Surface acoustic wave device and method for manufacturing the same
View Patent ↗A SAW chip ( 11 ) where ones are balanced signal terminals and the others are unbalanced signal terminals is mounted on a mounting board ( 12 ) in a flip chip manner, and the mounting board ( 12 ) and a surface of the SAW chip are covered with resin ( 19 ). At that time, grounds of first and second SAW filters ( 1, 2 ) in the SAW chip ( 11 ) are connected together and an annular pattern ( 14 ) is formed so as to surround a signal pattern of the SAW chip ( 11 ) on the mounting board ( 12 ) on which the SAW chip ( 11 ) is mounted, and the annular electrode ( 14 ) is connected to a ground pattern.
1. A SAW broadband filter device comprising: a SAW chip including a plurality of SAW filters with different central frequencies formed on one piezoelectric substrate, ones of input and output terminals of said plurality of SAW filters being constituted as balanced signal terminals and the others thereof being constituted of unbalanced signal terminals; a mounting board on which said SAW chip is mounted on connection electrodes via conductive bumps in a flip chip manner; and a resin layer which is formed so as to cover the mounting board and a surface of the SAW chip, wherein respective grounds of said plurality of SAW filters are connected together to be connected to one grounding pattern of said mounting board; and
at least one wiring pattern of one SAW filter of said plurality of SAW filters connected to said one grounding pattern on a mounting face of said mounting board and at least one wiring pattern of another SAW filter of said plurality of SAW filters connected to said one grounding pattern on the mounting face of the mounting board are connected to each other on said SAW chip; and wherein
said one grounding pattern is provided on said mounting face of said mounting board so as to be at least between one connection electrode connected to an input or an output terminal of said one SAW filter of said plurality of SAW filters and another connection electrode connected to an input or an output terminal of said another SAW filter of said plurality of SAW filters;
said one connection electrode and said another connection electrodes are electrically separated; and
of said conductive bumps, all of such conductive bumps that are connected to ground terminals are provided on said one grounding pattern.
2. The SAW device according to claim 1 , wherein an annular electrode is formed on a mounting face of said mounting board on which the SAW chip is mounted so as to surround a signal pattern of said SAW chip and said annular electrode is connected to a ground.
3. The SAW device according to claim 2 , wherein said annular electrode is connected to the ground via an inner layer wiring of said mounting board or a pattern formed on the mounting face.
4. The SAW device according to claim 1 , wherein metal films are formed on an upper face and side faces of said SAW chip and a portion of the mounting board.
5. The SAW device according to claim 2 , wherein said annular electrode is formed of a metal film.
6. A method for manufacturing a SAW broadband filter device comprising: a step of mounting a SAW chip including a plurality of SAW filters with different central frequencies formed on one piezoelectric substrate, ones of input and output terminals of said plurality of SAW filters being constituted as balanced signal terminals and the others thereof being constituted as unbalanced signal terminals, on connection electrodes of a mounting board via conductive bumps in a flip chip manner; and a step of, after mounting said SAW chip on said mounting board, forming an annular electrode on said mounting board by forming a metal film.