Pressure Sensor Package
Main products include metal package for hybrid integrated circuits, opto-electronic components, microwave components, wave filter components, sensor components and high-power devices. The products are applicable in such areas as aviation, aerospace, electronics and communication devices for military and commerciality. Company has undertaken the ministerial level scientific research projects, and recognized by users.
Pressure Sensor Package adopts compression sealing.It should withstand high pressure and physical stress such as mechanically pressing and thermal shocking and vibration.According to design,comperssion sealing should withstand high pressure level(up to 3000bar)very suitable for high pressure sensor.
Pressure sensor made by Stainless Steel brazing should be high reliable sealing parameter,suitable for high pressure,irritant medium,acid medium and other harse environment widely used in environment monitoring ,medical health,auto car and etc fileds.
Stainless header is one of main parts for stainless steel pressure sensors,acting as main role in pressure sensor header:
*Assembly、fixed sensitive components
*Hermetic , thermal isolated sensitive components and other material touch with transimission medium
*Sensible component and amplifier take a role as bridge
Due to specific requirement of pressure sensor header,stainless steel header should be high reliable:
*With stand of pressure difference it should meet the leak rate ≤1*10-3Pa.cm3/s
*Insulation Resistance between pin and package R is≥1*109Ω
*Inner pin bonding
*The surface of package is good weldable and so on properties.
Stainless steel soldered pressure sensor is high reliable hermetic suitable for high pressure,irritant medium,salt atmosphere and so on all kinds of harsh environment so that it is widely used in monitoring industry environment、medical treatment、automobile and so on fields.
The stainless steel header is a necessary important component for stainless steel pressure sensor.It plays a major role:
(1)mount、fix sensitive component;
(2)hermetic,isolate sensitive component and transform medium from touching other materials;
(3)mechanical、environment protection;(4)used as bridge between sensitive component and amplifier.
Due to specific requirement of usage for pressure sensor,the stainless steel header should be equipped with high reliable property.
(1)Standing with high pressure,it meets hermeticity ≦1*10-3Pa.cm3/s ,the difference of pressure at high level should be above 10000PSI;
(2)Insulation Resistance between pin and header should be R≧1*109Ω;
(3)Inner pin bonding;
(4)The surface is easily weldable and etc properties.
The stainless steel pressure sensor header is usually round in order to easy for brazing outer package in usage.It consists of three parts:header、leads、glass insulators.The header sealing with leads by glass insulators in high temperature and its main materials shown as tablet 1:
Main material of stainless steel pressure sensor header
|1||header||316/316L stainless steel|
The design of structure
To ensure the header standing high pressure without breaking glass sealing and guarantee the high reliable hermetic property,the design for the glass sealing part couldnot like normal header used for integrated circuit,while it should increase intensity of sintering between glass and package or change the sealing holes of header to stand extreme high pressure.
The first method is minimizing the cross section of glass sealing area and increasing the thickness of glass sealing.This method could directly solve the pressure when the pressure requirement is not high and it could be mostly adopted in the current.While in high pressure,its limitation is larger:(1)The diameter of glass sealing hole is smaller and To some extend it needs its wall thickness too thin to process;(2)The thickness increased to some extend,it needs some pieces of glass insulators to fill in the glass sealing hole.Even we use glass drawn tubes which would result in failure of sintering for gap and shrinking and etc issues.In this condition we use the second method:design the glass insulator of header into step shape and the header shown as pic1
(a)Characteristic of material:choose material with matched CTE;
(b)Pre-Oxidizing:Oxidize leads in high temperature and N2/H2/H2O environment,Oxidize package
in the air ensuring the thickness of package and oxidization layer of pin are proper.
(c)Sintering:Control temperature curve,atmosphere strictly according to characteristics of glass ensuring the quality of glass sealing.
(a)The surface status of bonding area:The roughness for bonding area of pin should be controlled under Ra=3.2~6.3um
(b)Plating status:Select prior plating solution and ensure the adhesive strength of finish and density level and purity through several time electroplating.