Hello Everyone,
Jerome Yeo had indicated that using N2 during his reflow soldering process improved yields but
was not used due to price constraints. There are Nitroen generators that use a diffusing
membrane which will allow fast gases such as oxygen to pass from the membrane and will produce a
varying purity of N2 depending on flow rate, pressure and nitrogen generator size. All of this
is produced from compressed air from in shop compressors (easy if you already have them).
I have used these systems for other applications and have found them very useful for producing
large volumes of N2 cost effectively.
The one company I am aware of that manufactures this equipment is Balston, Whatman Filter
Systems Division. The units are not cheap starting at several grand US but if you need N2 in
volume and don't like moving tanks, or cylinders around this is a good solution.
Regards,
John Bushie
Taconic ADD
--- On Tue, 20 Jan 1998 10:08:14 +0800 Jerome Yeo <[log in to unmask]> wrote:
Clinton Windsor,
My process engineer has reported seeing solder balls around the
components after solder reflow.
He is running this particular board in a no-clean process using
Alphametal LR-725 solderpaste, HASL PWB and without N2 at reflow.
Experiments show that turning the N2 on reduces the solder balls
dramatically.
However, due to cost constraints, it is necessary to run without
N2.
Is this the " squeeze balls " that you mentioned ?
Matthew,
Can you fax me the aperture shape definition ?
My fax number is 011-604-5064447
Thanks.
Jerome Yeo
[log in to unmask]
> -----Original Message-----
> From: Jay DeKing (EMA) [SMTP:[log in to unmask]]
> Sent: Tuesday, January 20, 1998 12:50 AM
> To: [log in to unmask]
> Subject: Re: [TN] Stencil Aperture Shapes -Reply
>
> Matthew,
>
> Please fax me the paste aperture shape definition. My fax number is
> (716)334-3481.
>
> Thanks,
>
> Jay DeKing
> EMA Mid-Atlantic, Inc.
> (716)334-2970 voice
> (716)334-3481 fax
> [log in to unmask]
>
> -----Original Message-----
> From: Matthew Park [SMTP:[log in to unmask]]
> Sent: Wednesday, January 07, 1998 11:37 AM
> To: [log in to unmask]
> Subject: [TN] Stencil Aperture Shapes -Reply
>
> Mr. Windsor:
> Post your fax number, so I may fax you a solderpaste
> aperture shape that I use for the complete elimination of
> solderballs for chip components. It was proven it works
> better than home plate shape.
>
> regards
> Matthew Park
>
> >>> Clinton Windsor
> <[log in to unmask]> January
> 7, 1998 1:27 am >>>
> Dear Technetters,
>
> We are trying to eliminate the occurence of solder balls in
> our
> production line by trialling various aperture shapes and
> reductions on
> the screen printer stencil. The nature of the solder balls
> suggests
> that paste is being trapped under the component and then
> forms a solder
> ball which adheres to the side of the component. I have seen
> this type
> of solder ball referred to as a "squeeze ball". We have tried
> the so
> called "home plate" (trapezoidal) shaped apertures with
> considerable
> success on nearly all the components except for the 0603
> capacitors.
>
> I would be interested to hear any ideas or suggestions of
> other aperture
> shapes or designs which could help solve this problem.
>
> Thanks in advance,
> Clinton Windsor
>
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---------------End of Original Message-----------------
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Name: John Bushie
E-mail: John Bushie <[log in to unmask]>
Date: 01/23/98
Time: 09:06:18
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