do you get your presensitised pcb's from?

In NZ you can probably get this from RS Components. Probably pretty
expensive, but if doing it just for hobbyist use where you only need a bit
now and then this may well be a small quantity way to do it. Don't get too
much as I believe the coating has a shelf life that is not too long (maybe a
year or so). Check this out before buying a great bundle.

Otherwise Russell's notes should help you.

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2003\11\24@093323 by Bob Barr

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On Mon, 24 Nov 2003 10:30:33 +0500, Shahid Sheikh wrote:

>> Double sided is OK with care.
>
>If you are looking for thru-hole plating, check out the
>http://www.lpkf.com website. The EasyContac
>(http://www.lpkf.com/others/1/233-rp_chapter_easycontac.pdf) is a manual
>thru-hole plating process in which you basically flare open the ends of
>a copper barrel after instering it thru the hole. That kit unlike the
>rest of their products wasn't overly expensive either.
>

What pricing do they have on their kits? They list the cost of these
little things at US$0.35 each. That could get real expensive real
fast.


Regards, Bob

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2003\11\24@101752 by Rafael Fraga

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I suppose so. If you make longer exposures. My 500W has phosphor inside
coating, to convert UV in visible "daylight" light. Maybe yours not.... Just
make a test!



----- Original Message -----
From: Luis Moreira <RemoveMELuis.MoreiraspamspamBeGoneJET.EFDA.ORG>
To: <spamBeGonePICLIST@spam@spamspam_OUTMITVMA.MIT.EDU>
Sent: Monday, November 24, 2003 8:12 AM
Subject: Re: [EE]:PCB etching: gravity method works


> Hi Rafael
> would it be possible to use an 80W bulb insted ? Is just for the fact that
I
> already have the complete thing.
> thanks
>                 Luis
>
> {Original Message removed}

2003\11\24@223707 by Colin Constant

picon face
>I use the gravity method, with saturated ferric chloride solution. As the
>specific gravity of the solution is higher than the board, it floats
>easily.
>Sadly, this is not so easy with ammonium perchlorate.

I'm not sure what you mean by "saturated", and I'm not sure what you mean by
"board".

But I"m sure that the 1/16" FR4 boards I'm using are denser than the ferric
chloride I'm using :-)

Colin

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2003\11\24@231727 by Jinx

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> I'm not sure what you mean by "saturated"

Saturated means no more crystals will dissolve at that temperature

Super-saturation is a temporary condition - when the solution cools
down the excess will recrystallise and drop out

> and I'm not sure what you mean by "board"

"Board" is the unetched stock

> But I"m sure that the 1/16" FR4 boards I'm using are denser than
> the ferric chloride I'm using :-)

Well, I've yet to find a board that sinks, phenolic or GRP

"sinks" means not on the top anymore, drowning, gurgle gurgle

"top", as in...........

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2003\11\25@003457 by Denny Esterline

picon face
That depends on the definition of "is".

Sorry couldn't resist- :-)

-Dk

----- Original Message -----
From: "Jinx" <TakeThisOuTjoecolquittspamspamCLEAR.NET.NZ>
To: <PICLISTEraseMEspamMITVMA.MIT.EDU>
Sent: Monday, November 24, 2003 11:15 PM
Subject: Re: [EE]:PCB etching: gravity method works


{Quote hidden}

subtopics
> (like ads or off topics) for you. See http://www.piclist.com/#topics
>

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2003\11\25@024654 by ahid Sheikh

flavicon
face
>> If you are looking for thru-hole plating, check out the
>> http://www.lpkf.com website. The EasyContac
>> (http://www.lpkf.com/others/1/233-rp_chapter_easycontac.pdf) is a
>> manual thru-hole plating process in which you basically flare open
the
>> ends of a copper barrel after instering it thru the hole. That kit
>> unlike the rest of their products wasn't overly expensive either.
>
> What pricing do they have on their kits? They list the cost of these
> little things at US$0.35 each. That could get real expensive real
fast.

I bought the kit (shown in the picture) for 180 euro. It includes 1000
rivets each of 0.8mm, 1.0mm, 1.2mm, and 1.4mm outer diameter. Inner dia
I think is 0.2mm less for each.

Individual rivet packs of 1000 pieces were 35 euro so that's 0.035 euro
each. That's about $0.041 per rivet. I would think their pricing for the
US market would be a bit better because it's a much bigger market.

Shahid

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2003\11\25@025521 by Jinx

face picon face
> That depends on the definition of "is".
>
> Sorry couldn't resist- :-)

s'OK - resist is quite pertinent to etching

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2003\11\25@110236 by Bob Barr

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face
On Tue, 25 Nov 2003 00:36:03 -0500, Denny Esterline wrote:

>That depends on the definition of "is".
>

That's going to be known historically as a "Clintonian" response. :=)

>Sorry couldn't resist- :-)

Neither could I. :=)


Regards, Bob

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2003\11\25@110237 by Bob Barr

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On Tue, 25 Nov 2003 11:58:07 +0500, Shahid Sheikh wrote:

>
>I bought the kit (shown in the picture) for 180 euro. It includes 1000
>rivets each of 0.8mm, 1.0mm, 1.2mm, and 1.4mm outer diameter. Inner dia
>I think is 0.2mm less for each.
>
>Individual rivet packs of 1000 pieces were 35 euro so that's 0.035 euro
>each. That's about $0.041 per rivet. I would think their pricing for the
>US market would be a bit better because it's a much bigger market.
>

Thanks for your reponse. That price sounds a lot more reasonable than
what I was thinking. It appears that they slipped a decimal point on
their web page, $,035 is a lot more reasonable than $.35 each. (Their
quoted price must have been calculated when the Euro and the US$ were
about equal.)


Regards, Bob

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2003\11\25@233844 by Rafael Fraga

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Saturated: dissolve crystals until there is impossible to continue doing it.
Board: 1.5 mm single sided copper clad FR4

{Original Message removed}

2003\11\26@164332 by Rick C.

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Just released!
My version on making thru-hole connections.
http://www.pic101.com/pcb/thru.htm
Rick C.

Bob Barr wrote:

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2003\11\26@173615 by Tony Nixon

flavicon
picon face
"Rick C." wrote:
>
> Just released!
> My version on making thru-hole connections.
> http://www.pic101.com/pcb/thru.htm
> Rick C.


A method I used was to create a blank pad next to the IC pin on the top
of the PCB. Bend the IC socket pin out and solder to top PCB trace. Most
times this trace can be routed to another through hole component which
will complete the connection to the underside of the PCB.

If not a simple wia next to the IC pin suffices. wia = a wire filled via
;-) This method is servicable.

Another method using machine pin sockets (although a bit time consuming)
is to knock out the pins from the plastic cradle and solder them to a
double sided PCB, top and bottom. You can place all the loose pins on
the pin legs of another socket and plug all of them into the holes at
once. After soldering, remove the socket.

regards

Tony

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2003\11\26@181428 by William Chops Westfield

face picon face
On Wednesday, Nov 26, 2003, at 14:32 US/Pacific, Tony Nixon wrote:

> "Rick C." wrote:
>> My version on making thru-hole connections.

> A method I used was to create a blank pad next to the IC pin on the top
> of the PCB.

One of the interesting issue with home-brew PCBs is that it can be
useful to ADD vias if it helps avoid relying on PTH for connections
from one side of the board to the other.  It's easy to solder a wire in
a via, and rather less easy to
ensure that a non-plated hole makes contact on both sides.  I don't
think I've found a good way to convince Eagle to do that sort of thing,
however.

BillW

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2003\11\26@185035 by Rick C.

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face
The artwork layout on boards I prototype are usually the ones that are
completely functional and just about ready for mass production. They have to
look and work like the production ones. Every effort to make the boards
exactly the way the final production units are has to be made. There has to
be a minimum amount of vias (some pc houses calculate the vias in the cost
estimates), and extra blank pads. But your suggestion is a usable alternative

for single quantity fabrication.
Rick C.

William Chops Westfield wrote:

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