Custom or Off-The Shelf Medical Connector Design Path

1

A custom connector allows each
design element to be incorporated

When designing a new device, one of the decisions that medical device makers are faced with is choosing a connector and mating receptacle.  For some applications, a standard, or off-the-shelf connector, is a viable option.  For other applications, a custom or hybrid connector may be more appropriate..

Reasons why a device manufacturer may consider a custom medical connector instead of an off-the-shelf connector are:

  • A unique design is required to assure that only a specific cable or connector can be mated to the device
  • The shape of the connector needs to match the profile of the device
  • A variety of signal types must be carried within a single connector (high voltage, low voltage, high bandwidth, data, thermocouple)
  • An off-the-shelf connector is may not meet the cost target
  • Custom logo or markings on the connector are desired or required
  • Lead-time for an off-the-shelf connectors may be unacceptably long

Safety may be enhanced by designing a custom connector.  Unique pin-to-socket patterns or connector shape can prevent mating by incompatible connectors thereby enhancing safety.

Custom 11 contact connector

Custom 11 contact connector

Custom connector fits contour of device case

Custom connector fits contour
of device case

A custom connector will typically involve engineering and tooling fabrications costs.  These up-front charges can be a roadblock to selecting a custom connector solution.  However, once the costs to design the connector and fabricate tooling are realized, a custom connector can often cost much less than an off-the-shelf connector.

Physical Properties

With a custom connector solution, each desired physical property can be addressed.  A custom connector can be designed so that mate and un-mate force matches specific customer requirements.  This force is composed of the friction from each pin and socket as well as the mechanical interface of the connector and receptacle.

Moisture protection is often a consideration in medical interconnect systems.  Off-the-shelf connectors typically incorporate shells and pre-molded boots or collars.  When these components are assembled into a finished connector, they often do not offer the required degree of ingress protection.  Custom overmolded connectors can be designed with any required ingress protection (IP) rating.

Standard boots typically do not provide high levels of ingress protection

Standard boots typically do not provide
high levels of ingress protection

Custom edge card connector designed to mate directly with PCB

Custom edge card connector designed
to mate directly with PCB

Availability of connectors from major manufacturers can also be an issue with lead times of 8-16 weeks being common.  Once tooling has been fabricated, the lead time for custom connectors can be much shorter than for off-the-shelf connectors.

Design Requirements

Establishing detailed design requirements is one of the first steps in determining whether a custom or standard connector is the best option.  Factors that may require consideration include:

  • Number and type of contacts (pins or sockets and specifications for each)
  • Cable configuration (ECG, defib, power, analog, digital, bandwidth, pneumatic, fiber optic, or combination of two or more.)
  • Cable diameter, materials and shape
  • Regulatory and environmental ratings (RoHS, REACH, ISO 10993, UL)
  • Strain relief requirements
  • Shielding requirements for both the connectors and the cable
  • Voltage and current requirements
  • Size constraints and/or desired physical size
  • Ingress protection (IP) requirements or rating
  • Number of mate and un-mate cycles required
  • Locking mechanism – if any
  • Keying requirements
  • Desired mate and un-mate force
  • Cleaning, disinfection and sterilization requirements
  • Logos, markings and serialization
Custom connector with customer’s branding

Custom connector with
customer’s branding

Keyway prevents non-keyed connector from being mated

Keyway prevents non-keyed
connector from being mated

Components of Custom Connectors

A custom connector typically involves an injection molded hard plastic insulator into which pins, sockets or both are inserted.  Termination of conductors to the pins or sockets by solder or crimp is most common.  This assembly is then overmolded with a rigid material such as polypropylene which holds the construction together and provides physical strength.  A second overmolding with a material such as a thermoplastic resin or silicone gives the connector the desired color, finish, look and feel.

Hybrid Connectors

For some applications, a hybrid connector may be the best option.  A hybrid connector is an off-the-shelf connector with custom features such as an overmolded grip or strain relief.  Design and tooling costs for a hybrid connector can be less than for a custom connector yet the finished product can have the look, feel, and some of the additional performance advantages of a custom connector.  Besides lower engineering costs, a hybrid connector can have a shorter design and development schedule than a fully custom connector design.

Off-the-shelf connector with custom overmolded bend relief becomes hybrid connector

Off-the-shelf connector with custom overmolded bend relief becomes
hybrid connector

Hybrid 3M MDR connector with custom angled overmolded strain relief

Hybrid 3M MDR connector with custom
angled overmolded strain relief

Freedom to Design

Example of custom ECG plug and custom case-mounted receptacle

Example of custom ECG plug and
custom case-mounted receptacle

Summary

A custom or hybrid connector can provide unique features and benefits for medical devices.  Each design element can be addressed with less need to compromise as compared to using an off-the-shelf connector.  Safety and reliability can be enhanced and a custom connector may be a more cost effective solution.  However custom and hybrid connectors typically require a greater investment in engineering and tooling than an off-the-shelf connector.

Whether you need a custom connector, an off-the-shelf connector or a hybrid connector, the Affinity engineering team can help.  Affinity Medical has decades of experience and expertise in designing and manufacturing custom medical connectors and cable assemblies.  For additional information, please contact Affinity at +1 949-477-9495 or email to customercare2@affinitymed.com.