products outside of the machine. In today’s world, manual intervention
should be rare. If it is not, something is wrong.
Recently, I inspected an old aqueous system that originally had been
designed for through-hole boards. Originally the system had been fast
and efficient but now it was cleaning BGA circuits. The cleaning cycle had
slowed almost 50%. Technicians spent extra ten minutes on each board
manually drying them with compressed air. This inexpensive but inflexible cleaning system had suddenly become a very expensive choice.
To price out your labor costs, obtain the “fully-loaded labor rate”
for the technicians who will operate the machine (this number will
be at least two to three times the actual take home pay). Remember
to include the value of the engineer’s time, making sure the solvents
remain within specs and the waste treatment systems are operating
correctly. Also include the cost of training, the costs of the maintenance
techs, and any chemical safety training. If turnover is a problem, add
additional funds for quarterly supplemental training.
Big machines have complex maintenance problems, and aqueous systems have the most complexities. In part, this is due to the size of the
systems ( 30 feet long is not unusual) and the number of moving parts.
They also have complex water treatment and recycling processes which
must be maintained and sustained for the life of the machine. Another
complexity is the alkaline additives used to boost the cleaning power of
many systems; these additives coat the machine’s interior and can cause
additional maintenance problems.
But vapor systems are not maintenance-free. Filters need to be
checked and replaced. From time to time, the solvent in the degreaser
needs to be boiled down and the sludge at the bottom of the system
removed. This usually results in the loss and disposal of approximately
10% of the solvent in the machine on a quarterly basis.
In the rough: Indirect costs
In today’s litigious environment, there are no issues more crucial than
health, safety and environmental protection. The diligent engineer must
dig through the hype to get the real facts.
For example, everyone agrees that n-propyl bromide (nPB) is a great
cleaner. But the product has significant toxicity issues, so the chemical has
to be handled in a sophisticated manner, with modern, “tight” degreasing
equipment. An old, leaky open-top degreaser will expose employees to
dangerous levels of the solvent and is simply no longer acceptable. This
situation imposes certain costs on users which may make the cleaner an
unattractive choice; that’s for each company to decide. But you must dig,
and research, and question again and again to get the real facts.
Environmental issues also will shape your choices. In California,
tight VOC regulations suggest that water cleaning might be optimal. But
the high cost of water and electricity may make that choice unaffordable
today, and one of the major contributors to global warming is the burning of fossil fuels to generate electricity. Energy efficiency is not only
good for the purse, it’s good for the planet.
Planning for the future is also difficult. For example, in the 1990s the
electronics industry migrated from vapour cleaning to aqueous technologies and enjoyed years of success cleaning their through-hole and SMT
designs. But now ultra-dense BGA boards are the norm. As a result, many
electronics manufacturers now are swinging back to vapor degreasing
which easily cleans dense designs with less electricity and without water.
So some plucky engineer needs to grab the old crystal ball and
search for a cleaning technology which will not become prematurely
obsolete. A best question is “What assumption am I making today
which could derail this technology tomorrow?” Finding the weakest
assumption is the toughest job for engineers today.
The 19th hole
As we have seen, there are many factors to tabulate when selecting a new
cleaning system. The first recommendation is always to try to pass the job
to somebody else. Failing that, use the following cleaning scorecard:
a. Determine the likely cleaning requirements for today’s products as
well as those of tomorrow. Average those requirements into a daily or
hourly rate of required throughput.
b. Compare different cleaning technologies. Send samples to the
equipment makers to prove the ability of their systems to clean the
components to your specifications. Winnow out the systems that can’t
do the job.
c. From among the surviving candidates, collect comparative data
on every important characteristic. Be sure to examine up-front capital
costs, floor space costs, installation costs, energy costs, water costs, sol-
vent costs, labor costs and maintenance costs.
d. Convert all of the cost data into a performance index. The indus-
try’s most popular index is total cost per part cleaned.
e. Select the option which minimizes total cost per part cleaned.
Using standard statistical tools, engineers can model all the operating
costs for systems of different types and sizes. If this process is completed
accurately, thoroughly and impartially, the savvy engineer can be confident that the selected system will become a valued part of the production process for years to come.
Mike Jones is Vice President of MicroCare Corp., a benchtop cleaning
company based in New Britain, Conn. He can be reached at
Checklist of Cleaning Costs
One-Time Capital Costs
• Cost of Cleaning System
• Freight and Insurance
• Site Engineering and Architectural Planning
• Electrical Changes
• System Set-Up
• Cost of Capital
• Actual Footprint or Size of Machine
• Work Space Multiplier
• Cost Per Square Foot
Throughput Calibration Factors
• Cycle Time
• Boards Per Cycle
• Max. Boards/Hr.
• Required Operating Hours/Day
• Stand-by Hours/Day (normally much lower
• Labor: Operator, Cost Per Hour
• Labor: Inspection & Recleaning, Cost Per Hour
• Labor: System Maintenance, Cost Per Hour
• Consumables (Filters, etc.)
• Solvent Losses (Drag-Out)
• Solvent Disposal