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Solderality problems with SN100C Lead Free Hasl

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#44077

Solderality problems with SN100C Lead Free Hasl | 21 September, 2006

Just wondering if there are any users of SN100C lead free hasl finsh out there. If so what kind of results are you getting as far as solderability is concerned?

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Cmiller

#44086

Solderality problems with SN100C Lead Free Hasl | 21 September, 2006

We have used it and it seems to be fine. I think we have probably run a few thousand boards with it across maybe 6 different assemblies.

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greg york

#44091

Solderality problems with SN100C Lead Free Hasl | 22 September, 2006

Interesting you should ask this what problems are you seeing. Non wetting and blow holes and shallow fillets at all??? Cheers Greg

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#44102

Solderality problems with SN100C Lead Free Hasl | 22 September, 2006

Greg,

All the above. It looked like it was going to be a drop for SNPB HASL at first but after a few thousand boards we started running into all the problems you are describing. We first started seeing non wetting on SMT pads. The solder would wet to the lead but the pad would literally repel the solder. We were told the cause of this problem was the finish being applied too thin leaving the intermetallic layer exposed, but now it is applied at the proper thickness and we are still seeing wetting problems on SMT pads. We have been seeing blow holes all along. As far as hole fill goes we increased the contact time, raised the pot temp and started filling holes better.

We are switching to immersion silver. I will let you know how it goes.

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#44160

Solderality problems with SN100C Lead Free Hasl | 26 September, 2006

Hello Brad, I think Greg is a mind reader!! Thanks for the opportunity to give an update to the forum on SN100CL Lead Free HASL. Conversions to SN100CL HASL is occuring at a rapid pace worldwide. As of July 2006, there were over 250 HASL machines running SN100CL (some over 6 years!)so the number of SN100CL coated boards must be in the millions. If the issues you brought up were common, I feel the increase in conversions would not be there. Please work with your board shop to review the issues as they do not appear to be related to the HASL process. Regards, Bob Gilbert Technical Sales Manager FCT Assembly, Inc. 970-988-6243

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#44174

Solderality problems with SN100C Lead Free Hasl | 26 September, 2006

Is there a difference between SN100, SN100C, and SN100CL?

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RDR

#44176

Solderality problems with SN100C Lead Free Hasl | 26 September, 2006

Bob should answer this but yes there is a diiference, I wonder if you do not need to add the SN100(cu???) to get your alloy correct again, I believe that additional copper must be added on a scheduled basis.

Russ

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#44219

Solderality problems with SN100C Lead Free Hasl | 27 September, 2006

Hello Steve, Yes, there are differences in the various alloys and I have described briefly below these differences:

SN100- a common name for 100% tin that is used to increase the tin content in 63/37.

SN100C-Name for Tin/Copper/Nickel/Germanium alloy used for wave solder, tinning, wire solder and solder paste.

SN100Ce- Tin/Nickel/germaniuum top-up alloy used IF the copper content exceeds the recommended limit of 0.85% in the wave or tinning pots.

SN100CL-Tin/Copper/Nickel/Germanium alloy used for Hot Air Solder Level (HASL).

SN100CLe-Tin/Nickel/germaniuum top-up alloy used IF the copper content exceeds the recommended limit of 1.2% in the HASL pot.

Regards, Bob Gilbert

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#44258

Solderality problems with SN100C Lead Free Hasl | 2 October, 2006

Bob,

I agree that these are all board shop issues. I think the only one that is related to the Hasl process is the surface mount solerability issues. I think they are still putting the coating on too thin even though they say it is fine. This problem is affecting 5 percent of our boards. Is there anyting I can put in my specifications beyond calling out a thickness between 3-10um to try to get the consitency I need.

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cuculi54986@yahoo.com

#44300

Solderality problems with SN100C Lead Free Hasl | 3 October, 2006

Our board suppliers tell us, there is no specification they use for HASL thickness, other than "coverage". They also say they have very little control over the HASL thickness.

This was not an issue for us in the past, until we started using Pb-free HASL.

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C.K. the Flip

#44307

Solderality problems with SN100C Lead Free Hasl | 3 October, 2006

Cuculi,

I'll have to go ahead and disagree with you. Very few PCB Suppliers (if any, and if there are any, they're lying) will promise an exact thickness spec. be it Sn/Pb HASL or this fancy, schmancy Sn100c HASL balogna. After all, the HASL process is essentially wave soldering, and molten metal IS molten metal, regardless of the molten metal.

"You can't talk to molten solder....."

Just ask T2...he'll tell ya! :)

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C.K. the Flip

#44308

Solderality problems with SN100C Lead Free Hasl | 3 October, 2006

It sounds as if this Sn100c HASL process is still in its infancy requiring further process development and characterization..weather its a better more active flux or a different profile... Given your situation of the Sn100c coating actually "repelling" the component leads and terminations, it does sound like a non-wetting issue...as if the Sn100c never wet to the base metal (Copper) to form an intermetallic. I've heard of this phenomenom happening with Immersion Ag as well, but only in situations where an IAg PCB is sent back to the PCB Mfgr. for rework...again, though, it goes back to the plating process not forming a good intermetallic to begin with.

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greg york

#44312

Solderality problems with SN100C Lead Free Hasl | 4 October, 2006

Now seen the Blow Holes and shallow inverted and non wetting problem an aweful lot over here. Over came the Blow Holes and shallow inverted joints by washing the bare PCB with hot Saponifier then rinse and dry = problem dissapears. Think most PCB vendors use cold water to wash flux off and this is gelling up and becoming difficult to remove. The SMD non wetting is just poor solderability from probably one dip in the HASL process.As most know it requires a double dip with more exposure to the laminate. Not a mind reader Bob just a good problem solver. Cheers Greg BLT

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#44360

Solder-ability problems with SN100C Lead Free HASL | 5 October, 2006

Good afternoon all!

Theoretically, there should not be any issues soldering to the SN100C as the tin content of the molten paste alloy should wet to the finish with no problem.

I would just ensure that the peak temperature of the joint is above the melting point of the SN100C during the reflow process. More information can be found at knowledge.indium.com.

Should you have any further questions, please don't hesitate to ask. My contact information is below.

Regards,

Mario Scalzo, SMT CPE Technical Support Engineer - Southwest Region mscalzo@indium.com 315-853-4900

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