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Can the IB100 Inspection Booth be used in ambient light or does it need to be in a darkened room?

The single & double inspection booths can be used in ambient light and have UV tube lights built in. the system was designed for inspecting PCB's with a UV trace present in the coating and as such is black inside. However, additional light shielding may be advisable if the ambient light is very bright as it works better in the dark.

What is the weight of the IB100 Inspection booth?

The weight of the unit should be in the region of 60 / 65kg.

How do you control the coating thickness in the dipping process and what is the tolerance of the coating thickness?

The dip speed is controlled by air over oil hydraulics which can control the speed down to 2" per minute which is very slow and more than adequate for conformal coating. Repeatability is about getting accurate viscosity control since the withdrawal rates and viscosity control the coating thickness.

Typical speeds for conformal coatings at viscosity of 200 cps are 6" withdrawal speed giving a 25-50um coating for an acrylic coating. This does vary from coating material to material so control measures should be put in place if accurate thickness is required.

The typical coating tolerance is depending on what you measuring on? If it is a flat coupon, then with a known viscosity of product you should be able to achieve +/- 5um.

How do I monitor the viscosity

The viscosity is monitored by utilizing a zahn type measuring cup. This is essentially an egg cup with a hole in the base on a wire. You dip the cup into the liquid and lift it out of the coating. Since the volume of the cup is known and fixed, if you time the flow of the coating out of the cup you get a relatively accurate and simple method of measuring viscosity which is certainly suitable in 99% of cases.

What is the loading mechanism for the DS100 dip system?

The PCBs are hung on the cross rods by hooks (we can supply or you make / buy your own?) or any other form of jigging ( we can custom build). The immersion and withdrawal of the cross rods is carried out by a custom piston which moves up and down at a controlled rate down to 1-2”/min since we use an air over oil system.

Can the DS100 utilise in line curing?

This is a batch dip system without inline curing. If you wish inline curing you will be adding a zero to the price. Sort of range is £30K-70K depending on size of system, rate of cure, type of material to use.

Can the CC100 Curing Cabinet be used at higher temperatures?

The CC100 system as an ambient temperature cure cabinet for wet coated PCBs. The purpose of the cabinet is to take away harmful solvents and keep dust away from the PCBs.

How do I spray PCBs with coating without ruining the ESD board I am spraying onto and meeting ESD requirements?

There are several ways and no ideal solution. Basically, you can spray onto boards that are covered in paper or ESD bag material which will then earth to the turntable of the booth. Since the operator should be earthed via the ESD points or the floor then you creating good protection for the device.

However, it is important to change the material regularly since a build up of coating turns the material to an insulator fairly quickly!

How does the extraction & filtration system work in the spray booth?

The Two layer mesh filtration means that the filters used are formed from two layers. A rougher, thicker, less dense filter is used on top and the coating is prayed on to this one(which is also less costly to replace) and a finer, thinner, more dense filter is used on the bottom to give you a laminate air flow.

The extraction should be fitted by a local air conditioning company to the customer. Due to the difficulties in supply of the correct extraction, which is dependent on location of booth to the exhaust chimney, local hse regulations, it isn’t practical for us in the UK to fit it.

The CFM is calculated from the fact that you need 0.7 m/s air flow through the spray booth to provide adequate extraction (this is a law in the UK). In order to work out the CFM we must multiply the face velocity by the area of the front aperture and then do the relevant conversion to get the figure into cubic feet per minute. The CB100 requires 3

What are the freight details for the spray booth?

A stamped crate is dimensions 1.75 x 1.0 x 0.85 m and weighs approx 150kgs.

Can you supply lighting fittings for the USA market?

No problem with supplying 60 hz lighting and plugs for the CB100. We can fit them for you.

What are the dangers of solvent exposure with conformal coating?

Many widely used coatings contain large percentages of harmful which can cause great harm to operators if used incorrectly. For instance, toluene, a widely used solvent is now classified as a Class III carcinogen which can cause cancer.

Therefore everyone in a company should take the issues of safe solvent use seriously, including company directors who are ultimately held accountable by law down to the operators who use these dangerous solvents in their process. Ultimately, a mistake can seriously harm a person and/or end in serious litigation costing a company dearly.

So what options are there when considering solvent conformal coatings?

Option 1: Regularly measure the solvent exposure to operators.

Solvents can be used safely. However, the exposure of the operator to the solvent fumes must be REGULARLY measured and RECORDED. This ensures a safe operating environment and if a HSE problem does arise in the future, evidence exists to rule out the conformal coating process as the culprit.

The regular measurement of solvent fumes can be a low cost, easy exercise using products such as Solvent Exposure Monitors (SEA’s). SEA’s can easily be integrated into the coating process, continuously monitoring the solvents and raising an alarm if needed when exposure limits are reached. This ensures operators stay safe and have the confidence to use the processes safely.

Option 2: Change to a safer conformal coating material

Solventless conformal coatings are now widely available and are almost a drop-in replacement due to the advances in technology. Types available include water based acrylics and polyurethanes, solventless silicones and UV curable acrylics and all do a similar job in protecting the boards compared to solvent based materials.

Changing materials would mean no need to measure solvent fumes, operators would not be exposed to hazardous coatings, and litigation due to employee sickness would be much less likely.

Option 3: Use an Independent Subtract Coating Service.

This solution using an independent coating service eliminates all the hazards of solvents immediately. Allowing another company to utilize the harmful coating materials means no re-qualification is required without needing to invest in operator safety and equipment.

Summary

There are three options for companies using solvent based conformal coatings.

Measure the solvent fumes regularly to ensure the operators are always safe.
Change to a solventless conformal coating eliminating the issue completely.
Subcontract the hazardous process to a coating service.

SCH Technologies are experts in all aspects of conformal coating whether it is providing the Humiseal range of conformal coatings, coating application equipment including spray booths and dip systems, subcontract conformal coating service and providing SEA solvent exposure monitoring equipment.

First we need to understand a few bits of terminology. Once you have a grasp of these then it is a fairly straightforward process.

First, what you are looking at here are Workplace Exposure Limits (WELs). These are the Occupational Exposure Limits (OELs) that have been set by the Health and Safety Commission and are there to help protect the health of workers.

WELs are concentrations of hazardous substances in the air, averaged over a specified period of time referred to as a time-weight average (TWA). Two time periods are used: long term (8 hours) and short term (15 min). Short-term exposure limits (STELs) are set to help prevent effects, such as eye irritation, which may occur following exposure for a few minutes.

Therefore, LT EXP 8 hrs and ST EXP 15 min translate as the Long Term Exposure Limit of 8 hours and the Short Term Exposure Limit of 15 minutes. These two values set the maximum level of exposure on average that a worker should receive whilst using the solvents.

The values are defined in ppm (parts per million) and it is these exposure limits that should be compared with measured values that should be taken whilst the worker is carrying out his tasks.

If you do not carry out this check and your workers are over-exposed to the solvents then the worker may become ill in a variety of ways. There may be short and long term effects that ultimately could lead to occupational diseases that may not appear until a long time after the first exposure. Therefore, it is critical to know in advance how to protect the health of people working with hazardous substances.

How can I measure the ppm levels that my workers are exposed to for the conformal coatings?

There are several ways to do this that take a “snap shot” of typical day including having your staff wearing personal monitoring devices and then having the monitoring devices sent away and analysed. This is an excellent way to accurately identify the risks at that exact time but can be time consuming and very costly. Also, any change in the system, whether that is a change in material, equipment, process or operator action will ultimately mean that you will need to re-test to prove that system is still sound.

An alternative is to use large amounts of extraction with your process and hope that this prevents any exposure. However, you are reliant that there are no failures in the extraction & equipment and that your operator does not change the process in any manner.

Therefore, the only way to really be sure of the system being safe for your workers is to use a combination of factors.

First, set up a process that ensures that the worker is safe within the environment. This is done with adequate extraction, an identified process with boundaries and good staff training.

Second, and most importantly, is to continuously monitor the process, recording the exposure to the worker. With new technology, this can be achieved cost-effectively and accurately enough to remove risk to operators using VOC monitoring systems.

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