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September 2001

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Subject:
From:
Thomas Highland <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 19 Sep 2001 15:25:51 -0500
Content-Type:
text/plain
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text/plain (223 lines)
Peter:
Do you have a temperature mole? From your description of the problem, one
contributing factor may be insufficient pre-heat. I would suggest taking a
heat profile of the PCB is ensure that the component side temperature, as
the PCB enters the wave, is adequate to allow for proper wetting. The root
cause could be pre-heat temperature or conveyor speed. I hope this assists
you.
Regards,
Thomas C. Highland
Quality Assurance Manager
Innovatec Communications, LLC.



-----Original Message-----
From: Peter Crain [mailto:[log in to unmask]]
Sent: Wednesday, September 19, 2001 14:47
To: [log in to unmask]
Subject: Re: [TN] Insufficient solder, spray fluxer


hey all, thanks for the response and input!

To clarify things:

Our problem: Insufficient solder - lack of bottom side fillets, they are
flat or are concave around the lead. This happen periodically to certain
populated products. - we are seeing problems with products that used to be
produced without problems, i.e.. they are not consistent.

Our machine and maintenance:

We use a foam fluxer with an air knife. - it appears that the flux is
getting to the top of board through the populated lead holes. we are getting
good wetting for top-side fillets.

We don't use nitrogen with our solder pot.

We conduct titration tests on the no-clean flux solution every 2 hours of
operation. We change flux, clean the flux pot and stones every 3 days.

We are pretty strict with cleanliness in our assembly area of the PCB's as
to reduce the amount of contamination from the parts and the PCB's.

Our pre-heaters and conveyor speed are standardized for each product.

There must be a lurking variable in the process, so we are looking at
standardizing as much as possible. This is why we are looking at a spray
fluxer.

What does the specific gravity tests tell us and how would one conduct one
for flux solution?

Peter Crain
Manufacturing Engineering
GE Substation Automation Solutions
Calgary Alberta, Canada

* 403 214 4560
* 403 214 4776





-----Original Message-----
From: Jack Crawford [mailto:[log in to unmask]]
Sent: Wednesday, September 19, 2001 12:47 PM
To: [log in to unmask]
Subject: Re: [TN] Insufficient solder, spray fluxer


>>> Thomas Highland <[log in to unmask]> 09/19/01 01:18PM >>>

Peter,
Yves mentions some very good points to consider. May i ask for
clarification? What do you consider as 'insufficient solder"? Are you
speaking of vertical solder fill? Are sections of the PCB totally void of
solder?
Regards,

Thomas C. Highland
Quality Assurance Manager
Innovatec Communications, LLC.



-----Original Message-----
From: Jack Crawford [mailto:[log in to unmask]]
Sent: Wednesday, September 19, 2001 12:01
To: [log in to unmask]
Subject: Re: [TN] Insufficient solder, spray fluxer


>>> "Yves.Dupuis" <[log in to unmask]> 09/19/01 11:24AM >>>

        Hi Peter,

        On your first point: "what variables tend to cause this defect?", I
would say that the answer would include amount of flux applied, pre-heat
profile and immersion depth from the machine standpoint. From the product
standpoint, factors affecting results include finish and layout.
Insufficient flux, excessive or insufficient pre-heating, insufficient
immersion depth could all be part of your problem. Also, many people have to
use more flux or different process parameters to successfully solder
immersion gold finish versions of a product previously built on HASL. This
is also true of some other finishes.

        On your second point, it is possible that a spray fluxer would make
it easier to control exactly how much flux goes on and when. This will only
reduce your defects if level and/or consistency of flux application is a
cause of those defects.

        Are there any obvious patterns to your insufficient solder defects ?
Are certain parts, times, boards, more likely to show this defect ?

        I'm sure there are a good number of people on the forum that would
be willing and able to answer specific questions on your problems. If I can
help, feel free to contact me.

        yves

Yves Dupuis
Process Engineering
Leitch Technology
25 Dyas Road, North York, Ontario M3B 1V7
Phone: 416-445-9929 X3389 / Fax: 416-445-7927

> -----Original Message-----
> From: Jack Crawford [SMTP:[log in to unmask]]
> Sent: Tuesday, September 18, 2001 2:20 PM
> To:   [log in to unmask]
> Subject:      [TN] Insufficient solder, spray fluxer
>
> >>> Peter Crain <[log in to unmask]> 09/18/01 12:55PM >>>
>
> I am having troubles with insufficient solder coming from wave solder
> machine.
>
> First, what variables tend to cause this defect?
>
> Second, we have a base model wave solder with a foam fluxer. I am thinking
> of purchasing a spray fluxer for our machine to help reduce this defect.
> Would this greatly reduce defects from the wave machine?
>
> I am new engineer in the electronic manufacturing world so please take it
> easy on me if my questions are too broad and simple.
>
> Peter Crain
> GE Harris
> Calgary, Alberta, Canada
>
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