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Do you know what's should be the best surface finish?

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soppcb

soppcb

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Hi, we are manufacturer of PCB, do you know what should be the best choice for your board about the surface finish, HASL/LEAD, HASL/LEAD FREE, ENIG, IMMERSION SILVER, OSP AND SO ON?

Jack
soppcbtech at gmail dot com
 

Different matrial use for different perpose. ENIG is best..now a days HASL is not using..

Regards
Praveen
 

Hi, praveen, I don't agree with you, in my experience for nearly 10 years in this field, most clients ask HASL lead free and HASL with lead for their boards. Of course,yes, ENIG is also common.
 

I beg to differ further, HASL is no good for fine pitch surface mount, or any SMD assemblys realy, forms a convex meniscus.
The most popular according to IPC data is ENIG. And ENIG is the one I would reccomend, used it for years with no problems
This recent release may be of interest, comparing finishes:
Laying It Out: Off to the Races: Creating Winning Finishes
 

It depends.
As marce pointed out for any fine pitch ENIG is best. But for military applications HASL is still the most requested. There are still some issues with tin whiskers on the lead free process.
 

I do military and use ENIG with tin lead solder no problems.
HASL just has to many problems with even basic SMD components, amount of solder in the joint, flux ratio etc etc. Just not woth the hasle these days IMO.
 

Our military customers require HASL. They do not allow any other finishes.
 

Hi, Marce, thanks for your information, to some extent of assembly, according to the quality, ENIG is really better for SMD assembly than HASL. But accually, HASL is also a common, maybe most common for prototype as I know in my 10 years for sales of PCB fabrication and assembly. But according to the cost, HASL is much cheaper than ENIG, now the former is about RMB100 lower than the latter per square meters.

Jack
soppcbtech at gmail dot com

---------- Post added at 10:57 ---------- Previous post was at 10:52 ----------

Hi, loosemosse, I have some friends who made the project for military who also needs HASL for their boards. Some need immersion silver, ENIG has a good assembly performance, which is really true from Marce.
Anyway, if any PCB project, maybe you could contact me.

Jack
soppcbtech "at" gmail "dot" com

---------- Post added at 10:59 ---------- Previous post was at 10:57 ----------

maybe, :smile:
 

I'm curious as to what technology they are using on their boards. For SMD design based products and from two recent PCB designer get togethers* ENIG was the finish of choice, but this was standard small BGA QFN (bottom terminated components). HASL is no good for QFNs and numerous other SMD compnents today, especialy 0.5mm pitch QFP's. As I have said for PTH and SOIC type SMD, you can probably get away with HASL, tin/lead HASL has many advantages (ie we've always used this finish, blah bal balh, which is why quite a few mill designs still use it cos they are dinasours), BUT if you use modern SMD (0603, BGA QFN) then one of the flat surface finishes is a requirement, be it ENIG, Immersion silver, OSD. You cant even screen small components properly with HASL's meniscus.

Anyway what I would reccomend is that if you are members of the IPC, have a look at their website and the amount of research that has been done on surface finishes for PCBs. They also have data from the majority of the world PCB manufacturers. They are the ultimate resource for any information regarding any aspect of PCB design. Also the solder paste screen printing research done with various surface finishes. And the SMTA is another source of info, oh and NASSA, and the SMART group in the UK.

Tin whiskers is not related to surface finish (unless it is tin), it is more to do with lead free components having matt tin terminations, and lead free solders. Funnily adding about 3% lead to tin stops the dendritic growth of tin whiskers. The best source for info is NSSA:
NASA Goddard Tin Whisker Homepage

For the record I have been studying surface finishes for both tin/lead, lead free, and lead free components with tin/lead solder for over 10 years. From my research and numerous high tech, low tech boards the best all round surface finish is ENIG, it dosn't lead every category, but when you look at all the other knock on effects it comes out top, though ENIPIG will probably overtake it.
Shelf life and storage conditions,solderability, high speed, screen printing, cost, reliability (a cheap finish is no good if you get solder defects, the cost of one duff board will usualy pay for a better finish on a few 100-1000 boards).
*One was a military only on flex and felx rigid design.
 

Maybe I could check with my clients their reasons and convey your meaning, Marce, thanks/

Jack

soppcbtech at gmail dot com
marce said:
I'm curious as to what technology they are using on their boards. For SMD design based products and from two recent PCB designer get togethers* ENIG was the finish of choice, but this was standard small BGA QFN (bottom terminated components). HASL is no good for QFNs and numerous other SMD compnents today, especialy 0.5mm pitch QFP's. As I have said for PTH and SOIC type SMD, you can probably get away with HASL, tin/lead HASL has many advantages (ie we've always used this finish, blah bal balh, which is why quite a few mill designs still use it cos they are dinasours), BUT if you use modern SMD (0603, BGA QFN) then one of the flat surface finishes is a requirement, be it ENIG, Immersion silver, OSD. You cant even screen small components properly with HASL's meniscus.

Anyway what I would reccomend is that if you are members of the IPC, have a look at their website and the amount of research that has been done on surface finishes for PCBs. They also have data from the majority of the world PCB manufacturers. They are the ultimate resource for any information regarding any aspect of PCB design. Also the solder paste screen printing research done with various surface finishes. And the SMTA is another source of info, oh and NASSA, and the SMART group in the UK.

Tin whiskers is not related to surface finish (unless it is tin), it is more to do with lead free components having matt tin terminations, and lead free solders. Funnily adding about 3% lead to tin stops the dendritic growth of tin whiskers. The best source for info is NSSA:
NASA Goddard Tin Whisker Homepage

For the record I have been studying surface finishes for both tin/lead, lead free, and lead free components with tin/lead solder for over 10 years. From my research and numerous high tech, low tech boards the best all round surface finish is ENIG, it dosn't lead every category, but when you look at all the other knock on effects it comes out top, though ENIPIG will probably overtake it.
Shelf life and storage conditions,solderability, high speed, screen printing, cost, reliability (a cheap finish is no good if you get solder defects, the cost of one duff board will usualy pay for a better finish on a few 100-1000 boards).
*One was a military only on flex and felx rigid design.
Click to expand...
 

In our military and naval products we do not use anything smaller than 0805's. The reason for this is high vibration environment. You run into trouble with smaller components. So flatness is not a problem.
But their the biggest fear is still tin whisker's.They just do not want to risk failure of the unit. Especially in the field. HASL is a know process for decades.
 

So is ENIG.
I would disagree on the smaller components having done a board that goes in a long tube that is fired att high speed and has horrendus vibration, the smaller components have less mass so absorb less energy.
Alos smaller components survive the ballistics test better than big ones.
As said some mil design is from the dark ages, trying to get them to change is hard work, even if it is for the better.
And as stated before ENIG has nothing to do with tin whiskers...
All the footprints used have mainly been to the IPC-7351 Nominal standard, the least possibly does not have the Pad area to get a robust enough joint for balistics and vibration, though have done numerous tests
All my designs for the last 4 years have been specificly military, all have used ENIG, all have been through all the tests with no problems, 0402's all over the place, though I dont work for a US Military company again the last 4 years designs have been for one of the biggest US military contracters so I reckon there is nowt wrong with the designs or the technology. I have aalso spent 4 years looking at tin whiskers and the research out there. Matt Tin termination on component leads is probably the biggest worry and the use of lead free solder, with ENIG and Tin/Lead solder there is no reason for concern.
 

Every thing has its reason to be existed, HASL and ENIG have their own advantages.

Jack
soppcb at gmail dot com
 

Yes, I used HASL for many years, the crossover was between 1998 to 2002, where some designs were HASL and some were ENIG,. And even now I get to see jobs with HASL. Some like immersion silver, for very high speed and GHz RF its the best finish as it gives the best solder joint in terms of resistance.
Others like organic finishes, and others tin!
Without discussions and debate though we would not be aware of other finishes, and in my case it prompts me to re-read my documentation and also look for new documentation.
What I would reccomend is signing up to this, its a great source of PCB related news:
https://www.pcbupdate.com/
 

Hi, marce, do you know any other forum or website in your place or other places about PCB discussion?

Jack
soppcbtech at gmail dot com
marce said:
Yes, I used HASL for many years, the crossover was between 1998 to 2002, where some designs were HASL and some were ENIG,. And even now I get to see jobs with HASL. Some like immersion silver, for very high speed and GHz RF its the best finish as it gives the best solder joint in terms of resistance.
Others like organic finishes, and others tin!
Without discussions and debate though we would not be aware of other finishes, and in my case it prompts me to re-read my documentation and also look for new documentation.
What I would reccomend is signing up to this, its a great source of PCB related news:
https://www.pcbupdate.com/
Click to expand...
 

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