Hi Denny - my experience is with SnPb HASL and not Pbfree HASL so I don't have any use experience in that arena. There have been a number of good technical papers released this last year on Pbfree HASL. My "guess" is that the complexities of the Pbfree solder alloys may make Pbfree HASL have a tighter processing window but how that would translate into assembly surface finish properties/characteristics is still being developed/refined/defined in real time. Dave [log in to unmask] 09/30/2009 05:41 PM To [log in to unmask], [log in to unmask] cc Subject Re: [TN] ENIG / HASL CO-PLANARITY One question - are we talking about lead-free HASL for the world, or eutectic solder HASL for the USA? Wouldn't lead-free HASL start to have the same copper erosion issues as lead-free re-work with solder fountains? Or are we already talking about the newer lead-free SnCu+X alloys that have lower erosion potential? Denny Fritz -----Original Message----- From: David D. Hillman <[log in to unmask]> To: [log in to unmask] Sent: Wed, Sep 30, 2009 6:17 pm Subject: Re: [TN] ENIG / HASL CO-PLANARITY Hi Bob - The two disadvantages of HASL surface finishes are coplanarity and solderability - both due to improper processing of the HASL finish. Typically the pwb fabricator gets too aggressive with the hot air process parameter settings causing a thin HASL deposit that also becomes very "bumped" in terms of surface topography. As you detailed, the advantages of HASL are great wetting and processability if properly applied. HASL also has very good use environmental resistance in comparison to either immersion tin or immersion silver. We just need someone to figure out how to apply Unattainium to our pwbs and all our surface finish issues would go away. : - ) Dave "Robert Kondner" <[log in to unmask]> 09/30/2009 04:50 PM Please respond to <[log in to unmask]> To "'TechNet E-Mail Forum'" <[log in to unmask]>, <[log in to unmask]> cc Subject RE: [TN] ENIG / HASL CO-PLANARITY Dave, Since we stencil print the boards, and machine place onto the stencil printed paste coplanarity does not seem like a issue. Other than coplanarity are there any other problems with a HASL finish? Thanks, Bob Kondner -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Wednesday, September 30, 2009 4:29 PM To: [log in to unmask] Subject: Re: [TN] ENIG / HASL CO-PLANARITY Hi Paul - the reason the coplanarity issue comes up is that many folks have issues with getting consistent and reproducible HASL finish coplanarity. All of the pwb surface finishes have advantages/disadvantages and HASL is no exception. HASL surface finishes were the primary finish of choice for our surface mount lines for many years and as you detailed, we also ran a very successful process. However, the inherent coplanarity of the immersion surface finish family (ImAg, ImSn, and ENIG) is better than HASL for our approved group of pwb fabricators. I have little doubt that if I had more control over pwb fabricator selection, I would share your experience but I have found that the immersion surface finish family provides me an expanded process window for BGAs/CSPs and many of the new Bottom Terminated Component styles (such as QFNs, ). HASL is still one of our approved finishes but we now include the immersion surface finish family as additional options in our "tool box". Dave Hillman Rockwell Collins [log in to unmask] Paul Edwards <[log in to unmask]> 09/30/2009 12:27 PM To TechNet E-Mail Forum <[log in to unmask]>, "[log in to unmask]" <[log in to unmask]> cc Subject RE: [TN] ENIG / HASL CO-PLANARITY Why does this always come up? With everything that is said about the real and potential metallurgical problems with ENIG, how can ENIG be considered a good replacement for a HASLed PCB, unless you are considering only the PCB fabrication of RoHS boards or the bulk buying PCB materials ? Look at the flatness numbers for HASLed PCBs...Unless you have huge pads and a very bad PCB fabricator the HASL thickness variation is typically no more than 0.0007" on standard part pads... That is better than the planarity on everything but LCCs and QFN type structures and well within the solder paste print height tolerances of most systems... Besides the last time I checked we all put solder paste on pads before we stuck parts to the PCB so there is at least 0.004" of solder compliance to compensate for any bumping of the HASL... Have built a lot of high-density high-rel PCAs and over a lot of years and I will take a HASLed PCA over any other kind of surface finish... Paul Paul Edwards Surface Art Engineering -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Wednesday, September 30, 2009 7:54 AM To: [log in to unmask] Subject: Re: [TN] ENIG / HASL CO-PLANARITY Hi Lee - You might try another approach with the customer. Image that you have a very large, nonflexible beach ball and you are trying to balance it on your local parking lot speed bump - if you are using a HASL finish and processing BGAs or CSPs you are doing the same procedure. Sometimes having a visual reference is worth a pound of tolerance measurements. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] Lee Whiteman <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 09/25/2009 09:09 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to [log in to unmask] To [log in to unmask] cc Subject [TN] ENIG / HASL CO-PLANARITY Happy Friday. Does anyone have a reference on comparing the co-planarity between ENIG and HASL (SnPb)? I know that ENIG is more planar than HASL, but by how much (quantifying the argument). I'm anticipating a question from my customer on why I want to use ENIG instead of HASL for fine pitch applications. Thanks. 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