Home > Industry news

Solder Flags on a Printed Circuit Board-WAVE SOLDERING DEFECTS

Solder flags or spikes are due either to inconsistent flux application or poor control of solder drainage from the wave.

If poor flux application is the cause, there will be other evidence on the surface of the board, like thin whiskers of solder similar to snail trails on a garden path.

Poor control of separation from the solder wave would tends to be a random fault, not on the same contacts every time. This is due to the back flow of the wave not being set correctly on a lambda style wave. The solder should flow at the same speed and direction as the board during separation from the wave. Running slightly faster will not normally cause spiking, but running slow or not flowing at all will increase spikes.

Figure 1: Solder flags or spikes
Figure 1: Solder flags or spikes.

If the spikes are always on the tip of the leads it may be a solderability issue caused by bare cut ends. If leads are cut by the supplier or cut and stored for a long period of time, the bare end of the lead will oxidise and be difficult to wet with solder. If the lead is slow to wet, it will also be slow to drain, hence a spike can form.

On some occasions, the spiking can be a thermal problem simply eliminated by a longer immersion time in the wave or increase pre heat. A component that has a high mass may have a lead of the same size as other parts. During pre-heat of the board there may not be an opportunity for heat to be absorbed by the lead to overcome this thermal load. As the leads of the component separate from the wave they will cool much more quickly, leaving either spikes or shorts.

The solder flags shown in Figure 2 are probably due to inconsistent fluxing, which should be visible on other areas of the board. The length of the pins is also excessive. Lead length should not exceed 1.5-2.0mm below the level of the board. Shorting can also occur during exit from the back of the wave if the component leads are dragged through the wave oxide layer rather the exiting from a clean surface.

Figure 2: Inconsistent fluxing likely caused these solder flags
Figure 2: Inconsistent fluxing likely caused these solder flags.

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 machine,SMT SPI machineSMT X-Ray machineSMT assembly line equipmentPCB production Equipment smt spare partsetc 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: Mr Tommy

Phone: 13691605420

Tel: 0755-85225569

Email: sales@flason-smt.com

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