Sintered Material Production
Blended powders are compacted to their near net shape in a contained die system. Tool design and press selection by ECL's engineering staff ensure optimal pressing efficiency. The mass-volume relationship of these compacted contacts is a key element of the quality of sintered contacts. Consequently, this process is closely monitored and subjected to statistical controls. Rotary presses, single die mechanical presses and hydraulic presses are all used to ensure the appropriate densities are achieved for the wide range of contacts ECL supplies. The essential steps involved in the production of discrete sintered contacts through unit compaction powder metallurgy are compaction, sintering, infiltration and solder flushing.
The sintering process is an essential step in the production of unit compaction sintered discrete contacts. High temperature heating of the compacted contacts fuses together the constituent materials as the materials are "wetted" together. The furnace temperature, atmosphere and the time contacts are in the heat are all key elements of the process.
Infiltration is the process in which the pores inside a sintered contact are filled with either the molten silver or copper. Infiltrating is performed through the high temperature heating of the sintered contact and the infiltrant in furnaces which have reducing atmosphere. Aside from the furnace atmosphere, the temperature and the process time are critical elements of the process. Depending upon the final application, infiltrated contacts are supplied with or without serrated backs. The serrations provide a surface that captures the excess infiltrant and is also well suited to the resistance brazing process. Where high currents are involved the surfaces to be brazed are typically machined flat prior to solder flushing.
Brazing alloy, commonly called solders, are most often required to attach discrete contacts to their supports when creating contact assemblies. In many cases the braze alloy is applied prior to the delivery of the contact for its subsequent braze attachment. Contacts are solder flushed whether they are wrought or sintered and whether they have serrated backs or machined surfaces. Typically, contacts are placed on a precut shim of the required braze alloy and these two components are then passed through a high temperature furnace. The furnace temperature and the length of time in heat allows for the solder to adhere to the contact's brazing surface. Furnace atmosphere is also an important feature of this process.