Magnetic sensor and method for fabricating the same

Abstract

The magnetic sensor is fabricated such that a magnetic sensor chip, having a one-chip structure in which MRE bridges and a comparator are included, is mounted onto a lead frame using an adhesive material, and then the magnetic sensor chip mounted on the lead frame is encapsulated by molding in a molded material. The magnetic sensor includes a magnetic-field generating portion formed by magnetizing at least one of the chip mounting member, the adhesive material, and the encapsulating material.

What is claimed is:  
     
         1 . A magnetic sensor comprising: 
 a magnetic sensor chip;    a chip mounting member on which the magnetic sensor chip is mounted;    an adhesive material for bonding the magnetic sensor chip to the chip mounting member;    an encapsulating material for encapsulating the magnetic sensor chip; and    a magnetic-field generating portion formed by magnetizing at least one of the chip mounting member, the adhesive material, and the encapsulating material.    
     
     
         2 . The magnetic sensor according to  claim 1 , wherein the encapsulating material is magnetized at a portion opposite to the position at which the magnetic sensor chip is mounted.  
     
     
         3 . The magnetic sensor according to  claim 1 , wherein the encapsulating material is magnetized at a portion that is located on a side of the magnetic sensor chip.  
     
     
         4 . The magnetic sensor according to  claim 1 , wherein the chip mounting member is magnetized at a portion on which the magnetic sensor chip is mounted.  
     
     
         5 . The magnetic sensor according to  claim 1 , wherein the adhesive material is formed on a surface on which the magnetic sensor chip is mounted, and is entirely magnetized.  
     
     
         6 . A magnetic sensor comprising: 
 a magnetic sensor chip;    a chip mounting member, for mounting the magnetic sensor chip thereon, with a magnetized portion on which the magnetic sensor chip is mounted;    a magnetized adhesive material for boding the magnetic sensor chip to the chip mounting member; and    an encapsulating material for encapsulating the magnetic sensor chip therein, the encapsulating material having a magnetized portion on a surface opposite to the mounting surface of the magnetic sensor chip on the chip mounting member, the magnetized portion of the encapsulating material corresponding to the magnetized portion of the chip mounting member.    
     
     
         7 . A method for fabricating a magnetic sensor comprising: 
 mounting a magnetic sensor chip on a chip mounting member by using an adhesive material for bonding;    encapsulating the chip mounting member and the magnetic sensor chip mounted thereon by using an encapsulating material; and    forming a magnetic-field generating portion by magnetizing at least one of the chip mounting member, the adhesive material, and the encapsulating material.    
     
     
         8 . The method for fabricating a magnetic sensor according to  claim 7 , wherein the encapsulating material is magnetized at a portion opposite to the position at which the magnetic sensor chip is mounted.  
     
     
         9 . The method for fabricating a magnetic sensor according to  claim 7 , wherein the encapsulating material is magnetized at a portion that is located on a side of the magnetic sensor chip.  
     
     
         10 . The method for fabricating a magnetic sensor according to  claim 9 , wherein the chip mounting member has a predetermined portion reduced in shape relative to its peripheral portion to make the predetermined portion highly resistive, the method further comprising: 
 allowing a large current to flow through the chip mounting member while externally applying a magnetic field to the encapsulated magnetic sensor chip, thereby generating heat at the portion reduced in shape of the chip mounting member to magnetize the vicinity of the portion reduced in shape.    
     
     
         11 . The method for fabricating a magnetic sensor according to  claim 7 , wherein the chip mounting member is magnetized at a portion on which the magnetic sensor chip is mounted.  
     
     
         12 . The method for fabricating a magnetic sensor according to  claim 7 , wherein the adhesive material is formed on a surface on which the magnetic sensor chip is mounted, and is entirely magnetized.  
     
     
         13 . A method for fabricating a magnetic sensor comprising: 
 magnetizing a portion of a chip mounting member on which a magnetic sensor chip is mounted;    magnetizing an adhesive material for bonding the magnetic sensor chip to the chip mounting member;    mounting the magnetic sensor chip on the chip mounting member by using the adhesive material;    encapsulating the chip mounting member and the magnetic sensor chip mounted thereon by using an encapsulating material; and    magnetizing a portion of the encapsulating material on a surface opposite to the mounting surface of the magnetic sensor chip on the chip mounting member, the portion of the encapsulating material corresponding to the magnetized portion of the chip mounting member.    
     
     
         14 . The method for fabricating a magnetic sensor according to  claim 13 , wherein the magnetized portion is demagnetized once and magnetized again.