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'American Wire Gauge Table for PICSTERS'
1999\01\03@225847 by

See table below for wire sizes and suggested current ratings, etc.
File away for future use.

----------
From: Ricardo Ponte G <rniniverCANTV.NET>
To: PICLISTMITVMA.MIT.EDU
Subject: How can I know the cable type ??????
Date: Tuesday, December 29, 1998 12:22 AM

Hi, how are you ? :

I  have a doubt:

I4m trying to know How can I calculate the cable type (AWG or
somethig
like it) if a know how much current will flow throught it (some 40mA).

I need to know it because want to build a bobbin.

Any formulas ????

thanks.
----------

----------

No formulas here, but instead a wire table listing that should have the
info you desire.

AWG Wire Table for BARE COPPER Wire Compiled by a program written by Fr.
Tom McGahee

Compiled by Fr. Tom McGahee tom_mcgaheesigmais.com

AWG = American Wire Gauge size
Dia-mils = Diameter in mils (1 mil = .001 inch)
TPI = Turns Per Inch (Ignoring thickness of unknown insulation)
Dia-mm = Diameter in millimeters (For comparison with non-USA coilers)
Circ-mils = Circular Mils. (circular mils = diameter in mils squared)
Ohms/Kft = Ohms Per 1,000 Feet
Ft/Ohm = Feet Per Ohm
Ft/Lb = Feet Per Pound
Ohms/Lb = Ohms Per Pound
Lb/Kft = Pounds Per 1,000 Feet
NormAmps = Normal Average Amp Capacity based on 500 circular mils per Amp
MaxAmps = Maximum recommended Average Amp Capacity in Open Air based on 438.489
circular mils per Amp

Actual Amp capacity of a wire depends on form factor and method of cooling!
MaxAmps assumes free flow of air around wire. Do NOT exceed this maximum without
cooling!
Wire wrapped in a coil or without any form of cooling may over-heat at MaxAmps!
Many factors govern the ACTUAL Max Amps you can pass through a wire continuously
. Be careful!

AWG       Dia-mils  TPI       Dia-mm    Circ-mils Ohms/Kft  Ft/Ohm    Ft/Lb
Ohms/Lb   Lb/Kft    NormAmps  MaxAmps

0000       459.99    2.1740    11.684    211592    0.0490     20402    1.5613
0.0001    640.48    423.18    482.55
000        409.63    2.4412    10.405    167800    0.0618     16180    1.9688
0.0001    507.93    335.60    382.68
00         364.79    2.7413    9.2657    133072    0.0779     12831    2.4826
0.0002    402.80    266.14    303.48

AWG       Dia-mils  TPI       Dia-mm    Circ-mils Ohms/Kft  Ft/Ohm    Ft/Lb
Ohms/Lb   Lb/Kft    NormAmps  MaxAmps

0         324.85    3.0783    8.2513    105531    0.0983     10175    3.1305
0.0003    319.44    211.06    240.67
1         289.29    3.4567    7.3480     83690    0.1239    8069.5    3.9475
0.0005    253.33    167.38    190.86
2         257.62    3.8817    6.5436     66369    0.1563    6399.4    4.9777
0.0008    200.90    132.74    151.36
3         229.42    4.3588    5.8272     52633    0.1970    5075.0    6.2767
0.0012    159.32    105.27    120.03
4         204.30    4.8947    5.1893     41740    0.2485    4024.7    7.9148
0.0020    126.35    83.480    95.190
5         181.94    5.4964    4.6212     33101    0.3133    3191.7    9.9804
0.0031    100.20    66.203    75.489
6         162.02    6.1721    4.1153     26251    0.3951    2531.1    12.585
0.0050    79.460    52.501    59.866
7         144.28    6.9308    3.6648     20818    0.4982    2007.3    15.869
0.0079    63.014    41.635    47.476
8         128.49    7.7828    3.2636     16509    0.6282    1591.8    20.011
0.0126    49.973    33.018    37.650
9         114.42    8.7396    2.9063     13092    0.7921    1262.4    25.233
0.0200    39.630    26.185    29.858

AWG       Dia-mils  TPI       Dia-mm    Circ-mils Ohms/Kft  Ft/Ohm    Ft/Lb
Ohms/Lb   Lb/Kft    NormAmps  MaxAmps

10         101.90    9.8140    2.5881     10383    0.9989    1001.1    31.819
0.0318    31.428    20.765    23.678
11         90.741    11.020    2.3048    8233.9    1.2596    793.93    40.122
0.0505    24.924    16.468    18.778
12         80.807    12.375    2.0525    6529.8    1.5883    629.61    50.593
0.0804    19.765    13.060    14.892
13         71.961    13.896    1.8278    5178.3    2.0028    499.31    63.797
0.1278    15.675    10.357    11.810
14         64.083    15.605    1.6277    4106.6    2.5255    395.97    80.447
0.2031    12.431    8.2132    9.3654
15         57.067    17.523    1.4495    3256.7    3.1845    314.02    101.44
0.3230    9.8579    6.5134    7.4271
16         50.820    19.677    1.2908    2582.7    4.0156    249.03    127.91
0.5136    7.8177    5.1654    5.8900
17         45.257    22.096    1.1495    2048.2    5.0636    197.49    161.30
0.8167    6.1997    4.0963    4.6709
18         40.302    24.813    1.0237    1624.3    6.3851    156.62    203.39
1.2986    4.9166    3.2485    3.7042
19         35.890    27.863    0.9116    1288.1    8.0514    124.20    256.47
2.0648    3.8991    2.5762    2.9376

AWG       Dia-mils  TPI       Dia-mm    Circ-mils Ohms/Kft  Ft/Ohm    Ft/Lb
Ohms/Lb   Lb/Kft    NormAmps  MaxAmps

20         31.961    31.288    0.8118    1021.5    10.153    98.496    323.41
3.2832    3.0921    2.0430    2.3296
21         28.462    35.134    0.7229    810.10    12.802    78.111    407.81
5.2205    2.4521    1.6202    1.8475
22         25.346    39.453    0.6438    642.44    16.143    61.945    514.23
8.3009    1.9446    1.2849    1.4651
23         22.572    44.304    0.5733    509.48    20.356    49.125    648.44
13.199    1.5422    1.0190    1.1619
24         20.101    49.750    0.5106    404.03    25.669    38.958    817.66
20.987    1.2230    0.8081    0.9214
25         17.900    55.866    0.4547    320.41    32.368    30.895    1031.1
33.371    0.9699    0.6408    0.7307
26         15.940    62.733    0.4049    254.10    40.815    24.501    1300.1
53.061    0.7692    0.5082    0.5795
27         14.195    70.445    0.3606    201.51    51.467    19.430    1639.4
84.371    0.6100    0.4030    0.4596
28         12.641    79.105    0.3211    159.80    64.898    15.409    2067.3
134.15    0.4837    0.3196    0.3644
29         11.257    88.830    0.2859    126.73    81.835    12.220    2606.8
213.31    0.3836    0.2535    0.2890

AWG       Dia-mils  TPI       Dia-mm    Circ-mils Ohms/Kft  Ft/Ohm    Ft/Lb
Ohms/Lb   Lb/Kft    NormAmps  MaxAmps

30         10.025    99.750    0.2546    100.50    103.19    9.6906    3287.1
339.18    0.3042    0.2010    0.2292
31         8.9276    112.01    0.2268    79.702    130.12    7.6850    4145.0
539.32    0.2413    0.1594    0.1818
32         7.9503    125.78    0.2019    63.207    164.08    6.0945    5226.7
857.55    0.1913    0.1264    0.1441
33         7.0799    141.24    0.1798    50.125    206.90    4.8332    6590.8
1363.6    0.1517    0.1003    0.1143
34         6.3048    158.61    0.1601    39.751    260.90    3.8329    8310.8
2168.1    0.1203    0.0795    0.0907
35         5.6146    178.11    0.1426    31.524    328.99    3.0396     10480
3447.5    0.0954    0.0630    0.0719
36         5.0000    200.00    0.1270    25.000    414.85    2.4105     13215
5481.7    0.0757    0.0500    0.0570
37         4.4526    224.59    0.1131    19.826    523.11    1.9116     16663
8716.2    0.0600    0.0397    0.0452
38         3.9652    252.20    0.1007    15.723    659.63    1.5160     21012
13859    0.0476    0.0314    0.0359
39         3.5311    283.20    0.0897    12.469    831.78    1.2022     26496
22037    0.0377    0.0249    0.0284

AWG       Dia-mils  TPI       Dia-mm    Circ-mils Ohms/Kft  Ft/Ohm    Ft/Lb
Ohms/Lb   Lb/Kft    NormAmps  MaxAmps

40         3.1445    318.01    0.0799    9.8880    1048.9    0.9534     33410
35040    0.0299    0.0198    0.0226

'[EE:] Wire Gauge'
2004\09\04@133112 by
2004\09\04@162535 by
2004\09\05@063231 by
Olin Lathrop wrote:
> David Challis wrote:
>
>>The AWG "Wire gauge is the resistance per unit length in decibels,
>>where 10 AWG wire has 1 ohm per thousand
>>feet resistance."
>
>
> Decibels doesn't make sense in this context.  I guess they are really trying
> to say
>
>   gauge = 10 * Log10(mOhms / foot) ?
>
> But that implies that really fat wires have a negative gauge.  #0 cable
> would have 100uOhms/foot and have 3.2 times the diameter of #10.  Anything
> bigger would have to have a negative guage, although I've never heard of
> that.  Of course, I haven't worked with such fat cables either, so maybe
> they do have negative gauge numbers.  Or maybe by that size they are called
> something else, like "bus bars" and have a whole different numbering system?

Kinda.  Zero gauge is also known as 1/0 or "one aught".  The next bigger
size is 2/0 or 00 or "two aught".  And so forth, and so on.

Solid copper becomes a pain in the butt above about 4/0, but a lot of
times you see stranded construction stuff that goes much much bigger, of
course, and a few manufacturers put crazy stuff like 8/0 on the outside
jacket trying to say the stuff is the equivalent of a solid copper wire
that is that gauge.

Main distribution legs that are 1" or greater cross-section stuff in the
-48VDC battery systems at a telco central office is pretty common, that
stuff looks like small fire hoses.  And I got to see some again here
recently on a trip where some equipment I was responsible for was
installed in a CO.

The fun thing to see was the tool they use to crimp together cables that
size.  It looks similar to a "Sawsall" that is battery operated but its
only purpose in life is to crimp these huge sized cables to each other
using special soft metal rings that have two holes in them the size of
the cable.  Both cables are inserted and then the tool clamps down in
and crushes in a circular fashion -- for the first few, it was
fascinating to watch.  (Hey nothing like that is too interesting after
the first five or six of them.)

And I was more than willing to let those much-maligned Union
electricians climb around in overhead racks installing those, while I
remained planted firmly on the ground.  It was only about \$6 million
dollars worth of hardware they were building the power distribution
system for, while climbing around like monkeys overhead... I figured I'd
leave that liability to them.

Each of our systems pulls about a max of 10-12A at -48VDC, and each
cabinet has two of those, two Cisco switches (~.2A @ -48VDC), a cabinet
fan, and a remote power switching device to be able to turn any of those
devices on and off remotely, making for a maximum load of about 26-27A @
-48VDC per cabinet.  The full load is wired to the power switching
device and then broken out from there for the various hardware.  Six
cabinets of that and two more cabinets of supporting hardware running on
AC.  The main distribution frame for the power was about 30 cable feet
from the equipment, and then the distance from there to the battery
plant down the hall was easily over 150 cable feet.  Not a power system
to be messed with by non-professionals, for sure.

Would have been a fun trip -- if it hadn't been to New Jersey and the
hotel where we played "Name that Stain" with the carpet in the rooms.

--
Nate Duehr, natenatetech.com
_______________________________________________
http://www.piclist.com
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

> > The AWG "Wire gauge is the resistance per unit length in decibels,
> > where 10 AWG wire has 1 ohm per thousand
> > feet resistance."
>
> Decibels doesn't make sense in this context.  I guess they are really
trying
> to say
>
>   gauge = 10 * Log10(mOhms / foot) ?
>
> But that implies that really fat wires have a negative gauge.  #0 cable
> would have 100uOhms/foot and have 3.2 times the diameter of #10.  Anything
> bigger would have to have a negative guage, although I've never heard of
> that.  Of course, I haven't worked with such fat cables either, so maybe
> they do have negative gauge numbers.  Or maybe by that size they are
called
> something else, like "bus bars" and have a whole different numbering
system?

After 0 comes 00, 000, 0000

Then they start talking about size in 'circular mills'.

Bob Ammerman
RAm Systems

_______________________________________________
http://www.piclist.com
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

'[EE] Recommended wire gauge'
2012\07\11@104457 by
I am building a traffic light controller on a piece of perf-board.
What is the recommend gauge of wire for short lengths at about 1 amp ?
Can I safely use 18 gauge wire ?

Thanks,
Jason Whit

2012\07\11@110047 by
A quick and conservative answer: Yes. If I remember most 18 ga. is good for at least 6 amp. This is assuming that lengths are short (less than 10') where voltage drop due to wire resistance is not an issue.

On 7/11/2012 10:44 AM, Jason White wrote:
> I am building a traffic light controller on a piece of perf-board.
> What is the recommend gauge of wire for short lengths at about 1 amp ?
> Can I safely use 18 gauge wire ?
>
> Thanks,
> Jason Whit
Yes
However, if you are about to buy a spool of wire for prototype work 22 Gauge is what the plug in Prototype boards need.
Also, 18 Ga. takes a little more heat to solder than 22 and that leads to the frustration of having the trace on the board lift off/fail.
My method is to use flux, a very hot iron and minimize the time heating the connection.
Actually, I have a few long term projects on the wire plug prototype boards that have been around for years without trouble. Just don't try to make short, pretty wiring with them.

I always figure a good commercial manufactured special purpose PC board (double sided) is a bargain at \$15.
It takes a bit of bad experience to reach that value!

Good luck!

On 7/11/2012 10:44 AM, Jason White wrote:
> I am building a traffic light controller on a piece of perf-board.
> What is the recommend gauge of wire for short lengths at about 1 amp ?
> Can I safely use 18 gauge wire ?
>
> Thanks,
> Jason White

-- John Ferrell W8CCW
“During times of universal deceit,
Telling the TRUTH becomes a revolutionary act”
George Orwell

Thanks Everyone !

> I always figure a good commercial manufactured special purpose PC board
> (double sided) is a bargain at \$15.
> It takes a bit of bad experience to reach that value!
>
> Good luck!

What company offers these ? Though my problem is that most cheap
places have horrific lead times.

-- Jason Whit
I don't know of a vendor that works with small quantities, prompt and cheap!
Since I have no personal experience with ordering to spec I cannot make a recommendation.

I have been dabbling with toner transfer DIY boards lately and I still have a lot to learn. Even when you have etched a board there is much to be done. Few DIY processes provide plated through holes, alignment for double sided is difficult (for me) and drilling 40 or more tiny holes accurately gets old quick.

Manufacture of PC boards seems to be a commodity process. A substandard product is useless and the cost of doing business at the required precision is high. The risks are high due to the cost and availability of supplies.

There is a lot of information in the PICLIST archives and elsewhere on the net.

On 7/11/2012 11:34 AM, Jason White wrote:
{Quote hidden}

-- John Ferrell W8CCW
“During times of universal deceit,
Telling the TRUTH becomes a revolutionary act”
George Orwell

On 11/07/2012 17:37, John Ferrell wrote:
> I don't know of a vendor that works with small quantities, prompt and cheap!
> Since I have no personal experience with ordering to spec I cannot make
> a recommendation.

I got bored with all the toner transfer, etching, trying to through plate etc.  Fine pitch SMD is just no fun without a solder mask.

Now I just use the service run by Laen:http://oshpark.com/ <http://oshpark.com/> (disclaimer, I have not used this new site, I just email my orders).  I previously used BatchPCB.

Of course you don't get boards in 48 hour mail, but with a few projects on the go I always have enough things to play with.

Davi
So far the only company I've used is iteadstudio.com. They are really
cheap (\$9.90 for 10, 5cm x 5cm boards). But they are really slow, last
time I used them it was nearly a month and a half before the boards to
arrived. (I realize its more of a shipping than a manufacturing
problem)

On Wed, Jul 11, 2012 at 2:17 PM, David <listsedeca.net> wrote:
{Quote hidden}

>
At 10:44 AM 7/11/2012, Jason White wrote:
>I am building a traffic light controller on a piece of perf-board.
>What is the recommend gauge of wire for short lengths at about 1 amp ?
>Can I safely use 18 gauge wire ?
>
>Thanks,
>Jason White

As others have said, AWG 18 is overkill from the pov of handing 1A under
most sane conditions.

Especially if you're carrying mains voltage though, you should make
sure that the insulation is appropriately rated (usually 300V or better for
120VAC) and that there is a protective device (such as a fuse) that will open
before the wire gets red hot (or worse) in case of a fault. The minimum
allowable wire size before your fuse is probably something like AWG 18-
check your local regulations.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speffinterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

....Now I just use the service run by Laen:http://oshpark.com/...

+1 ...

Jac
On 7/11/2012 12:37 PM, John Ferrell wrote:
> I don't know of a vendor that works with small quantities, prompt and cheap!
> Since I have no personal experience with ordering to spec I cannot make
> a recommendation.
>
> I have been dabbling with toner transfer DIY boards lately and I still
> have a lot to learn. Even when you have etched a board there is much to
> be done. Few DIY processes provide plated through holes, alignment for
> double sided is difficult (for me) and drilling 40 or more tiny holes
> accurately gets old quick.
>
>

The biggest thing I had to learn about DIY PCB is trying to get out too cheap will cost you more in frustration and time and could lead you to never wanting to do it again. I tried the toner transfer method and there are so many variables that have to go right that it can be frustrating.  I now use the photo transfer method and now that I have it down I can make boards that are just about as good as any a factory turns out, minus the plated holes.  I was scared of it at first because it seemed too complex, but now wouldn't think of doing it any other way.

It cost me maybe \$3 to make a 4" x 3" double sided board.
I buy boards off ebay, plain copper for 20 boards for \$20.  I buy  dry film resist off ebay as well and it cost about \$10 for a pack of 10 sheets 8.5 " x 11" .  Don't use the spray on resist , it works but is very easy to do wrong. Developer is about \$10 a bottle and that will last through hundreds of boards as it is a 1 part developer 10 parts water mix, and you only need a teaspoon of developer concentrate. Etchant I use peroxide and muriatic acid. Final item I needed was a laminator, about \$30.

This guy on ebay sells the film and developer together.
http://www.ebay.com/itm/Photoresist-Dry-Film-A5-x-10-developer-for-DIY-PCB-Photo-Etched-PE-/250900965034?pt=Vintage_Electronics_R2&hash=item3a6adce6aa <http://www.ebay.com/itm/Photoresist-Dry-Film-A5-x-10-developer-for-DIY-PCB-Photo-Etched-PE-/250900965034?pt=Vintage_Electronics_R2&hash=item3a6adce6aa>

My bathroom has no windows so I use that for the process. I put a red light bulb in place of the normal white ones.
I use a compact fluorescent bulb , exposing each side for 12 minutes, no need to buy specialty lights.

To line up both sides of the board I made an exposure frame that I found in an old ham radio magazine from the 80's. Get two pieces of glass the same size, then you need a flat board of some type larger than the glass. Put a block of wood to use as a straight edge on one side. Tape your transparency for one side onto the glass, and do the same with the other side on the second glass so that they line up when you put them onto the frame. Now you just place your pc board onto the frame, put the glass on top, expose, flip the board, put the second glass on the frame, expose, and it lines up every time.

It takes some learning but works great and lines I can get are down to 10mil .  If I could do plated through holes I would be all set.

Mark
This sounds like something I need to try!

But somewhere I missed what the laminator is used for with the photo process??

On 7/14/2012 8:48 AM, Mark Hanchey wrote:
> Final item I needed was a
> laminator, about \$30.

-- John Ferrell W8CCW
“During times of universal deceit,
Telling the TRUTH becomes a revolutionary act”
George Orwell

John Ferrell wrote:
> On 7/14/2012 8:48 AM, Mark Hanchey wrote:
> > Final item I needed was a laminator, about \$30.
>
> This sounds like something I need to try!
>
> But somewhere I missed what the laminator is used for with the photo
> process??

I'm not the OP, but I'm guessing it's used to laminate the resist film to
the bare board prior to exposure.

-- Dave Twee
On 7/14/2012 12:24 PM, John Ferrell wrote:
> This sounds like something I need to try!
>
> But somewhere I missed what the laminator is used for with the photo
> process??
>
> On 7/14/2012 8:48 AM, Mark Hanchey wrote:
>> Final item I needed was a
>> laminator, about \$30.

The laminator is used to apply the film to the board, really that is the most difficult part of the process.
The film comes with a protective cover on both sides, peeling off the inner side that goes towards the board takes a few minutes because it is hard to get the inner cover started because it is so well applied to the inner film, also being in a room with only red light doesn't help a whole lot . Once you get a corner started though it peels right off. I wet the board slightly and apply the film, without the water it will stick instantly to the board and moving it around to center it on the board can be difficult without the water.  Once you have it on the board, you  feed it into the laminator and out comes the board ready to expose. Once you expose you remove the top protective layer, peeling it off . Drop in developer and your ready to etch.

After you etch you can remove the film with acetone, i  buy the pure acetone finger nail polish remover as I don't use large quantities of the stuff. Pour acetone on the board , wait about 5 secs and the film will break down and can be rinsed off.  Or if you want you can just scrape away the pads for soldering and leave the film attached and it makes a nice protective coating for the traces.

MG chemicals , maker of a lot of pcb products has a video tutorial on youtube, that is what I started with to learn the process.
http://www.youtube.com/watch?v=VkQroiEJBMs

Mark

On 7/15/2012 10:56 AM, Mark Hanchey wrote:
> MG chemicals , maker of a lot of pcb products has a video tutorial on
> youtube, that is what I started with to learn the process.
> http://www.youtube.com/watch?v=VkQroiEJBMs Mark
oops wrong link
http://www.youtube.com/watch?v=r9e0H21ev7g&feature=channel&list=UL <http://www.youtube.com/watch?v=r9e0H21ev7g&feature=channel&list=UL>

Original link shows how to use pre-sensitized boards, those work if you want to do without the film and laminator but it cost about 3x as much.

Mark
You can also buy presensitized boards (film already applied), I get
mine from circuitspecialists.com -3.91'' x 5.91'' single sided
phenolic , \$3.99

On Sun, Jul 15, 2012 at 10:56 AM, Mark Hanchey <markpixeltrickery.com> wrote:
{Quote hidden}

>
Hi Mark

this looks very good. How do You make the film for the curcuit board ??.

regards

Bjarne

{Original Message removed}
Hi Mark,

I see that MG sells the transparency film for the original artwork, and it claims to be printed with a laser printer.  Would ink jet  not bind to the film, or not have the proper opacity?
Not having a laser printer, I started looking for places to get transparencies laser printed.  I could not find the option for transparency at Staples, but did at FedEx and the on line price for a single 8.5 by 11 was \$.75 US.  Do you think this would work?

As a side note, without having a board designed just yet, using kicad, I opened up a demo (pic_programmer), chose Plot -> to Postscript, and uploaded the PS file to Fedex.  It seemed to render OK on their preview page.  I would physically bring the files to the office to actually do it.

Joe W

On 7/15/2012 11:02 AM, Mark Hanchey wrote:
{Quote hidden}

2 possibilities:
1: If the film is going to be used as a negative for a photo resist process, might work, most inkjets don't print well on smooth plastic surfaces, but I have heard of making overhead projector transparencies that probably would work. I don't have any experience with this, maybe someone else can help.

2: If you are planing to use a laminator or clothes iron  to heat transfer the toner to the PCB. The laser toner is actually melted on the paper (or film), and the inkjet ink will not work, it's not thick enough, and doesn't melt to bond to the PCB surface. I have printed with an inkjet, taken the paper to the local copy center, and have a gloss photo paper copy made with heavy toner setting. The nearest copy machine at the local hardware store would not wok for whatever reason. The only way you will know is to try. :( I now have a Hp Laserjet 4 Plus, but haven't etched any boards since getting it. Somewhere, I heard that not all toners will do the job, and I buy recycled toner.

On 7/15/2012 1:09 PM, Joe Wronski wrote:
{Quote hidden}

I print the artwork on semitransparent drawing film, the type you used before computers to do drawings by hand with ink. Printing is done with a standard laser printer (600 dpi I think). I set it to print black and white only (it is a color laser printer) and set the contrast setting to 75% (50% is normal).

The top side for a double sided board is printed mirrored so the printed side is directly facing the board when exposing it to uv-light.

I use boards with photoresist and a uv-lamp to expose the boards. The photoresist is then developed using ordinary sodium hydroxid diluted in water.

I try to keep traces at least 12 mil thick but can go as low as 8-9 mils. Diagonal traces seems to be a bit thinner when printed.

The board is etched in a solution of 1 part hydrocloric acid (35%), 1 part hydrogen peroxide (35%) and 3 parts water.

The photoresist remaining after etching is removed with ordinary methylated spirits.

The boards are then washed and coated with a protective varnish that also contains flux (SK10).

When the varnish has dried the boards are drilled. For vias I use a 0.5mm drillbit and solder one strand from a multistranded wire on both sides. Where I have to make a connection between both sides but can not get to one side because a component is in the way (usually a terminal connector), I drill one extra 0.5mm hole in the pad and solder a wire on both sides before the component is soldered.

Here are links to pictures of my latest board which is based on a PIC24FJ256GB106-I/PT (64 pin TQFP with 0.5 mm pitch).
<www.rjjournal.net/public_pics/bs.jpg>
<http://www.rjjournal.net/public_pics/ts.jpg>

/Ruben

> Hi Mark
>
> this looks very good. How do You make the film for the curcuit board ??.
>
> regards
>
> Bjarne
>
> {Original Message removed}
On 7/15/2012 6:21 PM, Ruben Jönsson wrote:
>   keep traces at least 12 mil thick but can go as low as 8-9 mils.
> Diagonal traces seems to be a bit thinner when printed.

My biggest problem with really small traces is the board quality needs to be good. I can etch the traces fine, but then when I go to solder the boards I have had problems where the traces peel from the board.

>
>
> The boards are then washed and coated with a protective varnish that also
> contains flux (SK10).

Another thing that you can use and is very easy to get is sharpie permanent markers. I use the ones that come in various colors, mainly red and blue. It dries almost instantly and you can color different traces to better mark things like power or data traces. To remove it if you make a mistake you can use acetone and it wipes away clean. It also doesn't seem to interfere with flux and solder as I haven't had to remove any when soldering.

{Quote hidden}

Those are some nice looking boards. I think photo etching is the way to go and I wish more people would give it a try as the process is really much better than toner transfer.

Mark
On 7/15/2012 1:09 PM, Joe Wronski wrote:
> Hi Mark,
>
> I see that MG sells the transparency film for the original artwork, and
> it claims to be printed with a laser printer.  Would ink jet  not bind
> to the film, or not have the proper opacity?

The reason for not using an inkjet is because inkjets typically don't print dark enough on transparencies to block the light completely. You can try inkjets and see, mine looks good on paper but transparencies when held to the light look grey and allow too much light. I use an hp laserjet 2100 that is at least 10 years old I got for \$35 with a new toner cart off ebay, works great.

> Not having a laser printer, I started looking for places to get
> transparencies laser printed.  I could not find the option for
> transparency at Staples, but did at FedEx and the on line price for a
> single 8.5 by 11 was \$.75 US.  Do you think this would work?

I haven't used those services for printing before but I can't see why it wouldn't work.

> As a side note, without having a board designed just yet, using kicad, I
> opened up a demo (pic_programmer), chose Plot ->  to Postscript, and
> uploaded the PS file to Fedex.  It seemed to render OK on their preview
> page.  I would physically bring the files to the office to actually do it..
>
> Joe W

The biggest thing for me is making sure I mirror the sides that need it before printing. I really like printing them at home where if I make a mistake I can run off another easily.  Check on places like ebay for reconditioned older printers. The laserjet  6 series are old but they were built like tanks and just keep on printing.

Mark
On 7/15/2012 12:43 PM, Bjarne Lassen wrote:
> Hi Mark
>
> this looks very good. How do You make the film for the curcuit board ??.
>
> regards
>
> Bjarne
>
>

The program I use for layouts is sprint layout from Abacom. It is one of the most user friendly programs I have used. If it doesn't have a part, you can design one in just a few minutes. One of the few programs I never really had to read the help file to use. It isn't free but they have a free trial:
http://www.abacom-online.de/uk/html/sprint-layout.html

For printing I bought a box of laser printer transparencies off ebay, 50 for \$10 and they work well with an old hp laserjet set to 600x600 dpi.

Mark

> On 7/15/2012 6:21 PM, Ruben Jönsson wrote:
> >   keep traces at least 12 mil thick but can go as low as 8-9 mils.
> > Diagonal traces seems to be a bit thinner when printed.
>
> My biggest problem with really small traces is the board quality needs
> to be good. I can etch the traces fine, but then when I go to solder the
> boards I have had problems where the traces peel from the board.
>
I have only seen that problem when I need to desolder something. I think the varnish which includes flux (SK10) helps a lot here. I also use a very thin solder wire with flux and a soldering iron set to 350 degrees C to heat the board as little as possible (400 when soldering large components or soldering something directly to the ground plane). The solder is very old so I don't think it is lead free.

With fine pitch ICs there will always be some pins that gets shorted when soldering. The only way to fix this up is to use a thin, fine stranded desoldering braid.

/Ruben

==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
rubenpp.sbbs.se
==============================

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