Using lead-free solder for first time raises question

Thread Starter

petewh

Joined Mar 23, 2016
37
I started trying lead free soldering. I'm putting in some 14 and 16 pin dip sockets on a general purpose prototype board. I went to measure my connections with an ohmmeter to check for solder bridges, etc. The meter reads zero ohms for connections when measured from the top of the board thru the socket but an open circuit when measuring the actual solder connection. Apparently when lead free solder rehardens it forms an electrically non conductive surface. Is this normal?

The solder is no longer shiny after melting.
 

jaredwolff

Joined Jul 1, 2017
58
I started trying lead free soldering. I'm putting in some 14 and 16 pin dip sockets on a general purpose prototype board. I went to measure my connections with an ohmmeter to check for solder bridges, etc. The meter reads zero ohms for connections when measured from the top of the board thru the socket but an open circuit when measuring the actual solder connection. Apparently when lead free solder rehardens it forms an electrically non conductive surface. Is this normal?

The solder is no longer shiny after melting.
Lead free solder is more of a pain. It requires higher temperatures and often a little more flux to get it to flow correctly. If you can adjust it, raise the temp of your soldering iron, hold it against the pin, wait, then add some more solder. It should have a nice sheen like a leaded solder connection.
 
Lead-free soldering has remarkable disadvantages over lead soldering. Lead free solders need higher temperature to melt, so it is kind of harder to solder and de-solder properly. Usually you don't get shiny joints. Consider that higher temperatures required for making good solder joints with lead-free solder could be responsible for the early failure of active semiconductor components. In general, I would say that lead-free solder might be environmental friendly, but not PCB friendly. Thus, life span is less with lead-free solder. Lead is an essential ingredient for reliable and quality, shiny solder joints. The only disadvantage of leaded solder: not environmental friendly.
 

dl324

Joined Mar 30, 2015
8,769
Apparently when lead free solder rehardens it forms an electrically non conductive surface. Is this normal?
You're confusing solder with flux. Some fluxes are more conductive than others. It should be removed after soldering to avoid problems.
 

crutschow

Joined Mar 14, 2008
23,157
Why are you using lead-free solder?
Can't you buy leaded?
Leaded solder is not a hazard to the person doing the soldering. It's only a perceived problem if it gets in landfills.
 

Thread Starter

petewh

Joined Mar 23, 2016
37
Why are you using lead-free solder?
Can't you buy leaded?
Leaded solder is not a hazard to the person doing the soldering. It's only a perceived problem if it gets in landfills.
I generally do consider lead slightly hazardous. Most articles I read do strongly recommend thoroughly cleaning of the hands and attention to work surfaces. Sorry, if this is news to you.
 

Thread Starter

petewh

Joined Mar 23, 2016
37
You're confusing solder with flux. Some fluxes are more conductive than others. It should be removed after soldering to avoid problems.
I'm going to do some cleaning up of the flux and see if that solves the problem.
 

nsaspook

Joined Aug 27, 2009
6,221
Lead-free soldering has remarkable disadvantages over lead soldering. Lead free solders need higher temperature to melt, so it is kind of harder to solder and de-solder properly. Usually you don't get shiny joints.
I sometimes have to rework new boards during a redesign cycle for equipment life extension. I despise working with lead-free solder and never use it for soldering.

Example:
Replacement of a CRT to LCD touch screen with added capability to display camera video on screen using a COMPtoVGA converter to eliminate another CRT video monitor.
A custom rs-232 touch controller to convert the modern touch data format the old proprietary EIA binary format of the OEM
From this 20yo CRT with lots of screen burn.

To this nice new LCD that I don't think will last 20 years.


Inside the COMPtoVGA converter during manual switch replacement with a uC controlled relay.
The dull matte finish of the switch solder is typical of what I see.


Its typical 'good' lead-free solder joint for something with large thermal mass.




More rework on the Light-link board from the touch converter/processor that also drives the camera view relay.




Removed SMA connectors.
 
Last edited:

nsaspook

Joined Aug 27, 2009
6,221
I generally do consider lead slightly hazardous. Most articles I read do strongly recommend thoroughly cleaning of the hands and attention to work surfaces. Sorry, if this is news to you.
Thanks.
Don't eat the yellow snow either.
 

dl324

Joined Mar 30, 2015
8,769
I generally do consider lead slightly hazardous. Most articles I read do strongly recommend thoroughly cleaning of the hands and attention to work surfaces. Sorry, if this is news to you.
It's old news and it's mostly overblown. The people who came up with RoHS had their hearts in the right place, but they were so misinformed and had their heads so far up their behinds that they couldn't see the forest for the trees. They have no idea how many problems they caused with tin whiskers. How many people died and how many millions of dollars were lost (think losses included some satellites) due to their misdirected intentions to do something good?

The problem with tin whiskers was discovered many decades before RoHS. The solution was to add lead to the solder. So the EU mandates that lead is so dangerous that it needed to be removed?? Duh!?!

The blood brain barrier will stop lead from reaching the brain in all but the youngest children.

If you use the same common sense you use when you handle anything dirty or "hazardous", you won't have any excessive risk from soldering with leaded solder (you are washing your hands and not putting solder in your mouth, right?). You're likely to ingest more lead from food than from soldering.
 

crutschow

Joined Mar 14, 2008
23,157
I generally do consider lead slightly hazardous. Most articles I read do strongly recommend thoroughly cleaning of the hands and attention to work surfaces. Sorry, if this is news to you.
Not news.
But I don't consider it being "slightly hazardous" sufficient reason to suffer with trying to use the lead-free stuff. :rolleyes:
 

BR-549

Joined Sep 22, 2013
4,936
Have you burnt yourself with the iron yet? Got a good unintentional snort of fumes? How about a taste of line voltage? Making sure you don't electrocute anyone.....will suffice. The rest is gravy.

The heat...the smoke and the fumes.......the construction of circuits is foundry work.
 

Thread Starter

petewh

Joined Mar 23, 2016
37
Not news.
But I don't consider it being "slightly hazardous" sufficient reason to suffer with trying to use the lead-free stuff. :rolleyes:
As I reply I am not leading a charge for lead free solder, just so we're clear. I hadn't worked in the electronics industry for 20 years and picked it up again as a hobby a few years back. I thought I would give lead free solder a try. Actually, I'm glad to here so many talk about using regular lead solder. I thought that maybe industry practice has changed in the last 20 years. I had always heard that lead free solder was hard to work with.
 

dl324

Joined Mar 30, 2015
8,769
Actually, I'm glad to here so many talk about using regular lead solder. I thought that maybe industry practice has changed in the last 20 years. I had always heard that lead free solder was hard to work with.
In most places, hobbyists are still allowed to use solder with lead. The last time I inquired, that included the UE.

In the US, California is leading the charge for a ban on lead. Not sure if it has reached solder used by hobbyists yet. Manufacturers removed lead years ago because it was required for selling in the EU. But there are billions of old, unused parts that contain lead and we can still buy new parts in the US that are non-RoHS compliant.

I have many lifetimes worth of 63/37 solder wire on hand.
 

Thread Starter

petewh

Joined Mar 23, 2016
37
In most places, hobbyists are still allowed to use solder with lead. The last time I inquired, that included the UE.

In the US, California is leading the charge for a ban on lead. Not sure if it has reached solder used by hobbyists yet. Manufacturers removed lead years ago because it was required for selling in the EU. But there are billions of old, unused parts that contain lead and we can still buy new parts in the US that are non-RoHS compliant.

I have many lifetimes worth of 63/37 solder wire on hand.
That is interesting to hear that manufacturers did make a switch. I did figure they would play into the European market. FYI, in regards to my original question I tries some isopropyl alcohol and a brush to remove flux and it worked. I get zero ohm readings between points when contacting soldered ares directly.
 

Thread Starter

petewh

Joined Mar 23, 2016
37
You're confusing solder with flux. Some fluxes are more conductive than others. It should be removed after soldering to avoid problems.
I removed the flux with some isopropyl alcohol and it worked. Thanks!!
 

dl324

Joined Mar 30, 2015
8,769
FYI, in regards to my original question I tries some isopropyl alcohol and a brush to remove flux and it worked.
I use 70% for the first cleaning and 90+% for the final cleaning. I use an acid brush with the horsehair cut down to 1/8" for stiffness.

Not as easy as using a commercial flux remover, but much more economical.
 

recklessrog

Joined May 23, 2013
988
Although slightly more expensive than ordinary lead free solder, you can buy lead free with a small percentage of silver added. I have found this to be excellent when re-working lead free equipment. Also, I have some Hi flux lead free which is nearly as good as leaded solder. However, my first choice wherever possible is lead/tin, even lead-tin-antimony for some applications. I still have a big reel of Savbit solder that contained copper as well.
 

Thread Starter

petewh

Joined Mar 23, 2016
37
Although slightly more expensive than ordinary lead free solder, you can buy lead free with a small percentage of silver added. I have found this to be excellent when re-working lead free equipment. Also, I have some Hi flux lead free which is nearly as good as leaded solder. However, my first choice wherever possible is lead/tin, even lead-tin-antimony for some applications. I still have a big reel of Savbit solder that contained copper as well.
I didn't have any trouble finding listings (on Amazon) of lead-free with a little silver, and I note, a little copper. I want to finish up what I'm building and will check it out electrically and decide which way to go. I figure I can always do a few more projects trying the lead free before coming to any conclusion. It is hotter working with the iron, and as pointed out is harder on the active components (caps too, I figure)
 

Lyonspride

Joined Jan 6, 2014
139
In most places, hobbyists are still allowed to use solder with lead. The last time I inquired, that included the UE.

In the US, California is leading the charge for a ban on lead. Not sure if it has reached solder used by hobbyists yet. Manufacturers removed lead years ago because it was required for selling in the EU. But there are billions of old, unused parts that contain lead and we can still buy new parts in the US that are non-RoHS compliant.

I have many lifetimes worth of 63/37 solder wire on hand.
It'll never be possible to ban lead solder, certain industries/sectors have exemption from it's use, Automotive, Defence, Aerospace, etc.
There was a very prominent aerospace engineer who once said that the day they make planes RoHS compliant is the last time he ever gets on one. Anything that is considered "safety critical" will have exemption from RoHS, basically because everyone knows that lead free solder leads to early life failures.

The whole thing is a farce, it's all about boosting consumerism by making modern electronics fail sooner.
 
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