JP5195456B2 - Socket, semiconductor device, and socket reliability evaluation method - Google Patents

Description

  The present invention relates to a socket used for pressing and connecting a first electrode on the upper surface of a circuit board and a second electrode on the lower surface of a semiconductor package via a conductive terminal having creep characteristics, a semiconductor device using the socket, and a socket In particular, the present invention relates to a socket capable of evaluating a decrease in reliability of electrical connection due to deterioration over time, a semiconductor device using the socket, and a reliability evaluation method of the socket.

  An LGA socket (land grid array socket) is widely used to mount a semiconductor package containing a large-scale integrated circuit on a circuit board. The LGA socket includes a conductive terminal that is sandwiched between a first electrode formed on the upper surface of the circuit board and a second electrode formed on the lower surface of the semiconductor package and has elasticity to connect the two electrodes. The semiconductor package is pressed and mounted on the circuit board via the conductive terminals, whereby electrical connection between the first and second electrodes is made via the conductive terminals. Therefore, by removing the pressure, the semiconductor package mounted on the circuit board can be easily detached. As described above, the semiconductor package can be detachably mounted by using the LGA socket.

  As a conductive terminal of an LGA socket, a terminal made of a conductive resin, for example, a resin terminal in which a metal filler is dispersed in a resin to impart conductivity is widely used. Such a conductive terminal made of resin has a large contact area and is less likely to cause poor contact due to the presence of dust, so that a highly reliable connection can be realized. Moreover, since it can be a simple columnar or spindle-shaped shape, a complicated shape for imparting elasticity is not required unlike a metal terminal.

  However, the conductive terminal made of conductive resin has a larger creep characteristic than the metal terminal. For this reason, when the operation period extends for a long time, the pressed conductive terminal is deformed so as to creep and the height of the conductive terminal is reduced (the distance between the upper and lower ends is reduced by being compressed). When the deformation further progresses, the conductive terminal may be crushed and an insulation failure may occur between adjacent conductive terminals.

  In order to avoid shortening the distance between the semiconductor package and the circuit board, a stopper (standoff) for holding the distance is inserted between the semiconductor package and the circuit board, and the distance is less than a predetermined distance. There is something to prevent. For example, a frame for holding a support plate provided around a support plate that supports conductive terminals or a part thereof is used as a stopper.

JP 2008-027753 A JP 2008-0779947 A

  As described above, in the conventional socket using the conductive terminal having the creep characteristic, the interval between the semiconductor package and the circuit board pressed against each other is set using a stopper (standoff) having a predetermined height sandwiched therebetween. It is held so that it is not less than a predetermined distance.

  However, when the distance between the semiconductor package and the circuit board, that is, the distance between the first electrode and the second electrode is fixed by the stopper, the load that presses the semiconductor package onto the circuit board as the creep of the conductive terminal progresses. The voltage is applied not only to the conductive terminal connecting the first and second electrodes, but also to the stopper. For this reason, the load is also distributed to the stopper, and the load applied to the conductive terminal is reduced. When the load applied to the conductive terminal is reduced in this way, a connection failure of the conductive terminal that electrically connects the first electrode and the second electrode is caused, and the reliability of the electrical connection of the socket is lowered. .

  The deterioration of the reliability of the electrical connection of the socket caused by such creep cannot be directly observed with the conventional socket. For this reason, the socket is replaced when a connection failure actually occurs or when a certain period of use has elapsed. This makes it impossible to accurately grasp the deterioration of the reliability of the socket. It is important to quickly and surely grasp the deterioration of the electrical connection of the socket in order to take appropriate measures in the development and use of the semiconductor device. For this reason, there is a demand for a technique for evaluating deterioration in reliability of electrical connection due to deterioration of the socket over time.

  The present invention relates to a semiconductor device in which a semiconductor package is mounted on a circuit board by pressing it through a socket, and relates to a socket capable of evaluating the reliability of electrical connection of the socket used in the semiconductor device. An object of the present invention is to provide a reliability evaluation method for semiconductor devices and sockets.

The first configuration of the present invention for solving the above-described problem is that between the first electrode disposed on the upper surface of the circuit board and the second electrode disposed on the lower surface of the semiconductor package so as to face the first electrode. In a socket including conductive terminals that are interposed between and electrically connected to the first and second electrodes by being pressed vertically by the circuit board and the semiconductor package,
A plurality of the conductive terminals having creep characteristics; a support plate that supports the conductive terminals by projecting the upper and lower ends of the conductive terminals up and down; and a frame that supports a peripheral portion of the support plate;
A socket comprising a load measuring element for measuring a vertical load applied to the frame body; and
The second configuration of the present invention includes a step of preparing a circuit board having a first electrode disposed on an upper surface and a semiconductor package having a second electrode disposed on a lower surface, and a plurality of conductive terminals having creep characteristics. A support plate for supporting upper and lower ends of the conductive terminal by projecting up and down, a frame body for supporting a peripheral portion of the support plate, and a load measurement for measuring a vertical load applied to the frame body A step of preparing a socket including an element, and pressing the semiconductor package on the circuit board via the socket so that the first and second electrodes facing each other are connected by the conductive terminal. Monitoring the output of the load measuring element, and the connection between the first and second electrodes based on the load applied to the frame body by being pressed by the circuit board and the semiconductor package. Reputation for reliability To be configured as a method of evaluating the reliability of the socket.

  According to the present invention, a decrease in the load applied to the conductive terminal is estimated by measuring the load dispersed in the frame of the socket. Since the reliability of the electrical connection of the socket is related to the load applied to the conductive terminal, the electrical amount of the socket mounted on the semiconductor device is determined from the estimated amount of decrease in the load applied to the conductive terminal. Connection reliability can be evaluated.

Semiconductor device assembly drawing of the first embodiment of the present invention The socket perspective view of a 1st embodiment of the present invention. Socket sectional view of the first embodiment of the present invention The circuit board perspective view of a 1st embodiment of the present invention. Sectional drawing of the semiconductor device of 1st Embodiment of this invention Sectional drawing for demonstrating the time-dependent change of the semiconductor device of 1st Embodiment of this invention. Perspective view of creep test sample Cross section showing creep test method Diagram showing the result of creep test A diagram showing the load dependency per terminal of contact resistance The figure showing the relationship between the load concerning a frame of a 1st embodiment of the present invention, and gauge resistance The figure explaining the reliability evaluation method of the electrical connection of 1st Embodiment of this invention Socket assembly drawing of the second embodiment of the present invention Sectional drawing of the semiconductor device of 2nd Embodiment of this invention

  The first embodiment of the present invention relates to a semiconductor device in which a semiconductor package is mounted on a circuit board via an LGA socket according to the present invention.

  FIG. 1 is an assembly diagram of a semiconductor device according to a first embodiment of the present invention, and shows a semiconductor device including an electrical connection deterioration monitoring circuit.

  Referring to FIG. 1, in the semiconductor device of the first embodiment, a semiconductor package 30 is mounted on the upper surface of a circuit board 20 via an LGA socket 10. The semiconductor package 30 is composed of an LGA package 30 provided with a large number of, for example, about 1000 to 2000 first electrodes (see FIG. 5) on the lower surface, and accommodates, for example, an integrated circuit including a CPU. The circuit board 20 is formed of, for example, a multilayer wiring board having a first electrode 22 (see FIG. 5) disposed on the upper surface so as to face the second electrode 32, and includes a monitoring circuit described later, other necessary integrated circuits, and an electronic circuit. Parts are installed.

  The structure in which the circuit board 20, the socket 10, and the semiconductor package 30 are overlapped is fastened and fixed from above and below using a fixing component 40.

  The fixed component 40 is a block shape in which a rectangular flat plate-like base 41 in which cylindrical columnar portions 41a are implanted at four corners, and a lower surface in which through holes 42a into which the columnar portions 41a are inserted are opened form a flat surface. An upper plate 42. On the upper surface of the upper plate 42, heat radiating fins 42d formed integrally with the upper plate 42 are provided.

  The circuit board 20 is provided with a through hole 20a into which the columnar part 41a is loosely fitted. The circuit board 20 is placed on the base 41 with the columnar part 41a passing through the through hole 20a. Note that the socket 10 and the semiconductor package 30 are overlaid on the upper surface of the circuit board 20.

  Further, the upper plate 42 is placed such that through holes 42 a provided at the four corners of the upper plate 42 are fitted into the columnar portions 41 a and the lower surface is in close contact with the upper surface of the semiconductor package 30. Next, the fixing screw 42b around which the helical spring 42c is wound is screwed into the screw hole formed on the top surface of the columnar portion 41a from the upper surface of the upper plate 42. Thereby, the upper plate 42 is pressed from above by the helical spring 42c, and presses the upper surface of the semiconductor package 30 downward. Therefore, the semiconductor package 30 and the circuit board 20 are fastened and fixed by the base 41 and the upper plate 42 from above and below by a load determined by the spring constant of the helical spring 42c.

  FIG. 2 is a perspective view of the socket according to the first embodiment of the present invention, showing a socket provided with a load measuring element. FIG. 3 is a cross-sectional view of the socket according to the first embodiment of the present invention, and represents a cross section AB in FIG. Moreover, the figure (a) and figure (b) in the ellipse in FIG. 2 represent the strain gauge 14 which functions as a load measuring element affixed on the frame.

  2 and 3, the socket 10 includes a support plate 12 made of a square or rectangular flat plate-like insulator and a frame body 13 that holds the periphery of the support plate 12. The support plate 12 has a square or rectangular planar shape with a thickness of 1.2 mm and an outer length of about 4 cm, for example, and the upper terminal 11 a protruding on the upper surface and the lower terminal 11 b protruding on the lower surface of the LGA semiconductor package 30. It arrange | positions at the position corresponding to the 1st electrode provided in the lower surface at the matrix form. These upper and lower terminals 11a and 11b have, for example, a truncated cone shape with a height of 0.6 mm and a minimum diameter of 400 μm, and the material is, for example, a resin imparted with conductivity by dispersing a metal filler. Such conductive resin has a large creep characteristic as compared with the metal spring material. The upper terminal 11 a and the lower terminal 11 b immediately below the upper terminal 11 a are electrically connected to each other by a via 11 c that penetrates the support plate 12 to constitute one conductive connection terminal 11. The via 11c can be integrally formed of the same conductive resin as the upper terminals 11a and 11b.

  The frame body 13 is for fixing the peripheral portion of the support plate 12 and holding the support plate 12 flat, and can be manufactured integrally with the support plate 12. Further, the height of the frame is set to a height lower than the height of the conductive terminal 11 such as 2.4 mm, for example 2.1 mm. As will be described later, the frame 13 functions as a stopper, and the height of the frame 13 is the minimum distance between the semiconductor package 30 and the circuit board 20.

  A strain gauge 14 is affixed to the side wall surface of the frame 13, for example, the outer wall surface. 2A and 2B, the strain gauge 14 is attached so that the strain detection direction 14a for detecting the strain most sensitively coincides with the vertical direction of the frame body 13. Therefore, the strain gauge 14 sensitively detects the deformation (for example, compression) of the frame due to the load generated when the frame 13 is pressed from the upper and lower surfaces. A load for measuring the load applied to the frame body in the vertical direction by checking the relationship between the load applied to the frame body of the strain gauge 14 and the amount of strain in advance. It can function as a measuring element.

  FIG. 4 is a perspective view of the circuit board according to the first embodiment of the present invention, showing the circuit board 20 on which the socket 10 and the monitoring circuit 21 are mounted.

  Referring to FIG. 4, socket 10 is installed on the upper surface of circuit board 20. At this time, alignment is performed such that the lower end surface of the lower terminal 11b disposed on the lower surface of the socket 10 and the first electrode 22 (see FIG. 5) formed on the upper surface of the circuit board 20 are in contact with each other. Further, a monitoring circuit 21 is mounted on the upper surface of the circuit board 20. The monitoring circuit 21 receives the output of the strain gauge 14 affixed to the side wall surface of the frame 13 through the lead wire 21a, and the monitoring circuit 21 measures the output of the strain gauge 14 constantly or at predetermined time intervals. . Then, when the output of the strain gauge, for example, the amount of change in the resistance value reaches or exceeds a predetermined value, to notify that the reliability of the electrical connection of the socket has fallen below a desired level. Create an alarm signal. This alarm signal is used to determine when to replace the socket or to perform other necessary processing associated with deterioration of the reliability of the electrical connection.

  FIG. 5 is a cross-sectional view of the semiconductor device according to the first embodiment of the present invention, showing the cross-sectional structure of the socket immediately after assembly.

  With reference to FIG. 5, in the semiconductor device 100 of the first embodiment, the semiconductor package 30 and the circuit board 20 are arranged so as to sandwich the socket 10 from above and below. Furthermore, the substrate 41 of the fixed component 40 and the upper plate 42 of the fixed component 40 are disposed on the lower surface of the circuit board 20 and the upper surface of the semiconductor package 30, respectively. Tightened. The tightening force is generated by screwing and fixing the fixing screw 42b to the columnar portion 41a, and is a constant load 50 generated by the helical spring 42c wound around the fixing screw 42b. Therefore, the semiconductor package 30 is always pressed against the circuit board 20 with a given constant load 50.

  Immediately after the semiconductor package 30 is mounted on the circuit board 20, the lower end surface of the conductive terminal 11 (the lower end surface of the lower terminal 11 b) is in contact with and pressed against the first electrode 22 provided on the upper surface of the circuit board 20. The upper end surface of the conductive terminal 11 (the upper end surface of the upper terminal 11 a) is in contact with and pressed against the second electrode 32 provided on the lower surface of the semiconductor package 30.

  On the other hand, although the frame 13 of the socket 10 is interposed between the semiconductor package 30 and the circuit board 20 and is sandwiched from above and below, a load is not substantially applied to the frame 13. That is, the initial height (vertical length) of the conductive terminal 11 is formed to be larger than the height of the frame body 11. Then, when a given constant load 50 is applied to the semiconductor package 30, the size of the load 50 and the number and strength of the conductive terminals 11 are designed so that the total load 50 is supported only by the conductive terminals 11. ing. For this reason, the frame body 11 does not contact the semiconductor package 30 and the circuit board 20, and accordingly, no load 50 is applied to the frame body.

  Note that when a constant load 50 is applied, the circuit board 20 and the semiconductor package 30 are electrically conductive so that they contact the upper and lower surfaces of the frame 13 in order to keep the distance between the circuit board 20 and the semiconductor package 30 constant. The elasticity of the flexible terminal 11 can also be selected. In this case, even if the contact is made, the load 50 distributed to the frame body 13 is smaller than the entire load 50, and has a negligible magnitude with respect to the reliability of the electrical contact of the conductive terminal 11. By doing in this way, the load per conductive terminal 11 can be made large enough to maintain the reliability of electrical contact.

  The operation of the semiconductor device according to the first embodiment of the present invention will be described below. First, the relationship between the structure of a semiconductor device and creep will be described. Note that creep refers to a phenomenon in which deformation of a material progresses with time when the material is left under a certain temperature and a load is applied. Creep characteristics refer to mechanical characteristics of a material that causes creep.

  FIG. 6 is a cross-sectional view for explaining the change over time of the semiconductor device according to the first embodiment of the present invention, and shows the conductive terminal 11 deformed based on creep after a long time has elapsed since mounting.

  Referring to FIG. 6, when the semiconductor package 30 is mounted on the circuit board 20 and used for a long time, the conductive terminal 11 made of a conductive resin creeps in an environment where a constant load 50 is applied from the upper and lower ends. It occurs and the height of the conductive terminal 11 decreases with time. As a result, the distance between the lower surface of the semiconductor package 30 and the upper surface of the circuit board 20 is shortened. The shortening of the distance proceeds until the lower surface of the semiconductor package 30 and the upper surface of the circuit board 20 are in contact with the frame body 11. After the contact with the frame body 11, the frame body 11 functions as a stopper. In other words, a part of the load 50 is dispersed in the frame body 11, so that the subsequent semiconductor package 30 and circuit board 20 The distance between them is kept constant. Accordingly, the height of the conductive terminal 11 is also kept constant thereafter.

  However, even if the distance between the semiconductor package 30 and the circuit board 20 is defined by the height of the frame body 11 and is kept constant, creep continues further because the load 50 continues to be applied to the conductive terminal 11. As a result, a part of the load 50 applied to the conductive terminal 11 is dispersed in the frame. As a result, the ratio of the load 50 applied to the conductive terminal 11 is reduced, and a poor electrical connection between the first electrode 22 and the second electrode 32 made via the conductive terminal 11 is likely to occur. The present invention has been made to provide a technique capable of evaluating the reliability of such an electrical connection. Therefore, when the conductive terminal has a creep characteristic that can cause electrical connection failure due to creep during the operation period of the semiconductor device, the present invention is effectively applied to avoid the insulation failure of the socket. Can do.

  In order to evaluate the reliability of the socket 10 used in the semiconductor device 100 of the first embodiment of the present invention, a creep test of the conductive terminal 11 was performed. Hereinafter, the creep test and the results will be described.

  FIG. 7 is a perspective view of a creep test sample, showing the test sample supplied to the creep test. FIG. 8 is a cross-sectional view showing the creep test method, and shows the arrangement of the creep test apparatus and the creep test sample during the creep test.

  Referring to FIG. 7, the support plate 12 is cut out into a rectangular shape from the socket 10 shown in FIGS. 2 and 3 so as to include nine conductive terminals 11 arranged in a matrix of three in each of the vertical and horizontal directions. The four conductive terminals 11 located at the center of each side were removed to obtain a creep test sample. That is, the creep test sample 60 includes a rectangular support plate 12 and a total of five conductive terminals 11, one at each of the four corners and the center thereof.

  Referring to FIG. 8, first, circuit board 66 was placed on the upper surface of bed 61a of the creep test apparatus. The circuit board 66 is obtained by cutting out the socket 10 mounting area from the circuit board 20, and the first electrodes 67 arranged in a matrix are formed on the upper surface. Then, the creep test sample 60 was positioned and placed on the circuit board 66 so that the lower terminal 11 b was in contact with the first electrode 67.

  Next, the second electrode 65 formed on the lower surface of the semiconductor package 64 was placed on the creep test sample 60 so as to be in contact with the upper terminal 11b. The semiconductor package 64 only needs to have the second electrodes 65 arranged in a matrix form on the lower surface thereof, and may simply have the second electrodes formed on the lower surface of a flat plate made of an insulator.

  Next, in order to conduct an accelerated creep test, a creep test was performed under a high-temperature ambient temperature of 85 ° C. First, the head 61b of the creep test apparatus was brought into close contact with the upper surface of the semiconductor package 64, and the head 61b was pressed down, and stopped when the compressive load 50 reached a predetermined value. Thereafter, the head 61b was held at this stop position and left in this state to conduct a creep test. That is, during the creep test, the distance between the semiconductor package 10 and the circuit board 20 and the distance between the first electrode 22 and the second electrode 32 are maintained at a constant distance. The compressive load 50 is measured by a load cell 61c provided on the lower surface of the bed 61a, whereby the load applied to the conductive terminal 11 in a compressed state is measured.

  FIG. 9 is a diagram showing the result of the creep test, and shows the change with time of the compressive load 50 applied to one conductive terminal 11. In addition, the vertical axis | shaft of FIG. 9 has converted and displayed the compressive load 50 to the load per conductive terminal 11. FIG.

  Referring to FIG. 9, the load per conductive terminal 11 was set to 70 g immediately after the load was applied. Thereafter, the load per conductive terminal 11 rapidly decreased and decreased to about 35 g in a short period of about 10 to 20 hours. This decrease in load is caused by the fact that the distance between the first electrode 22 and the second electrode 32 remains at the distance immediately after the load is applied, even though the conductive terminal 11 has shortened due to creep. This is due to a decrease in the applied compressive load. That is, in a state where the distance (distance) between the first and second electrodes 22 and 32 is kept constant, the load per conductive terminal 11 continues to decrease. After that, even after 700 hours, the load per conductive terminal 11 gradually decreased.

  FIG. 10 is a diagram showing the load dependency per terminal of the contact resistance, and shows the relationship between the resistance value between the first electrode 22 and the second electrode 32 and the load per conductive terminal 11 in the creep test. In addition, the arrow in FIG. 10 represents the direction of the load change with progress of time, and represents that a load reduces with time progress from the original load and about 70g.

  Here, as for the resistance value between the first electrode 22 and the second electrode 32, the electrical resistance between the first electrode 22 and the second electrode 32 was measured using a resistance measuring device 62. Further, the load (output of the load cell 61 c) and the resistance value at each time were recorded using a recorder 63.

  Referring to FIG. 10, as revealed in FIG. 9, the initial load (approximately 70 g) applied to the conductive terminal 11 decreases with time (see the arrow in the figure). When the load per conductive terminal 11 is in the range of 70 g to 30 g, the resistance value between the first electrode 22 and the second electrode 32 gradually increased as the load per conductive terminal 11 decreased. However, when the load per conductive terminal 11 is smaller than 30 g, the resistance value rapidly increases as the load decreases. This increase in resistance value indicates that the contact resistance between the first electrode 22 and the second electrode 32 and the conductive terminal 11 has increased due to a decrease in the load applied to the conductive terminal 11.

  The results shown in FIGS. 9 and 10 show that when the distance between the first electrode 22 and the second electrode 32 is kept constant, the conductive terminal 11 creeps and the load applied to the conductive terminal decreases. It has been clarified that the contact resistance of the conductive terminal 11 increases, particularly when the load becomes smaller than a specific value, for example, when it becomes smaller than 30 g, the contact resistance rapidly increases.

  Referring to FIGS. 5 and 6 again, in the first embodiment, the circuit board 20 and the semiconductor package 30 do not come into contact with the frame 13, or even if they make contact, only a slight load is distributed to the frame 13. At this time, the total load 50 is distributed to each conductive terminal 11, and a predetermined pressure, for example, 70 g, is applied to each conductive terminal 11.

  On the other hand, when the conductive terminal 11 is shortened by creep after a long time, the circuit board 20 and the semiconductor package 30 come into contact with the frame body 13. After the contact, since the frame 13 serves as a stopper, the distance between the circuit board 20 and the semiconductor package 30 is maintained at the height of the frame 13 and does not change any further. At this time, since the distance between the first electrode 22 and the second electrode 32 is maintained at the height of the frame body, the creep of the conductive terminal 11 proceeds as shown in FIGS. The load applied to each conductive terminal 11 decreases. As a result, the contact resistance of the conductive terminal 11 increases, and the reliability of electrical connection decreases with the progress of creep.

  Note that a decrease in the load applied to the conductive terminal 11 is dispersed in the frame body 13 and supported by the frame body 13. Therefore, after the circuit board 20 and the semiconductor package 30 are in contact with the frame body 13, pressure is applied to the frame body 13 from the vertical direction. Since the amount of pressure applied to the frame 13 is equal to the decrease in the total load applied to the conductive terminal, the load applied to the conductive terminal 11 can be known by measuring the pressure applied to the frame 13. . In the first embodiment, a load applied to the frame body 13 is detected as a distortion of the frame body 13 using a strain gauge 14 attached to the frame body 13.

  FIG. 11 is a diagram showing the relationship between the load applied to the frame body and the gauge resistance according to the first embodiment of the present invention, and the load applied to the frame body and the resistance value of the strain gauge attached to the side wall surface of the frame body. Represents the relationship.

  First, the conductive terminal 11 was removed from the socket 10 of the first embodiment, and the frame 13 and the support plate 1 were left as a test sample. A load 50 was applied to the frame 13 in the vertical direction using the creep test apparatus shown in FIG. 8, and the resistance change of the strain gauge 14 attached to the outer wall surface of the frame 13 was measured. The results are shown in FIG.

  Referring to FIG. 11, as the load 50 increases, the gauge resistance (resistance value of the strain gauge) decreases uniformly. The rate of decrease is approximately −0.4 mΩ / g. Since it is possible to measure the change in gauge resistance with an accuracy of 0.1 mΩ, a change of 0.25 g of the total load 50 can be detected. Therefore, assuming that the number of the conductive terminals 11 of the socket 10 is 1000, a change of 0.00025 g with respect to one conductive terminal can be detected. By using the strain gauge 14, the change in the load applied to the conductive terminal 11 can be measured with such high accuracy.

  FIG. 12 is a diagram for explaining the electrical connection reliability evaluation method according to the first embodiment of the present invention. Curves 91 and 92 in FIG. 12 are the total loads applied to the frame and the conductive terminals, respectively. This represents the change over time.

  Referring to curve 91 in FIG. 12, full load L <b> 0 is applied to conductive terminal 11 at time t <b> 0 immediately after assembly of semiconductor device 100. For example, in the socket 10 having 1000 conductive terminals 11, a total load L0 of 70 kg is applied in order to apply a load of 70 g to each conductive terminal. At this time t0, the circuit board 20 and the semiconductor package 30 are not in contact with the frame body 13, and the frame body 13 is not loaded with reference to the curve 92. This state is maintained until time t <b> 2 when the conductive terminal 11 creeps and the circuit board 20 and the semiconductor package 30 come into contact with the frame body 13.

  When the circuit board 20 and the semiconductor package 30 come into contact with the frame body 13 at time t2, a part of the total load L0 is dispersed in the frame body 13, and is applied to the conductive terminal 11 with reference to the curve 91. The applied load begins to decrease. On the other hand, with reference to the curve 92, the frame 13 is increased in load by the same amount as the load decrease of the conductive terminal 11. As described above, since the load increase of the frame 13 and the decrease of the total load of the conductive terminal 11 are equal, by measuring the load of the frame 13 (curve 92), the load of the conductive terminal 11 ( Curve 91) can be calculated.

  In the semiconductor device 100 of the first embodiment, referring to FIG. 4, a resistance change of the strain gauge 14 attached to the outer wall surface of the frame body 13 is measured by the monitoring circuit 21, and the measured value is applied to the frame body 13. Measure the applied load. Then, referring to curve 91 in FIG. 12, at time t <b> 3, the load applied to conductive terminal 11 decreases to a load L <b> 2 that cannot guarantee electrical connection. At the same time, referring to the curve 92, the load applied to the frame 13 reaches a load L1 represented by L1 = L0−L2. When the monitoring circuit 21 detects the load L1, the monitoring circuit 21 generates a signal notifying that the reliability has been lowered before the electrical connection cannot be guaranteed. With this signal, it is possible to know an appropriate replacement time of the socket 10. In a normal use environment, the replacement time is about several years to 10 years, and even if it is not replaced, it usually functions without problem for more than 10 years.

  The monitoring circuit 21 calculates and stores the product of the minimum load (hereinafter referred to as “minimum guaranteed load”) per conductive terminal that can guarantee electrical connection and the number of conductive terminals 11 as the load L2. . Note that, with reference to FIG. 10, the minimum guaranteed load is a load per conductive terminal 11 immediately before the contact resistance starts to increase rapidly as the load decreases, for example, 30 g. Further, as a load that can guarantee the reliability of the electrical connection of the socket 10, a value specified by the socket manufacturer can be used as the minimum guaranteed load.

  Further, the monitoring circuit 21 can output the observed load of the frame 13 sequentially or when requested. As a result, the load applied to the conductive terminal 11 can be monitored at any time. Therefore, the reliability of the electrical connection of the socket 10 used in the semiconductor device 100 in operation can be assured with the load and the minimum guarantee. It can be evaluated as a difference from the load.

  As described above, according to the first embodiment of the present invention, the load applied to the conductive terminal 11 can be monitored using the strain gauge 14 affixed to the frame 13. The reliability of the mechanical connection can be evaluated based on the load. For this reason, a highly reliable semiconductor device is realized.

  In the first embodiment described above, a terminal made of a conductive resin is used as the conductive terminal 11. However, the present invention is not limited to this, and other conductive terminals having creep characteristics that cause a change with time are problematic. Similarly, the present invention can be applied. Moreover, although the strain gauge 14 was used as a load measuring element for measuring the load applied to the frame 13, it should just be what can measure the load concerning the frame 13, and is not restrict | limited to this.

  The second embodiment of the present invention relates to a semiconductor device 101 using a socket 10A having a structure in which a support plate and a frame are separated. The semiconductor device 101 of the second embodiment is the same as the semiconductor device of the first embodiment except that the socket is different.

  FIG. 13 is a socket assembly diagram of the second embodiment of the present invention, and shows the structure of the socket 10A used in the second embodiment. A hatched plan view in FIG. 13 represents a cross-sectional shape of the upper frame 10 </ b> A constituting the upper part of the frame 13. FIG. 14 is a cross-sectional view of a semiconductor device according to the second embodiment of the present invention, and shows a cross-sectional structure of a socket 10A used in the semiconductor device 101 of the second embodiment.

  Referring to FIG. 13, the socket 10 </ b> A of the second embodiment is different from the socket 10 of the first embodiment in the shape of the frame 13. Others are the same as in the first embodiment.

  Referring to FIG. 13, the frame 13 of the socket 10 </ b> A according to the second embodiment includes an upper frame 13 </ b> A that configures the upper part of the frame 13 and a lower frame 13 </ b> B that configures the lower part of the frame 13. The upper frame 13A has a recess 13d that fits the semiconductor package 30 on the inner upper surface, and a recess 13e that fits the support plate 12 on the inner lower surface. And the convex part 13b which protrudes in a convex shape inside is provided in the middle position of 13 A of upper frames, and the hollow 13d and the hollow 1e are horizontally separated by this convex part 13b. The outer frame 13a and the convex portion 13b can be integrally formed.

  Referring to FIGS. 13 and 14, support plate 12 is inserted from below into a recess 13 e formed in the lower surface of upper frame 13 </ b> A. A conductive resin 11 is formed on the support plate 12, and a lower frame 13 c is attached to the lower surface periphery of the support plate 12 via an adhesive tape.

  The lower frame 13c is a frame-like plate having an outer periphery that has substantially the same planar shape as the support plate 12. The lower frame 13c forms a part of the frame 13 and functions as a stopper (standoff) together with the convex portion 13b as will be described later. To do. The outer frame 13a, the convex portion 13b, and the lower frame 13B may be made of the same insulating material or different insulating materials.

  The strain gauge 14 (load measuring element) is affixed to the tip end surface (the surface constituting the inner wall surface of the frame 13) of the protruding portion of the convex portion 13 b of the frame 13. Or it affixes on the inner wall face of the lower frame 13c. Of course, it can be attached to the outer wall surface of the outer frame 13a of the frame 13 or the outer wall surface of the lower frame 13c as necessary.

  Hereinafter, the assembly process of the semiconductor device using the socket 10A will be described.

  Referring to FIG. 14, first, the circuit board 20 having the first electrode on the upper surface is placed on the base 41 of the fixed component 40. Next, the support plate 12 having the conductive terminals 11 formed on the circuit board 20 is connected and fixed by aligning the conductive terminals 11 with the first electrodes 22 on the upper surface of the circuit board 20. Note that a lower frame 13 </ b> B is attached in advance to the periphery of the lower surface of the support plate 12. Further, the fixed component 40 is the same fixed component 40 as that of the first embodiment.

  Next, the support plate 12 is fitted into the recess 13e formed on the lower surface of the upper frame 13A, and the upper frame 13A is mounted on the support plate 12. Since the recess 13e and the support plate 12 are fitted, the upper frame 13A is automatically positioned with respect to the support plate 12.

  Next, the semiconductor package 30 is inserted into a recess 13d formed on the upper surface of the upper frame 13A. At this time, since the semiconductor package 30 is fitted into the recess 13d and aligned with the upper frame 13A, it is eventually aligned with the support substrate 12, and the second electrode 32 on the lower surface of the semiconductor package 30 is Positioning is performed so as to automatically contact the conductive terminal 11 formed on the support plate 12.

  Next, the upper plate 42 of the fixed component 40 is placed on the upper surface of the semiconductor package 30, and the upper plate 42 and the lower plate 41 of the fixed component 40 are referred to as in the semiconductor device 100 of the first embodiment with reference to FIG. 1. Are tightened using a fixing screw 42b and a spring 42c, and the semiconductor package 30 is pressed onto the circuit board 20 via the conductive terminals 11. Through the above-described steps, the semiconductor device 101 in which the semiconductor package 30 is fixed to the circuit board 20 is manufactured.

  In the semiconductor device 101 according to the second embodiment described above, the thickness (the height in the vertical direction in FIG. 14) of the convex portion 13b and the lower frame 13B constituting the frame body 13 is the same as that of the upper terminal 11a and the lower terminal 11b. It is thinner than the height. Therefore, the distance between the semiconductor package 30 and the circuit board 20 is determined by the height of the conductive terminal 11 in the initial stage of manufacturing the semiconductor device 101. A total load applied to the semiconductor package 30 is applied to the conductive terminal 11. Therefore, the conductive terminal 11 creeps during the operation period of the semiconductor device 101, and the interval between the semiconductor package 30 and the circuit board 20 is narrowed.

  After a long operation period, when the interval between the semiconductor package 30 and the circuit board 20 is narrowed and the upper surface of the circuit board 20 and the lower surface of the semiconductor package 230 are in contact with the convex portion 13b and the lower frame 13B, respectively, The frame 13B functions as a stopper, and the distance between the semiconductor package 30 and the circuit board 20 is not further narrowed.

  At the same time, part of the load applied to the semiconductor package 30 is dispersed in the convex portions 13b and the lower frame 13B that function as stoppers. For this reason, the load applied to the conductive terminal 11 decreases, and the reliability of the electrical connection of the socket 10A deteriorates.

  In the second embodiment, the load dispersed on the convex portion 13b and the lower frame 13B is detected by the strain gauge 14 attached to the inner wall surface of the convex portion 13b as strain of the convex portion 13b. In addition, it is the same as that of 1st Embodiment that the relationship between the load applied to the convex part 13b and the distortion amount of the convex part 13b is measured beforehand. Thereafter, as in the first embodiment, the load applied to the conductive terminal 11 is calculated from the observed load distributed on the convex portion 13b, and the reliability of the socket 10A is evaluated.

  The strain gauge 14 can also be attached to the lower frame 13B. Since the lower frame 13B is not constrained on the side surfaces, the load applied to the lower frame 13B can be accurately measured. Further, the load can be measured more sensitively by reducing the width of the lower frame 13B.

  By applying the present invention to an LGA socket, a highly reliable semiconductor device can be realized.

10, 10A Socket 11 Conductive terminal 11a Upper terminal 11b Lower terminal 11c Via 12 Support plate 13 Frame body 13A Upper frame 13a Outer frame 13b Protruding part 13B Lower frame 13d, 13e Depression 14 Strain gauge (load measuring element)
14a Strain detection direction 20, 66 Circuit board 20a, 42a Through hole 21 Monitoring circuit 21a Lead wire 22, 67 First electrode 30, 64 Semiconductor package 32, 65 Second electrode 40 Fixed component 41 Base 41 Column 42 Upper plate 42b Fixing screw 42c Spring 42d Radiation fin 50 Load 60 Creep test sample 61a Bed 61b Head 61c Load cell 62 Resistance measuring device 63 Recorder 100, 101 Semiconductor device

Claims (5)

The first electrode disposed on the upper surface of the circuit board and the second electrode disposed on the lower surface of the semiconductor package so as to face the first electrode are pressed in the vertical direction by the circuit board and the semiconductor package. A socket having a conductive terminal for electrically connecting the first and second electrodes;
A plurality of the conductive terminals having creep properties;
A support plate for supporting the conductive terminal by projecting the upper and lower ends of the conductive terminal up and down;
A frame that supports the periphery of the support plate;
A socket comprising: a load measuring element for measuring a vertical load applied to the frame. The socket according to claim 1, wherein the load measuring element is a strain gauge attached to a side wall surface of the frame. In the semiconductor device which mounted the semiconductor package on the upper surface of the circuit board via the socket according to claim 1 or 2,
A semiconductor device comprising: a monitoring circuit that monitors an output of the load measuring element and evaluates deterioration of connection between the first and second electrodes based on a load detected by the load measuring element. The monitoring device outputs a warning signal when a load detected by the load measuring element exceeds a preset load. Preparing a circuit board having a first electrode disposed on an upper surface and a semiconductor package having a second electrode disposed on a lower surface;
A support plate that supports a plurality of conductive terminals having creep characteristics by projecting the upper and lower ends of the conductive terminal up and down, a frame that supports the periphery of the support plate, and upper and lower applied to the frame Preparing a socket having a load measuring element for measuring a load in a direction;
A step of pressing and mounting the semiconductor package on the circuit board via the socket so that the first and second electrodes facing each other are connected by the conductive terminal;
A socket that monitors the output of the load measuring element and evaluates the reliability of the connection between the first and second electrodes based on the load applied to the frame body by being pressed by the circuit board and the semiconductor package. Reliability evaluation method.