A substantial amount of time, labor, and money are invested in producing ultra-clean medical devices. To ensure that the products arrive at the customer’s site in the same pristine condition, the packaging must be carefully chosen and tested.

The process of choosing cleanroom packaging for medical devices includes: Evaluating the requirements of the device being packaged; matching those requirements to the capabilities of the cleanroom packaging films available; and specifying the parameters of the package material and method.

Evaluating Requirements

What is expected from the product, construction and end-user requirements are a great starting place in designing an effective cleanroom package for a medical device. Additionally, if this is an upgrade for the material, looking at the records of past packaging failures can supply valuable information.

“This bag is FDA Approved for Food Contact” is often seen in Medical Device specifications. This only means that the polymer is not recycled but it can contain a number of additives and enhancers. Seal quality is enhanced using EVA (ethyl vinyl acetate), a low-melt temperate polymer that outgases heavily. The film can also have levels of “anti-block” and “slip” additives to give it good processing characteristics.

Under normal, non-clean packaging circumstances the presence of these additives would not be a problem. In a move to cleaner packaging, however, the presence of additives will cause problems. For example, the vinyl component (EVA) will outgas chlorides, contaminants that most users need to avoid in any concentration. The other additives can migrate, acting as “wild cards” in terms of ionic and contact transfer contamination.

One of the engineering goals for any cleanroom packaging material is the consistency of formula and the consistency of performance that follows. With commercial films – i.e., those not designed “clean” – this consistency is less important. Normal polymer blending and film extrusion isn’t a PPB industry: while this isn’t an evil plot, it is symptomatic of an industry that measures profit in fractions of pennies per pound, and one of the reasons for the considerable difference in price between “cleanroom packaging” and “commercial packaging.”

Matching Requirements

Cleanroom packaging’s cleanliness needs to be defined with a particulate standard and test method to guide your supplier. Chosen for its detail and repeatability even with relatively inexpensive equipment, the NASA-JPG5322.1 standard provides a requirement that all cleanroom packaging suppliers can understand and makes it clear that a rigid standard will be enforced. The specification also places important demands on vendors for record keeping and lot traceability, a feature those in the medical field recognize.

Most applications require consideration of nonvolatile residue (NVR). For this application, NASA JPG 5322.1 Level A (1 mg/sq. ft. film) is usually considered acceptable. While not an extremely low level for today’s high-performance films, it is well within the tolerance of most products being packaged.

Ionic contamination and the product’s tolerance of different levels of ionic contamination must be investigated with accuracy and great concern, especially in applications involving electronics and high purity metals.

The use of anti-static packaging materials for any intimate contact situation must be approached with great caution; not only can the additives contaminate by contact transfer, but outgassing of volatile components could cause chemical changes to plastics and metal even if not in direct contact.

In all medical packaging challenges, moisture protection for the product must be considered. Each product must be examined for moisture-caused degradation from the standpoint of keeping a product from performing to its intended expectations. The test standard for measuring moisture, moisture transmission rate (MVTR), is expressed in grams of moisture passing through 100 sq. in. of material in 24 hours.

Almost all polymers offer some amounts of protection, but the amount of protection may vary greatly. If the challenge is writing a specification for a moisture-sensitive product, a packaging engineer can help with formulas and packaging processes to help achieve the protection standards needed. In any packaging project, it is as important to be able to express your needs in a specification as it is to develop them.

In all packaging challenges, durability matters. Not only must the film provide the performance levels for a clean package, but it must also maintain a level of physical protection. In cleanroom packaging, the goal is to maintain the quality of the product until it’s in the hands of the customer. The package must deliver the product to the user in precisely the same condition as it was in when it left the cleanroom.

If a product’s shape or features make it difficult to protect, double- or triple-bagging can help. By combining several films with varied performance parameters, solutions can be developed to take advantage of the most desirable characteristics of each.

Keep in mind that evaluation parameters must include cost. Every consumer knows the term “sticker shock”; in the pricing of cleanroom packaging, however, “sticker terror” is closer to what most clean packaging neophytes experience. The difference in cost between using commercial polymers and clean, high-performance, low ionic contamination, low outgassing polymers, is substantial. Add to this the difference in cost of operating a Class 100 cleanroom as opposed an open production plant and the cost goes up some more.

The cost of running a testing lab, gowning workers, and buying wipers and associated consumables adds even more to the cost of clean packaging films. The style of the bag also affects the pricing of the product; if we could change this application requirement from the three-seal style bag to a tube-style bag, much of the cost of moving to clean packaging could be saved.

Specifying Parameters

The last part of this process is the creation of purchasing specifications.

Performance-based, measurable parameters. If you need polyethylene, don’t limit the spec by asking for a particular resin or manufacturer; ask for a film that has the performance parameters you need. Base the need for a clear film on “haze” and “light transmission” (both have standard testing methods) and all films are rated. Not only will this approach give you better control over the product you’re buying, but it will also put the burden of performing on the vendor.

The first information you need is the size and acceptable tolerances; your supplier can help by giving you normal manufacturing and material variations. With plastic film, the thickness of the material must be specified as well. Stating the composition of the material as one of the necessary performance criteria keeps you in control and helps a good vendor provide products that will work at the best possible value.

Outside standards. Be sure to specify any outside standards-FDA standards, for example, or customer requirements-your packaging must meet. Choose a standard to which you can test and demand certification. It is not out of the question to ask for test results to back up the certification of cleanliness on extremely critical packaging.

Special requirements. Indicate any special requirements clearly in your spec. Note how many bags per package and whether you need your bags double- or triple-packed. If you have requirements for boxing and labeling, include that information so the vendor knows all of his cost parameters.