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Claims  |
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What is claimed is:
1. 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 said substrate on which said adhesive material is provided, and in the direction of the opposite side thereof, whereby penetrating holes are formed and a part of said adhesive material is drawn
into said penetrating holes;
a step of adhering a conductive member over a particular region on said one surface including said penetrating holes on said substrate through said adhesive material;
a step of providing a material for forming external electrodes on said conductive member, and forming external electrodes through said penetrating holes and the inner side of said part of adhesive material drawn into the penetrating holes to
project from the surface opposite to the surface of said substrate on which said conductive member is formed; and
a step of electrically connecting electrodes of a semiconductor chip to said conductive member.
2. The method of manufacturing a semiconductor device as defined in claim 1,
wherein each of said external electrodes includes a base portion positioned within each of said penetrating holes and a projecting portion projecting from each of said penetrating holes, the diameter d of said base portion being related to the
diameter .phi. of said projecting portion by .phi..ltoreq.d.
3. The method of manufacturing a semiconductor device as defined in claim 1,
wherein said substrate is either of an insulating film and a printed substrate.
4. The method of manufacturing a semiconductor device as defined in claim 1, wherein said material for forming external electrodes is solder.
5. The method of manufacturing a semiconductor device as defined in claim 1, further comprising:
a step of punching said substrate around said semiconductor chip, after the step of electrically connecting electrodes of said semiconductor chip to said conductive member.
6. The method of manufacturing a semiconductor device as defined in claim 1,
wherein in the step of electrically connecting said electrodes of said semiconductor chip to said conductive member, said electrodes are connected to said conductive member through an anisotropic conductive material having conductive particles
dispersed in an adhesive.
7. The method of manufacturing a semiconductor device as defined in claim 1,
wherein in the step of electrically connecting said electrodes of said semiconductor chip to said conductive member, said electrodes are connected to said conductive member through wires.
8. A method of manufacturing a semiconductor device, comprising:
a step of providing a substrate of a material of a higher elasticity than external electrodes, having penetrating holes in which the internal wall surfaces have protrusions, and having a conductive member directly formed over a region including
said penetrating holes;
a step of providing a material for forming external electrodes on said conductive member, and forming external electrodes through said penetrating holes to project from the surface opposite to the surface of said substrate on which said
conductive member is formed; and
a step of electrically connecting electrodes of a semiconductor chip to said conductive member.
9. The method of manufacturing a semiconductor device as defined in claim 8, further comprising:
a step of punching said substrate before said conductive member is formed, wherein a part of said substrate is drawn into said penetrating holes and said protrusions are formed.
10. The method of manufacturing a semiconductor device as defined in claim 8,
wherein said penetrating holes are formed by a laser.
11. The method of manufacturing a semiconductor device as defined in claim 8,
wherein said penetrating holes are formed by wet etching.
12. The method of manufacturing a semiconductor device as defined in claim 8,
wherein each of said external electrodes includes a base portion positioned within each of said penetrating holes and a projecting portion projecting from each of said penetrating holes, the diameter d of said base portion being related to the
diameter .phi. of said projecting portion by .phi..ltoreq.d.
13. The method of manufacturing a semiconductor device as defined in claim 8,
wherein said substrate is either of an insulating film and a printed substrate.
14. The method of manufacturing a semiconductor device as defined in claim 8, wherein said material for forming external electrodes is solder.
15. The method of manufacturing a semiconductor device as defined in claim 8, further comprising:
a step of punching said substrate around said semiconductor chip, after the step of electrically connecting electrodes of said semiconductor chip to said conductive member.
16. The method of manufacturing a semiconductor device as defined in claim 8,
wherein in the step of electrically connecting said electrodes of said semiconductor chip to said conductive member, said electrodes are connected to said conductive member through an anisotropic conductive material having conductive particles
dispersed in an adhesive.
17. The method of manufacturing a semiconductor device as defined in claim 8,
wherein in the step of electrically connecting said electrodes of said semiconductor chip to said conductive member, said electrodes are connected to said conductive member through wires.
18. A method of manufacturing a semiconductor device, comprising:
a step of providing a substrate in which penetrating holes are formed and a conductive member is formed over a region including said penetrating holes;
a step of providing a material for forming external electrodes on said conductive member, and forming external electrodes through said penetrating holes to project from the surface opposite to the surface of said substrate on which said
conductive member is formed; and
a step of electrically connecting electrodes of a semiconductor chip to said conductive member;
wherein each of said external electrodes includes a base portion positioned within each of said penetrating holes and a projecting portion projecting from each of said penetrating holes, the diameter d of said base portion being related to the
diameter .phi. of said projecting portion by .phi..ltoreq.d.
19. The method of manufacturing a semiconductor device as defined in claim 18, wherein said material for forming external electrodes is solder.
20. The method of manufacturing a semiconductor device as defined in claim 18, further comprising:
a step of punching said substrate around said semiconductor chip, after the step of electrically connecting electrodes of said semiconductor chip to said conductive member.
21. The method of manufacturing a semiconductor device as defined in claim 18,
wherein in the step of electrically connecting said electrodes of said semiconductor chip to said conductive member, said electrodes are connected to said conductive member through an anisotropic conductive material having conductive particles
dispersed in an adhesive.
22. The method of manufacturing a semiconductor device as defined in claim 18,
wherein in the step of electrically connecting said electrodes of said semiconductor chip to said conductive member, said electrodes are connected to said conductive member through wires. |
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Claims |
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Description |
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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 .phi. of the projecting portion by .phi..ltoreq.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 .phi. of the projecting portion by .phi..ltoreq.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 .phi. of the projecting portion by .phi..ltoreq.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 the adhesive material is drawn into
the penetrating holes;
a step of adhering a conductive member over a particular region on the one surface including the penetrating holes on the substrate through the adhesive material;
a step of providing a material for forming external electrodes on the conductive member, and forming external electrodes through the penetrating holes and the inner side of the part of adhesive material drawn into the penetrating holes to project
from the surface opposite to the surface of the substrate on which the conductive member is formed; and
a step of electrically connecting electrodes of a semiconductor chip to the conductive member.
According to the present invention, when the substrate is punched and the penetrating holes are formed, at the same time part of the adhesive material can be drawn into the penetrating holes. When the external electrodes are formed through the
penetrating holes, this part of the adhesive material is interposed between the external electrodes and penetrating holes. With the thus obtained semiconductor device, the adhesive material acts as a stress absorption material, and 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 absorbed, and the occurrence of cracks in the external electrodes can be prevented.
(15) According to a seventh aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising:
a step of providing a substrate of a material of a higher elasticity than external electrodes, having penetrating holes in which the internal wall surfaces have protrusions, and having a conductive member directly formed over a region including
the penetrating holes;
a step of providing a material for forming external electrodes on the conductive member, and forming external electrodes through the penetrating holes to project from the surface opposite to the surface of the substrate on which the conductive
member is formed; and
a step of electrically connecting electrodes of a semiconductor chip to the conductive member.
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.
(16) The method of manufacturing the semiconductor device may further comprise a step of punching the substrate before the conductive member is formed, wherein a part of the substrate is drawn into the penetrating holes and the protrusions are
formed.
By this means, in the step of punching, the protrusions can be formed simply.
(17) In this method of manufacture, the penetrating holes may be formed by a laser.
When a laser is used, the protrusions occur naturally.
(18) In this method of manufacture, the penetrating holes may be formed by wet etching.
When wet etching is applied, the protrusions occur naturally.
(19) In this method of manufacture, 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 .phi. of the projecting portion by .phi..ltoreq.d.
By this means, 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.
(20) According to an eighth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising:
a step of providing a substrate in which penetrating holes are formed and a conductive member is formed over a region including the penetrating holes;
a step of providing a material for forming external electrodes on the conductive member, and forming external electrodes through the penetrating holes to project from the surface opposite to the surface of the substrate on which the conductive
member is formed; and
a step of electrically connecting electrodes of a semiconductor chip to the conductive member;
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 .phi. of the projecting portion by .phi..ltoreq.d.
With a semiconductor device fabricated according to the present invention, the diameter d of the base portion of the external electrodes is related to the diameter .phi. of the projecting portion by .phi..ltoreq.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 as a result the occurrence of cracks in the external electrodes can be prevented.
(21) The substrate may be either of an insulating film and a printed substrate.
(22) The material for forming external electrodes may be solder.
(23) The method of manufacturing a semiconductor device may further comprise a step of punching the substrate around the semiconductor chip, after the step of electrically connecting electrodes of the semiconductor chip to the conductive member.
(24) In the step of electrically connecting the electrodes of the semiconductor chip to the conductive member, the electrodes may be connected to the conductive member through an anisotropic conductive material having conductive particles
dispersed in an adhesive.
(25) In the step of electrically connecting the electrodes of the semiconductor chip to the conductive member, the electrodes may be connected to the conductive member through wires.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1(A) is a cross-sectional view of a first embodiment of the semiconductor device, and FIG. 1(B) is an enlarged view of the encircled portion of FIG. 1(A).
FIGS. 2A and 2B show the method of manufacturing the first embodiment of the semiconductor device.
FIG. 3 shows a modification of the first embodiment of the semiconductor device.
FIG. 4 is a cross-sectional view of a second embodiment of the semiconductor device.
FIG. 5 shows a third embodiment of the semiconductor device.
FIG. 6 shows a fourth embodiment of the semiconductor device.
FIG. 7 is a cross-sectional view of a fifth embodiment of the semiconductor device.
FIGS. 8A and 8B show the method of manufacturing the fifth embodiment of the semiconductor device.
FIG. 9 shows the method of manufacturing the fifth embodiment of the semiconductor device.
FIG. 10 shows the method of manufacturing the fifth embodiment of the semiconductor device.
FIG. 11 shows a circuit board on which is mounted the present embodiment of a semiconductor device.
FIG. 12 shows an electronic instrument provided with a circuit board on which is mounted the present embodiment of a semiconductor device.
DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention is now described in terms of a number of preferred embodiments, with reference to the drawings.
First Embodiment
FIG. 1(A) shows a first embodiment of the semiconductor device. A semiconductor device 10 comprises a semiconductor chip 12, being an example of a semiconductor chip, and an insulating film 14, being an example of a substrate, to which the CSP
type of package is applied. On the insulating film 14 are formed external electrodes 16, and the semiconductor chip 12 has a plurality of electrodes 13. In FIG. 1(A), the electrodes 13 are formed on only two opposite sides of the semiconductor chip 12,
but as is well known, may equally be formed on four sides.
The insulating film 14 is formed of a polyimide resin or the like, and has a plurality of penetrating holes 14a. As the substrate formed of polyimide resin may be used one such that for example:
Coefficient of thermal expansion =12 ppm/.degree. C.
Modulus of elasticity =900 kg/mm.sup.2
Or one such that:
Coefficient of thermal expansion =20 ppm/.degree. C.
Modulus of elasticity =302 kg/mm.sup.2
To one surface of the insulating film 14 is adhered a wiring pattern 18, being an example of a conductive element. In more detail, the wiring pattern 18 is adhered to the insulating film 14 by an adhesive 17. As the adhesive 17, being an
example of an adhesive material may be used one such that:
Coefficient of thermal expansion (50 to 150.degree. C.)=70 to 165 ppm/.degree. C.
Modulus of elasticity (150.degree. C.)=0.1 to 0.9.times.10.sup.8 Pa
Elongation after fracture=13 to 29%
And may be used one such that for example:
Coefficient of thermal expansion (50 to 150.degree. C.)=70 ppm/.degree. C.
Modulus of elasticity (150.degree. C.)=0.1.times.10.sup.8 Pa
Elongation after fracture 21%
A part of the adhesive 17 enters the penetrating holes 14a. It should be noted that in place of the adhesive 17 may be used an adhesive tape or the like. The wiring pattern 18 is formed so as to pass over the penetrating holes 14a, and although
not shown in FIG. 1(A), the portions including the position over the penetrating holes 14a are lands of greater width than other portions.
Further, in the insulating film 14 external electrodes 16 are formed, through the penetrating holes 14a, on the wiring pattern 18 (below in the figure). The external electrodes 16 include base portions 16a bonded to the wiring pattern 18 at
positions within the penetrating holes 14a, and projecting portions 16b projecting from the insulating film 14 on the opposite side to the wiring pattern 18. It should be noted that external electrodes 16 are formed of solder, copper, nickel, or the
like.
In this embodiment, as shown in enlargement in FIG. 1(B), a part of the adhesive 17 is interposed between the base portions 16a of the external electrodes 16 and the penetrating holes 14a. By means of this part of the adhesive 17, stress
(thermal stress or mechanical stress) applied to the external electrodes 16 is absorbed. The stress often occurs when heat is applied, and therefore the adhesive 17 is required to have a degree of flexibility and elasticity at least when heat is applied
such as to function to absorb the stress.
On each part of the wiring pattern 18 is formed a projection 18a. The projections 18a are formed to correspond to the electrodes 13 of the semiconductor chip 12. As a result, if the electrodes 13 are arranged on the four sides of the periphery
of the semiconductor chip 12, the projections 18a will also be arranged along the four sides. The electrodes 13 are electrically connected to the projections 18a, and through the wiring pattern 18 are conductively connected to the external electrodes
16. By the formation of the projections 18a, a wide gap can be formed between the insulating film 14 and the semiconductor chip 12 or between the wiring pattern 18 and the semiconductor chip 12.
The electrical connection of the electrode 13 and projection 18a is achieved by means of an anisotropic conductive film 20 being an example of an anisotropic conductive material. The anisotropic conductive film 20 comprises conductive particles
such as metal fine particles dispersed in a resin in sheet form. When the anisotropic conductive film 20 is compressed between the electrodes 13 and projections 18a, the conductive particles are also compressed, forming electrical connection between the
two. When the anisotropic conductive film 20 is used, the conductive particles conduct electricity only in the direction in which they are compressed, and do not conduct electricity in other directions. As a result, even when the sheet-form anisotropic
conductive film 20 is adhered on the plurality of electrodes 13, there is no electrical connection between adjacent of the electrodes 13.
In the above described example, the projections 18a are formed on the wiring pattern 18, but equally, bumps maybe formed on the electrodes 13 of the semiconductor chip 12, and in this case, the projections 18a do not need to be formed on the
wiring pattern 18.
In this embodiment, the anisotropic conductive film 20 is formed only between the electrodes 13 and projections 18a and in the vicinity thereof, but it may equally be formed only between the electrodes 13 and projections 18a, or may be formed
over the whole surface of the semiconductor chip 12, including the region in which a resin 22 described below is injected.
In the gap formed between the insulating film 14 and the semiconductor chip 12, a resin 22 is injected from a gel injection aperture 24. It should be noted that when the anisotropic conductive film 20 is formed over the whole surface of the
semiconductor chip 12 the injection aperture 24 is not necessary, and moreover the step of injecting the resin 22 is not required.
If as the resin 22 is used a material with a low Young's modulus and an ability to absorb stress, then in addition to the stress absorption function of the adhesive 17, further stress absorption can be achieved. For example, by using polyimide
resin, silicone resin, silicone denatured polyimide resin, epoxy resin, silicone denatured epoxy resin, acrylic resin, and so forth, the resin 22 provides a stress absorption unction.
Next, the principal steps in the method of manufacturing the present embodiment of the semiconductor device 10 are described.
First, the insulating film 14 with the adhesive 17 provided on one surface is taken, and penetrating holes 14a are formed in the insulating film 14. This step is shown in FIGS. 2A and 2B. More specifically, as shown in FIG. 2A, first, a punch 1
and a die 2 are disposed on the side on which the adhesive 17. In this figure, the insulating film 14 is positioned with the surface having the adhesive 17 uppermost, and the punch 1 is positioned above. It should be noted that the insulating film 14
is mounted on a support not shown in the figure. Then as shown in FIG. 2B, the insulating film 14 is penetrated by the punch 1, and penetrating holes 14a are formed. The punch 1 is guided by the die 2, and drags in the adhesive 17 as it penetrates the
insulating film 14. As a result, part of the adhesive 17 is drawn into the interior of the penetrating holes 14a. The adhesive 17 drawn into the penetrating holes 14a does not return when the punch 1 is withdrawn, but remains within the penetrating
holes 14a. It should be noted that in order for the adhesive 17 to be drawn into the penetrating holes 14a, it is preferable for there to be a clearance of the order of 10 to 50 .mu.m between the punch 1 and die 2.
Preferably, at the same time that the penetrating holes 14a are formed, a gel injection aperture 24 is also formed in the insulating film 14.
Then a conductive film such as a copper foil is adhered to the insulating film 14, and by etching the wiring pattern 18 is formed. By masking the region of formation of the projections 18a and etching so that other portions are made thin, when
the mask is removed, the projections 18a can be formed.
Next, the anisotropic conductive film 20 is adhered on the insulating film 14 over the projections 18a. In more detail, when the plurality of projections 18a are arranged along two opposing sides, the anisotropic conductive film 20 is adhered in
two parallel strips, and when the projections 18a are arranged along four sides, the anisotropic conductive film 20 is adhered so as to describe a corresponding rectangle.
In this way, the above described insulating film 14 is pressed onto the semiconductor chip 12 such that the projections 18a and electrodes 13 correspond, an | | |
