We had the opportunity to use Kester 951 on a production contract last
year and had very good results.
We used an old Electrovert Ultra Pack - UPK337-15/FA with two heating
zones located on the bottom. We put aluminum foil on the top for more
efficient pre-heating (classy). We normally use Kester HF1189-Citric
Acid (lemon juice) on a Sensbey LGC-500S and are used to very active
fluxing so I thought that we would end up with solderability problems.
To my surprise the only solderability problems encountered were on a
batch of very old components (which is a story in itself and I won't
go into). It took us about 4 days to fully implement the flux. This
included resurrecting the machine from storage to producing
practically defect free boards. Best results came about with a solder
bath of 500F, CCA top side surface temperature of 210F to 220F, and a
belt speed of 3.5 - 4.0 ft/min. Close attention must be given to the
flux's density and evaporation, and of course, board and component
solderability integrity. Since the flux is not as active as citric
acid or RMA one must make up for it with good solderable materials and
process controls.
We checked flux density twice a day and made adjustments accordingly.
The material is mostly alcohol and it evaporates FAST! We covered the
fluxer when not in use. For density checks we used Kester's Flux
Tester Kit PS-22
Our product at the time was through hole, single sided CCA's of
various sizes. The CCA's contained an assortment of components
including radial's, axial's, connectors, and odd parts including coax
connectors, TB's, coils and more.
I think the material is very usable with the advantage that it does
not require cleaning:)...just watch out for that evaporation and
don't over heat during preheat, it is a small window between flux
activiation and flux death.
Good luck!!!
Regards Rick Jaramillo, ME
Signal Processing Systems
13112 Evening Creek Dr. S.
San Diego, CA 92128
(619) 679-6313.
PS Sorry but I'll have E-Mail next month. We are being reconnected.
______________________________ Reply Separator _________________________________
Subject: Re: Temperature profile
Author: [log in to unmask] at PMDF
Date: 1/11/97 6:42 AM
At 10:09 10/01/97, you wrote:
>
>Can anyone help?
>We are using kester 951 low residue flux in a dual wave solder process for
>mixed technology.
> What would you recommend for a temperature profile and what solder temp. is
>recommended for this product.
>we have been experiencing skips or no solders on the SMT components.
>Any help would be greatly appreciated.
>
=========================================================================
Dear Raymond,
It seems that you are talking about a low residual flux.
Don't worry about it,
Try to preheat at 120ºC in the circuit. and solder at wave bath temperature
arround 240-250ºC.
If you have and old machine, prepared only for colophone fluxes, and you
can't get the 120ºC required. Try to improvise a close tunnel in the
preheating zone, in order to increase this temperature, due to refractation.
If you need more information, please contact me by E-mail or Fax (here enclosed)
Best regards
- -
( O O )
========oOOo===\o/===oOOo=========
= ANTONI CHERTA =
= E-mail: [log in to unmask] =
= Fax: +34.3.274.00.80 =
= BARCELONA =
==================================
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