Electronics are getting smaller and denser, which makes cleaning difficult. The article examines the environmental issues associated with cleaning circuit boards and suggest an analytical tool engineers can use to make more informed cleaning choices.
When it comes to selecting a new cleaning process, feel sorry for the poor production engineer. Engineers are always expected to clean more boards while using less machinery, water, electricity and money. It’s a tough bind, for two reasons. First, electronics are getting smaller and denser, which makes cleaning difficult. However, at the same time manufacturers around the globe, are being asked to change their processes to protect the environment. This article will examine the environmental issues associated with cleaning circuit boards and suggest an analytical tool engineers can use to make more informed cleaning choices.
Air, Water and Soil Issues
Some of the world’s most polluted cities are in India, according to the World Health Organization,and Ludhiana is rated number 4 according to the World Health Organisation. But India is far from the only country with an environmental problem:
- In the Philippines, there are nearly 5,000 premature deaths each year due to respiratory and cardiovascular diseases from exposure to poor air quality[i]
- In Jakarta, more than 300 million cubic meters of water are pulled from aquifers each year, about three times the rate of replenishment. Indonesia faces ‘a serious scarcity problem within three to five years’unless action is taken to conserve water.[ii]
- In Vietnam, only 4.26 per cent of all the industrial sewage and waste water is treated before being released into the environment.
- Simple energy efficiency should be a goal everywhere. But Switzerland produces $9,293 of domestic output for every ton of CO2 released into the atmosphere whilst Thailand only produces $760/ton, India produces $579/ton.
This is not sustainable. Sooner or later, businesses will be required to pollute less and become more energy-efficient. In terms of cleaning circuit boards, the new requirement is for a cleaning process that is effective, consistent, versatile, safe, fast, sustainable and affordable.
A number of companies around the globe like MicroCare Corp. offer innovative, affordable and effective circuit board cleaning systems that minimize pollution and costs. But cleaning systems capabilities and their costs can differ dramatically. Look at just two contenders: water cleaning versus solvent cleaning. Aqueous cleaners are relatively slow but inexpensive, while vapor degreasers are fast but require expensive solvents. How can an engineer compare these disparate technologies in a fair and meaningful manner?
The answer is to use a procedure that balances the benefit of each option against its costs. Here at MicroCare, we call it the “cleaning scoreboard.”
The Cleaning Score Board
When people talk about football, basketball or other ball games, the final score pretty much says it all. The same is true with electronics cleaning. Engineers can develop a cleaning ‘score’that compares all the different cleaning technologies – aqueous cleaners, semi-aqueous cleaners, hydrocarbon cleaners and vapor cleaners – and make meaningful comparisons between dissimilar systems. The best cleaning score is the lowest ‘total-cost-per-part-cleaned (CPPC).’
CPPC is a number, ranging from hundredths of a rupeeto hundreds of them. This score summarizes all of the direct cleaning costs, environmental inputs, labour costs, and waste disposal costs, into one simple question: how much does it cost to clean a single part? This cost becomes the tool that allows the savvy engineer to compare totally different cleaning technologies fairly.
So here’s the crucial teaching of this report: stop caring about prices. It’s not the ‘rupee-per-litre’that really matters; it’s the ‘total-rupee-per-part-cleaned.’That’s where profits will be made or lost.
Take a Practice Swing
When buying a new baseball bat, tennis racquet or golf club, people select the one that fits their strength, size and swing. Similarly, cleaning machines come in all different sizes and with varying features. It’s important to select the cleaning system that best fits the company’s cleaning application. This requires a four-step process.
SIZE -The first parameter is size. Too small a system and there will be a backlog. Too large a system and it will be sitting idle, which is money wasted. The ‘fit’ of a cleaning system is judged by its throughput, measured in boards-per-hour.
Here’s an example: A batch aqueous machine that cleans twenty boards in forty minutes has an average throughput of one board every two minutes, about thirty boards perhour. A batch vapour degreaser that cleans only five boards at a time, but cleans them in five minutes, will have a throughput of 60 boards perhour.
Throughput affects operating expenses dramatically, especially as cleaning systems reach their operational limits. For example, a small, modern vapour degreaser should have solvent losses that do not exceed about 20 grams perhour. In stand-by mode, this drops to about 4 grams perhour. To compute total cleaning costs, engineers will need to estimate how many hours each day the system will be cleaning and how many hours the system will be idle.
Many factors affect throughput. For example, systems that need to pause while warming up will have longer cycles. Complex loading and unloading processes also delay the cycle. Drying times may delay cleaning cycles. Water-based machines often cycle quickly when cleaning large, simple shapes; vapour systems are faster when cleaning tight spaces or components with many voids.
PERFORMANCE -Engineers should explicitly define the level of cleanliness required and then ensure each system can achieve that requirement. Simple visual inspection may be sufficient in many instances; surface insulation testing (SIT) may be essential for more demanding applications. Whatever the standard is, define it before the testing stage.
- Engineers must consider where the cleaning will occur. For example, benchtop machines are slow, small and cheap, so it’s easy to have them conveniently scattered around the plant. Centralised high-volume systems are larger, more capable, more efficient and more expensive, but technicians waste time walking PCBs over to the centralised cleaning system. Convenience is complex.
TEST & VERIFY – Lastly, it is essential to conduct real-world tests of the systems. Prepare a batch of products with typical contamination loads. Have each system manufacturer run them through their cleaning systems. Double-check to ensure that cleaning did not degrade components or leave residues in hard-to-reach locations. Each equipment manufacturer should be able to produce a brief written report that describes the process, results, fluids, temperatures and times. Disqualify any system that cannot clean successfully.
At this point in your equipment search, these four criteria should produce a short list of cleaning systems which fit the company’s requirements. Now comes the hard part: determining which system will produce clean parts at the lowest total cost.
Three Types of Costs
Once the throughput has been defined, the engineer must research the direct operating costs, the indirect operating costs, and the fixed costs for each alternative. Direct operating costs include the cost of consumables and labourrequired by the cleaning system when it is operating. Importantly, when the machine stops,so do the costs stop as well. Direct costs are directly proportional to throughput. Indirect costs are those costs that occur even when the machine is not cleaning, such as rent and training. Fixed costs are usually one-time installation capital costs. Let’s take a look at each of these:
Direct Operating Costs
Electrical costs are a big issue for most cleaning systems. Typically, the total electrical costs of an aqueous system will be five to ten times the costs of a vapor degreaser due to the need to heat the water, pump the water, spray the water, and dry the water. Waste-water treatment systems are also very energy-hungry.
Water is cheap to buy but expensive to re-purify. Solvents and saponifiers can be expensive and are subject to drag-out. (Drag-out is wasted cleaning fluid that is trapped inside or around the parts as they are removed from the cleaning system.) Vendors should be able to estimate fluid consumption based on the sample parts provided to them.
Big machines have big maintenance problems, and large aqueous systems have the most complexities. Filters must be checked and replaced. Blowers, motors and conveyors must be maintained. Complex water-treatment and recycling processes must be monitored. Alkaline additives boost the cleaning power of many systems; these additives coat the machine’s interior and cause additional maintenance problems. All of these should be included in the system’s direct operating costs.
Labourcosts should be carefully tabulated. Most of the labour is found loading and unloading the systems, which is pretty straightforward. But also look for time wasted by technicians performing auxiliary inspections, such as hand-spraying, re-cleaning or hand-drying the products outside of the machine. In today’s world, manual intervention should be rare. If it is not, something is wrong. To measure hourly labour costs, many companies use the ‘fully-loaded labour rate’ for the technicians who will operate the system.
Indirect Costs
Indirect labour can be difficult to measure. This might include (a) the cost of a supervising an engineer’s time, (b) the cost of training, (c) the hourly cost of maintenance techs, and (d) any chemical safety training. If employee turnover is a problem, add additional funds for quarterly supplemental training.
There is an essential element to indirect labour that is often ignored: the complexities of managing water-based cleaning systems require many hours of well-training, experienced technical experts. Their time is used managing the water purification systems, the pH and additives of the water in the system, and the resulting waste-water treatment systems. The commitment in engineering required to operate a water system properly typically results in ongoing costs that far surpass those of vapour systems.
Another indirect cost is floor space, and sometimes a large one. Aqueous and semi-aqueous systems require more floor space than solvent-based systems and water-treatment facilities which can be as large as the cleaners themselves[i]. They also have slower cycle times, so more space is needed for storage, work-in-progress, supplies, conveyor systems and access aisles.
For example, your author has seen an aqueous cleaning system which used 20 square meters of floor space in the factory. But the system actually consumed 140 square metersof floor space when work-in-progress and ancillary systems were included. That is a 7X floor-space factor (140 s.m./20 s.m.). Forcomparable vapour systems, which are smaller with equivalent capacity, a 4X factor would be a reasonable.
To estimate floor space costs, include the cost of the space itself, plus heating, cooling lighting, and some portion of the cost of shared facilities, like the lavatories. Factory space in India rents for about 976 rupee/s.m./month, so the cost of the large aqueous cleaner cited above would be approx 136,600 rupeesper month. If the system cleans 10,000 parts per month, that adds 13.6 rupeesto the cost of each part cleaned.
Fixed Acquisition and Installation Costs
The final costs to include are the fixed and acquisition costs.
Up-front capital costs should include the cost of the machine and sub-systems, freight, site preparation and set-up costs. Building renovations, ventilation enhancements, electrical upgrades and water-treatment subsystems required to support the new system. It is essential that all of the sub-systems be included in the cost analysis.
Savvy engineers also consider making extra investments in optional features which speed cleaning or reduce costs; trading up-front capital investment for lower operating costs. For example, aqueous systems have money-saving options such as air-knives and extra drying chambers which speed cleaning but increase electrical consumption.
Planners should include the cost of the funds that will be tied up in the investment. Use thePayment’ (PMT) financial function in a spreadsheet to estimate the cost-per-month of the equipment, which can easily be converted into a cost-per-part.
Once the total purchase and installation costs are determined, divide that cost by the total number of parts expected to be cleaned by the system over its operational life. For example, a large cleaning system (say, 100 million rupee initial cost) might be expected to last 12 years, and clean 10,000 boards/month. In that case, the cost-per-part-cleaned is about 8.7rupeeper part cleaned.
The Winning Score
As we have seen, there are many factors to tabulate when selecting a new cleaning system. A detailed spreadsheet is available for downloading which could serve as a template for an engineer planning this comparison.[ii] But, in general, use the following ‘cleaning score board’ to find the winning technology for your company:
a. Determine the likely cleaning requirements for today’s products as well as those of tomorrow. Average those requirements into an 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.
c. From among the remaining candidate systems, collect comparative data on every important characteristic. Be sure to include up-front capital costs, plus the direct and indirect operational costs (supervisory and engineering labour costs, plus energy, water, solvent, labour and maintenance).
d. As the various costs are collected, divide them by the expected through-put of the system to calibrate them into a cost-per-part-cleaned index.
- Sum all the data into a single performance index, the ‘total cost-per-part-cleaned.’
f. Select the system with the lowest 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.
Checklist of Cleaning Costs
Operating Costs
Labour: Operator, Cost Per Hour (fully-loaded labor rate)
Electricity
Water or Solvents or Saponifiers
Consumables (Filters, etc.)
Water-Treatment System Consumables
Waste Disposal
Indirect Operating Costs
Labour: System Maintenance, Cost Per Hour
Floor Space Cost Per Square Meter
Training of Operators
Supervisory Staff
Lighting, Ventilation & Other Services
One-Time Capital Costs
Cost of Buying the Cleaning System
Freight, Duties, Customs Fees & Insurance to Get It Delivered
Site Engineering & Architectural Planning Costs
On-Site Construction
Electrical Changes
Water/Plumbing Changes
Ventilation Changes
System Set-Up & Configuration (Delivery)
Cost of Capital
About the author
For more than two decades Mike Jones has been a Vice President of MicroCare Corp., the world leader in critical cleaning. MicroCare’s products include water-based cleaners, a wide array of solvent, hydrocarbon and terpene cleaners, and innovative benchtop tools which help reduce cleaning costs. Contact Mr. Jones at MikeJ@MicroCare.Com.
