Circuit substrate, circuit module and method for manufacturing the circuit substrate

Abstract

A thin circuit substrate and a circuit module are arranged such that the circuit module includes an IC mounted on a circuit substrate, the IC includes an IC body and an solder bump located on a mounting surface of the IC body, and the circuit substrate includes a substrate including a recess formed by recessing a portion of a mounting surface of the substrate on which the IC is to be mounted, and a terminal protruding from the mounting surface of the substrate. The terminal is to be electrically connected to the solder bump.

1 . A circuit substrate on which a first electronic component including a bump is to be mounted, the circuit substrate comprising:
 a substrate including a mounting surface on which the first electronic component is to be disposed, the mounting surface including a recess defined by a recessed portion of the mounting surface; and   a terminal to be electrically connected to the bump of the first electronic component, the terminal protruding from the mounting surface within the recess.   
   
   
       2 . The circuit substrate according to  claim 1 , further comprising an electrode on the mounting surface outside the recess, the electrode being to be joined to a second electronic component. 
   
   
       3 . A circuit module comprising:
 a first electronic component; and   a circuit substrate on which the first electronic component is mounted; wherein   the first electronic component includes an electronic component body and a bump on the electronic component body, and the circuit substrate includes a substrate including a mounting surface on which the first electronic component is disposed and including a recess defined by a recessed portion of the mounting surface, and a terminal protruding from the mounting surface within the recess and electrically connected to the bump.   
   
   
       4 . The circuit module according to  claim 3 , wherein the electronic component body is disposed within the recess when viewed in the direction of the normal to the substrate. 
   
   
       5 . The circuit module according to  claim 3 , wherein the electronic component body covers the recess beyond edges of the recess when viewed in the direction of the normal to the substrate and is in contact with the substrate. 
   
   
       6 . The circuit module according to  claim 3 , further comprising a second electronic component, wherein the circuit substrate further includes an electrode on the mounting surface outside the recess, and the second electronic component is joined to the electrode via a solder layer therebetween. 
   
   
       7 . A method for manufacturing a circuit substrate on which a first electronic component having a bump is to be mounted, the circuit substrate including a terminal to which the bump of the first electronic component is to be electrically connected, the method comprising the steps of:
 forming a mask layer on a portion of a main surface of a first sheet;   forming a through-hole in the mask layer;   filling the through-hole with a conductive material;   stacking a plurality of second sheets and the first sheet having the mask layer such that the mask layer defines an uppermost layer, and compressing the stack to embed the mask layer in the first sheet; and   removing the mask layer from the stack of the first sheet and the second sheets.   
   
   
       8 . The method according to  claim 7 , wherein the mask layer is formed by applying a resin paste onto the first sheet in the step of forming the mask layer. 
   
   
       9 . The method according to  claim 7 , wherein the through-hole is formed by irradiating the mask layer with a laser beam in the step of forming the through-hole. 
   
   
       10 . The method according to  claim 7 , wherein the first sheet and the second sheets are ceramic green sheets, and the mask layer is made of a resin, and wherein the step of removing the mask layer is performed by firing the first sheet and the second sheets together with the mask layer, thereby consuming the mask layer. 
   
   
       11 . The method according to  claim 7 , wherein the through-hole is formed so as to pass through the first sheet and the mask layer in the step of forming the through-hole. 
   
   
       12 . The method according to  claim 7 , further comprising the steps of forming an electrode to which a second electronic component is to be joined, in a region other than the mask layer, and printing a solder paste on the electrode through a mask pattern.