Hi Cheryl,
The number of bottom preheaters is typically not less than 2. Depending on
the amount of flux applied to the board, desired profile shape, the board's
thermal mass, and the desired conveyor speed 3 bottom may be required.
Convection preheaters afford the most reliable method of driving of the
water based fluxes, while not exposing the board to potentially high IR
emission temperatures. (imagine drying a wet cup in the sun or with a blow
dryer, which works better?) A topside IR heater or two sometimes will help
with particularly heavy boards. There are situations where topside
convection heaters make sense.
VOC-Free fluxes are best applied with spray fluxers. Simple spray-in-air,
ultrasonic and jetflux systems are available to minimize amount applied,
while gaining proper topside hole wetting. Consider transfer efficiencies
in your cost of ownership model; flux traveling up the exhaust stack and/or
landing on the wave solder system is wasted and a maintenance issue.
At the wave, make sure your water based flux is properly prepared. Water
presented to molten solder results in tell-tale fizzles and solder balls.
Nitrogen can help promote better surface tension if soldering issues are
found.
Shean Dalton
Austin American Technology
www.aat-corp.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Reuven ROKAH
Sent: Monday, August 16, 2004 7:56 AM
To: [log in to unmask]
Subject: Re: [TN] Anyone using VOC-free wave solder flux?
1. Number of preheaters on wave - 3, convection, IR and quartz heaters
2. Typical conveyor speed - 0.8 to 1 m / min
3. Typical topside/bottomside preheat temp 110 to 130 deg c
4. Do you wave solder SOIC or other components besides chips? - yes
Cheryl Tulkoff
<cheryl.tulkoff@ To: [log in to unmask]
NI.COM> cc:
Sent by: TechNet Subject: [TN] Anyone using
VOC-free wave solder flux?
<[log in to unmask]
>
16/08/2004 15:42
Please respond
to TechNet
E-Mail Forum;
Please respond
to Cheryl
Tulkoff
Is anyone out there using a VOC-free (water-based) wave solder flux? I'm
looking for users who would be willing to share some information with me
like the following:
1. Number of preheaters on wave
2. Typical conveyor speed
3. Typical topside/bottomside preheat temp
4. Do you wave solder SOIC or other components besides chips?
Thanks, Cheryl
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