Homebrew PCBs

Hi, all,

Just recently, I had a chance to mill my own PCBs with a script that exports a toolpath from Eagle Cad to a Modela milling machine.  The resulting boards are gorgeous!  Unfortunately, the soldering has become very difficult.  

Because very thin traces are being cut to isolate the actual wire connections from the ground plane, it's fairly easy to spill some solder onto the trace and have a hard time cleaning off the resulting bridge.  

I wanted to ask, when milling your own boards from copper-clad board, how do you control the soldering process?  Are their techniques to get the solder to stay on just the pad that's been isolated from the ground plane?  Should I look for a precise flux pen that will dribble just a teeny bit of flux onto the pad?

Many thanks, everyone, and I look forward to your input!

Sincerely,

Poofjunior

I had the same problem and what I started doing was bringing the trace
outline into Aspire and doing an larger offset and then doing an area mill
of that offset (hope that makes some sense) but ending up with much more
removed copper and so the chance to bridge is less - basically giving the
traces more isolation

Jamie
Check out my CNC projects (and more) at http://www.backyardworkshop.com



On Thu, Sep 27, 2012 at 11:13 AM, poofjunior <seeifyoucanmeetme@...>wrote:

> **
>
>
> Hi, all,
>
> Just recently, I had a chance to mill my own PCBs with a script that
> exports a toolpath from Eagle Cad to a Modela milling machine. The
> resulting boards are gorgeous! Unfortunately, the soldering has become very
> difficult.
>
> Because very thin traces are being cut to isolate the actual wire
> connections from the ground plane, it's fairly easy to spill some solder
> onto the trace and have a hard time cleaning off the resulting bridge.
>
> I wanted to ask, when milling your own boards from copper-clad board, how
> do you control the soldering process? Are their techniques to get the
> solder to stay on just the pad that's been isolated from the ground plane?
> Should I look for a precise flux pen that will dribble just a teeny bit of
> flux onto the pad?
>
> Many thanks, everyone, and I look forward to your input!
>
> Sincerely,
>
> Poofjunior
>
>  
>


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

I've soldered up a lot of prototype boards without solder mask but
never a milled board.  The solder will stick anywhere your soldering
iron touches.  I had to do fine pitch IC's and 0201/0402 parts and I
made a mess a few times.  You might need to try a different tip so you
are only heating the pad and not letting it touch the ground plane
too.  The only other way is to solder mask your board or as Jamie
said, increase your isolation distance.  I have been using Weller ETR
1/16" Narrow Screwdriver tips for years and I love them.
http://www.hmcelectronics.com/product/Weller/ETR  They give me the
control to put the soldering iron exactly where I want even in
confined spaces.  I have a variety of soldering tips but this is my go
to one for most jobs.  When soldering I rarely add flux for most
standard parts but when doing re-work I always use lots of flux.  When
I took my IPC J-STD-001 test I found out I was using too much solder.
It really doesn't require that much to make a good joint.

--
Erik L. Knise
Seattle, WA

On Thu, Sep 27, 2012 at 8:13 AM, poofjunior <seeifyoucanmeetme@...> wrote:
> Hi, all,
>
> Just recently, I had a chance to mill my own PCBs with a script that exports a toolpath from Eagle Cad to a Modela milling machine.  The resulting boards are gorgeous!  Unfortunately, the soldering has become very difficult.
>
> Because very thin traces are being cut to isolate the actual wire connections from the ground plane, it's fairly easy to spill some solder onto the trace and have a hard time cleaning off the resulting bridge.
>
> I wanted to ask, when milling your own boards from copper-clad board, how do you control the soldering process?  Are their techniques to get the solder to stay on just the pad that's been isolated from the ground plane?  Should I look for a precise flux pen that will dribble just a teeny bit of flux onto the pad?
>
> Many thanks, everyone, and I look forward to your input!
>
> Sincerely,
>
> Poofjunior
>

I normally tin all the exposed copper before soldering the components in place, just to prevent corrosion of the bare copper. I do get some solder bridges which are fairly easy to clean up with an exacto knife. I usually lightly sand the board to remove rough edges on the milled areas which helps the solder pull away from the isolation cuts. One way to avoid problems with bridges is to avoid narrow isolation cuts under components during layout of the board. It is fairly easy to fix bridges that are easily seen, but when under components they are very difficult to see or fix.

Bob

--- On Thu, 9/27/12, poofjunior <seeifyoucanmeetme@...> wrote:

From: poofjunior <seeifyoucanmeetme@...>
Subject: [Homebrew_PCBs] Soldering Tricks for Milled Boards
To: Homebrew_PCBs@yahoogroups.com
Date: Thursday, September 27, 2012, 9:13 AM
















 



  


    
      
      
      Hi, all,



Just recently, I had a chance to mill my own PCBs with a script that exports a toolpath from Eagle Cad to a Modela milling machine.  The resulting boards are gorgeous!  Unfortunately, the soldering has become very difficult.  



Because very thin traces are being cut to isolate the actual wire connections from the ground plane, it's fairly easy to spill some solder onto the trace and have a hard time cleaning off the resulting bridge.  



I wanted to ask, when milling your own boards from copper-clad board, how do you control the soldering process?  Are their techniques to get the solder to stay on just the pad that's been isolated from the ground plane?  Should I look for a precise flux pen that will dribble just a teeny bit of flux onto the pad?



Many thanks, everyone, and I look forward to your input!



Sincerely,



Poofjunior





    
     

    
    






  










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

Another trick is to spray the board with conformal lacquer before 
soldering. Direct application of a soldering iron will burn through the 
lacquer allowing you to solder but accidentally brushing against a track 
won't. For surface mount components you will have to tin the pads to 
burn off the lacquer before mounting the components.

Les

On 27/09/2012 16:46, Bob Butcher wrote:
> I normally tin all the exposed copper before soldering the components in place, just to prevent corrosion of the bare copper. I do get some solder bridges which are fairly easy to clean up with an exacto knife. I usually lightly sand the board to remove rough edges on the milled areas which helps the solder pull away from the isolation cuts. One way to avoid problems with bridges is to avoid narrow isolation cuts under components during layout of the board. It is fairly easy to fix bridges that are easily seen, but when under components they are very difficult to see or fix.
>
> Bob
>

Erik Knise wrote:

 > I've soldered up a lot of prototype boards without solder mask but
 > never a milled board. The solder will stick anywhere your soldering
 > iron touches. I had to do fine pitch IC's and 0201/0402 parts and I
 > made a mess a few times. You might need to try a different tip so you
 > are only heating the pad and not letting it touch the ground plane
 > too. The only other way is to solder mask your board or as Jamie
 > said, increase your isolation distance. I have been using Weller ETR
 > 1/16" Narrow Screwdriver tips for years and I love them.
 > http://www.hmcelectronics.com/product/Weller/ETR They give me the
 > control to put the soldering iron exactly where I want even in
 > confined spaces. I have a variety of soldering tips but this is my
 > go to one for most jobs. When soldering I rarely add flux for most
 > standard parts but when doing re-work I always use lots of flux.
 > When I took my IPC J-STD-001 test I found out I was using too much
 > solder. It really doesn't require that much to make a good joint.

There are always tricks to soldering fine pitch boards.

I have many prototype boards, 6mil lines 8mil spacing, tinned
with no solder mask. My trick is to use liquid RMA, Rosin Medium
Activation, flux along with the flux in .040" quality solder.
The stuff is liquid as water. However, it is slightly corrosive
and needs to be cleaned well afterwards.

1. I use a fine chisel tip temperature controlled iron.
    The flux is in a small Gerber baby food jar and apply it
    liberally with a tooth pick. The flux is active enough to
    eliminate surface tension on the melted solder so bridging
    is almost non existent.

2. For surface mount ICs I purposely run the solder along with
    the RMA flux over all the pins and after use "Solder Wicket"
    desoldering braid to remove excess solder.
    Fast and works like a charm.

Note! I'm not a fan of the really small diameter solder.
I find the .040" solder works better because if has a bit of
"heat sinking" quality which slows down it's melting rate
and gives me a bit more control.

Duane

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Can you post pictures of the board?  What trace width and spacing are you
achieving?

 

Jeff

 

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of poofjunior
Sent: Thursday, September 27, 2012 11:14 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Soldering Tricks for Milled Boards

 

  

Hi, all,

Just recently, I had a chance to mill my own PCBs with a script that exports
a toolpath from Eagle Cad to a Modela milling machine. The resulting boards
are gorgeous! Unfortunately, the soldering has become very difficult. 

Because very thin traces are being cut to isolate the actual wire
connections from the ground plane, it's fairly easy to spill some solder
onto the trace and have a hard time cleaning off the resulting bridge. 

I wanted to ask, when milling your own boards from copper-clad board, how do
you control the soldering process? Are their techniques to get the solder to
stay on just the pad that's been isolated from the ground plane? Should I
look for a precise flux pen that will dribble just a teeny bit of flux onto
the pad?

Many thanks, everyone, and I look forward to your input!

Sincerely,

Poofjunior





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

Is there an equivalent to conformal lacquer that can be purchased at the big
box hardware stores?

 

Jeff

 

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Les Newell
Sent: Thursday, September 27, 2012 12:39 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Soldering Tricks for Milled Boards

 

  

Another trick is to spray the board with conformal lacquer before 
soldering. Direct application of a soldering iron will burn through the 
lacquer allowing you to solder but accidentally brushing against a track 
won't. For surface mount components you will have to tin the pads to 
burn off the lacquer before mounting the components.

Les

On 27/09/2012 16:46, Bob Butcher wrote:
> I normally tin all the exposed copper before soldering the components in
place, just to prevent corrosion of the bare copper. I do get some solder
bridges which are fairly easy to clean up with an exacto knife. I usually
lightly sand the board to remove rough edges on the milled areas which helps
the solder pull away from the isolation cuts. One way to avoid problems with
bridges is to avoid narrow isolation cuts under components during layout of
the board. It is fairly easy to fix bridges that are easily seen, but when
under components they are very difficult to see or fix.
>
> Bob
>





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

I just use regular brush on lacquer.

http://m.homedepot.com/p/Minwax-1-qt-Satin-Clear-Brushing-Lacquer-15510/100552614/

Seems to work fine for me.


Sent from my iPhone

On Sep 27, 2012, at 3:26 PM, "Jeff Heiss" <jeff.heiss@...> wrote:

> Is there an equivalent to conformal lacquer that can be purchased at the big
> box hardware stores?
> 
> Jeff
> 
> _____ 
> 
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Les Newell
> Sent: Thursday, September 27, 2012 12:39 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Soldering Tricks for Milled Boards
> 
> Another trick is to spray the board with conformal lacquer before 
> soldering. Direct application of a soldering iron will burn through the 
> lacquer allowing you to solder but accidentally brushing against a track 
> won't. For surface mount components you will have to tin the pads to 
> burn off the lacquer before mounting the components.
> 
> Les
> 
> On 27/09/2012 16:46, Bob Butcher wrote:
> > I normally tin all the exposed copper before soldering the components in
> place, just to prevent corrosion of the bare copper. I do get some solder
> bridges which are fairly easy to clean up with an exacto knife. I usually
> lightly sand the board to remove rough edges on the milled areas which helps
> the solder pull away from the isolation cuts. One way to avoid problems with
> bridges is to avoid narrow isolation cuts under components during layout of
> the board. It is fairly easy to fix bridges that are easily seen, but when
> under components they are very difficult to see or fix.
> >
> > Bob
> >
> 
> [Non-text portions of this message have been removed]
> 
> 


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

An acrylic spray laccquer should also work. As far as I know the only 
real difference with the 'proper' stuff is that it has a UV dye in it, 
making identification and checking easier.

Les

On 27/09/2012 21:26, Jeff Heiss wrote:
> Is there an equivalent to conformal lacquer that can be purchased at the big
> box hardware stores?
>
>   
>
> Jeff
>
>

I'm not too familiar with CAD, SMD technology and so on, so not sure this technique will apply in this case or solve your bridging problem.

I've been successfully soldering components to small pads by heating only the component wire. The solder itself heats the pad. It's neat, quite easy to control and results are pretty consistent. 

Here's a breakdown of the two handed process.which takes about 3-seconds - not long enough to fry the component.

With the component in place, the soldering iron tip is applied with the flat against the wire just above the pad and without touching it. 
Apply the pre-fluxed solder on the opposite side of the wire. As the solder begins to melt, remove the solder and at the same time rotate the soldering iron so the flat faces downward, still without touching the pad. What effectively happens, the solder flows down the wire, heats the pad and forms a nice neat joint. Snip the excess wire.

 The whole process can be imagined as a short sequence. "Iron, solder, turn, done" The rest is timing.

Peter
MM5PSL
Shetland Islands

--- In Homebrew_PCBs@yahoogroups.com, "poofjunior" <seeifyoucanmeetme@...> wrote:

>
> Hi, all,
> 
> Just recently, I had a chance to mill my own PCBs with a script that exports a toolpath from Eagle Cad to a Modela milling machine.  The resulting boards are gorgeous!  Unfortunately, the soldering has become very difficult.  
> 
> Because very thin traces are being cut to isolate the actual wire connections from the ground plane, it's fairly easy to spill some solder onto the trace and have a hard time cleaning off the resulting bridge.  
> 
> I wanted to ask, when milling your own boards from copper-clad board, how do you control the soldering process?  Are their techniques to get the solder to stay on just the pad that's been isolated from the ground plane?  Should I look for a precise flux pen that will dribble just a teeny bit of flux onto the pad?
> 
> Many thanks, everyone, and I look forward to your input!
> 
> Sincerely,
> 
> Poofjunior
>

I am doing some tests with dry film photoresist.  Can you guys recommend a
bulb that can be used for a dark room light?  Are there any simple methods
to using a regular fluorescent or incandescent light for the purpose?  Maybe
covering the bulb with a color saran rap as a filter?

 

Jeff



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

You can use those yellow lights that are used for bugs

Sent from my iPhone

On Oct 6, 2012, at 10:38 PM, "Jeff Heiss" <jeff.heiss@...> wrote:

> I am doing some tests with dry film photoresist. Can you guys recommend a
> bulb that can be used for a dark room light? Are there any simple methods
> to using a regular fluorescent or incandescent light for the purpose? Maybe
> covering the bulb with a color saran rap as a filter?
> 
> Jeff
> 
> [Non-text portions of this message have been removed]
> 
> 


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

Are you wanting a safety light that wont affect the photo-resist or a light to expose the photo-resist?

The ready coated presensitized boards are nowhere near as sensitive as photographic film. 
I work with presensitized boards in fluorescent and incandescent light without covering them.
You need light of a specific narrow wavelength to make the exposure work.

John G3UGY   

From: Jeff Heiss 
Sent: Sunday, October 07, 2012 4:38 AM
To: Homebrew_PCBs@yahoogroups.com 
Subject: [Homebrew_PCBs] recommend a dark room light


  
I am doing some tests with dry film photoresist. Can you guys recommend a
bulb that can be used for a dark room light? Are there any simple methods
to using a regular fluorescent or incandescent light for the purpose? Maybe
covering the bulb with a color saran rap as a filter?

Jeff



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

Correct, I am looking for what a safely light that won't affect photoresist
(dry film photoresist in my case).  Maybe working in dim light is good
enough?  I read that dry film photoresist is fairly sensitive without taking
much to expose it though.  

 

Jeff

 

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of John
Sent: Sunday, October 07, 2012 3:45 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] recommend a dark room light

 

  

Are you wanting a safety light that wont affect the photo-resist or a light
to expose the photo-resist?

The ready coated presensitized boards are nowhere near as sensitive as
photographic film. 
I work with presensitized boards in fluorescent and incandescent light
without covering them.
You need light of a specific narrow wavelength to make the exposure work.

John G3UGY 

From: Jeff Heiss 
Sent: Sunday, October 07, 2012 4:38 AM
To: Homebrew_PCBs@yahoogroups.com <mailto:Homebrew_PCBs%40yahoogroups.com>  
Subject: [Homebrew_PCBs] recommend a dark room light

I am doing some tests with dry film photoresist. Can you guys recommend a
bulb that can be used for a dark room light? Are there any simple methods
to using a regular fluorescent or incandescent light for the purpose? Maybe
covering the bulb with a color saran rap as a filter?

Jeff

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





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

--- On Sun, 7/10/12, Jeff Heiss <jeff.heiss@...> wrote:

From: Jeff Heiss <jeff.heiss@...>
Subject: [Homebrew_PCBs] recommend a dark room light
To: Homebrew_PCBs@yahoogroups.com
Date: Sunday, 7 October, 2012, 3:38
















 



  


    
      
      
      I am doing some tests with dry film photoresist.  Can you guys recommend a

bulb that can be used for a dark room light?  Are there any simple methods

to using a regular fluorescent or incandescent light for the purpose?  Maybe

covering the bulb with a color saran rap as a filter?



Jeff



Hello Jeff,
If you are concerned about accidental exposure of the photo-resist under normal lighting conditions in your dark room, try covering a normal 50Watt incandesent bulb with a single layer of green arc-welding sheet.
These sheets are used by welders to surround the work area to prevent the UV rays from the arc from damaging other workers eyes.
This sheet is a leaf green colour, by assumption, a sheet of green "pin spot" gel should suffice(who remembers disco lights?)




  










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

Hi Jeff,

I use a "Bright Lab Jr." 11W red bulb (#35110).  They are quite expensive today, about $19 list: http://www.cpmdelta1.com/safelights.htm

I actually prefer the ones that are red glass or painted on the inside, but lost mine many years ago.  I don't think a few scratches on the bulb will affect what you are doing.

I got mine at a photography store.  You will probably need a store that has supplies for black and white photography.

John
 
--- In Homebrew_PCBs@yahoogroups.com, "Jeff Heiss" <jeff.heiss@...> wrote:

>
> I am doing some tests with dry film photoresist.  Can you guys recommend a
> bulb that can be used for a dark room light?  Are there any simple methods
> to using a regular fluorescent or incandescent light for the purpose?  Maybe
> covering the bulb with a color saran rap as a filter?
> 
>  
> 
> Jeff
> 
> 
> 
> [Non-text portions of this message have been removed]
>

On Sat, 6 Oct 2012 23:38:39 -0400, you wrote:

>I am doing some tests with dry film photoresist.  Can you guys recommend a
>bulb that can be used for a dark room light?  Are there any simple methods
>to using a regular fluorescent or incandescent light for the purpose?  Maybe
>covering the bulb with a color saran rap as a filter?
>
> 
>
>Jeff
>
Take a look at red or yellow fluorescent tubes with an inch or so
of the ends wrapped with black electrical tape (the coating may not
extend all the way to the end cap and thus leak UV). We did have 
to use standard start tubes; the rapid start used a different material 
and were not safe (at least the red ones, I didn't test yellow).

I used a 20" red in my darkroom for years. It was significantly
"safer" than the high dollar Kodak glass filters . 

Back in the '60s an area newspaper had offset presses and the 
room where they made the plates had yellow fluorescent. 
You could walk in there from the composing room and have no trouble
moving around.

You will need to check the current production. A good test is to lay a
piece of sensitized material face up in your working area and put
a quarter in the center. Leave it there for three or four times your
normal working time. Develop the material and if you can see the
outline of the quarter the light source isn't "safe".



Keith Bowers WB4LSJ- Thomasville, NC

Hello,
The majority of Photoresist materials both positive and nagative are very much resistant to the usual artificial lighting, they require a specific wave length to activate [UV], there is a small percentage of UV in daylight tubes and bulbs so it would be advisable not to take too long when preparing a board for exposure otherwise no special considerations need to be taken, except don't do it outdoors in the sun!!
regards,
David


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

I tried exposing some presensitized pcb using 100W household mains bulb 2 feet away from the board for 15 minutes.
I swished the pcb in developer for 5 minutes.  There was no trace of the image.  The same goes for household fluorescent lights. 

In bright sunshine I got a good image after 5 minutes exposure, the board etched fine.

Using a UV lamp of the correct wavelength and Wattage exposure time for me is 2 to 3 minutes.

If you have some left over pcb do a test. Use some cardboard and expose parts of a board for various times and try developing.

John G3UGY

From: D. Gareth Hughes 
Sent: Sunday, October 07, 2012 5:14 PM
To: Homebrew_PCBs@yahoogroups.com 
Subject: [Homebrew_PCBs] Re: recommend a dark room light


  
Hello,
The majority of Photoresist materials both positive and nagative are very much resistant to the usual artificial lighting, they require a specific wave length to activate [UV], there is a small percentage of UV in daylight tubes and bulbs so it would be advisable not to take too long when preparing a board for exposure otherwise no special considerations need to be taken, except don't do it outdoors in the sun!!
regards,
David 


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

--- In Homebrew_PCBs@yahoogroups.com, Spencer W <upnxwood16@...> wrote:
>
> You can use those yellow lights that are used for bugs
> 
>

Yellow Bug Light is what I use, never have had any problems from it.

Ben