Electronics Assembly Knowledge, Vision & Wisdom
What Causes Solder Balls During Hand Soldering?
What Causes Solder Balls During Hand Soldering?
We have experienced solder balls during automated reflow. Now we are finding solder balls during the hand soldering.
Board Talk
Board Talk is presented by ITM Consulting

Phil Zarrow
Phil Zarrow, ITM Consulting
With over 35 years experience in PCB assembly, Phil is one of the leading experts in SMT process failure analysis. He has vast experience in SMT equipment, materials and processes.

Jim Hall
Jim Hall, ITM Consulting
A Lean Six-Sigma Master Blackbelt, Jim has a wealth of knowledge in soldering, thermal technology, equipment and process basics. He is a pioneer in the science of reflow.

ITM Consulting
* EMS Qualification, Evaluation and Selection
* SMT Process Consulting and Troubleshooting
* SMT Process Development and Set-up
* SMT Process Audits
* Lead-free Process Readiness Audits
* SMT Process Optimization
* On-Site Workshops
Submit A Comment
Comments are reviewed prior to posting. You must include your full name to have your comments posted. We will not post your email address.

Your Name

Your Company

Your E-mail

Your Country

Your Comment

Welcome to Board Talk with Jim Hall and Phil Zarrow of ITM Consulting, the assembly brothers. So what question is drifting our way today Jim?  

This comes from C.P. We have experienced solder balls during automated reflow and tweaked the process to eliminate them. Now we are finding solder balls during the hand soldering of some eight-lead SMT components.

Any idea what causes solder balls during hand soldering?  

Everything and anything just like what causes solder balls in reflow and wave. I guess the first question we would probably ask is what's different in terms of thermally or chemically.

The first thing Phil is to say are you using paste in doing your hand soldering which you used in reflow and found that adjusting the thermal profile eliminated solder balls or what I think is more likely is that you're using some sort of cored wire.

So the parameters are much different. Solder balls are typically caused by incomplete fluxing because the flux does not clean all the solder surfaces, becomes molten, the solder does not coalesce into one single mass and you get these little guys floating off on their own as balls with their own little oxide coating around them preventing them from coming back together.

So do you have adequate flux in your hand soldering operation and also I think as you indicated Phil, the thermal profile. Are your operators trained. Are they using the proper tip size and tip temperatures and IPC specified soldering techniques.

As Jim said, do you have the right tips? Do you have the right heat range for what you're doing? Have the irons been calibrated? That's another prerequisite.

And again how well trained are your operators? Are they soldering with the right end of the soldering iron?

I feel that my experience is that solder balls are not common in hand soldering.  One other thing that you would think of, if that was just a problem would be contamination of the leads of the parts that you're soldering.

But if they work in reflow with paste, I would think that that would not be the issue. But you can never be sure.

Whatever end of the soldering iron you're using, whatever you do don't solder like my brother.

And don't solder like my brother.

One question I'd like to ask: is it lead free solder that you're using? That would have an impact as well...
Peter Woodhouse, New Zealand
We are facing SMT components No solder and solder bridging issue (Glue PCBA) at wave soldering process. Fine tuned the wave parameters improved but not able to eliminate the issue. Suspecting because of moisture pad and component leads contaminated due this we are facing this issue.

After SMT Reflow process with in how many days wave soldering process to be completed for glue PCB'S & Normal PCB'S. or is their any other reason please suggest.
Shankar, India
Being trained extensively in High Reliability Soldering and Connections since 1976. I notice, when at my home hobby lab (dc-15 ghz capable) because it is quiet, I have long experienced the same issues using paste for rework/repairs. I also try not to use it(paste) opting for wire solder instead. One other item of interest is the amount of these balls is proportional to the loudness of "the sizzle" sound. I can agree some what with the moisture idea but just the flux itself "sizzling off" is also propelling balls in the area. Try this to see it yourself. get digital microscope cam, focus on little dab of paste, plunge in iron or hot air (hot air generates less due to more slow even heating) inspect area around dab and there they are>>>>
William Jones, Harimatec Inc.
Also, in agreement that most issues come from hand soldering techniques. I have found operators who do not keep the solder iron tip clean, will leave solder balls and splash around the solder joint, usually from the dross build-up on the iron. Feedback and refresher training help.
Bonnie Dewey, CIT, CQT, Saunders Electronics
Moisture is a contributor to solder balls. Trapped moisture, when ramped up to solder temperatures creates steam per se, pressure and out-gasses. Solder gets expelled from the solder joint, displaced, creating a ball. Keep in mind when using aqueous cleaning of PCBA's that they should be baked out prior to hand assembly or thru-hole. In the case presented here, its possible the 8 pin device they were hand soldering contained moisture. If the anomaly were specific to that part.
Tom McCarthy, TJM Electronics, USA
I agree that solder balls during the hand soldering process can often be attributed to hand soldering techniques. Use of a heat transfer bridge and a reduced feed rate of solder into the joint have helped me address this problem. Operators may try to improve their speed/efficiency by feeding too much solder into the joint too quickly. In a no clean process, when no external flux is applied, solder balls can result. IPC hand soldering training DVDs cover both topics and are a great training resource.
Anna Hill, Burton Industries, USA
Free Newsletter Subscription
Every issue of the Circuit Insight email newsletter will bring you the latest information on the issues affecting you and your company.

Insert Your Email Address

Directory Search

Program Search
Related Programs
bullet Fill the Void II: An Investigation into Methods of Reducing Voiding
bullet Surface Treatment Enabling Low Temperature Soldering to Aluminum
bullet Behavior of Materials in the Manufacturing Environment
bullet Solder Joint Embrittlement Mechanisms, Solutions and Standards
bullet Issues With Fillets on Via Holes?
bullet Rheology and Wetting Characterizations of Flux and Solder Paste
bullet Challenges for Bottom Termination Components
bullet Converting Cable Assembly to Lead Free Solder
bullet Why is Solder Dross Sticking to Our PCBAs?
bullet Will Nitrogen Reduce Wave Solder Defects?
More Related Programs