Packaging. Not the most complex subject when choosing a conformal coating, but treat the decision too lightly at your peril. There are a surprising number of options available, each suitable to very specific needs and conditions. In this brief presentation we will discuss, from smallest to largest, the various packaging choices available to you, along with the advantages and disadvantages of each.

Cartridges and Syringes

Cartridge and syringe packaging are rarely if ever utilized for conformal coatings in electronics. Their small volume and need for frequent replacement make them impractical for anything but the most unique smaller applications. They are most commonly used for hand application and touch-up needs, higher viscosity protective coatings and gels that are difficult to pump, and ancillary products such as staking compounds and masking polymers. To summarize features and limitations of cartridge and syringe packaging, they are

• 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

Aerosol Cans

The next step up in the packaging ladder is the choice of aerosol cans. As you would expect, aerosol packaging can be one of the simplest forms of packaging for conformal coating operations of smaller volume. Only a limited number of the most popular conformal coatings are available in aerosol format, but for smaller users, aerosols can be used to coat PCBs in reasonable volumes albeit at a relatively high net cost. Features and considerations regarding aerosols include

• simple application; no need for capital investment in spray equipment
• pre-mixed; no requirement for additional thinners
• relatively high per unit cost
• spray only; will likely require extensive masking
• only small number of coating choices

Metal or Plastic Bulk Packaging

Bulk packaging in cans of one, five, and 20-liter volume is probably the most common choice of PCB manufacturers using conformal coatings. Compared to cartridges and aerosols, there is a significant savings both in packaging cost and cost of container change over time. As an organization moves from tens and hundreds of PCBs per day to numbers in the thousands and more, bulk packaging becomes the obvious choice. One must be cautious in going with too large a container in the pursuit of savings, however, since opening and reopening containers can lead to degradation of some chemistries sensitive to humidity or oxygen exposure. Features and considerations for bulk packaging include  

• 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

Bladder Bags

Bladder bag packaging consists of a flexible, often multilayer bag filled with your adhesive or coating. Bladder bags are the preferred approach to packaging for humidity or light-sensitive chemistries. These most commonly include humidity curing mechanism chemistries such as silicones and urethanes, as well as light-cured adhesives and coatings. When packaging such as pails or drums are used, these products are exposed to atmospheric humidity and light, which can degrade the products or initiate premature curing. These problems become even more dramatic when pails and drums are only partially used and have to be opened and resealed multiple times. Features and considerations of bladder bag packaging:

• best option for high-volume, light or humidity sensitive applications
• relatively high cost of packaging
• not suitable for solvents and some hazardous materials

We hope that this presentation has been enlightening and assists you and your organization in choosing appropriate packaging for conformal coatings. As a supplier of electronics protection polymers and coatings, Chase Corporation and our employees can help you with an unbiased approach to evaluating your application and process. We’ll show you how to maximize efficiency, minimize cost, and improve product reliability. Our outstanding manufacturing and technical support groups can provide your organization with reliable global supply, unmatched quality, and superior technical support.