Steven Latimer & Martin Muir
Compaq Computer Manufacturing
Study on the effectiveness and benefits of the Solder Reclamation System
Erskine Pca Waste Solder Process
- As part of Compaq's
continuing Commitment to the environment, waste elements removed from
the board shop for processing outside the factory are to be processed
in-house. As stated this function since the day the Board-shop opened
was performed by an outside source, any solder reclaimed is returned
at a reduced cost or concessions made for the purchase of new solder
While this method was an acceptable solution at the time more and more
emphasis is now being placed on companies to provide solutions for their
own waste, to this end a way for Compaq to process the waste in-house
had to be found.
There Any Processes Available To Us Which Can Recover Solder From Dross?
- Initial investigations
returned a manufacturer that supplied a machine that would meet these
requirements, the supplier of the EVS also agreed to allow a period
of approval to assess the machines capabilities and suitability for
The main purpose for this machine is to reclaim as much of the usable
solder from the dross collected as possible, the manufacturer of the
machine claimed rates of up to 75% reclamation which if achievable would
more than meet the requirements. During trials and subsequent production
the EVS averaged a 61% recovery rate.
Machine Operation And Maintenance.
- Another requirement
for this system is its ergonomics. Since it would be line operators
that would be operate this system then the operation and maintenance
should be both simple and efficient.
The basic operation of the system involves initially switching the machine
on and allowing it to come to operating temperature, The operator would
then place the waste dross into the cylinder for processing, a single
machine can be de-drossed and the process takes approx. 7 minutes per
cycle (total de-dross time was consistently measured at 60 minutes).
This cylinder has a piston at one end which when activated squeezes
the solder dross until all the recoverable solder has been removed.
This solder is then returned in the form of ingots and can be returned
to the solder pot. (A sample of the reclaimed solder was analysed by
our solder supplier and found indistinguishable from virgin solder of
the same grade).
The operator can carry out maintenance for this system and due to its
construction there are very few parts that require regular maintenance,
the main requirement is for the piston and the chamber itself to be
regularly cleaned of dust build up and for the stand-alone filter to
be properly maintained.
The only facility which would be required for installing the Solder
Recovery System would be a pneumatic supply and two 13Amp, 3pin sockets.
The EVS is supplied on it's own trolley which can be freely wheeled
between separate wave solder machines.
Evaluating the effectiveness of the EVS. Below are the figures for solder
usage and dross reclamation for 1995 (pre-EVS).
Weight x Cost per KG
solder supply cost for 1995
If we were to use the EVS for this period:
solder costs Total
Weight x Cost per KG
dross produced before SRS (41.1% dross rate)*
Dross recovered through SRS (61% recovery rate)#
*41.1% dross rate (based on 1995 figures for CAR 9642234).
#based on 61% average solder recovery rate.
We would still receive credit for the 2,034.1kg of dross produced after
the EVS process. At £0.80 this would give £1,627.28 credit.
After installation of the EVS in April 1997 measurements taken showed
the EVS to be outperforming expectations.
The machine was returning a 34% saving on solder costs.
- When properly
maintained this machine is extremely reliable. Any problems that have been encountered have been remedied by the manufacturer
and suggested improvements have been included in the design of subsequent
machines. Service and spares have also been of an acceptable standard
during the time we have owned the machine.
- From trials and
subsequent production we can achieve an average 61% recovery rate, with
a rate as high as 80% on occasions. The variation in rates can be attributed
to the differences in how operators perform this operation. Some operators
"squeeze" the solder before placing dross in the EVS. This
therefore means a lower recovery rate.
The machine also contributes
to Compaq's ISO14001 targets.
Prepared By -
Steven Latimer And Martin Muir - Pca Engineering
Approved By -
Tony Howard Snr Process Engineer - Pca Operations Compaq Computer