Sensor Bonding

Graphite Conductivity Sensor

S-Bond joins metals, ceramics, carbon, carbides, and semiconductors making S-Bond a viable process assemble and bond sensors and sensor housings. Applications include the fluxless joining of electrical signal leads to sensor elements where twisted leads can be bonded to graphite or even active ceramic elements to make conductivity or strain sensors. S-Bond can join bimetallic, ceramic-metals, active ceramic and passive ceramic elements. The range of S-Bond joining alloys permits the assembly of many sensor types for measuring stress, strain, temperature, pressure, IR, radiation, etc. S-Bond can join silicon to metals and ceramics as a sensor for measuring deflection in applications such as strain and pressure transducers. S-Bond also successfully joins many piezo-electrical materials such as Barium Titanate, Bismuth Ferrite Lanthanum Gallium Silicate, Lead Scandium Tantalite and Lead Zirconate Titanate (PZT), making effective active ceramic sensor components.

Many sensors need to be enclosed for protection. S-Bond joints are hermetic and can bond a wide range of dissimilar metals, ceramics, and glass that are typically used in enclosures or housings. Some examples of housings include the bonding of sapphire windows to thin walled titanium tubes. These assemblies are joined by S-Bond at 250ºC to lower assembly-related distortion and produce a robust, hermetic seal. S-Bond uses lower joining temperatures; the resultant compliant solder interface makes these types joint more stable and reliable.

S-Bond is being used to join a range of sensor/optical windows as seen in the bottom figure where quartz or sapphire are joined to Kovar® or other metallic frame materials. S-Bond has the capability to join to a wide range of UV and IR inorganic crystal windows, such as ZnSe, BaF2 and LiF.

These window assemblies are typically brazed or conventionally soldered after a metallization is first placed on the edge of the window and the metallic housing. These metallization processes are either vacuum vapor deposited or are sintered, using a Mo-Mn deposition followed by a Ni-plating to produce an adherent, metallic layer that solders or braze filler metals can adhere to. S-Bond can, in one step, metallize and later join the ceramic lenses to the metallic frames or enclosures at temperatures lower than brazing, thus minimizing distortion, which is especially useful when making larger sensor housings and windows.

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Sensor Bonding