Five Facts About Connectors

By: Joyce Laird and Yvonne Klöpping

Selecting a connector for medical applications is closely tied to the use of the end product. The pointers below should help you find a connector supplier to meet your needs.

List Your Basic Requirements

Medical device companies in the market for connectors should make a list of their requirements including basics such as current ratings, the number of circuits and which system components need to be connected, according to the medical engineering and business development team at Hypertronics Corp. (Hudson, Massachusetts, USA). They also suggest that medical device companies note the voltage to be used, both between contacts, and between contacts and the outside world.

For board stacking connectors in medical applications, customers are mostly concerned with maximising space on their printed circuit boards and overall reliability, says Ann Cibelli, Director of Communications at Advanced Interconnections Corp. (West Warwick, Rhode Island, USA). “Pin-to-pin spacing (pitch) and the contact current rating of the pins are important considerations when specifying a connector system,” Cibelli explains. A higher current rating means more contacts can be assigned to data/signal transfer and fewer pins are needed to handle power and earthing.

Miniaturisation is another important factor to consider, according to Deborah West, Marketing Communications at Hypertronics. “Today’s medical device market is demanding smaller and smaller devices that have higher density, so the connectors need to be smaller in order to produce these devices,” she stresses. “You need to ensure that your connectors supplier has the technology to make a smaller connector but can maintain a high level of reliability.”

Consider Lifetime Reliability and Safety

“The number of mating cycles that a connector can withstand is something to consider when assessing a connector’s reliability,” says Serge Buechli, Product Manager, Lemo SA (Ecublens, Switzerland). To be reliable, the connectors also must be shock resistant and impervious to wear and corrosion. Another consideration, according to Buechli, is contact resistance, which is expressed in milliohms. This value should be constant over time to ensure the electrical contact and correct reading of medical instruments and probes, he explains.

Diane Cupples, Vice President of Marketing at Schurter (Santa Rosa, CA, USA), stresses the importance of avoiding risky features, citing as an example connectors with fuse holders that can be removed without a tool. To avoid accidents during operation or replacement, she suggests looking for “extra-safe” fuse holders that require the use of a tool for fuse removal.

Know Your Applications

It is important to be aware of the type of application for which your product will be used. “In choosing a connector for MRI applications, for instance, you need to be sure that they are free of any material that can distort the image,” West explains. “If you are looking for connectors for an implantable device, you need to ensure that they are biocompatible and have a low insertion force. And the leads need to mate easily.”

Think about Sterilisability

Medical device companies should consider if the connector or cable can withstand repeated sterilisation cycles, advises Buechli. “Autoclave and steam sterilisation are very hard on the plastics of the connectors,” he notes. For applications requiring sterilisation, he recommends using a connector with a polyetherimide shell rather than one using polysulphone.

Scrutinise Your Supplier

“Because connectors are used in an array of diagnostic systems, choosing a connector that precisely meets your needs is often difficult,” says Günter Rohr, Director of Marketing and Sales, ODU Steckverbindungssysteme (Mühldorf, Germany). He thus advocates doing business with a company that can develop custom products.

Work with companies that have global manufacturing locations, advises Tim Beck, Product Manager, Tyco Electronics (Middletown, Pennsylvania, USA), because they tend to offer fast delivery and competitive pricing. In today’s demanding marketplace, adds West, it is good to check if your supplier is ISO 13485–certified. “That means that they understand the requirements for the medical device industry and will provide connectors to meet those standards,” she says.