This paper gives comparison and discussion of adhesives used for attachment
of silicon piezoresistive pressure sensor dies. Special attention is paid on
low pressure sensor dies because of their extreme sensitivity on stresses,
which can arise from packaging procedure and applied materials. Commercially
available adhesives ?Scotch Weld 2214 Hi-Temp? from ?3M Co.? and
?DM2700P/H848? from ?DIEMAT?, USA, were compared. First of them is aluminum
filled epoxy adhesive and second is low melting temperature (LMT) glass
paste. Comparing test results for low pressure sensor chips we found that LMT
glass (glass frit) is better adhesive for this application. Applying LMT
glass paste minimizes internal stresses caused by disagreement of
coefficients of thermal expansions between sensor die and housing material.
Also, it minimizes stresses introduced during applying external loads in the
process of pressure measuring. Regarding the measurements, for the sensors
installed with filled epoxy paste, resistor for compensation of temperature
offset change had negative values in all cases, which means that linear
temperature compensation, of sensors installed this way, would be impossible.
In the sensors installed with LMT glass paste, all results, without
exception, were in their common limits (values), which give the possibility
of passive temperature compensation. Furthermore, LMT glass attachment can
broaden temperature operating range of MEM silicon pressure sensors towards
higher values, up to 120 ?C.
Design and Application of a High Sensitivity Piezoresistive Pressure Sensor for Low Pressure Conditions
