solder plating - Page 2 - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th December 2006, 07:31 PM   #11
Nixie is offline Nixie  Canada
Banned
 
Join Date: Jan 2006
Location: Vancouver, BC
Like I said, tin alone affects the copper in a bad way, as well as having a tendency to grow whiskers over time, eventually leading to shorts.

It is possible to electroplate with solder (tin/lead). That's what my initial question was about.

As for using wicking braids -- with the current prices of copper, not to mention the projections...
  Reply With Quote
Old 16th December 2006, 10:58 PM   #12
EdT is offline EdT  Canada
diyAudio Member
 
Join Date: Dec 2006
No one in the PCB manufacutring industry plates tin, they just wet tin on and blow off, they do gold plate traces and pads though. By tin I mean 63/37 Sn/Pb eutectic solder. Tin or lead by itself has a higher melting temperature than a of mix 63/37 Sn/Pb, at this precise ratio it becomes an eutectic alloy meaning it turns from solid to liquid without a slush stage unlike older 60/40 solder.
  Reply With Quote
Old 18th December 2006, 01:29 PM   #13
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally posted by Nixie
Like I said, tin alone affects the copper in a bad way, as well as having a tendency to grow whiskers over time, eventually leading to shorts.

It is possible to electroplate with solder (tin/lead). That's what my initial question was about.

As for using wicking braids -- with the current prices of copper, not to mention the projections...
I have purchased parts which have been plated with lead and tin. It is done at the same time, in one bath.

The primary issue was one of deposition rate. One metal plates differently from the other. There is a correct current density which gives the proper deposition ratio, go over it and one metal plates more, lower, and the other metal.. From what I can remember, the deposit goes lead heavy where the current is lower, but that was long ago.

All the plating vendors I dealt with did not electroplate solder, just seperate lead and tin. The plated surface may have the correct alloy ratio, but it is not yet solder, it needs to be reflowed. Plated only is porous, the base metal will oxidize until the plating is reflowed.

The only problem with removing molten solder is the possibility of removing too much, leaving a copper/tin alloy. This alloy can be difficult to solder to as the flux is not normally good enough to cut this.

Cheers, John
  Reply With Quote
Old 18th December 2006, 03:39 PM   #14
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
Tin is very easy to solder to. Almost as easy as gold.
Partly because it does not tarnish/corrode.

Try soldering a tin can (hot dipped steel can) if you don't believe me. Have a look at the rolled seam, it is soldered.
__________________
regards Andrew T.
  Reply With Quote
Old 18th December 2006, 05:43 PM   #15
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally posted by AndrewT
Hi,
Tin is very easy to solder to. Almost as easy as gold.
Partly because it does not tarnish/corrode.
Gold, yes. Tin forms an oxide, but that oxide is easily stripped by low activity fluxes.

Gold unfortunately embrittles a solder. The best gold thickness for solderability is about 50 microinches, and not a bright finish, but a matte.

Soldering to copper is two stage...first, a copper tin alloy forms at the copper surface, it is yellowish in appearance...then a second copper/tin alloy, this a more whitish look..then, over that is the solder alloy itself.

If you wipe the solder alloy off with a cloth, you can expose the second copper/tin alloy...this is the hard to solder part I speak of. It requires an activated flux to form a metallic bond during subsequent soldering.

Cheers, John
  Reply With Quote
Old 18th December 2006, 05:53 PM   #16
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi John,
these two copper/tin alloys;
are they different chemical compounds or different proportions of alloy mixture.

I note that lead didn't get a mention in either layer.
Does the lead only appear in the solder layer? Is this layer richer in lead compared to the parent solder ?
Presumably, if the underlayers of copper/tin are not exposed then soldering to the covered layers is always easy with conventional fluxes?

When you talk of activated flux, what exactly needs to be specified?
__________________
regards Andrew T.
  Reply With Quote
Old 18th December 2006, 06:19 PM   #17
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally posted by AndrewT
Hi John,
these two copper/tin alloys;
are they different chemical compounds or different proportions of alloy mixture.
Different alloys. The one closest to the copper is Cu3Sn, the next is Cu6Sn5.


I googled to find this, I could not find the article I was thinking of, it's somewhere in this darn office.. man, google has been very good to me lately..

http://www.ami.ac.uk/courses/topics/...ntm/index.html

Quote:
Originally posted by AndrewT

I note that lead didn't get a mention in either layer.
Does the lead only appear in the solder layer? Is this layer richer in lead compared to the parent solder ?
I would assume so, but the two intermetallic layers are not that thick.

Quote:
Originally posted by AndrewT

Presumably, if the underlayers of copper/tin are not exposed then soldering to the covered layers is always easy with conventional fluxes?
Yes..that has been my experience.

Quote:
Originally posted by AndrewT

When you talk of activated flux, what exactly needs to be specified?
I can use R for all my work. When the molten solder has been wiped, R will not work at all, forcing RMA or heaven forbid, RA. Or, removing the mess and starting at bare copper again.

Cheers, John
  Reply With Quote
Old 18th December 2006, 06:30 PM   #18
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi John,
illuminating.
That confirms my science teacher saying that there is a chemical reaction at the surface, not just solder lying on top.

The Cu(3)Sn layer, does that explain the copper erosion that happens with unplated tips?
__________________
regards Andrew T.
  Reply With Quote
Old 18th December 2006, 06:47 PM   #19
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally posted by AndrewT
Hi John,
illuminating.
That confirms my science teacher saying that there is a chemical reaction at the surface, not just solder lying on top.

The Cu(3)Sn layer, does that explain the copper erosion that happens with unplated tips?
Give or take.(I'm hedging my bets... )

Copper is soluble in solder.. If the wires are small enough guage, they quickly dissapear in a solder pot.

The cu/sn intermetallic formed freezes two degreees C above pure solder, this gives a sandy/grainy surface finish if the pot is too contaminated with copper.

That little tidbit came from a different paper and also duplicates my experience.. that paper did not elaborate on which alloy it was, I never bothered checking on which either.


Cheers, John
  Reply With Quote
Old 18th December 2006, 07:13 PM   #20
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
John,
thanks for your time.

did you get my Email?
__________________
regards Andrew T.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Stripping and plating an old chassis Original Burnedfingers Everything Else 1 20th November 2008 12:20 PM
Tin Plating PCB:s Loial Parts 2 29th August 2005 04:51 PM
DIY tin plating AudioWizard Everything Else 9 26th July 2005 08:28 AM
Golden plating Tomek Chip Amps 5 26th September 2003 01:49 AM
Tin Plating PCBs Freddie Parts 6 10th September 2001 08:18 AM


New To Site? Need Help?

All times are GMT. The time now is 12:41 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2