Packaging for chip-on-board pressure sensor

Abstract

A method of packaging for chip-on-board pressure sensor that includes a buffer layer with a coefficient of thermal expansion (CTE) intermediate between the transducer and a main chip-on-board substrate by which thermally induced package stresses can be greatly reduced or eliminated. Additionally, the use of a buffer layer with higher stiffness (elastic modulus) than the chip-on-board substrate further prevents or reduces flexural (bending) stresses from being transferred to the transducer. Such a buffer layer also enables a wider choice of materials for bonding and stable performance of pressure sensor in harsh media and environmental conditions. The pressure transducer can be adhesively bonded to a ceramic layer, which in turn can be adhesively bonded to an epoxy laminate chip-on-board substrate.

1 . A packaging method for a chip-on-board pressure sensor, comprising:
 providing a chip-on-board substrate;   connecting at least one pressure transducer to said chip-on-board substrate;   locating a buffer layer between said at least one pressure transducer and said chip-on-board substrate, wherein said buffer layer includes a coefficient of thermal expansion between that of said at least one pressure transducer and said chip-on-board substrate.   
   
   
       2 . The method of  claim 1  wherein said buffer layer comprises a material with higher elastic modulus than said chip-on-board substrate. 
   
   
       3 . The method of  claim 1  wherein said buffer layer comprises a ceramic material. 
   
   
       4 . The method of  claim 1  wherein said chip-on-board substrate comprises an epoxy laminate material. 
   
   
       5 . The method of  claim 1  wherein locating said buffer layer between said at least one pressure transducer and said chip-on-board substrate further comprises adhesively bonding said buffer layer to said at least one pressure transducer. 
   
   
       6 . The method of  claim 1  further comprising attaching said buffer layer to said chip-on-board substrate using an eutectic metal solder. 
   
   
       7 . The method of  claim 1  further comprising configuring at least one electrical circuit trace, at least one via, and at least one bond pad upon said buffer layer. 
   
   
       8 . The method of  claim 1  configuring said buffer layer to further comprise a multilayer structure comprising a plurality of cavities or buried channels. 
   
   
       9 . The method of  claim 1  further comprising:
 creating a plurality of buffer layer structures in an array for batch assembly of said at least one pressure transducer to said array.   
   
   
       10 . The method of  claim 1  further comprising configuring said at least one pressure transducer to comprise silicon anodically bonded to a glass layer. 
   
   
       11 . A packaging method for a chip-on-board pressure sensor, comprising:
 providing a chip-on-board substrate;   connecting at least one pressure transducer to said chip-on-board substrate;   locating a buffer layer between said at least one pressure transducer and said chip-on-board substrate; and   configuring said at least one pressure transducer to comprise silicon anodically bonded to a glass layer, wherein said buffer layer comprises a material with higher elastic modulus than said chip-on-board substrate and wherein said buffer layer includes a coefficient of thermal expansion between that of said at least one pressure transducer and said chip-on-board substrate.   
   
   
       12 . The method of  claim 11  wherein said buffer layer comprises a ceramic material and said chip-on-board substrate comprises an epoxy laminate material. 
   
   
       13 . The method of  claim 11  wherein locating said buffer layer between said at least one pressure transducer and said chip-on-board substrate further comprises adhesively bonding said buffer layer to said at least one pressure transducer. 
   
   
       14 . The method of  claim 11  further comprising attaching said buffer layer to said chip-on-board substrate using an eutectic metal solder. 
   
   
       15 . The method of  claim 11  further comprising configuring at least one electrical circuit trace, at least one via, and at least one bond pad upon said buffer layer. 
   
   
       16 . The method of  claim 11  configuring said buffer layer to further comprise a multilayer structure comprising a plurality of cavities or buried channels. 
   
   
       17 . A chip-on-board pressure sensor apparatus, comprising:
 a chip-on-board substrate;   at least one pressure transducer connected to said chip-on-board substrate;   a buffer layer located between said at least one pressure transducer and said chip-on-board substrate, wherein said buffer layer is adhesively bonded to said at least one pressure transducer and wherein said buffer layer includes a coefficient of thermal expansion between that of said at least one pressure transducer and said chip-on-board substrate.   
   
   
       18 . The apparatus of  claim 17  wherein said buffer layer comprises a material with higher elastic modulus than said chip-on-board substrate. 
   
   
       19 . The apparatus of  claim 17  wherein said buffer layer comprises a ceramic material and said chip-on-board substrate comprises an epoxy laminate material. 
   
   
       20 . The apparatus of  claim 17  further comprising:
 at least one electrical circuit trace, at least one via, and at least one bond pad configured upon said buffer layer; and   a plurality of buffer layer structures configured in an array for batch assembly of said at least one pressure transducer to said array.