Electronics Assembly Knowledge, Vision & Wisdom
PCBA Cleaning with Sodium Bicarbonate
PCBA Cleaning with Sodium Bicarbonate
Is there an effect on PCBA long-term reliability when cleaned with a sodium bicarbonate scrub followed by DI water rinse? The Assembly Brothers, Jim Hall and Phil Zarrow, answer this question.
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



Transcript
Phil
Welcome to Board Talk. This is Jim Hall and Phil Zarrow, the Assembly Brothers, coming to you from high atop Mount Rialto here in New Hampshire.

Jim
Our question today is about cleaning. It comes from L.P. "Is there an effect on PCBA long-term reliability for assemblies cleaned with a sodium bicarbonate scrub followed by DI water rinse to remove tarnishing of silver immersion plating?

I assume that you have checked the compatibility of all the materials on your circuit board, your components, compatibility with the sodium bicarbonate and your cleaning operation. But most important is that sodium bicarbonate to the best of my knowledge is a caustic solution, as many traditional cleaners have been, and you absolutely need to get it all off the board when you're done.

Phil
We would suspect that DI water probably is not quite hacking it.

Jim
It depends upon the components on your board, the clearances and so forth and the mechanical action during this "scrub," whether it's forcing sodium bicarbonate under low clearance parts such as a QFNs. 

If you leave sodium bicarbonate on your board, you are definitely taking a risk.

Phil
He may be talking about a bare board that they've stored too long and they're tarnished.

Jim
He's talking about an assembly so I interpret that as having soldered components on the printed circuit board, or a printed wiring board if we want to be more descriptive.

Phil
Immersion silver finish has been around for a while now. And it's becoming really popular.  This is a common problem. I would check with some of the industry cleaning companies.

Jim
You want to get a product that's designed to be compatible with all your electronic materials.  

Phil
Happy scrubbing and happy cleaning. And when you go to solder those boards, whatever you do -

Jim
Don't solder like my brother.

Phil
Don't solder like my brother.


Comments
Sodium bicarbonate can act as a mild abrasive but it it may enter the surface of whatever you are scrubbing (the same as any abrasive), leaving a possibility of problems. I would say it is imperative to give a mild acid rinse (say 3-5% hydrochloric acid) at room temperature for 5 minutes BEFORE at least 2 good DI rinses. This will decompose any poorly-soluble weak ionic residues into very soluble ones, which will dissolve in the rinses.
Brian Ellis
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 pH neutral Cleaning Agents - Market Expectation & Field Performance
bullet Effect of SMT Component Package Design on Cleaning Effectiveness
bullet Results with Benchtop PCB Cleaning
bullet Video Analysis of Solder Paste Release from Stencil Printing
bullet Seeking Alternatives to Solvent Cleaning
bullet Incoming Circuit Boards - How Clean Is Clean?
bullet Is Cleaning Critical to POP Assemblies?
bullet Ultrasonics as an Option for Electronics Assembly Cleaning
bullet Cleaning High Reliability Assemblies with Tights Gaps
bullet Alternative Solvent with Low Global Warming Potential
More Related Programs