Mounting structure of semiconductor element

[0002] This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 9-28087 filed on Feb. 12, 1997, the contents of which are incorporated herein by reference.

[0003] 1. Field of the Invention:

[0004] The present invention relates to a mounting structure of a semiconductor element such as a flip chip IC, which is mounted on an insulation substrate.

[0005] 2. Related Arts:

[0006] FIG. 1A shows a conventional structure of a ceramic laminated substrate 1 made of alumina (referred to as an alumina laminated substrate) and a flip chip IC 7 mounted on the alumina laminated substrate. The alumina laminated substrate 1 has via holes 2 (referred to as vias) filled with conductive material and inside wires 3 provided therein. Further, conductive lands 4 are provided on the surface of the alumina laminated substrate 1 and are connected to the vias 2. The flip chip IC 7 has solder bumps 8, and is joined to the alumina laminated substrate 1 by aligning the solder bumps 8 with the conductive lands 4.

[0007] In this case, due to a difference in thermal expansion coefficient between the flip chip 7 and the substrate 1, the larger the size of the flip chip IC 7 becomes, the larger thermal distortion of the solder bumps 8 becomes. Therefore, reinforcement resin 9 is injected into a space between the flip chip IC 7 and the substrate 1 in order to prevent the distortion of the bumps 8. In addition, inspection lands 6 for inspecting the flip chip IC 7 are disposed on the surface of the substrate 1 and are connected to the conductive lands 4 through wiring members 5 made of conductive material as shown in FIG. 1B.

[0008] During thermal testing of the above-mentioned mounting structure, separation of the reinforcement resin 9 from the substrate 1 started from a joining portion between an edge portion A (herebelow referred to as a fillet portion) of the reinforcement resin 9 around the flip chip 7 and the wiring members 5. Then, the separation progressed inside of the joining portion. As a result, the reinforcement resin 9 did not sufficiently reinforce the solder bumps 8, so that cracks were produced in the solder bumps 8. It is assumed that the reason why the separation started from the joining portion between the fillet portion A of the reinforcement resin 9 and the wiring members 5 is because the adhesive strength between the reinforcement resin 9 and the wiring members 5 is significantly small compared to that between the reinforcement resin 9 and the alumina laminated substrate 1.

[0009] This kind of problem is not limited to the above-mentioned mounting structure of the flip chip IC 7, and may occur to the other mounting structures. For example, when a bare chip like a semiconductor element is mounted on an insulation substrate through wires, the wires are generally connected to bonding pads (wire lands) provided on the substrate. The semiconductor element is sealed with sealing resin. Even in this structure, a wiring pattern for connecting inspection lands and the wire lands is provided on the surface of the substrate, so that there arises a similar problem that the sealing resin is separated from the wiring pattern. Consequently, the wires are opened.

[0010] The present invention has been made in view of the above-mentioned problems and an objective of the present invention is to provide a mounting structure of a semiconductor element mounted on an insulation substrate with resin interposed therebetween without producing separation of the resin from the substrate. More specifically, the object of the present invention is to prevent the separation of the resin from the substrate on a wiring member for an inspection land.

[0011] In a mounting structure according to the present invention, a semiconductor element is mounted on an insulation substrate through a conductive land disposed on the insulation substrate. A resin member is then disposed around the semiconductor element and the conductive land on the insulation substrate. Further, an inspection land is disposed on an outside of the resin member on the insulation substrate, and is connected to the conductive land through an inside wire provided in the insulation substrate so as to bypass the resin member. In this structure, there is no wiring pattern for the inspection land on the insulation substrate. The inside wire connecting the inspection land and the conductive land does not contact the resin member. Therefore, avoiding separating the resin member from the insulation substrate.

[0012] The semiconductor element may have a bump and can be mounted on the insulation substrate through the bump and the conductive land which are electrically connected to each other. In this case, the resin member is disposed in a space between the semiconductor element and the insulation substrate. The semiconductor element may be connected to the conductive land through a wire. In this case, the resin member covers the semiconductor element and the wire. The insulation substrate may be a laminated substrate having a via.

[0013] These and other objects and features of the present invention will become more readily apparent from a better understanding of preferred embodiments described below with reference to the following drawings.

[0014] FIG. 1A shows a cross-sectional view showing a mounting structure of a flip chip IC according to a prior art;

[0015] FIG. 1B is a plan view showing the mounting structure of the flip chip IC shown in FIG. 1;

[0016] FIG. 2A is a cross-sectional view showing an alumina laminated substrate and a flip chip IC before mounted on the substrate in a first preferred embodiment of the present invention;

[0017] FIG. 2B is a plan view showing the alumina laminated substrate before mounting the flip chip IC thereon in the first embodiment;

[0018] FIG. 3A is a cross-sectional view showing a mounting structure of the flip chip IC and the alumina laminated substrate in the first embodiment;

[0019] FIG. 3B is a plan view showing the mounting structure of the flip chip IC and the alumina laminated substrate in the first embodiment;

[0020] FIG. 4 is a cross-sectional view showing a mounting structure of the flip chip and a printed multi-layer substrate in the first embodiment;

[0021] FIG. 5 is a cross-sectional view showing a mounting structure of a semiconductor bare chip and a substrate in a second preferred embodiment; and

[0022] FIGS. 6A and 6B are cross-sectional views for explaining a position where a wire land is to be provided on a via in the second embodiment.

[0023] In embodiments, the parts and components similar to those in the prior art shown in FIGS. 1A and 1B are shown by the same reference numerals and similar descriptions thereof will be simplified.

[0024] As shown in FIGS. 2A and 2B, an alumina laminated substrate 1 in a first preferred embodiment has wiring patterns composed of vias 2 and inside wires 3 therein. Further, conductive lands 4 and inspection lands 6 are disposed on the surface of the alumina laminated substrate 1 and respectively connected to the vias 2. The vias 2 and the inside wires 3 provided in the alumina laminated substrate 1 electrically connect various electronic parts mounted on the alumina laminated substrate 1, and simultaneously electrically connect the conductive lands 4 and the inspection lands 6. The electronic parts include a semiconductor element, a capacitor, a resistor, and the like. The conductive lands 4 and the inspection lands 6 are made of materials including copper, silver, nickel, gold, platinum, palladium, or tin as a main material.

[0025] A flip chip IC 7 has solder bumps 8 formed on electrodes thereof. As shown in FIG. 2A, the solder bumps 8 are positioned with respect to the conductive lands 4, and the flip chip IC 7 is mounted on the alumina laminated substrate 1 by fusing the solder bumps 8. Then, as shown in FIG. 3A, reinforcement resin 9 is injected into a space between the flip chip IC 7 and the alumina laminated substrate 1. An epoxy system resin including glass filler of 70 wt % can be used as the reinforcement resin 9. The plan view of the thus formed mounting structure is shown in FIG. 3B.

[0026] In the above-mentioned mounting structure, the inspection lands 6 are electrically connected to the conductive lands 4 through the vias 2 and the inside wires 3 provided in the alumina laminated substrate 1. That is, the wiring structure of the inspection lands 6 and the conductive lands 4 bypass the fillet portion A of the reinforcement resin 9. Accordingly, the fillet portion A of the reinforcement resin 9 does not contact wiring members of the inspection lands 6. The fillet portion A of the reinforcement resin 9 only contacts the alumina laminated substrate to have large adhesive strength. As a result, the reinforcement resin 9 does not separate from the alumina laminated substrate 1 even under thermal cycles, stress such as moisture, and the like.

[0027] Although the alumina laminated substrate 1 is employed as an insulation substrate in this embodiment, another laminated substrate baked at a lower temperature may be used as the insulation substrate. The insulation substrate may be a printed multi-layer substrate 1A shown in FIG. 4 including an alumina substrate 1aand an insulation glass member 1bdisposed on the alumina substrate 1a. In this case, because the adhesive strength between the reinforcement resin 9 and the insulation glass member 1bis large, the same effect as mentioned above can be obtained. The insulation substrate may be a single layer substrate. In this case, vias are formed to penetrate the substrate, and conducive lands formed on the surface of the substrate are electrically connected to the inspection lands formed on the other surface of the substrate through the vias and wiring members.

[0028] In a second preferred embodiment, a semiconductor bare chip 11 is mounted on the alumina laminated substrate 1 as shown in FIG. 5. The alumina laminated substrate 1 has the vias 2 and the inside wires 3 therein to form inside wiring patterns as in the first embodiment. The alumina laminated substrate 1 further has wire lands 10 and the detection lands 6 that are respectively connected to the vias 2. The semiconductor bare chip 11 is bonded to the alumina laminated substrate 1 by adhesives 12 including, for example, epoxy resin and silver filler. Then, wire bonding is performed to electrodes of the semiconductor bare chip 11 and the wire lands 10 by using wires 13 made of gold, aluminum, or the like. Then, the semiconductor bare chip 11 is sealed with sealing resin 14 including epoxy system resin or the like. The wire lands 10 can be made of conductive materials such as copper, aluminum, gold, silver, or the like.

[0029] In the second embodiment, the inspection lands 6 are electrically connected to the wire lands 10 through the vias 2 and the inside wires 3 as in the first embodiment. Therefore, the wiring structure in the second embodiment bypaths an edge portion B of the sealing resin 14 as well. As a result, the edge portion B of the sealing resin 14 only contacts the alumina laminated substrate to have sufficient adhesive strength. Consequently, separation of the sealing resin 14 from the alumina laminated substrate 1 can be prevented even under thermal cycles, stress such as moisture, or the like.

[0030] In the second embodiment, when the wires 13 are respectively bonded to the wire lands 10, it is difficult for the wires 13 to be bonded on the wire lands 10 just above the vias 2. This is because, as shown in FIG. 6A, surface roughness of each of the wire lands 10 just above the vias 2 is relatively large. Therefore, it is preferable that the wires 13 are bonded to the wire lands 10 not to be just above the vias 2 as shown in FIG. 6B. To bond the wires 13 in such a manner, it is preferable that the conductive lands 10 are formed on the vias 2 such that each center of the conductive lands 10 is shifted from each center of the vias 2.

[0031] In the second embodiment, a laminated substrate baked at a low temperature, a single layer substrate, a printed multi-layer substrate, or the like can be used as the insulation substrate in place of the alumina laminated substrate 1 as well. In the first and second embodiments, it is not always necessary that the number of the inspection lands 6 is equal to that of the conductive lands 4 or 10. The number of the inspection lands 6 can be determined based on a number of terminals used for an inspection.

[0032] While the present invention has been shown and described with reference to the foregoing preferred embodiment, it will be apparent to those skilled in the art that changes in form and detail may be made therein without departing from the scope of the invention as defined in the appended claims.