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Hermetic Feedthroughs for Autoclavable Medical Devices

Hermetic Autoclave Solutions by Winchester Interconnect

Customer Challenge

A manufacturer of surgical cameras approached Winchester Interconnect regarding a new camera design utilizing 4K video. The customer needed a biocompatible hermetic laser weldable 28 pin feedthrough that would protect sensitive electronics while undergoing intense autoclave cycles with a minimal overall footprint. The manufacturer’s current feedthrough was bulky, costly in resources and time, and more importantly, experiencing leaks damaging the sensitive electronics during autoclave cycles. 

The goal of this new camera was to utilize 4K video and survive a minimum of 1,000 autoclave cycles for repeatable use in surgery. An autoclave sterilizes devices by killing microorganisms and spores by combining pressure, steam, and time. For an autoclave to be effective, the system must reach and maintain a temperature of 121°C by using saturated steam at 15 psi for 30 minutes. This harsh environment requires a hermetic package that creates an impervious seal from all external influences (heat, moisture, dust, etc.) with an extended shelf life greater than that of epoxy. 



Challenge Review

The main challenge of upgrading this customer’s product to a more compact 4K video device was reusability. The camera would come in contact with biofluids and bacteria during surgery, requiring it to be disinfected and sterilized several hundred times over its useful life. The customer’s solution was to sterilize the device using an autoclave.

Due to the harsh conditions of an autoclave, the customer was experiencing leaks in their power and signal feedthroughs. The customer requirements with regards to surviving the autoclave process were to functionally withstand a minimum of 1,000 autoclave cycles at 132°C for 20 minutes. The customer’s enclosure needed to meet a maximum leak rate of less than 1 X 10-8cc/second of helium along with an insulation resistance between the electrical contacts and the housing of 100 M-ohms minimum at 100 VDC.

As the feedthrough packaging footprint decreases, the pin spacing within the hermetic feedthrough becomes denser resulting in a more challenging seal geometry that surpassed the technical capability of the incumbent supplier. The customer’s current supplier did not directly bond titanium to glass, therefore requiring a process to prep the titanium. Consequently, the additional prep work would no longer allow the feedthrough to be laser weldable without an additional post-manufacturing machining process. These extra preparation steps resulted in a higher manufacturing cost and a lower yield.

Winchester Solution

Winchester Interconnect’s engineers recommended a glass to titanium hermetic seal to create a compact high reliability 28 pin hermetic feedthrough that was rated to 1 X 10-9cc/sec helium leak maximum with insulation resistance between the contacts and the enclosure of 5,000 M-ohms minimum. These specs are what allow Winchester Interconnect’s titanium to glass hermetic feedthroughs to protect the customer’s sensitive electronics while undergoing 1,000 harsh autoclave cycles. Winchester Interconnect’s unique ability to reliably seal high-density pin patterns directly into titanium provided the optimum solution for this problem. In addition to providing a more reliable seal with a smaller footprint, Winchester Interconnect’s product required no secondary machining to prepare the laser weld surface. This can be attributed to the benefits of Winchester Interconnect’s “oxide-free” sealing process. The removal of this secondary machining operation reduced manufacturing time and increased yield which ultimately provided the customer with highly reliable feedthroughs.

Customer Improvement

By working closely with the customer, Winchester Interconnect’s engineering team was able to fully understand the challenges the customer faced and provide a superior part that outperforms the specifications. This new glass to titanium hermetic feedthrough allowed the customer to offer a high reliability 4K surgical camera that can withstand the harshest of surgical and cleaning environments.