Seal Grade Tungsten for Lamp Leads
The making of welded tungsten lamp leads requires the use of seal grade tungsten cuts to insure a gas tight seal of the lamp envelope.
Grinding to Remove Surface Defects
The typical seal grade tungsten used in the past was made from rod that was centerless ground with diameter reductions as high as ten percent. The grinding removed surface defects such as splits and laps providing a good glass to metal seal. The process of making and grinding rod adds significantly to the cost of the tungsten seal material.
Cost Reduction with Cut Wire and Etching
To reduce this cost the seals are being made from cut wire then chemically etchted to remove or open any defects which helps make a tight glass to metal seal. Some of the issues with this these type of seals are trapped carbon residue from the wire drawing process. In some cases additional surface cleaning is required to prevent the formation of bubble lines in the seal area.
Component InterTechnologies continues to innovate in the field of resistor elements with the newest techniques in automated manufacture of 4 terminal current shunts.
A. Standard DIP Package
These 4 lead welded assemblies are welded and tested automatically on computer controlled fully automated machines to provide consistent product with resistance tolerances < 1%.
B. Standard SIP Package
These elements can be formed and used as Open Air devices or formed and molded into DIP or SIP packages for use in automatic insertion. They can also be molded as axial lead four terminal packages.
C. Welded Element Assembly
D. Axial Lead Package
For more solutions see: Metal Resistor Elements