Packaging. Not the most complicated topic when choosing a conformal coating, but to treat the decision too lightly at your risk. There are a surprising number of conformal coating types available, each suited to very particular needs and conditions. In the article, we will explore, from the smallest to the biggest, the different packaging options available to you, as well as the advantages and disadvantages of each.
Aerosols
As you would imagine, aerosol packaging can be one of the easiest types of packaging for conformal, smaller-volume coating operations. Only a limited number of the most common conformal coatings are available in the aerosol format, but for smaller consumers, aerosols may be used to coat PCBs in acceptable quantities, although at a reasonably high net cost.
Features:
- Simple application; no need for capital investment in spray equipment
- Pre-mixed; no requirement for additional thinners
- Relatively high per-unit cost Spray only
- It will likely require extensive masking
Cartridges and Syringes
Cartridge and syringe packaging are seldom used for conformal coatings in electronics. Their limited volume and the need for regular replacement render them impractical to all but the most unique smaller applications. They are most widely used for hand application and touch-up applications, higher viscosity protective coatings and gels that are difficult to pump, and ancillary items such as stinging compounds and masking polymers.
Features:
- Good for small, manual applications
- Capable of precise placement of liquids
- Capable of the simple mixing of two-component coatings
- Relatively high cost and require frequent replacement
- Mainly used for touch-up applications
Metal or Plastic Bulk Packaging
Bulk packaging in cans of 1, 5 and 20 litres is possibly the most popular option of PCB manufacturers using conformal coatings. Compared to cartridges and aerosols, there are considerable savings over time in both packaging costs and bottle change costs. As a company transitions from tens and hundreds of PCBs per day to thousands and more, bulk packaging becomes an obvious option. One must be careful when using too large a container in search of savings, however, opening and re-opening containers can lead to the deterioration of certain chemicals that are sensitive to moisture or oxygen exposure.
Features:
- Lowest unit cost option
- Suitable for brushing, dipping, or spraying
- The need to be aware of shelf life and degradation issues
- The potential requirement of capital investment in spray equipment
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