Steve,
If you are new to this don't be surprised, you will probably see it again if you use lead free HASL coated PCB's. Here where I work we have had at least 5 of these events with lead free HASL. They occurred at several different facilities. In most cases the first reflow lead to major non-wetting due to large areas of intermetallic on pads. XRF can help to identify it on a raw board by mapping the thickness of the solder/intermetallic present. Numbers too thin indicate most or all of the material is intermetallic. Nothing can be done from a production process point of view to remedy this.
Drew Meyer
Benchmark Electronics, Inc.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, October 02, 2013 2:20 PM
To: [log in to unmask]
Subject: Re: [TN] HASL question
I think Gerry nailed it.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerry Gagnon
Sent: Wednesday, October 02, 2013 2:05 PM
To: [log in to unmask]
Subject: Re: [TN] HASL question
Hi Steve,
Good work!
Speaking strictly about the board:
The picture is enough for me to postulate that the product was hot air levelled.
I also think that it is lead free.
I think that most of the deposit showing did not "wet" because the wetted solder applied during HASL was blown off by excessive hot air knife pressure on one board side leaving grey copper-tin intermetallic areas behind.
You may see one side good and one side not so good because regardless of hot air levelling method (Horizontal/Vertical), both sides of the board get solder applied and immediately go through hot air knives on both sides to blow off the excess solder applied. Thus there is always the possibility of side-to-side differences in hot air knife pressure.
In any case you can see the grey copper-tin intermetallic areas and the "free solder" pooling where there is enough wettable surface underneath.
For the assembly:
The short of it is, these boards will not solder correctly.
Best regards,
Gerry
> Date: Wed, 2 Oct 2013 11:35:37 -0600
> From: [log in to unmask]
> Subject: Re: [TN] HASL question
> To: [log in to unmask]
>
> Hi Gerry,
>
> Problem is I don't have any more in stock, we only had three panels
> and a solder sample panel... :o(
>
> But I did take a photo of the side of the solder sample panel that I didn't print paste on, and angled it so that you can kind of see the topography of the pads:
>
> http://stevezeva.homestead.com/SolderSamplePrimary.jpg
>
> It does look like the HASL is really thin. They also look just like a picture that Günter Grossmann sent me (thank-you Günter!) from a case that had the same problem as I have.
>
> Steve
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerry Gagnon
> Sent: Wednesday, October 2, 2013 6:20 AM
> To: [log in to unmask]
> Subject: Re: [TN] HASL question
>
> Hi Steve!
>
> I would recommend you select a bare board from the stock that produced the assembly photos and take a picture of both sides. When taking the picture, if the pads exhibit a topography, try to take the pic at an angle that shows the topography. If the pads do not show a topography make sure the pics you select show that too.
>
> With these pictures, I think we can all nail this one from the bare board side because the assembly pics tend to add some confusion.
>
> Brs,
>
> Gerry Gagnon
>
>
> > Date: Tue, 1 Oct 2013 17:14:03 -0600
> > From: [log in to unmask]
> > Subject: Re: [TN] HASL question
> > To: [log in to unmask]
> >
> > Okay here's another picture. I printed a solder sample and sent it
> > through the oven and this is what it looked like:
> >
> > http://stevezeva.homestead.com/SolderSample.jpg
> >
> > You can see all the non-wetting going on. The board was profiled
> > and it was fine. We are using a FCT Assembly WS889 SN100C solder paste.
> >
> > What is even more strange is that the first side of the board looked
> > okay, but the second side looks like in the photos, like the problem
> > is confined to one side of the board if that's possible.
> >
> > The solder sample was only reflowed once, but I printed the paste on
> > the side that was to be built last. Weird huh?
> >
> > I know you can't tell anything for sure just from some photos, but
> > it's the strangest thing I've seen in a while...
> >
> > Steve
> >
> > -----Original Message-----
> > From: Steve Gregory
> > Sent: Tuesday, October 1, 2013 4:46 PM
> > To: [log in to unmask]; Steve Gregory
> > Subject: RE: [TN] HASL question
> >
> > Here's one picture:
> >
> > http://stevezeva.homestead.com/NonWetting.jpg
> >
> > Look at the left pad and the tarnish that you see there, does that
> > look like tarnished nickel?
> >
> > This is after the board was washed. I have places all over the board
> > that looks like this.
> >
> > I'll post a picture of what it looks like after I printed a solder
> > sample with paste and sent it through the reflow over
> >
> > Steve
> >
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
> > Sent: Tuesday, October 1, 2013 4:16 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] HASL question
> >
> > Ahhhh....it's what I figured. I think that's what happened. I'll
> > have pictures later.
> >
> > Steve
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
> > Sent: Tuesday, October 1, 2013 4:15 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] HASL question
> >
> > No. Not unless somebody screwed up.
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
> > Sent: Tuesday, October 01, 2013 6:11 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] HASL question
> >
> > Hi all,
> >
> > It's funny that the HASL topic has come up today, because we just
> > ran a board today that supposedly was lead-free HASL finished, and
> > man it looks like crap!
> >
> > Question; does a PCB get nickel before it gets Lead-free HASL'ed?
> >
> > Steve
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev.
> > PhD
> > Sent: Tuesday, October 1, 2013 2:23 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] HASL question
> >
> > Hello Victor,
> >
> > It wouldn't solder in a first palce.
> >
> > --
> > Best regards,
> >
> > Vladimir Igoshev. PhD
> > mailto:[log in to unmask]
> >
> > SENTEC Testing Laboratory Inc.
> > 11 Canadian Road, Unit 7.
> > Scarborough, ON M1R 5G1
> > Tel: (416) 899-1882
> > Fax: (905) 882-8812
> > www.sentec.ca
> >
> > ____________________________________________________________________
> > __ This email has been scanned by the Symantec Email Security.cloud
> > service.
> > For more information please contact helpdesk at x2960 or
> > [log in to unmask]
> > ____________________________________________________________________
> > __
> >
> > ____________________________________________________________________
> > __ This email has been scanned by the Symantec Email Security.cloud
> > service.
> > For more information please contact helpdesk at x2960 or
> > [log in to unmask]
> > ____________________________________________________________________
> > __
> >
> > ____________________________________________________________________
> > __ This email has been scanned by the Symantec Email Security.cloud
> > service.
> > For more information please contact helpdesk at x2960 or
> > [log in to unmask]
> > ____________________________________________________________________
> > __
> >
> > ____________________________________________________________________
> > __ This email has been scanned by the Symantec Email Security.cloud
> > service.
> > For more information please contact helpdesk at x2960 or
> > [log in to unmask]
> > ____________________________________________________________________
> > __
> >
> > ____________________________________________________________________
> > __ This email has been scanned by the Symantec Email Security.cloud
> > service.
> > For more information please contact helpdesk at x2960 or
> > [log in to unmask]
> > ____________________________________________________________________
> > __
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or
> [log in to unmask]
> ______________________________________________________________________
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or
> [log in to unmask]
> ______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
