Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – Outside periphery of package having specified shape or...
Reexamination Certificate
2001-11-26
2004-11-09
Lee, Hsien Ming (Department: 2823)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
Outside periphery of package having specified shape or...
C257S780000, C257S786000, C438S106000, C438S107000, C438S666000
Reexamination Certificate
active
06815815
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and method of manufacture thereof, a circuit board, and an electronic instrument.
2. Description of Related Art
With the recent increasingly compact nature of electronic instruments, there is a demand for semiconductor device packages appropriate for high-density mounting. In response to this, surface-mounted packages have been developed, such as Ball Grid Array (BGA) and Chip Scale/Size Package (CSP). With such surface-mounted packages, a substrate is often used on which a wiring pattern for connection to the semiconductor chip is formed. Penetrating holes are formed in the substrate, and external electrodes are often formed so as to project through these penetrating holes from the surface opposite to that of the wiring pattern.
With a semiconductor device to which a package of this construction is applied, after mounting on the circuit board, because of the difference in coefficient of thermal expansion between the circuit board and semiconductor device, a stress may be applied to the external electrodes, and cracks may form in the external electrodes.
SUMMARY OF THE INVENTION
The present invention solves these problems, and has as its object the provision of a semiconductor device and method of manufacture thereof, a circuit board, and an electronic instrument such that cracks in the external electrodes can be prevented.
(1) According to a first aspect of the present invention, there is provided a semiconductor device comprising:
a substrate in which penetrating holes are formed;
a semiconductor chip having electrodes;
a conductive member adhered on one side of the substrate by an adhesive material over a particular region of the one side including the penetrating holes, and electrically connected to the electrodes of the semiconductor chip on the side opposite to the surface of being adhered by the adhesive; and
external electrodes which are provided through the penetrating holes, electrically connected to the conductive member, and extending as far as outside of the other side of the substrate;
wherein a part of the adhesive material is interposed between internal wall surfaces forming the penetrating holes and the external electrodes within the penetrating holes.
According to the present invention, external electrodes are formed within penetrating holes, and between the external electrodes and penetrating holes part of an adhesive material is interposed. Therefore, since the adhesive material forms a stress absorption material, stress caused by differences in the coefficient of thermal expansion with the circuit board (thermal stress) and mechanical stress applied to the circuit board from the outside can be absorbed. In this way, the occurrence of cracks in the external electrodes can be prevented.
It should be noted that in the present invention, the adhesive material may be continuous from between the substrate and conductive member to the internal wall surfaces of the penetrating holes, or may exist discontinuously within the penetrating holes.
(2) In this semiconductor device, a part of the adhesive material may enter and exist within the penetrating holes.
(3) According to a second aspect of the present invention, there is provided a semiconductor device comprising:
a substrate in which penetrating holes are formed;
a semiconductor chip having electrodes;
a conductive member directly formed over a particular region including the penetrating holes on one side of the substrate, and electrically connected to the electrodes of the semiconductor chip; and
external electrodes which are provided through the penetrating holes, electrically connected to the conductive member, and extending as far as outside of the other side of the substrate;
wherein the substrate is formed of a material of a higher elasticity than the external electrodes; and
wherein protrusions are formed in the internal wall surfaces of the penetrating holes by the material constituting the substrate.
According to the present invention, since protrusions are formed in the internal wall surfaces of the penetrating holes, deformation is easier than with flat internal wall surfaces. Therefore, stress caused by differences in the coefficient of thermal expansion with the circuit board (thermal stress) and mechanical stress applied to the circuit board from the outside can be absorbed. In this way, the occurrence of cracks in the external electrodes can be prevented.
(4) Each of the external electrodes may include a base portion positioned within each of the penetrating holes and a projecting portion projecting from each of the penetrating holes, the diameter d of the base portion being related to the diameter &phgr; of the projecting portion by &phgr;≦d.
By this means, the diameter of the external electrode is not squeezed by the penetrating hole, and no necking occurs. Therefore, stress caused by differences in the coefficient of thermal expansion with the circuit board (thermal stress) and mechanical stress applied from outside the circuit board is not concentrated, and the occurrence of cracks in the external electrodes can be prevented.
(5) According to a third aspect of the present invention, there is provided a semiconductor device comprising:
a substrate in which penetrating holes are formed;
a semiconductor chip having electrodes;
a conductive member adhered on one side of the substrate by an adhesive material over a particular region of the one side including the penetrating holes, and electrically connected to the electrodes of the semiconductor chip on the side opposite to the surface of being adhered by the adhesive; and
external electrodes which are provided through the penetrating holes, electrically connected to the conductive member, and extending as far as outside of the other side of the substrate;
wherein each of the external electrodes includes a base portion positioned within each of the penetrating holes and a projecting portion projecting from each of the penetrating holes, the diameter d of the base portion being related to the diameter &phgr; of the projecting portion by &phgr;≦d.
According to the present invention, external electrodes are formed within penetrating holes. The diameter d of the base portion of the external electrodes is related to the diameter &phgr; of the projecting portion by &phgr;≦d. In other words, the diameter of the external electrodes is not squeezed by the penetrating holes, and no necking occurs. Therefore, stress caused by differences in the coefficient of thermal expansion with the circuit board (thermal stress) and mechanical stress applied from outside the circuit board is not concentrated, and the occurrence of cracks in the external electrodes can be prevented.
(6) The substrate may be an insulating substrate.
(7) The substrate may be a printed substrate.
(8) The external electrodes may be formed of solder.
(9) The outline form of the substrate may be larger than the semiconductor chip outline form.
(10) The electrodes of the semiconductor chip may be electrically connected to the conductive member through an anisotropic conductive material having conductive particles dispersed in an adhesive.
(11) The electrodes of the semiconductor chip may be electrically connected to the conductive member through wires.
(12) According to a fourth aspect of the present invention, there is provided a circuit board on which the above described semiconductor device is mounted.
(13) According to a fifth aspect of the present invention, there is provided an electronic instrument having the above described circuit board.
(14) According to a sixth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising:
a step of providing a substrate with an adhesive material provided on one surface thereof;
a step of carrying out punching from the side of the substrate on which the adhesive material is provided, and in the direction of the opposite side thereof, whereby penetrating holes are formed and a part of t
Lee Hsien Ming
Oliff & Berridg,e PLC
Seiko Epson Corporation
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