Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Dendritic Growth

Views: 9962


GCF

#73722

Dendritic Growth | 19 March, 2015

Hi guys, i do not have a lot experience on this wave solder process, in my plant now i have the opportunity to work in this area, and a lot issues are been happening on the process and it could be possible that i request information about this, i hope to have a support from You. I saw some topics about the process and is interesting for me to know a new things. Is the flux the root cause of the dendritic Growth?

Regards.

reply »

#73723

Dendritic Growth | 20 March, 2015

Yes generally speaking yes if there is not contamination on the board from PCB manufacture. for dendrite formation you also need moisture and voltage during operation of the product. You can see many of my IPC Defect of the Month videos at showing you the cause of different problems with wave soldering. See https://www.youtube.com/user/MrBobwillis

there is also our training CD ROM on Wave Soldering see http://www.bobwillis.co.uk/Interactive.asp

Many thanks Bob Willis

reply »

#73724

Dendritic Growth | 20 March, 2015

Dendrite growth is not typically associated with a flux reation but rather is a result of mechanical stress. The stress can be from any source including stress induced by other components, environment, plating or even bimetallics. Dendrites are most typically seen when pure tin is used for plating and lead free solder is used for assembly. Alloying is the best solution to this problem. Tin/Lead solders don't exhibit this behavior at a troublesome level because the soft lead tends to lower the mechanical stress that is felt by the joint.

reply »


GCF

#73727

Dendritic Growth | 20 March, 2015

Thanks by the information provided for you. How can we prevent the Dendritic Growth, exist some table where i can see the quantity of flux that i can apply to the PCB.

Thank You.

reply »

#73728

Dendritic Growth | 21 March, 2015

Think you are talking about tin whiskers and not dendrites which are a different thing?

Bob Willis

reply »


GCF

#73729

Dendritic Growth | 21 March, 2015

Thanks Guys by your comments, I am talking about Dendritic Growth, I asked about flux application because the residues of flux can be a factor of the Dendritic Growth right.

Thank You

reply »

#73730

Dendritic Growth | 21 March, 2015

You're right on both accounts. Thanks for straightening things out.

reply »

#73735

Dendritic Growth | 23 March, 2015

Dendritic growth is always a result of three combined factors:

Conductive/corrosive residues

Electrical current

Moisture

A wave solder process normally applies a higher volume of flux than a printed process. Flux however is not the only source. Flux, even weak low-solids "no-clean" (more appropriately called low-residues) combined with residues from board fabrication, component fabracation, and the assembly process can combine with moisture (even humidity caused moisture) and electrical current to create ECM issues including dendritic growth and parceedic leakage.

The best way to ensure ECM issues can not form is to remove the residues that cause ECM.

Here's a link to a recorded technical presentation on modern ECM issues. It's about an hour long so clear your schedule :-)

https://vimeo.com/100244222

Mike Konrad Konrad@aqueoustech.com

reply »


GCF

#73740

Dendritic Growth | 25 March, 2015

Thanks by the information Mike, Another question for you is, the clean process must be developed even if we are using flux "no clean".

Regards

reply »

Plasma Prior to Conformal Coating

Heller Industries Mark 5获得了 2015年中国SMT远见奖 - 回焊炉领域