ELECTRONIC DEVICE AND METHOD OF MANUFACTURING THE SAME

In a method of producing an electronic device, a thermoplastic resin film is sandwiched between an electronic component having electrodes and a mounting member having a substrate to produce a lamination assembly. Via holes are formed in the thermoplastic resin film and filled with conductive paste. Through holes as depressed sections are formed in at least one of an area in the substrate, which faces the thermoplastic resin film, and an area in a connecting section formed on the substrate and which is not contact with the conductive paste in the via holes. The lamination assembly is heated and pressed in a lamination direction, thereof, simultaneously in order to sinter the conductive paste in the via holes. This produces an interlayer connection member in each via hole and the electronic device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the various embodiments, like reference characters or numerals designate like or equivalent component parts throughout the several diagrams.

First Exemplary Embodiment

A description will be given of an electronic device and a method of manufacturing the electronic device according to a first exemplary embodiment with reference toFIG. 1toFIG. 5.

FIG. 1is an overall view showing a cross section of the electronic device comprised of a mounting member10, and a bonding member20and an electronic component30(a semiconductor chip) according to the first exemplary embodiment. As shown inFIG. 1, the electronic device according to the first exemplary embodiment has a structure in which the electronic component30(i.e. a semiconductor chip) is mounted onto the mounting member10through the bonding member20.

In particular, the mounting member10is a printed circuit board (PCB), etc. in which wiring patterns (omitted from drawings) and connecting sections12are formed on a surface11aof a substrate11having a rectangle shape.

FIG. 2is a plan view of the mounting member10in the electronic device according to the first exemplary embodiment of the present invention shown inFIG. 1. As shown inFIG. 2, each of the three connecting sections12has a rectangle shape and arranged in a longitudinal direction of the substrate11of the mounting member10. However, the shape of the connecting sections is not limited.

For example, the substrate11in the mounting member10is made of a glass epoxy substrate, and the wiring pattern (not shown) is made of copper (Cu), etc. The cross section of the electronic device shown inFIG. 1is obtained using the I-I line which crosses the electronic device shown inFIG. 2.

As shown inFIG. 1andFIG. 2, a plurality of through holes13is formed in the substrate11along a thickness direction of the substrate11as the mounting member10. That is, the two through holes13are formed in the area of the substrate11, which correspond in position to the bonding member20. As shown inFIG. 2, in the structure of the electronic device according to the first exemplary embodiment, the two through holes13are formed in the area of the substrate11, which corresponds to the area in the bonding member20in which no connecting section is formed.

Each of the through holes13corresponds to a depressed section used in the claims of the present invention. The through holes13will be explained in detail later. A thermoplastic resin flows into the through holes13as the depressed sections during the manufacturing of the electronic device. That is, the thermoplastic resin flows from the surface11aof the substrate11into the inside of the through holes13formed in the substrate11. As shown inFIG. 1, an upper half of each of the through holes13at the surface11aside of the substrate11is filled with the thermoplastic resin. The dotted line inFIG. 2indicates the bonding member20arranged on the mounting member10.

The bonding member20is made of a thermoplastic resin film21. Via holes22are formed at the position in the thermoplastic resin film21which correspond to the connecting sections12of the mounting member10. The via holes22penetrate in a thickness direction of the thermoplastic resin film21. Further, an interlayer connection member23is formed in each of the via holes22. Each of the interlayer connection members23is electrically connected to the corresponding connecting section12of the mounting member10.

In the electronic device according to the first exemplary embodiment, each of the via holes22has a tapered shape in which a diameter of the via hole22is gradually decreased toward the mounting member10side, as shown inFIG. 1. However, the concept of the present invention is not limited by this structure of the via holes22. It is possible for each of the via hoes22to have another tapered shape in which the diameter of the via hole22is gradually increased toward the mounting member10side or the via hole22has a constant diameter, i.e. has a cylindrical shape.

The interlayer connection member23is formed by sintering a conductive paste24. The conductive paste24is obtained by adding organic solvent such as paraffin to metal particles of Ag—Sn, etc. The thermoplastic resin film21has a glassy-transition temperature which is higher than a sintering temperature of metal particles which form the interlayer connection member23, and lower than a melting point of the mounting member10and the electronic component30(a semiconductor chip).

The electronic component30is comprised of a semiconductor chip, etc. The electronic component30has a plurality of electrodes31at a surface thereof. When the electrodes31are electrically connected to the interlayer connection members23formed in the via holes22, the electrodes31of the electronic component30are electrically connected to the connecting sections12through the interlayer connection members23formed in the via holes22.

The electronic device according to the first exemplary embodiment has the improved structure previously described.

Next, a description will now be given of the method of manufacturing the electronic device having the structure previously described according to the first exemplary embodiment with reference toFIG. 3A,FIG. 3B,FIG. 4AandFIG. 4B.

FIG. 3Ais a view showing a cross section of a component member40before the via holes22are filled with the conductive paste24in a process of manufacturing the electronic device according to the first exemplary embodiment shown inFIG. 1.FIG. 3Bis a view showing a cross section of the component member40after the via holes22are filled with the conductive paste24in the process of manufacturing the electronic device according to the first exemplary embodiment shown inFIG. 1.

In the method of manufacturing the electronic device, as shown inFIG. 3A, the thermoplastic resin film21is prepared. The via holes22are formed in the thermoplastic resin film21by using a gas laser, etc.

As shown inFIG. 3B, the via holes22are then filled with the conductive paste24. This produces the component member40. The conductive paste24is composed of a paste obtained by adding organic solvent such as paraffin to metal particles of Ag—Sn having a melting point of 480° C.

It is possible to use a device capable of filling the conductive paste24into the via holes22which is disclosed, for example in a patent document JP 2010-50356.

In a brief explanation, the thermoplastic resin film21is placed on a supporting table through an adsorption paper so that a back surface of the thermoplastic resin film21faces the adsorption paper on the supporting table. The adsorption paper is a wood free paper which is easily available on the commercial market. That is, it is sufficient to use a paper so long as it can absorb the organic solvent contained in the conductive paste24.

The via holes22are filled with the conductive paste24while the conductive paste24is melted. At this process, because the wood free paper adsorbs the organic solvent contained in the conductive paste24, it is possible to fill the vial holes22with the metal particles contained in the conductive paste24.

FIG. 4AandFIG. 4Bare views showing a cross section of the electronic device in the manufacturing process according to the first exemplary embodiment shown inFIG. 1.

As shown inFIG. 4A, the mounting member10is prepared, in which the wiring patterns (not shown), the connecting sections12and the through holes13are formed. The component member40(made of the thermoplastic resin film21having the via holes22with the conductive paste24) is arranged on the mounting member10so that the conductive paste24in the via holes22is electrically contacted with the connecting sections12, and the electrodes31of the electronic component30(semiconductor chip) are electrically connected with the conductive paste24in the via holes22. The through holes13are formed in the substrate11. The surface11aof the substrate11faces the connecting sections12and the component member40(as the thermoplastic resin film21). This produces the lamination assembly50.

As shown inFIG. 4B, the lamination assembly50is comprised of the electronic component30, the component member40and the mounting member10. The lamination assembly50is placed between a pair of pressing boards. The lamination assembly50is heated at a predetermined heating temperature and pressed toward a lamination direction thereof simultaneously by a pressing machine, for example. The heating temperature is higher than a sintering temperature of the metal particles contained in the conductive paste24in the via holes22and a deformation temperature of the thermoplastic resin film21in the component member40at which the thermoplastic resin film21becomes soften, and also higher than a melting point of the mounting member10and a melting point of the electronic component30.

The thermoplastic resin contained in the thermoplastic resin film21is softened, and the softened thermoplastic resin flows on the surface30aof the electronic component30. The thermoplastic resin bonds the electronic component30on the bonding member20. Further, the softened thermoplastic resin also flows on the surface11aof the substrate11of the mounting10and bonds the bonding member20on the mounting member10. Still further, the conductive paste24in the via holes22is heated and pressed simultaneously by flowing the softened thermoplastic resin. This makes it possible to sinter and bond the metal particles together contained in the conductive paste24. That is, a diffusion bonding is formed between the metal particles, the connecting sections12and the electrodes31of the electronic component30. That is, the interlayer connection members23are formed in the via holes22. As a result, the electrodes31of the electronic component30are electrically connected to the connecting sections12through the interlayer connection members23formed in the via holes22.

At this time, because the through holes13have been formed in the substrate11, the thermoplastic resin flows into the through holes13. This makes it possible to prevent the thermoplastic resin from flowing toward the surface11aof the substrate11.

As previously described in detail, the method of manufacturing electronic devices according to the first exemplary embodiment uses the substrate11in which the through holes13are formed. This structure of the substrate11makes it possible to suppress the thermoplastic resin from flowing in a surface direction of the surface11aof the substrate11because the thermoplastic resin flows into the inside of the through holes13when the electronic component30, the bonding member20and the mounting member10are bonded together to form the lamination assembly50. This also makes it possible to suppress the via holes22(which is filled with the conductive paste24) from being shifted toward the surface direction on the surface11aof the substrate11. It is therefore possible to avoid occurrence of a connection fault between the connecting sections12, the electrodes31, and the interlayer connection members23generated by sintering the conductive paste24.

In addition, it is possible to adjust the thickness of the bonding members20by adjusting an amount of the thermoplastic resin flowing into the through holes13. That is, the more the amount of thermoplastic resin flowing into the through holes13is increased, the more the thickness of the bonding member20decreases. On the other hand, the more the amount of thermoplastic resin flowing into the through holes13is decreased, the more the thickness of the bonding member20increases.

When a plurality of the electronic components30is arranged on the mounting member10, it is possible to form the bonding member20having a flat surface (which faces the surface30aof the electronic component30). The flat surface of the bonding member20has the same height measured from the other surface of the bonding member20(which faces the surface11aof the substrate11in the mounting member10) without changing a size of the surface11aof the substrate11.

FIG. 5is a view showing a modification of the electronic device according to the first exemplary embodiment shown inFIG. 1, in which two electronic components30(semiconductor chips) are mounted on the mounting member10through the bonding member20.

As shown inFIG. 5, even if each of the component member40(which corresponds to the thermoplastic resin film21) has a slightly different thickness and each of the electronic components30has a slightly different thickness, it is possible to form the surface of the bonding member20with the same height which is measured from the surface11aof the mounting member10because the thickness of the bonding member20is changed by adjusting an amount of thermoplastic resin flowing into the through holes13.

Further, the electronic device and the method according to the first exemplary embodiment use the conductive paste24which contains metal particles of Ag—Sn having a melting point of 480° C. This makes it possible to increase the capability of reflow resistance when components such as the bonding member20are mounted on and fixed to the mounting member10by solder.

The first exemplary embodiment shows the through holes13formed in the substrate11as the mounting member10, which correspond to the area between the adjacent connecting sections12in the bonding member20. However, the concept of the present invention is not limited by this structure. It is of course possible to form the through holes13at desired positions, for example, in the outside areas of the connecting sections12in the bonding member20.

Second Exemplary Embodiment

A description will be given of the electronic device and method according to a second exemplary embodiment with reference toFIG. 6andFIG. 7.

The first exemplary embodiment shows the electronic device having the structure in which the through holes13are formed in the mounting member10as previously described. However, the concept of the present invention is not limited by this structure.

The second exemplary embodiment shows the electronic device having another structure in which through holes12aare formed in connecting sections12-1in a bonding member20-1. Other components in the electronic device according to the second exemplary embodiment have the same structure and function of the components in the electronic device according to the first exemplary embodiment. The explanation of the same components is omitted here.

FIG. 6is a view showing a cross section of the electronic device according to the second exemplary embodiment.FIG. 7is a plan view of the mounting member10-1in the electronic device according to the second exemplary embodiment shown inFIG. 6.

As shown inFIG. 6andFIG. 7, the bonding member20-1in the electronic device according to the second exemplary embodiment has three connecting sections12and12-1. In particular, as shown inFIG. 6andFIG. 7, through holes12aare formed in the two connecting sections12-1. The two connecting sections12-1are formed at both the side areas in the bonding member20-1. The connecting sections have a plate shape.

The cross section of the electronic device comprised of the electronic component30, the bonding member20-1and the mounting member10-1in the electronic device shown inFIG. 6is obtained using the VI-VI line which crosses the electronic device shown inFIG. 7. The dotted line inFIG. 7indicates the bonding member20-1arranged on the mounting member10-1.

The method of manufacturing the electronic device according to the second exemplary embodiment performs the same processes of the method according to the first exemplary embodiment excepting a process of preparing the mounting member10-1having the through holes12a.

In the method of manufacturing the electronic device according to the second exemplary embodiment, the thermoplastic resin flows into the through holes12aformed in the connecting sections12-1in the bonding member20-1when the electronic component30, the bonding member20-1and the mounting member10-1are assembled together to form the lamination assembly. This process makes it possible to prevent the thermoplastic resin from flowing toward a surface direction on the surface11aof the substrate11-1as the mounting member10-1, and to have the same effects of the electronic device and the method according to the first exemplary embodiment previously described.

The second exemplary embodiment shows the structure in which the three connecting sections12and12-1are formed in the bonding member20-1. However, the concept of the present invention is not limited by this structure. It is possible for the bonding member20-1to have a structure in which the through hole12ais formed in one connecting section only, or the through holes12aare formed in all of the connecting sections. Still further, it is possible to change the position of the connecting section12-1in the bonding member20-1.

Third Exemplary Embodiment

A description will be given of the electronic device and method according to a third exemplary embodiment with reference toFIG. 8andFIG. 9.

FIG. 8is a view showing a cross section of the electronic device according to the third exemplary embodiment.FIG. 9is a plan view of the mounting member10-2of the electronic device according to the third exemplary embodiment shown inFIG. 8.

The third exemplary embodiment shows the electronic device having a structure in which two protruding sections14are formed on the surface11aof the substrate11-2. Other components in the electronic device according to the third exemplary embodiment have the same structure and function of the components in the electronic device according to the first exemplary embodiment. The explanation of the same components is omitted here.

As shown inFIG. 8andFIG. 9, the two protruding sections14are formed at both the outer sides of the bonding member20-2. That is, each of the protruding sections14is formed on the surface11aof the mounting member10-2, which corresponds to an outer side of the connecting sections12in the bonding member20-2.

In the structure of the electronic device according to the third exemplary embodiment, the protruding sections14are made of copper (Cu), etc. like the connecting sections12and the wiring patterns (not shown) formed on the substrate11-2. Further, the protruding sections14are not electrically connected to the connecting sections12and the interlayer connection members23formed in the via holes22in the bonding member20-2. In other words, the protruding sections14are dummy patterns.

The cross section of the electronic device comprised of the electronic component30, the bonding member20-2and the mounting member10-2in the electronic device shown inFIG. 8is obtained using the VIII-VIII line which crosses the electronic device shown inFIG. 9. The dotted line inFIG. 9indicates the bonding member20-2arranged on the mounting member10-2.

The method of manufacturing the electronic device according to the third exemplary embodiment performs the same processes of the method according to the first exemplary embodiment excepting a process of preparing the mounting member10-2having the protruding sections14.

In the method of manufacturing the electronic device according to the third exemplary embodiment, the protruding sections14can prevent the thermoplastic resin from flowing toward a direction of the surface11aof the substrate11-2. This process makes it possible to prevent the via holes22(filled with the conductive paste24or interlayer connection member23) from being deformed in a surface direction on the surface11aof the substrate11-2, and to have the same effects of the electronic device and the method according to the first exemplary embodiment previously described.

The third exemplary embodiment shows the structure of the electronic device in which the two protruding sections14are formed on the substrate11-2. However, the concept of the present invention is not limited by this structure. It is possible for the electronic device to have a structure in which four protruding sections14are formed around the connecting section12, or a structure in which an outer frame is formed around the three connecting sections12.

Fourth Exemplary Embodiment

A description will be given of the electronic device and method according to a fourth exemplary embodiment with reference toFIG. 10andFIG. 11.

FIG. 10is a view showing a cross section of an electronic device according to the fourth exemplary embodiment.FIG. 11is a plan view of the mounting member10in the electronic device according to the fourth exemplary embodiment shown inFIG. 10.

The electronic device according to the fourth exemplary embodiment has connecting sections12-2which are different in shape from the connecting sections12disclosed in the first to third exemplary embodiments. Other components in the electronic device according to the fourth exemplary embodiment have the same structure and function of the components in the electronic device according to the first exemplary embodiment. The explanation of the same components is omitted here.

As shown inFIG. 10andFIG. 11, in the structure of the electronic device according to the fourth exemplary embodiment, a through hole12bis formed in the connecting section12-3. The through holes12bcorrespond to second depressed sections used in the claims of the present invention. That is, the surface11aof the substrate11is exposed to the interlayer connection member23formed in the via hole22. In other words, the surface11aof the substrate11is directly connected to the electrically interlayer connection members23formed in the via holes22through the through hole12b.The through hole12bcorresponds to the depressed section used in the claims of the present invention. As shown inFIG. 10, the interlayer connection members23is formed in the via hole23, and also formed as a wedge in the through hole12b.

The cross section of the electronic device comprised of the electronic component30, the bonding member20-3and the mounting member10in the electronic device shown inFIG. 10is obtained using the X-X line which crosses the electronic device shown inFIG. 11. The dotted line inFIG. 11indicates the bonding member20-3arranged on the mounting member10.

The structure of the electronic device according to the fourth exemplary embodiment shown inFIG. 10andFIG. 11makes it possible to increase the contact area between the interlayer connection members23and the connecting section12-3. This further increases the strength of connecting the bonding member20-3to the substrate11of the mounting member10.

A lamination assembly is comprised of the electronic component30, a component member40(as thermoplastic resin film21) and the mounting member10. The lamination assembly in the electronic device according to the fourth exemplary embodiment is manufactured using the following method. The component member40is arranged on the mounting member10so that the through hole12is sealed with the conductive paste24. The electronic component30is arranged on the component member40(thermoplastic resin film21) so that the electrodes31of the electronic component30are contacted with the conductive paste24.

Fifth Exemplary Embodiment

A description will be given of the electronic device and method according to a fifth exemplary embodiment with reference toFIG. 12AtoFIG. 12D.

FIG. 12AtoFIG. 12Dare views showing cross sections of the electronic device according to the fifth exemplary embodiment during a process of manufacturing the electronic device. The fifth exemplary embodiment shows an improved method of producing the lamination assembly. Other components in the electronic device according to the fifth exemplary embodiment have the same structure and function of the components in the electronic device according to the first exemplary embodiment. The explanation of the same components is omitted here.

As shown inFIG. 12A, in the method according to the fifth exemplary embodiment, the thermoplastic resin film21is bonded onto the surface30aof the electronic component30. In more detail, the thermoplastic resin film21is arranged on the surface30aof the electronic component30, and the assembly composed of the thermoplastic resin film21and the electronic component30is pressed with a predetermined pressure while heating the assembly.

As shown inFIG. 12B, a plurality of the via holes22is formed in the thermoplastic resin film21by using carbon dioxide laser (CO2laser), etc. The electrodes31of the electronic component30are exposed to the corresponding via holes22formed in the thermoplastic resin film21.

As shown inFIG. 12C, the via holes22are filled with the conductive paste24. Because one surface of each of the via holes22uses the corresponding electrode31of the electronic component30in the fifth exemplary embodiment, it is not necessary to use any absorbent paper.

After this, as shown inFIG. 12D, the component member40(as the thermoplastic resin film21) is arranged on the mounting member50so that the connecting sections12are contacted with the conductive paste24in the via holes22. This makes the lamination assembly10. After this, the lamination assembly50is heated and pressed simultaneously, like the method according to the first exemplary embodiment. The production of the electronic device is completed.

The method according to the fifth exemplary embodiment does not use any absorbent paper. Further, because the electrodes31of the electronic component30are contacted with the via holes22, this structure makes it possible to suppress the separation of the conductive paste24from the via holes22and to suppress the conductive paste24from dropping. The fifth exemplary embodiment provides a simple manufacturing process and an easy design of the via holes as well as having the same effects of the first exemplary embodiment.

In the structure of the electronic device according to the first exemplary embodiment previously described, the through holes13which penetrate in the substrate11of the mounting member10are used as the depressed section defined in the claims of the present invention. However, the concept of the present invention is not limited by this structure. It is possible to use holes which do not penetrate the substrate11, instead of the through holes13.

In the structure of the electronic device according to the second exemplary embodiment previously described, the through holes12awhich penetrate in the connecting section12-1in the bonding member20-1are used as the depressed section defined in the claims of the present invention. However, the concept of the present invention is not limited by this structure. It is possible to use holes which do not penetrate the connecting section12-1, instead of the through holes12a.

In the structure of the electronic device according to the fourth exemplary embodiment previously described, the through holes12bwhich penetrate in the connecting section12-3in the bonding member20-3are used as the depressed section defined in the claims of the present invention. However, the concept of the present invention is not limited by this structure. It is possible to use holes which do not penetrate the connecting section12-3, instead of the through holes12b.

For example, it is possible to combine two or more of the structures of the electronic devices according to the first, second, third and fourth exemplary embodiments. For example, it is possible to combine the structures of the electronic devices according to the first and second exemplary embodiments. In this case, the through holes13are formed in the substrate11and the through holes12aare formed in the connecting sections12-1.

Further, it is possible to combine the structures of the electronic devices according to the second and third exemplary embodiments. In this case, the through holes12aare formed in the connecting sections12-1and the protruding sections14are formed in the substrate11-2.

Still further, it is possible to combine the structures of the electronic devices according to the second and fourth exemplary embodiments. In this case, the through holes12aand12bare formed in the connecting sections of the bonding member.

Furthermore, it is possible to combine the structures of the electronic devices according to the third and fourth exemplary embodiments. In this case, the protruding sections14are formed in the substrate11-2and the through holes12bare formed in the connecting sections12-3.

Furthermore, it is possible to combine the structures of the electronic devices according to the first, second, third and fourth exemplary embodiments. In this case, the through holes13and the protruding sections14are formed in the substrate11-2and the through holes12aand12bare formed in the connecting sections.

Still further, it is possible to combine the fifth exemplary embodiments with one or more of the first to fourth exemplary embodiments. In this case, the electronic device30equipped with the component member40(made of the thermoplastic resin film21) is arranged on the mounting member10.