JP2011198810A - Mounting structure and mounting method for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve mounting reliability and improvement in quality of a semiconductor device.SOLUTION: A mounting structure for a semiconductor device is configured as follows. A reinforcing plate 6 is provided in a region corresponding to the outside of a semiconductor chip 4 on the side of the lower surface 9b of a printed circuit board 9. In that state, a heat sink 8 is mounted by applying pressure onto the semiconductor chip 4. In order to slightly bend both of a wiring board 2 and the printed circuit board 9, it is configured to respectively utilize a load applied to the printed circuit board 9 via a plurality of solder balls 7 under the chip, because a region 9c under the chip of the printed circuit board 9 is not supported, and a load applied to the wiring board 2 via the semiconductor chip 4. Consequently, a load (P) applied onto the semiconductor chip 4 is dispersed to the whole of the rear surface of the wiring board 2, thereby reducing deformation of the plurality of solder balls 7.

Description

  The present invention relates to a mounting technique for a semiconductor device, and more particularly to a technique that is effective when applied to improve the reliability of mounting a semiconductor device when a heat dissipation member is attached.

  For example, Japanese Patent Application Laid-Open No. 2001-168562 (Patent Document 1) discloses a structure in which a heat sink (heat radiating member) is arranged on a semiconductor package (semiconductor device) and a heat sink.

JP 2001-168562 A

  In an electronic device such as a mobile phone, a semiconductor device (semiconductor package) such as a CPU (Central Processing Unit) is mounted on a printed circuit board (mounting board). In this type of semiconductor device, power consumption tends to increase with increasing processing speed and multifunctionality, and the amount of heat generated during operation also tends to increase rapidly in proportion thereto.

  A flip-chip connection type BGA (Ball Grid Array, hereinafter also simply referred to as FC-BGA) is known as an example of a semiconductor device that supports higher processing speed and multi-function. The FC-BGA structure is such that a semiconductor chip is mounted face down on a wiring board, which is a package board, by flip chip connection, and a plurality of solder balls serving as external connection terminals are provided in a grid on the back surface of the wiring board. It has been.

  In such an FC-BGA, in order to ensure stable operation, it is necessary to improve the heat dissipation of the FC-BGA. Therefore, a heat dissipation member for improving the heat dissipation performance of a semiconductor device such as a heat sink is provided in the semiconductor device. The structure provided in is essential.

  When a heat sink is provided on the FC-BGA, a heat sink is often provided according to user specifications. Therefore, a heat sink cannot be provided on the FC-BGA in advance, and after mounting the FC-BGA on the printed circuit board, the FC-BGA Often, a heat sink is provided at the top.

  However, in recent FC-BGA, since there is a demand for cost reduction, weight reduction, or size reduction, wiring boards and printed boards are becoming thinner. Therefore, when the heat sink is provided on the top of the FC-BGA after the FC-BGA is mounted on the printed circuit board as described above, the heat sink as the heat radiating member is disposed on the semiconductor device and the FC- A heat sink is attached by applying pressure to the BGA.

  Here, the present inventor assumes that the heat sink is attached. 1. When the lower region of the FC-BGA on the lower surface side of the printed circuit board (mounting substrate) is supported by a support member; In the case where the lower area of the FC-BGA on the lower surface side of the printed circuit board is not supported, pressure is applied from above the FC-BGA, and the mounting state of the FC-BGA on the printed circuit board (the solder ball which is an external connection terminal) The connection state and the like were evaluated.

  As a result, in 1 evaluation, when the lower part of the package (FC-BGA) is supported by the support member, the load is transmitted to the printed circuit board through the semiconductor chip. The present inventors have found a problem that the solder balls are crushed and deformed, and the balls are short-circuited. In general, the ball electrode in the region under the chip is a portion where the maximum stress is generated in the thermal cycle, and this inherently has a problem that the ball electrode is destroyed and the life of the ball electrode is shortened.

  Further, in the evaluation of 2, since the lower part of the package is not supported by the support member, a phenomenon occurs in which the printed circuit board (mounting board) bends downward at the lower part of the package. Due to the difference, the problem that the solder balls arranged mainly on the outer peripheral portion of the wiring board are deformed was found. That is, the subject that the solder ball arrange | positioned at the edge part of a wiring board deform | transforms was discovered.

  Due to the various problems described above, the present inventors have found a problem that reliability in mounting FC-BGA (semiconductor device, package) is lowered.

  The present invention has been made in view of the above problems, and an object thereof is to provide a technique capable of improving the reliability of mounting a semiconductor device.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

  A mounting structure of a semiconductor device according to a typical embodiment includes a wiring board, a semiconductor chip mounted on the wiring board, and ball electrodes that are a plurality of external connection terminals provided on the back surface of the wiring board. And a semiconductor device in which the ball electrode is disposed in both the lower and outer regions of the semiconductor chip, a mounting substrate on which the semiconductor device is mounted via the plurality of ball electrodes, and the semiconductor chip A heat dissipating member provided on the mounting substrate, a reinforcing plate provided in a region outside the semiconductor chip on the lower surface of the mounting substrate, and a pressure applied on the semiconductor chip by engaging the heat dissipating member and the reinforcing plate. A pressure member, and a pressure is applied to the semiconductor chip by the pressure member in a state in which a region outside the semiconductor chip on the lower surface of the mounting substrate is supported by the reinforcing plate. Is shall.

  In addition, a semiconductor device mounting method according to a representative embodiment includes a wiring board, a semiconductor chip mounted on the wiring board, and ball electrodes that are a plurality of external connection terminals provided on the back surface of the wiring board. And mounting the semiconductor device on a mounting substrate, wherein the ball electrode is disposed in both the lower and outer regions of the semiconductor chip, and (a) mounting the semiconductor device on a mounting substrate; b) applying a predetermined pressure on the semiconductor chip to attach a heat radiating member onto the semiconductor chip; and in the step (b), in a region outside the semiconductor chip on the lower surface of the mounting substrate. Pressure is applied on the semiconductor chip in a state where the reinforcing plate is provided.

  Of the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  The reliability of the mounting of the semiconductor device can be improved.

  In addition, the quality of the semiconductor device can be improved.

It is sectional drawing which shows an example of the structure of the semiconductor device of Embodiment 1 of this invention. FIG. 2 is a back view showing an example of a ball arrangement of the semiconductor device shown in FIG. 1. FIG. 2 is a cross-sectional view and a plan view illustrating an example of a mounting structure of the semiconductor device illustrated in FIG. 1. FIGS. 2A and 2B are a cross-sectional view and a plan view illustrating an example of a pressurized state when the heat sink of the semiconductor device illustrated in FIG. FIG. 6 is a cross-sectional view and a plan view showing a first modification of the mounting structure of the semiconductor device shown in FIG. 1. FIG. 8 is a cross-sectional view and a plan view showing a second modification of the mounting structure of the semiconductor device shown in FIG. 1. FIG. 10 is a cross-sectional view and a plan view showing a third modification of the mounting structure of the semiconductor device shown in FIG. 1. FIG. 10 is a cross-sectional view and a plan view showing a fourth modification of the mounting structure of the semiconductor device shown in FIG. 1. FIG. 10 is a cross-sectional view and a plan view showing a fifth modification of the mounting structure of the semiconductor device shown in FIG. 1. FIG. 10 is a cross-sectional view and a plan view showing a sixth modification of the mounting structure of the semiconductor device shown in FIG. 1. It is sectional drawing which shows the effect of the structure shown in FIG. FIG. 10 is a cross-sectional view and a plan view showing a seventh modification of the mounting structure of the semiconductor device shown in FIG. 1. It is sectional drawing which shows the 8th modification of Embodiment 1 of this invention. It is sectional drawing which shows the 9th modification of the structure of the semiconductor device of Embodiment 1 of this invention. It is sectional drawing which shows the 10th modification of the structure of the semiconductor device of Embodiment 1 of this invention. It is sectional drawing which shows the 11th modification of the structure of the semiconductor device of Embodiment 1 of this invention. It is sectional drawing which shows the 12th modification of the mounting structure of the semiconductor device of Embodiment 2 of this invention. It is sectional drawing which shows the 13th modification of the mounting structure of the semiconductor device of Embodiment 2 of this invention. It is sectional drawing which shows the 14th modification of the mounting structure of the semiconductor device of Embodiment 2 of this invention. It is a top view which shows the structure of the reinforcement board in the mounting structure shown in FIG. It is sectional drawing which shows the 15th modification of the mounting structure of the semiconductor device of Embodiment 2 of this invention. It is sectional drawing and a top view which show the 16th modification of the mounting structure of the semiconductor device of Embodiment 2 of this invention. It is sectional drawing which shows the 17th modification of the mounting structure of the semiconductor device of Embodiment 2 of this invention. It is sectional drawing which shows an example of the structure of the semiconductor device of Embodiment 3 of this invention. FIG. 25 is a back view showing an example of a ball arrangement of the semiconductor device shown in FIG. 24. FIG. 25 is a cross-sectional view and a plan view illustrating an example of a mounting structure of the semiconductor device illustrated in FIG. 24.

  In the following embodiments, the description of the same or similar parts will not be repeated in principle unless particularly necessary.

  Further, in the following embodiment, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments, but they are not irrelevant to each other unless otherwise specified. The other part or all of the modifications, details, supplementary explanations, and the like are related.

  Also, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), particularly when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and it may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps) are not necessarily indispensable unless otherwise specified and clearly considered essential in principle. Needless to say.

  Further, in the following embodiments, regarding constituent elements and the like, when “consisting of A”, “consisting of A”, “having A”, and “including A” are specifically indicated that only those elements are included. It goes without saying that other elements are not excluded except in the case of such cases. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted.

(Embodiment 1)
1 is a cross-sectional view showing an example of the structure of the semiconductor device according to the first embodiment of the present invention, FIG. 2 is a back view showing an example of a ball arrangement of the semiconductor device shown in FIG. 1, and FIG. 3 is a semiconductor device shown in FIG. FIG. 4 is a cross-sectional view and a plan view showing an example of a pressurized state when the heat sink of the semiconductor device shown in FIG. 1 is attached.

  As shown in FIGS. 1 and 2, the semiconductor device according to the first embodiment is a semiconductor package in which a semiconductor chip 4 is mounted on a substrate. Here, as an example of the semiconductor device, a semiconductor by flip-chip connection is used. A flip-chip type semiconductor device in which the chip 4 is mounted on a substrate will be taken up, and an FC-BGA (hereinafter also referred to simply as BGA 1) whose external connection terminal is a ball electrode will be taken up and explained.

  The configuration of the BGA 1 shown in FIGS. 1 and 2 will be described. A wiring board 2 that is a board having a main surface 2a and a back surface 2b opposite to the main surface 2a, and a plurality of solder bumps 5 on the main surface 2a of the wiring board 2. The semiconductor chip 4 mounted via the semiconductor chip 4, the underfill resin 3 filled around the solder bumps 5 and the side surface of the semiconductor chip 4, and the back surface 2 b of the wiring substrate 2. And a plurality of solder balls 7 which are external connection terminals. The plurality of solder balls 7 that are ball electrodes of the external connection terminals are arranged in a lattice shape (grid shape), for example, on the back surface 2 b of the wiring board 2.

  The wiring board 2 is called a package board or a BGA board, and has wiring and through-hole wiring (not shown) provided therein. Therefore, electrical signals transmitted and received by the semiconductor chip 4 are transmitted to the solder bumps 5 and wiring. It is transmitted via wiring inside the substrate 2 and through-hole wiring, and solder balls 7 on the back surface 2 b of the wiring substrate 2.

  In the BGA 1 according to the first embodiment, as shown in FIG. 2, solder balls 7 as external connection terminals are provided in a lattice shape over the entire back surface 2b of the wiring board 2. That is, the solder ball 7 is a full-bump type BGA 1 arranged on the entire back surface of the wiring board 2. Therefore, the solder ball 7 is located in both the region below the semiconductor chip 4 and the region outside the semiconductor chip 4. Has been placed.

  The semiconductor chip 4 has a main surface 4a on which electrode pads 4c as a plurality of surface electrodes are formed, and a back surface 4b opposite to the main surface 4a, and is connected to the wiring substrate 2 by flip chip connection. Electrically connected. In other words, the semiconductor chip 4 is electrically connected to the wiring substrate 2 via the plurality of solder bumps 5 electrically connected to the plurality of electrode pads 4c. Since the semiconductor chip 4 is mounted on the wiring board 2 by flip chip connection, it is mounted face-down on the wiring board 2, and the main surface 2a of the wiring substrate 2 and the main surface 4a of the semiconductor chip 4 are formed. Therefore, the back surface 4b of the semiconductor chip 4 is exposed upward.

  Next, the mounting structure of the semiconductor device according to the first embodiment shown in FIG. 3 will be described.

  The mounting structure shown in FIG. 3 is obtained by mounting the BGA 1 shown in FIG. 1 on a printed circuit board 9 that is a mounting board, and a heat sink 8 that is a heat radiating member is joined to the semiconductor chip 4. Yes.

  More specifically, the mounting structure has a top surface 9a and a bottom surface 9b opposite to the top surface 9a, and a printed circuit board 9 on which the BGA 1 is mounted on the top surface 9a via a plurality of solder balls 7, and the semiconductor chip 4 The heat sink 8 is provided, and the reinforcing plate 6 is provided in a region corresponding to a region outside the semiconductor chip 4 on the lower surface 9b of the printed board 9.

  Here, the reinforcing plate 6 reduces deformation of the solder balls 7 when a load is applied from above the semiconductor chip 4, and corresponds to a region outside the semiconductor chip 4 on the lower surface 9 b of the printed circuit board 9. A pressure (load) is applied on the semiconductor chip 4 with the region supported by the reinforcing plate 6.

  As an example of a process in which pressure is applied from above the semiconductor chip 4, a process of attaching a heat sink 8 as a heat radiating member on the semiconductor chip 4 as shown in FIG. 4 will be described.

  The heat sink 8 has a flat plate shape and is bonded to the semiconductor chip 4 by applying pressure. Since the pressure is concentrated only on the chip region, it is possible to absorb variations in the height direction of the mounting structure of the BGA 1. Furthermore, since the heat sink 8 is bonded to the back surface 4b of the semiconductor chip 4 through an adhesive such as a silicone resin 10 having high thermal conductivity, the thickness of the silicone resin 10 can be reduced, and uniformity and adhesion can be reduced. The heat dissipation effect can be enhanced as well as the performance.

  Moreover, since the heat sink 8 is flat and can be easily processed, the cost of the heat sink 8 can be reduced.

  FIG. 4 shows a chip pressing state when the heat sink 8 is mounted on the semiconductor chip 4, and the heat sink 8 and the reinforcing plate 6 are sandwiched between the heat sink 8 and the reinforcing plate 6 by the clipper 11 as a pressing member. Is attached. At that time, a load (pressure) P is applied to the back surface 4 b of the semiconductor chip 4. This load P is always applied to the semiconductor chip 4 while the clipper 11 is fitted, and further applied to the wiring board 2, the plurality of solder balls 7 and the printed board 9 through the semiconductor chip 4. When removed, the mounting structure shown in FIG. 3 is not applied to the semiconductor chip 4, and the semiconductor chip 4 is released from the load P (excluding the weight of the heat sink 8).

  The clipper 11 is a pressing member that engages with the heat sink 8 and the reinforcing plate 6 to sandwich the structure shown in FIG.

  Here, the detailed structure of the reinforcing plate 6 will be described. The reinforcing plate 6 according to the first embodiment is a thin plate-like member, and is formed in a frame shape as shown in FIG. 4, and therefore, a hole 6a is formed at the center. The reinforcing plate 6 is preferably a metal plate made of a material such as aluminum or stainless steel. For example, the cost of the reinforcing plate 6 can be reduced by forming with an aluminum material. However, it may be formed of, for example, hard resin other than metal. That is, a metal material or a material other than metal may be used as long as it is a plate material harder than the printed circuit board 9.

  The mounting structure of the semiconductor device according to the first embodiment is characterized in that the reinforcing plate 6 is not provided at a location where pressure on the printed circuit board 9 is concentrated when pressure is applied to the semiconductor chip 4. . That is, when the pressure is applied on the semiconductor chip 4, the reinforcing plate 6 is not provided in the chip lower region 9c, which is a place where the pressure is applied to the printed circuit board 9 through the semiconductor chip 4. The reinforcing plate 6 has a shape that escapes (avoids) the chip lower region 9c. That is, the reinforcing plate 6 escapes (opens) using the chip lower region 9c of the printed circuit board 9 as the hole 6a.

  Here, the frame-shaped range of the reinforcing plate 6 in the width direction is as follows. First, the position of the inner peripheral portion (inner side) 6b is changed from the ball electrode array closest to the semiconductor chip 4 outside the chip to the outermost solder ball 7. The position of the outer peripheral portion (outer side) 6c is set to a position corresponding to the range from the second ball electrode row outside the chip to the outside of the wiring board 2. Preferably, as shown in FIG. 3, the position of the inner peripheral portion 6 b corresponds to the solder ball electrode row closest to the semiconductor chip 4 among the plurality of solder balls 7 arranged in the region outside the semiconductor chip 4. Position. That is, the position corresponds to the position of the solder ball 7 in the first row outside the chip.

  On the other hand, the position of the outer peripheral portion 6c is preferably a position corresponding to the outermost solder ball electrode array as shown in FIG. The position of the frame-shaped outer peripheral portion 6c of the reinforcing plate 6 is set to a position corresponding to the outermost solder ball electrode array. The area of the printed board 9 that receives pressure due to the load P is provided with a plurality of solder balls 7. Therefore, the position corresponds to the outermost solder ball electrode array.

  This can reduce the influence of the load P on other electronic components (devices) mounted around the BGA 1 on the printed circuit board 9.

  Next, a method for mounting the semiconductor device according to the first embodiment will be described.

  First, as shown in FIG. 4, the BGA (FC-BGA) 1 is mounted on the upper surface 9 a of the printed circuit board 9. For example, the BGA 1 on the printed circuit board 9 is soldered by solder reflow or the like. At that time, the BGA 1 has a wiring board 2, a semiconductor chip 4 mounted on the wiring board 2, and a plurality of solder balls 7 provided in a grid on the back surface 2b of the wiring board 2, and the solder balls Reference numeral 7 denotes a semiconductor device arranged in both the lower region of the semiconductor chip 4 and the outer region thereof.

  Thereafter, the reinforcing plate 6 is set at a predetermined position. Here, the frame-shaped reinforcing plate 6 is set on the lower surface 9 b side of the printed circuit board 9 so that the reinforcing plate 6 is provided in a region outside the semiconductor chip 4 on the lower surface 9 b of the printed circuit board 9. That is, the chip lower region 9c on the lower surface 9b of the printed circuit board 9 is not supported at all, and the solder ball region around the outside of the chip lower region 9c on the lower surface 9b of the printed circuit board 9 is supported. A frame-shaped reinforcing plate 6 is set on the lower surface 9 b side of the printed circuit board 9.

  Thereafter, a heat sink 8 as a heat radiating member is mounted on the back surface 4b of the semiconductor chip 4 via an adhesive such as a silicone resin 10 or the like.

  Thereafter, the clipper 11 is fitted on both sides and a predetermined pressure P (load P) is applied to the semiconductor chip 4 to attach the heat sink 8 onto the semiconductor chip 4. Here, the clipper 11 is fitted on both sides so as to engage the heat sink 8 and the reinforcing plate 6, and the reinforcing plate 6 is disposed only in the region outside the semiconductor chip 4 on the lower surface 9 b of the printed circuit board 9. The pressure P is applied to the semiconductor chip 4 to attach the heat sink 8 on the semiconductor chip 4 (the heat sink 8 and the semiconductor chip 4 are joined).

  Note that the heat sink 8 may be first mounted on the back surface 4b of the semiconductor chip 4 when the reinforcing plate 6 is set after the mounting of the BGA 1 on the printed circuit board 9 is completed. That is, after mounting the BGA 1 on the printed circuit board 9, the heat sink 8 is arranged on the semiconductor chip 4, and then the reinforcing plate 6 is set, and then the pressure P is applied between the clippers 11 to apply the semiconductor chip 4 and the heat sink 8. You may join.

  Further, after attaching the heat sink 8 on the semiconductor chip 4, the clipper 11 may be removed or may be sandwiched as it is. If the state is sandwiched as it is, the pressure P is always applied to the semiconductor chip 4 and the printed board 9.

  According to the mounting structure and mounting method of the semiconductor device (BGA1) of the first embodiment, the semiconductor chip with the reinforcing plate 6 provided in the outer peripheral region of the chip lower region 9c on the lower surface 9b side of the printed board 9 is provided. 4 is attached to the heat sink 8 by applying a pressure P to the lower surface 9b side of the printed circuit board 9 so that the chip lower region 9c is not supported and is applied to the printed circuit board 9 via a plurality of solder balls 7 below the chip. Both the wiring board 2 and the printed board 9 can be bent slightly by using the load and the load applied to the wiring board (package board 2) via the semiconductor chip 4 respectively.

  At that time, the plurality of solder balls 7 in the region outside the lower region of the semiconductor chip 4 supported by the reinforcing plate 6 also receives a load. Therefore, the load applied on the semiconductor chip 4 when the heat sink 8 is attached. Can be distributed and hung over the entire back surface 2b of the wiring board 2.

  This can reduce the deformation of the plurality of solder balls 7 provided on the back surface 2b of the wiring board 2. In particular, in the plurality of solder balls 7 provided in the vicinity of the end portion of the wiring board 2, it is possible to reduce the deformation of the ball shape in an oblique direction.

  On the other hand, in the plurality of solder balls 7 provided in the lower region of the semiconductor chip 4, deformation of the solder balls 7 being crushed can be reduced. Since the deformation that the solder balls 7 are crushed can be reduced, the occurrence of electrical shorts between the solder balls 7 can be reduced.

  In addition, since a small load is applied to the plurality of solder balls 7 in the lower region of the semiconductor chip 4, the movement of the plurality of solder balls 7 in this region is restricted and it is difficult to move in the horizontal direction. As a result, the stress generated in the thermal cycle is relaxed and is not easily broken, and the life of the solder ball 7 in the lower region of the semiconductor chip 4 can be extended.

  As described above, the mounting reliability of the BGA (semiconductor device) 1 can be improved.

  Note that the technology of the reinforcing plate described in FIG. 10 and FIG. 11 of [prior art document] Japanese Patent Application Laid-Open No. 2001-168562 taken up in [Background Art] of the present invention reinforces a place where pressure is applied via a heat sink. Although supported by a plate, the reinforcing plate 6 of the first embodiment is opened without supporting a portion where pressure is applied to the printed circuit board 9, and the above [prior art document] is a technical idea. Are completely different.

  Next, a modification of the first embodiment will be described.

  5 is a cross-sectional view and a plan view showing a first modification of the mounting structure of the semiconductor device shown in FIG. 1. FIG. 6 is a cross-sectional view and a plan view showing a second modification of the mounting structure of the semiconductor device shown in FIG. 7 is a cross-sectional view and a plan view showing a third modification of the mounting structure of the semiconductor device shown in FIG. 1. FIG. 8 is a cross-sectional view and a plan view showing a fourth modification of the mounting structure of the semiconductor device shown in FIG. FIG. 9 is a sectional view and a plan view showing a fifth modification of the mounting structure of the semiconductor device shown in FIG. 10 is a sectional view and a plan view showing a sixth modification of the mounting structure of the semiconductor device shown in FIG. 1, FIG. 11 is a sectional view showing the effect of the structure shown in FIG. 10, and FIG. 12 is the semiconductor shown in FIG. FIG. 13 is a cross-sectional view and a plan view showing a seventh modification of the mounting structure of the apparatus, and FIG. 13 is a cross-sectional view showing an eighth modification of the first embodiment of the present invention. 14 is a sectional view showing a ninth modification of the structure of the semiconductor device according to the first embodiment of the present invention. FIG. 15 is a sectional view showing a tenth modification of the structure of the semiconductor device according to the first embodiment of the present invention. 16 and 16 are sectional views showing an eleventh modification of the structure of the semiconductor device according to the first embodiment of the present invention.

  The modification shown in FIGS. 5-9 changes the position of the inner peripheral part 6b or the outer peripheral part 6c about the frame shape of the reinforcement board 6 variously.

  First, in the first modification shown in FIG. 5, the position of the outer peripheral portion 6c (the position of the outermost solder ball row) is not changed with respect to the shape of the reinforcing plate 6 of FIG. Is made closer to the outer peripheral portion 6c to increase the size of the hole 6a.

Further, in the second modification shown in FIG. 6, the position of the inner peripheral portion 6b (the position of the solder ball row closest to the chip outside the chip) with respect to the shape of the reinforcing plate 6 in FIG. Only the position of the outer peripheral part 6c is brought close to the inner peripheral part 6b to minimize the width of the frame. In this case, the width of the frame is about one solder ball 7. When the frame shape is set to the minimum width, the pressure received per unit area in the ball pad that is the electrode on the back surface 2b of the wiring board 2 on which the solder balls 7 are mounted is 7.46 (kgf / mm ² ). It is preferable to be as follows.

For example, when evaluation was performed by applying a load of 30 kgf with a 560-pin BGA 1, the solder ball 7 at the central portion received a pressure of 7.46 (kgf / mm ² ) per unit area. At that time, after the long-term temperature cycle evaluation, the solder ball 7 in the central part becomes adjacent short circuit failure due to excessive deformation due to pressure, while the wiring board 2 is also deformed to be excessively deformed. It was found that the solder ball 7 of part) was pulled and led to open breakage. Therefore, the pressure received per unit area of the ball pad to which the solder balls 7 of the wiring board 2 are connected is 7.46 (kgf / mm ² ) or less, so that the solder balls 7 and the wiring board 2 Excessive deformation is relieved, the solder ball 7 is less likely to be shorted and broken, and the life of the solder ball 7 can be extended.

  Further, in the third modified example shown in FIG. 7, the position of the inner peripheral portion 6b (the position of the solder ball row closest to the chip outside the chip) is not changed with respect to the shape of the reinforcing plate 6 in FIG. Only the position of the outer peripheral part 6c is extended to the outside of the printed circuit board 9, and the frame shape is enlarged.

  Further, in the fourth modified example shown in FIG. 8, the position of the outer peripheral part 6c is set to the same position outside the printed circuit board 9 with respect to the shape of the reinforcing plate 6 of the third modified example of FIG. The position of 6b is the position of the third solder ball row from the outermost periphery toward the inside.

  Further, in the fifth modification shown in FIG. 9, the position of the outer peripheral portion 6c is set to the same position outside the printed circuit board 9 with respect to the shape of the reinforcing plate 6 of the third modification shown in FIG. The position 6b is the position of the outermost solder ball row.

  Even if the reinforcing plate 6 of the modification shown in FIGS. 5 to 9 is used, the same effect as that of the reinforcing plate 6 shown in FIG. 3 of the first embodiment can be obtained.

  Next, in a sixth modification shown in FIGS. 10 and 11, a rubber sheet 12 that is an elastic member is interposed between the printed board 9 and the reinforcing plate 6. That is, the rubber sheet 12 that is an elastic member is interposed between the lower surface 9 b of the printed circuit board 9 and the reinforcing plate 6.

  This is due to the difference in rigidity between the printed circuit board 9 and the reinforcing plate 6, and the amount of bending deformation caused by the load may be different. Due to this difference in deformation amount, the printed circuit board 9 is in contact with the reinforcing plate 6. May be reduced, and the load may be concentrated on the local area to cause damage to the printed circuit board 9. Therefore, the rubber sheet 12 is interposed between the printed circuit board 9 and the reinforcing plate 6 to absorb the difference in deformation amount between them, and the load P is applied to the entire surface of the reinforcing plate 6 as shown in FIG. It is possible to prevent it from being concentrated on.

  Thereby, the damage applied to the printed circuit board 9 by the load P can be reduced.

  In addition, the magnitude | size of the rubber sheet 12 may be substantially the same as the reinforcement board 6, for example.

  Next, the modified example of FIG.12 and FIG.13 shows the modified example of a heat radiating member. The seventh modification of FIG. 12 is a BGA 1 to which a finned heat sink (heat dissipating member) 13 is attached and has fins, so that the heat dissipating effect can be further enhanced.

  Further, the eighth modification of FIG. 13 shows a stepped heat sink (heat radiating member) 14 having a step portion at the center. By using this stepped heat sink 14, no spacer is used even when height adjustment is required for mounting, and only the stepped heat sink 14 need be attached.

  Next, the modification shown in FIGS. 14 to 16 is a type of semiconductor device. First, the ninth modification shown in FIG. 14 is a BGA 1 a in which a heat spreader 15 is mounted on a semiconductor chip 4. That is, the BGA 1a is obtained by mounting the heat spreader 15 on the exposed back surface 4b of the semiconductor chip 4 via the heat conductive adhesive 16, and the semiconductor chip 4 is electrically connected to the wiring board 2 by flip chip connection, similarly to the BGA 1. This is a flip-chip type BGA 1a having a structure connected to.

  The heat conductive adhesive 16 is, for example, a silicone-based resin or a sheet material. Since the BGA 1 a includes the heat spreader 15, the BGA 1 a can release heat from the heat spreader 15, and thus has higher heat dissipation than the BGA 1.

  Next, the tenth modification shown in FIG. 15 is a flip having a structure in which the heat spreader 15 mounted on the semiconductor chip 4 is supported by the support ring 17 provided on the peripheral portion on the wiring board 2 via the heat conductive adhesive 16. It is a chip type BGA 1 b, and the support ring 17 is in contact with the heat spreader 15 and the wiring board 2. Therefore, the heat transferred from the semiconductor chip 4 to the heat spreader 15 via the heat conductive adhesive 16 can be released to the wiring board 2 via the support ring 17, and the heat dissipation is further improved compared to the BGA 1a of FIG. be able to.

  Next, an eleventh modification shown in FIG. 16 is a resin-sealed wire bonding type BGA 1c. The semiconductor chip 4 is mounted on the wiring board 2 by face-up mounting, and the back surface 4b is a die bond material 18. It is joined to the wiring board 2 via Further, the electrode pad 4c of the semiconductor chip 4 is electrically connected to the wiring board 2 via a wire 19 such as a gold wire. The semiconductor chip 4 and the plurality of wires 19 are resin-sealed by a sealing body 20 formed of, for example, a thermosetting resin.

  The modified BGAs 1a, 1b, and 1c shown in FIGS. 14 to 16 are applicable to the mounting structure and mounting method of the semiconductor device of the first embodiment, and the same effects as in the case of the BGA 1 can be obtained. .

(Embodiment 2)
17 is a sectional view showing a twelfth modification of the mounting structure of the semiconductor device according to the second embodiment of the present invention. FIG. 18 is a sectional view showing a thirteenth modification of the mounting structure of the semiconductor device according to the second embodiment of the present invention. 19 is a sectional view showing a fourteenth modification of the mounting structure of the semiconductor device according to the second embodiment of the present invention. FIG. 20 is a plan view showing the structure of the reinforcing plate in the mounting structure shown in FIG. FIG. 21 is a sectional view showing a fifteenth modification of the mounting structure of the semiconductor device according to the second embodiment of the present invention. FIG. 22 shows a sixteenth modification of the mounting structure of the semiconductor device according to the second embodiment of the present invention. FIG. 23 is a sectional view showing a seventeenth modification of the mounting structure of the semiconductor device according to the second embodiment of the present invention.

  In the second embodiment, a modified example of the mounting structure of the BGA 1 described in the first embodiment will be described. First, in a twelfth modification shown in FIG. 17, a heat sink 8 is mounted on a semiconductor chip 4 via a silicone resin 10 on a BGA 1 mounted on a printed circuit board 9, and the heat sink 8 and a mobile phone are mounted. The printed circuit board 9 and the BGA 1 are sandwiched between a housing (housing) 22 of an electronic device such as a car navigation device or the like, and the heat sink 8 and the housing 22 are fixed by screws with a screw member 21 as a pressing member. At that time, a frame-shaped reinforcing plate 6 is provided between the printed circuit board 9 and the housing 22. Further, the mounting structure of the BGA 1 can be downsized by using the wall of the casing 22 of the electronic device as a heat sink.

  Also in this mounting structure, since the heat sink 8 is screwed to the housing 22 by the screw member 21, the load P is always applied to the back surface 4 b of the semiconductor chip 4, and the bottom surface 9 b side of the printed circuit board 9 is applied. By providing the frame-shaped reinforcing plate 6, it is possible to obtain the same effect as the mounting structure of the BGA 1 of the first embodiment. Furthermore, since the heat transmitted from the semiconductor chip 4 to the heat sink 8 can be transmitted to the housing 22 via the screw member 21, the heat dissipation of the BGA 1 can be further enhanced. Note that the heat sink 8 may be used instead of the housing 22, and in this case, the upper heat sink 8 and the lower heat sink 8 are fixed by screws with the screw members 21.

  Next, in the thirteenth modification shown in FIG. 18, a heat sink 8 is mounted on the semiconductor chip 4 via the silicone resin 10 with respect to the BGA 1 mounted on the printed board 9, and the heat sink 8 and the printed board are mounted. 9, a frame-like reinforcing plate 6 provided on the lower surface 9b side is sandwiched and fixed by a clipper 11a which is a pressing member. The clipper 11a may be a U-shaped and elastic member, and may be a spring or the like.

  Also in this case, since the heat sink 8 is sandwiched between the clipper 11 a and the reinforcing plate 6, the load P is always applied to the back surface 4 b of the semiconductor chip 4, and the bottom surface 9 b side of the printed circuit board 9 is applied. By providing the frame-shaped reinforcing plate 6, it is possible to obtain the same effect as the mounting structure of the BGA 1 of the first embodiment.

  Next, the 14th modification shown in FIG.19 and FIG.20 is provided with the support part 6d in the four corner parts of the frame-shaped reinforcement board 6, and the through-hole 6e is formed in each support part 6d, In this mounting structure, one end of a clipper (pressing member) 23 is engaged with the through-hole 6e so as to be sandwiched between the heat sink 8.

  That is, a heat sink 8 is mounted on the semiconductor chip 4 of the BGA 1 mounted on the printed circuit board 9 via a silicone resin 10 or the like, and a frame-shaped reinforcing plate provided on the heat sink 8 and the lower surface 9b side of the printed circuit board 9. 6 is sandwiched by the clipper 23, whereby the printed circuit board 9 and the BGA 1 are sandwiched.

  At that time, the clipper 23 is an elastic member and has a substantially L shape. One end of the clipper 23 engages with the through hole 6e of the support portion 6d of the reinforcing plate 6 so as to sandwich the printed circuit board 9 and the BGA1. It is fixed.

  Also in this case, since the heat sink 8 is sandwiched between the clip plate 23 and the reinforcing plate 6, the load P is always applied to the back surface 4 b of the semiconductor chip 4, and the bottom surface 9 b side of the printed circuit board 9 is applied. By providing the frame-shaped reinforcing plate 6, it is possible to obtain the same effect as the mounting structure of the BGA 1 of the first embodiment.

  Next, a fifteenth modification shown in FIG. 21 is a mounting structure in which a spring member (elastic body) 24 is provided instead of the reinforcing plate 6 provided on the lower surface 9b side of the printed circuit board 9. That is, instead of the reinforcing plate 6, the spring member 24 is provided between the printed circuit board 9 and the housing 22 (or the heat sink 8). In this case, the spring member 24 may be a frame-like member as in the case of the reinforcing plate 6 as long as it is an elastic force acting in the height direction of the BGA 1. It may be a thing.

  In the structure of the fifteenth modified example of FIG. 21, the heat sink 8 is mounted on the semiconductor chip 4 via the silicone resin 10 with respect to the BGA 1 mounted on the printed circuit board 9. The printed circuit board 9 and the BGA 1 are sandwiched between the housing (housing) 22 and the like, the heat sink 8 and the housing 22 are fixed by the side plate 25, and the side plate 25 and the heat sink 8, and the side plate 25 and the housing 22 are respectively connected. The screw is fixed by a screw member 21a which is a pressing member.

  At this time, the heat sink 8 and the side plate 25 and the side plate 25 and the housing 22 are fixed with screws by the screw members 21 a, respectively, and the printed circuit board 9 and the BGA 1 have the spring members 24 interposed between the heat sink 8 and the housing 22. Since the semiconductor chip 4 is sandwiched in such a state, a load P is always applied to the back surface 4 b of the semiconductor chip 4.

  In addition, since the plurality of spring members 24 are provided on the lower surface 9b side of the printed circuit board 9, the same effect as the mounting structure of the BGA 1 of the first embodiment can be obtained. Further, since heat transferred from the semiconductor chip 4 to the heat sink 8 can be transmitted to the housing 22 via the screw member 21a and the side plate 25, the heat dissipation of the BGA 1 can be further improved. Note that the heat sink 8 may be used instead of the housing 22.

  In addition, by providing a spring member 24 on which the elastic force acts in the height direction of the BGA 1 on the lower surface 9b side of the printed circuit board 9 instead of the reinforcing plate 6, the variation in height (T) after mounting the BGA 1 is corrected. In addition, the semiconductor chip 4 and the heat sink 8 can be brought into close contact with each other.

  Next, the sixteenth modification shown in FIG. 22 has a structure in which the size of the outer peripheral portion 6c of the reinforcing plate 6 is made the same as that of the outer peripheral portion of the printed circuit board 9, and through holes 6e are formed at both ends of the reinforcing plate 6. The heat sink 8, the printed circuit board 9, and the reinforcing plate 6 are fixed by screws with a screw member 26 and a nut 27 which are provided and are pressing members.

  Also in this structure, since the heat sink 8 is sandwiched between the reinforcing plate 6 by the screw member 26 and the nut 27, the load P is always applied to the back surface 4 b of the semiconductor chip 4. By providing the frame-shaped reinforcing plate 6 on the lower surface 9b side, the same effect as the mounting structure of the BGA 1 of the first embodiment can be obtained.

  Next, the seventeenth modification shown in FIG. 23 is a frame-like structure in which the BGA 1 mounted on the printed circuit board 9 is arranged on the heat sink 8 mounted on the semiconductor chip 4 and the lower surface 9b side of the printed circuit board 9. In the mounting structure clamped by the reinforcing plate 6, the screw member 26 and the nut 27 that are engaged with the heat sink 8 and the reinforcing plate 6 are fixed by screws, and the wiring board 2 of the BGA 1 and the heat sink 8 that is a heat radiating member A plurality of spring members (elastic bodies) 28 are provided between them, and the plurality of spring members 28 are distributed around the semiconductor chip 4.

  Also in this structure, since the heat sink 8 is sandwiched between the reinforcing plate 6 by the screw member 26 and the nut 27, the load P is always applied to the back surface 4 b of the semiconductor chip 4. By providing the frame-shaped reinforcing plate 6 on the lower surface 9b side, the same effect as the mounting structure of the BGA 1 of the first embodiment can be obtained.

  Furthermore, since the plurality of spring members 28 are distributed around the semiconductor chip 4, the load applied to the printed circuit board 9 via the wiring board 2 is distributed and reduced. Even when the thickness is small, damage to the printed circuit board 9 can be reduced.

  Further, in this structure, the adhesiveness between the heat sink 8 and the semiconductor chip 4 can be improved by setting the magnitude of the load P to the heat sink 8 larger than the elastic force of the spring member 28. Further, in the case of the BGA 1 having a small adhesion area with the heat sink 8 (the size of the semiconductor chip 4 is small), the plurality of spring members 28 are arranged around the semiconductor chip 4 so that the heat sink 8 is attached. The balance can be improved and the flatness of the heat sink 8 can be secured.

(Embodiment 3)
24 is a cross-sectional view showing an example of the structure of the semiconductor device according to the third embodiment of the present invention, FIG. 25 is a back view showing an example of the ball arrangement of the semiconductor device shown in FIG. 24, and FIG. 26 is the semiconductor device shown in FIG. It is sectional drawing and a top view which show an example of this mounting structure.

  In the third embodiment, a modified BGA structure and its mounting structure will be described. The semiconductor device shown in FIGS. 24 and 25 is a flip-chip connection type BGA type semiconductor device, similar to the BGA 1 in the first and second embodiments, but is an external connection terminal as shown in FIG. The arrangement method of the solder balls 7 is not the full bump type, but the BGA 29 is thinned out without arranging the solder balls 7 between the lower region of the chip and the outer region.

  That is, the BGA 29 is provided with a plurality of solder balls 7 in a grid shape divided into a central portion and an outer peripheral portion of the back surface 2b of the wiring board 2.

  Note that the thinning-out arrangement of the solder balls 7 such as the BGA 29 can also be applied to the BGAs 1a, 1b, and 1c of the modified examples shown in FIGS.

  FIG. 26 shows a mounting structure of the BGA 29. A heat sink 8 as a heat radiating member is bonded to a semiconductor chip 4 mounted on a printed board 9 as a mounting board via a silicone resin 10 or the like. And a frame-shaped reinforcing plate 6 provided in a region corresponding to a region outside the semiconductor chip 4 on the lower surface 9b of the substrate 9.

  The reinforcing plate 6 reduces deformation of the solder balls 7 when a load is applied from above the semiconductor chip 4, and corresponds to an area outside the semiconductor chip 4 on the lower surface 9 b of the printed circuit board 9. A pressure (load) is applied to the semiconductor chip 4 in a state in which is supported by the reinforcing plate 6.

  Also in the mounting structure of the third embodiment, when the heat sink 8 is attached, when a load is applied to the back surface 4b of the semiconductor chip 4 via the heat sink 8, a frame-shaped reinforcing plate is formed on the lower surface 9b side of the printed circuit board 9. 6 is provided, it is possible to obtain the same effect as the mounting structure of the BGA 1 of the first embodiment.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments of the invention. However, the present invention is not limited to the embodiments of the invention, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

  For example, in the first to third embodiments, the case where the reinforcing plate 6 has a frame shape has been described. However, the reinforcing plate 6 may not necessarily have a frame shape. That is, if the portion corresponding to the chip lower region 9c of the printed circuit board 9 that is a mounting substrate is open, and the portion corresponding to the peripheral region outside the chip lower region 9c is a supportable shape, It may be a shape other than the frame shape.

  The present invention is suitable for an electronic device mounting method.

1, 1a, 1b, 1c BGA (semiconductor device)
2 Wiring board 2a Main surface 2b Back surface 3 Underfill resin 4 Semiconductor chip 4a Main surface 4b Back surface 4c Electrode pad 5 Solder bump 6 Reinforcement plate 6a Hole portion 6b Inner periphery portion 6c Outer periphery portion 6d Support portion 6e Through hole 7 Solder ball (external) Terminal for connection, ball electrode)
8 Heat sink (heat dissipation member)
9 Printed circuit board (mounting board)
9a Upper surface 9b Lower surface 9c Lower chip area 10 Silicone resin 11, 11a Clipper (pressing member)
12 Rubber sheet (elastic member)
13 Heat sink with fins (heat dissipation member)
14 Stepped heat sink (heat dissipation member)
DESCRIPTION OF SYMBOLS 15 Heat spreader 16 Thermal conductive adhesive 17 Support ring 18 Die-bonding material 19 Wire 20 Sealing body 21,21a Screw member (pressing member)
22 Case 23 Clipper (Pressing member)
24 Spring member (reinforcement plate)
25 Side plate 26 Screw member (pressing member)
27 Nut 28 Spring member (elastic body)
29 BGA (semiconductor device)

Claims (16)

A wiring board; a semiconductor chip mounted on the wiring board; and a plurality of ball electrodes which are external connection terminals provided on a back surface of the wiring board; A semiconductor device arranged in both areas,
A mounting substrate on which the semiconductor device is mounted via the plurality of ball electrodes;
A heat dissipating member provided on the semiconductor chip;
A reinforcing plate provided in a region outside the semiconductor chip on the lower surface of the mounting substrate;
A pressing member that engages the heat dissipation member and the reinforcing plate to apply pressure on the semiconductor chip;
Have
A mounting structure of a semiconductor device, wherein pressure is applied to the semiconductor chip by the pressing member in a state where a region outside the semiconductor chip on the lower surface of the mounting substrate is supported by the reinforcing plate.   2. The mounting structure of a semiconductor device according to claim 1, wherein the reinforcing plate is formed in a frame shape.   3. The mounting structure of a semiconductor device according to claim 2, wherein the position of the inner peripheral portion of the frame-shaped reinforcing plate is closest to the semiconductor chip among the plurality of ball electrodes arranged in an outer region of the semiconductor chip. A mounting structure of a semiconductor device, wherein the mounting structure is a position corresponding to a ball electrode array at a close position.   2. The mounting structure of a semiconductor device according to claim 1, wherein the reinforcing plate is a metal plate.   2. The mounting structure of a semiconductor device according to claim 1, wherein an elastic member is interposed between the mounting substrate and the reinforcing plate. A wiring board; a semiconductor chip mounted on the wiring board; and a plurality of ball electrodes which are external connection terminals provided on a back surface of the wiring board; A method for mounting a semiconductor device arranged in both areas,
(A) mounting the semiconductor device on a mounting substrate;
(B) applying a predetermined pressure on the semiconductor chip and attaching a heat dissipation member on the semiconductor chip;
Have
In the step (b), a method of mounting a semiconductor device, wherein pressure is applied to the semiconductor chip in a state where a reinforcing plate is provided in a region outside the semiconductor chip on the lower surface of the mounting substrate.   7. The method of mounting a semiconductor device according to claim 6, wherein the semiconductor device includes a plurality of ball electrodes in a grid shape on the entire back surface of the wiring board.   7. The method of mounting a semiconductor device according to claim 6, wherein the semiconductor device is provided with a plurality of ball electrodes in a grid shape divided into a central portion and an outer peripheral portion of the back surface of the wiring board. Mounting method of semiconductor device.   7. The method of mounting a semiconductor device according to claim 6, wherein the reinforcing plate has a frame shape.   10. The mounting method of a semiconductor device according to claim 9, wherein the position of the inner peripheral portion of the frame-shaped reinforcing plate is closest to the semiconductor chip among the plurality of ball electrodes arranged in an outer region of the semiconductor chip. A mounting method of a semiconductor device, wherein the mounting position is a position corresponding to a ball electrode array at a close position.   11. The method of mounting a semiconductor device according to claim 10, wherein a position of an outer peripheral portion of the frame-shaped reinforcing plate is a position corresponding to an outermost ball electrode array.   7. The method of mounting a semiconductor device according to claim 6, wherein the reinforcing plate is a metal plate.   7. The semiconductor device mounting method according to claim 6, wherein an elastic member is interposed between the mounting substrate and the reinforcing plate.   7. The method of mounting a semiconductor device according to claim 6, wherein the semiconductor chip is flip-chip connected to the wiring board.   7. The method of mounting a semiconductor device according to claim 6, wherein the ball electrode is a solder ball.   7. The method of mounting a semiconductor device according to claim 6, wherein a plurality of elastic bodies are provided between the wiring board and the heat radiating member, and the plurality of elastic bodies are distributed around the semiconductor chip. A method for mounting a semiconductor device.

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