Sounds like you already know the problem.  Are these boards HASL,roller
plated or ???    I would however question why the solder is being reflowed
on the top of the board if the bottom side of the pad and hole is solder
masked.  You may have to reduce your topside board temperature during
preheat or increase the conveyor speed to reduce the contact time in the
wave to prevent the top of the board from reaching reflow temperature.  One
or both methods may be required depending on your current setting.  I would
also have to question the plating quality of the boards so maybe a board
dip solderability test is in order and a talk with your board vender.  IPC
spells out the board solderability test in ANSI/J-STD-003.


Ken Kirby





 (Embedded
 image moved   Virgil Lenton <[log in to unmask]>
 to file:      05/14/99 10:13 AM
 pic32359.pcx)




To:   Kenneth Kirby <[log in to unmask]>
cc:   TechNet@IPC>ORG@COOKSON (bcc: Kenneth Kirby/ElectrovertUS/Cookson)
Subject:  Re: [TN] Solder balls forming on top side during wave soldering.




Thanks for your quick response.
No, the pot does not have the Omega option.
No, it is not coming from a hole close by.
Ive watched the solderballs form with my own eyes. It is
like the plating is becoming molten and then dewetting to
form solderballs. I'll see if can arrange some pictures.

On Fri, 14 May 1999 08:31:47 -0500 Kenneth Kirby
<[log in to unmask]> wrote:

>
>
>
> Virgil,
> If you can get pictures of this it would help.  Does the
> new pot have the Omega option?  If so you may be running it
> too high and it is forcing solder around the mask and into
> the mounting hole.  Could the solder ball be coming from
> another through hole close by?
>
> Ken Kirby
> Product Specialist
> Speedline
>
>
>
>
>
>
>  (Embedded
>
>  image moved   Virgil Lenton <[log in to unmask]>
>
>  to file:      05/13/99 04:14 PM
>
>  pic32295.pcx)
>
>
>
>
>
>
> To:   [log in to unmask]
> cc:    (bcc: Kenneth Kirby/ElectrovertUS/Cookson)
> Subject:  [TN] Solder balls forming on top side during wave
> soldering.
>
>
>
>
> Hi
> We are having a problem with solder balls forming around
> and in mounting holes that have been spot masked. The
> problem seems to have surfaced after upgrading our Hollis
> wave machine to use an Electrovert Lambda Wave Solder pot.
> Other than the Solder balls forming, soldering quality is
> very good.
>
> Any Suggestions would be appreciated.
>
> Flux - RMA thinned to Manufacturer's recommendations.
> Spot Mask - Tech Spray Water Washable
> Solder Temperature(SN63) - 500F
> Top Board Temp before solder pot - 200F
>
> Thanks
> Virgil
>
> ----------------------
> Virgil Lenton - Manufacturing Engineering
> SED Systems Inc   18 Innovation Boulevard
> P.O. Box 1464    Saskatoon, SK    S7K 3P7
> Ph. (306)931-3425       Fax (306)933-1486
> Email:[log in to unmask]
>
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----------------------
Virgil Lenton - Manufacturing Engineering
SED Systems Inc   18 Innovation Boulevard
P.O. Box 1464    Saskatoon, SK    S7K 3P7
Ph. (306)931-3425       Fax (306)933-1486
Email:[log in to unmask]