Hermetic Seal Feedthrough Connectors
By Jasmine Sailor- Business Development Specialist
Client-Medical Equipment and Supplies OEM
Hermetic Seals require leads to be sealed inside of a body/housing. The leads must not be connected to the hermetic seal body but still be able to pass current through the leads. Leads can be sealed within body/housings using either a glass or ceramic seal, with glass-to-metal being the most common feed-through. Due to the temperature of the sealing process for the glass and ceramic hermetic seals, selective plating of the feed-through pins is a critical requirement. Plating of the hermetic seal feed-through connectors can be designed according to the unique project requirement. Dependent upon the requirement of plating and specifications, including chemical or corrosion resistance, electrical conductivity, and thermal conductivity, common finishes include Gold, Rhodium, Platinum, Palladium, and Palladium-Nickel. Feed-through connectors have been proven useful throughout the Medical, Defense, and Aerospace industries as reliable connectors that can withstand harsh environments such as high temperatures, shock, and typical steam or sterilization methods used in medical device industries while insulating and channeling electricity. Glass-to-metal seals are the most common feed-through as it prevents the diffusion of gases that typically result in degradation or malfunctioning of the electrical components of other parts.
The Challenge
Previous technology was exposed to moisture contamination and leakage when the wire was attached to a glass or ceramic sealed pin. The first sealing technology was to mold epoxy to provide a seal. This posed an issue where the leads would encounter the housing and provide a current shortstop. This has been incrementally improved with the development of glass and ceramic fillers to seal the connector leads into the housing without the connection to the housing. Glass-to-metal and ceramic hermetic seals create plating challenges. Due to the melting point of glass and ceramic being higher than the melting point of the plated metals required, the molten material flows out is not able to create a tight bond. The thermal expansion of the glass and metal must be closely matched for the seal to remain in place after cooling. This does not allow leads to be plated entirely before being sealed, or the seal will not have a tight seal. Medical technology requires the dependability of all components reliable encapsulation and to withstand the different environments the device will have to go through, whether it is short or long term use medical device. Most medical connectors need to be sterilizable and autoclavable, and for implantable medical devices, the feed-through must be corrosion-resistant and biocompatible. The challenge of processing a hermetic seal after the sealing process is completed is that most applications cannot tolerate plating on the housing; therefore, selective plating techniques are required for successful outcomes whether the feed-through pins are pre-plated selectively prior to assembly or selectively plated post connector assembly.
The Engineered Solution
ProPlate® has developed a proprietary process to electroplate hermetic seals by using selective masking, racking/fixturing, and plating capabilities. ProPlate® can selectively mask and plate the leads precisely where the plating is required outside of the glass/ceramic seal prior to the sealing process. When the feed-through goes through the sealing process, the molten seal material can form a tight bond to the raw base material, and the plating is not compromised due to selective plating only being applied in the areas that will not flow out from the sealing process. The plating must be held to a tight tolerance for the sealing operation to succeed. ProPlate® has capabilities to electroplate the leads at either the distal or proximal end and keep the rest of the feed-through pins free from plating, whichever is required, prior to assembly of the hermetic seal. ProPlate has also developed masking and plating fixtures to allow electroplating of leads that are already sealed within glass or ceramic and outer body of the build, as opposed to pre-plating the leads prior to the sealing activity. Through the utilization of selective masking/plating and racking, ProPlate has capabilities to form electrical connections to the leads, which results in a body/housing that is free of any plating. These solutions allow the lead pins to be plated before or after the hermetic sealing process, dependent on the customer’s needs.
Learn more about ProPlate’s plating capabilites and hermetic seals.
