Home > Industry news

How to Prevent Solder Joint Voiding and Cold Solder Defects during the SMT Reflow Process


solder joint voidingSolder joint voiding is a phenomenon that causes empty spaces or voids to occur within the joint. Solder joint voiding often occurs on BGAs and larger pads. Voids are related to flux that’s entrapped in the joint, as well as paste oxidation. A large number of voids will reduce the soldering joint’s reliability.
Analysis of Root Causes
  1. Too much flux is applied in the solder paste. The flux doesn’t have sufficient time to outgas before the solder has transitioned to a solid state.
  2. The preheat temperature is too low so any solvent in the flux is difficult to vapour out completely.
  3. The soak zone time is too short during the reflow process.
  4. Lead-free solder typically has a 4% shirinkage in volume when it is cooled down to a solid state. It is possible to obtain voids when large pads are cooled down unevenly.
  5. Paste oxidation occurs.
Corrective Actions
  1. Reduce the amount of solder paste deposited.
  2. For large pads, use small opening grids instead of a large aperture.
  3. Extend the preheat time so it is long enough.
  4. Extend the soak zone time so it is long enough.
  5. Always consider new solder paste for BGA assembly.
While a normal solder joint is usually bright and shiny, a cold Solder joint is an abnormally dull, non-reflective, rough surface on the solder joint.
Analysis of Root Causes
  1. The pre-heat time is too long and too high, preventing the flux from activating.
  2. The solder paste has expired.
  3. There is not enough heat absorbed by the solder.
  4. The cooling speed is too slow.
Corrective Action
  1. Adjust the reflow profile according to the manufacturer’s specification.
  2. Ensure the peak temperature is at least 15°C above the solder’s melting point for more than 45 seconds.
  3. Change to a new type of solder paste.

Flason Electronic Co.,ltd provide a full smt assembly line solutions, including SMT reflow ovenwave soldering machinepick and place machinesolder paste printerPCB loaderPCB unloaderchip mounterSMT AOI machineSMT SPI machineSMT X-Ray machineSMT assembly line equipmentPCB production Equipment smt spare parts etc any kind SMT machines you may need, please contact us for more information: wechat whatsapp:008613691605420, Skype: flasonsmt, Email: sales@flason-smt.com


FAQ

1) This is the first time I use this kind of machine, is it easy to operate?

There is English manual or guide video that show you how to use machine.

If you still have any question, please contact us by e-mail / skype/ phone /trademanager online service.

2) If machine have any problem after I receive it, how can I do ?

Free parts send to you in machine warranty period.

If the part is less than 0.5KG, we pay the postage.

If it exceeds 0.5KG, you need to pay the postage.

3) MOQ ?

1 set machine, mixed order is also welcomed.

4) How can I buy this machine from you? ( Very easy and flexible !)

A. Consult us about this product on line or by e-mail.

B. Negotiate and confirm the final price , shipping , payment methods and other terms.

C. Send you the proforma invoice and confirm your order.

D. Make the payment according to the method put on proforma invoice.

E. We prepare for your order in terms of the proforma invoice after confirming your full payment.

And 100% quality check before shipping.

F.Send your order by air or by sea.

5)Why choose us ?

A. Gold supplier on Alibaba !

B. Trade assurance to US$54,000 !

C. Best price & Best shipping & Best service !


Contact information



CONTACT US

Contact: Andrey

Phone: 13691605420

Tel: 0755-85225569

Email: sales@flason-smt.com

Add: Flason Industry park Shajing Town Baoan district shenzhen China 518104