JP2011204622A - Connector, electronic device, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To follow change of the shapes of a semiconductor device and a wiring board, and to maintain electric connection between a connector, a semiconductor device and a wiring board.SOLUTION: In an electronic device 100, a land 112 of the semiconductor device 110 and an electrode pad 122 of the wiring board 120 are electrically connected to each other via an LGA connector 130. The LGA connector 130 has an electrically insulating frame 131 which serves as a support member and an electrically conductive column 140 which serves as a connection terminal. The column 140 is placed within a through-hole formed in the frame 131 and protrudes from the frame 131. The column 140 has a metal portion 143 containing a shape memory alloy. In an embodiment, the column 140 has electrically conductive elastomers 141 and 142 on contact surfaces of the land 112 and the electrode pad 122, respectively, and the metal portion 143 is disposed between the elastomers 141 and 142.

Description

  The present invention relates to a connector for electrically connecting a land grid array (LGA) type package to a wiring board, an electronic device including the connector, and a method for manufacturing the same.

  A ball grid array (BGA) type or land grid array (LGA) in which a large number of terminals are arranged in a grid pattern on one surface of a package as electronic devices such as servers and personal computers (PCs) become highly functional and sophisticated. ) Type semiconductor devices are widely used. The LGA package can be pressure-mounted on a wiring board such as a system board. Since the pressure mounting of the LGA package is electrically connected using mechanical contact, a high-temperature process for solder fusion bonding is not required, and the repair work of the semiconductor device is facilitated. . In pressure mounting of an LGA package, an electrical connection is generally achieved between a land of the LGA package and an electrode pad of a wiring board via a connector called an LGA connector or an LGA interposer.

  FIG. 1 shows an example of a mounting structure including a conventional LGA connector. A semiconductor device 10 that is an LGA package is mounted on the system board 20 via an LGA connector 30. The LGA package 10 and the system board 20 are sandwiched between a reinforcing plate (bolster plate) 51, a heat spreader 52, and a heat sink base 53 arranged outside thereof, and are tightened by a spring-loaded screw 54. The LGA package 10 includes a package substrate 11, lands 12 arranged in a lattice pattern on the lower surface thereof, and a semiconductor chip 13. The system board 20 includes a substrate 21 and electrode pads 22 arranged on the upper surface thereof in a grid pattern. The electrode pads 22 of the system board have the same pattern as the lands 12 of the LGA package. In addition, in an actual server, PC, or the like, a heat sink or a housing having heat radiating fins is generally attached in addition to the configuration of FIG.

  The LGA connector 30 includes a frame (also referred to as a socket) 31 that is a support member, and a plurality of connection terminals (hereinafter referred to as columns) 40 that penetrate the frame and protrude from both sides of the frame. The columns 40 are arranged in the same pattern as the lands 12 of the LGA package and the electrode pads 22 of the wiring board. The column 40 is made of conductive rubber in which a conductive filler is dispersed. The column 40 is compressed between the land 12 and the electrode pad 22 by pressurization with a spring-loaded screw 54, and these can be electrically connected.

  However, electrical connectivity between the column 40 and the lands 12 and / or electrode pads 22 may be reduced by prolonged pressurization and / or heat generation during operation of the electronic device. For example, when the column 40 is deformed due to creep of a rubber material or the like, the column 40 may not be able to follow the warpage of the LGA package 10 and the system board 20 due to heat generated from the semiconductor chip. Further, when the warpage of the LGA package 10 and / or the system board 20 is increased, a gap 60 is generated between the column 40 and the land 12 and / or the electrode pad 22, as shown in FIG. Will interfere with continuity.

  In relation to this or other problems, a configuration using a spring for the column and a configuration using a composite member such as a combination of a spring and an elastomer for the column are known.

Special table 2004-519075 gazette JP 2002-100431 A JP 2004-296301 A JP 2008-226841 A

  However, the known connectors using springs or composite members for the column have the following problems. Although the followability to the warp of the semiconductor device and / or the wiring board can be improved by expanding the expansion / contraction range by a spring or the like, the resistance increases due to the length and thinness of the wire constituting the spring. Further, the spring material itself or the elastomer to be combined is deformed by creep or the like, and the followability to a change in shape of the semiconductor device or the like can be lowered.

  Therefore, there is still a demand for a technology that can follow the change in the shape of the semiconductor device and the wiring board and maintain the electrical connectivity between the pressure-mounted semiconductor device and the wiring board.

  According to one aspect, a connector is provided that includes an electrically insulating frame and a connection terminal protruding from the frame. A through hole is provided in the frame, and a connection terminal is disposed in the through hole. The connection terminal includes a metal part including a shape memory alloy.

  According to another aspect, an electronic device is provided that includes a wiring board, a semiconductor device provided above the wiring board, and a connection terminal that electrically connects the wiring board and the semiconductor device. The connection terminal includes a metal part including a shape memory alloy.

  According to another aspect, an electronic device manufacturing method is provided. The method includes a step of disposing a connector having a frame, a through-hole provided in the frame, and a connection terminal disposed in the through-hole and protruding from the frame on a wiring board. The connection terminal includes a metal part including a shape memory alloy. The method further includes the steps of disposing the semiconductor device on the connector and electrically connecting the connection terminal to the wiring board and the semiconductor device.

  When the distance between the semiconductor device and the wiring board increases due to heat generation from the semiconductor device, the metal part of the connection terminal extends due to the shape memory effect, thereby maintaining the electrical connectivity between the connection terminal, the wiring board, and the semiconductor device. can do.

It is sectional drawing which illustrates the mounting structure using the conventional LGA connector. It is sectional drawing which shows typically the problem seen in the conventional LGA connector. It is sectional drawing which illustrates the LGA connector and electronic device which concern on 1st Embodiment. It is a top view which illustrates the arrangement pattern of a column. It is sectional drawing which expands and shows the column of FIG. 3, and its peripheral part. It is sectional drawing which shows the effect of the LGA connector of FIG. 3 typically. It is sectional drawing which shows one modification of a metal part. FIG. 4 is a cross-sectional view illustrating a method for manufacturing the LGA connector of FIG. 3. It is sectional drawing for demonstrating the LGA connector which concerns on 2nd Embodiment. It is sectional drawing which shows the effect of the LGA connector of FIG. 9 typically. FIG. 10 is a cross-sectional view illustrating a method for manufacturing the LGA connector of FIG. 9.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the drawings, various components are not necessarily drawn to the same scale. Throughout the drawings, the same or corresponding components are denoted by the same or similar reference numerals.

(First embodiment)
First, a schematic configuration of the electronic device 100 and the connector 130 according to the first embodiment will be described with reference to FIGS.

  As shown in FIG. 3, the electronic device 100 includes a semiconductor device 110, a wiring board 120, and a connector 130. The semiconductor device 110 is mounted on the wiring board 120 via the connector 130. The semiconductor device 110 and the wiring board 120 are sandwiched between a bolster plate 151 and a heat dissipation mechanism (for example, a heat spreader 152 and a heat sink base 153) disposed outside the semiconductor device 110 and tightened by a spring-loaded screw 154. Typically, the electronic device 100 has 3 to 4 spring-loaded screws 154. In addition, in an actual server, PC, or the like, the electronic device 100 can include, for example, a heat sink or a housing having heat radiation fins in addition to the configuration of FIG.

  The semiconductor device 110 includes a package substrate 111, a plurality of pads (lands) 112 arranged on the lower surface of the package substrate 111 in a lattice pattern, and a semiconductor chip 113. Such a semiconductor device is called an LGA package or the like. The LGA package 110 may also include other elements depending on its internal implementation. For example, when the semiconductor chip 113 is flip-chip mounted on the package substrate 111, an underfill resin can be filled between the chip and the package substrate 111. In addition, when the semiconductor chip 113 is connected to the package substrate 111 by a bonding wire, a sealing resin or the like for sealing the chip and the bonding wire is provided. The wiring board 120 is, for example, a system board, and includes a board 121 and a plurality of electrode pads 122 arranged on the upper surface of the board 121. The electrode pads 122 on the system board have the same pattern as the lands 112 on the LGA package. In general, the land 112 of the LGA package and the electrode pad 122 of the system board are formed by, for example, copper (Cu) plating, and the surface is subjected to gold (Au) plating.

  The connector 130 includes an electrically insulating frame (also referred to as a socket) 131 that is a support member, and a plurality of conductive connection terminals (hereinafter referred to as columns) 140 that penetrate the frame and protrude from both sides of the frame. Have. The frame 131 includes, for example, a resin containing polyimide or glass cloth inside. Such a connector is called an LGA connector or an LGA interposer. The columns 140 are arranged in a two-dimensional pattern similar to the lands 112 of the LGA package and the electrode pads 122 of the system board in the plane of the frame 131 as illustrated in the top view of FIG. Therefore, the column 140 is sandwiched between the land 112 and the electrode pad 122 by pressing with the spring-loaded screw 154, and the opposing land 112 and the electrode pad 122 can be electrically connected. As shown in FIG. 4, the frame 131 may have an opening 131 a in a portion where the column 140 does not exist. Further, for example, when the number of columns is large, the frame 131 may extend beyond the spring-loaded screw 154 in the lateral direction, and may have a screw passage hole corresponding to the position of the screw 154.

  Next, the column 140 included in the LGA connector 130 will be described in more detail with reference to the enlarged sectional view of FIG.

  Each column 140 includes a first conductive elastomer 141 provided on the LGA package 110 side, a second conductive elastomer 142 provided on the system board 120 side, and a metal part provided between the two elastomers. 143. The metal part 143 is inserted through a through hole 132 formed in the frame 131. The metal part 143 also has a length larger than the thickness of the frame 131 and protrudes from both the LGA package side and the system board side of the frame 131. The elastomers 141 and 142 have insertion holes 141a and 142a for receiving the protrusions of the metal part 143, respectively, and are in contact with the metal part 143 on the inner surfaces of the insertion holes. Further, the elastomers 141 and 142 have, for example, an outer shape obtained by cutting the top of a cone, and come into contact with the land 112 of the LGA package and the electrode pad 122 of the system board at the top surfaces 141b and 142b, respectively.

  The first and second elastomers 141 and 142 include conductive rubber in which conductive filler such as silver (Ag) filler is dispersed. Moreover, the metal part 143 contains the shape memory alloy. Therefore, each column 140 can be configured as a composite member in which conductive rubber and a shape memory alloy are connected. The shape memory alloy of the metal part 143 is, for example, a nickel-titanium alloy such as 51Ni-49Ti, a copper-based alloy such as Cu-Zn-Al, and an iron-based material such as Fe-Mn-Si in consideration of the transformation point temperature. A variety of shape memory alloys such as alloys may be selected. Shape memory alloys may also be selected taking into account other considerations, such as those with low temperature hysteresis and / or low cost. Based on the principle of phase transformation, shape memory alloys can shrink with a small load when in the martensite phase, and when they return to the austenite phase (parent phase) at temperatures above the transformation temperature, they exhibit a shape memory effect. Recover shape.

  FIG. 6 schematically shows the effect of using the column 140 configured as such a composite member. FIG. 6 shows a part of the electronic device 100 in two temperature ranges (a) near room temperature and (b) when the temperature rises (for example, around 80 ° C.).

  In the vicinity of room temperature, the metal part 143 including the shape memory alloy is in a state of being compressed according to the load received from the LGA package 110 and the system board 120 by tightening with the spring-loaded screw 154. The length of the metal part 143 at this time is L1. Of course, the same load is applied to the conductive elastomers 141 and 142, and the elastomers 141 and 142 are pressed against the lands 112 of the LGA package and the electrode pads 122 of the system board, respectively.

  When the electronic device 100 is in operation, the temperature of the LGA package 110, the system board 120, and the LGA connector 130 rises due to heat generated by the semiconductor chip 113 included in the LGA package 110, and these elements may be warped. Usually, due to the thermal expansion of these elements and the tightening with the spring-loaded screw 154, the LGA package 110 tends to be convex upward and the system board 120 tends to be convex downward as shown. Therefore, the distance between the LGA package 110 and the system board 120 increases. At this time, the metal portion 143 including the shape memory alloy expands to the length L2 following the increased separation distance due to the shape memory effect (L2> L1), and the elastomers 141 and 142 are extended to the land 112 and the electrode pad 122, respectively. Acts to press against.

  The behavior shown in FIGS. 6 (a) and 6 (b) selects the type and composition of the shape memory alloy so that it is in the martensite phase near room temperature and in the parent phase when the temperature rises to cause warpage. This can be realized. For example, the transformation point temperature of the shape memory alloy used for the metal part 143 is selected to be a temperature between room temperature and a temperature at which significant warpage occurs, for example, a temperature between room temperature and the maximum operating temperature in the device design. obtain.

  Thus, the height of the column 140 including the metal portion 143 follows the thermal deformation of the LGA package 110 and the system board 120 both near room temperature and at the time of temperature rise using the phase transformation of the shape memory alloy. Can change. Therefore, the column 140 prevents a gap from being generated between the land 112 and the electrode pad 122, and can maintain good electrical connectivity between the LGA package 110 and the system board 120.

  Also, each column 140 abuts the conductive elastomers 141 and 142 to the corresponding lands 112 and pads 122, thus preventing damage to the Au plating on the land surface and the pad surface seen when directly contacting the metal. can do. Therefore, it can be avoided that Cu is exposed and oxidized, and also from this point, it can contribute to maintaining good electrical connectivity.

  Referring back to FIG. 5, the LGA connector 130 preferably has a metal film 133 formed on the inner wall of the through hole 132 of the frame 131. The metal film 133 can be a Cu plating film, for example. The LGA connector 130 preferably has a metal pad 134 that surrounds each through-hole 132 on the surface of the frame 131 on the LGA package 110 side and the system board 120 side or on one surface thereof. The metal pad 134 may be an Au plating film, for example. When present, the metal film 133 and the pad 134 communicate and surround each through-hole 132.

  The metal film 133 or the metal pad 134 contacts the column 140 having the conductive elastomers 141 and 142 and the metal part 143, and contributes to conduction between the land 112 of the LGA package and the electrode pad 122 of the system board. In particular, when the shape memory alloy of the metal part 143 has a relatively high electrical resistance due to its material and / or shape, the metal film 133 and the metal pad 134 significantly reduce the resistance parasitic to the column 140, Signal delay between the LGA package 110 and the system board 120 can be reduced.

  In addition, this embodiment is not limited to providing the metal part 143 containing a shape memory alloy in all the columns 140, You may provide the metal part 143 only in a part of column. As an example, the metal part 143 may be provided only in the inner peripheral column of the grid-like column 140 shown in FIG. 4 in correspondence with the warp shape as shown in FIGS. . As another example, when a reverse warp shape is predicted due to a mismatch in thermal expansion coefficients between components, for example, the metal portion 143 may be provided only in the outer peripheral portion or the corner portion column.

  Further, the shape of the metal part 143 is not limited to a rod shape, and other shapes such as a coil shape or a corrugated plate shape may be used. A coil-shaped or corrugated shape-memory alloy can realize a movable range capable of dealing with a larger warp or the like.

  Furthermore, the length of the metal part 143 is not limited to that greater than the thickness of the frame 131, and the length can be determined according to the predicted amount of warpage. For example, when the length of the required shape memory alloy is smaller than the frame thickness, the shape memory alloy is positioned only in a part of the height direction in the through hole, inserted into the through holes in the conductive elastomers 141 and 142, and shaped. You may provide the rod-shaped part contact | abutted or adhere | attached on a memory alloy. Alternatively, as shown in FIG. 7, a metal part 143 ′ is configured as a first metal part 143-1 having a shape memory alloy and a second metal part 143-2 having another metal or alloy, like a column 140 ′. May be. By using a low resistance metal such as Cu as the second metal portion 143-2, the electric resistance of the column can be further reduced.

  Next, an example of a method for manufacturing the LGA connector 130 and the electronic device 100 will be described with reference to FIG.

  First, as shown in FIG. 8 (a), a through hole having a pattern corresponding to the land pattern of the LGA package is formed in a frame 131 having an insulating material such as resin containing polyimide or glass cloth by a drill or a laser. 132 is formed.

  Next, as shown in FIG. 8B, a metal plating film 133 is formed on the inner wall of the through hole 132 of the frame, and a metal pad 134 is formed around the plated through hole 132. For example, the metal plating film 133 can be a Cu plating film, and the metal pad 134 can be an Au pad.

  Next, as shown in FIG. 8C, the metal part 143 including the shape memory alloy is inserted into the through hole 132. The metal part 143 can be formed in advance so as to have a diameter smaller than the diameter of the through hole 132 and a desired length. At the time of insertion, a method such as suction from the side opposite to the insertion side of the through hole 132 may be used. The shape memory alloy may be, for example, a NiTi alloy, but may be other alloys having physical properties that recover from the compressed state at room temperature to the original shape in the operating temperature range of the electronic device 100. Moreover, you may use the shape memory alloy which has other shapes, such as coil shape or a corrugated sheet shape.

  Finally, as shown in FIG. 8D, the conductive elastomers 141 and 142 are attached to the metal part 143 protruding from the frame 131. Using the insertion holes 141a and 142a formed in the conductive elastomers 141 and 142, respectively, the metal part 143 and the conductive elastomers 141 and 142 can be fitted, and the elastomers 141 and 142 can be brought into contact with the metal pad 134. Is possible. The conductive elastomers 141 and 142 may be, for example, conductive rubber containing a conductive filler. As an example, a rubber material containing an Ag filler can be poured into a mold, and a conductive rubber having a conical outer shape whose top is cut flat and an insertion hole provided in the center of the bottom can be molded. However, other conductive fillers or conductive particles or other shapes may be used.

  In manufacturing the electronic device 100, the system board 120, the LGA connector 130, and the LGA package 110 are stacked so that the pads 122, the columns 140, and the lands 112 are aligned to form a stack. The stack is arranged between the bolster plate 151, the heat spreader 152, and the heat sink base 153, and tightened by the spring-loaded screw 154, whereby the pad 122, the column 140, and the land 112 can be brought into contact with each other with sufficient contact force. .

Example 1
Through holes having a pitch of 1.27 mm and a diameter of about 0.75 mm are formed in a frame having a thickness of about 1.95 mm. Cu plating is performed on the inner wall of the through hole to form an Au pad around the through hole. A rod-shaped NiTi alloy having a composition ratio of Ni: 49% and Ti: 51% is inserted into the through hole. On both the LGA package side and the system board side of the frame, conductive rubber containing, for example, an Ag filler is fitted into the NiTi alloy portion protruding from the frame. As a result, a column having a total height of about 2.3 mm when not pressurized is formed.

  The case of using an LGA connector having this column (hereinafter referred to as connector 1) was compared with the case of using an LGA connector having a column made of only conductive rubber (hereinafter referred to as a conventional connector). .

  When the contact state between the LGA package and the column of the LGA connector was observed at room temperature and 80 ° C., a gap of 10 μm to 30 μm was generated in the conventional connector at 80 ° C., but no gap was observed in the connector 1. Since the shape recovery strain of the NiTi alloy is about 3%, the rod-shaped NiTi alloy having a length of about 2.15 mm can be extended by about 65 μm due to the phase transformation when the temperature rises, and the generation of the gap can be prevented. it can.

  In addition, when a conventional connector is used, the load on the column reaches a maximum of 70 to 90 g, exceeding the design upper limit load of 60 g. For this reason, the column is extremely deformed and does not follow the change in the separation distance between the LGA package and the system board accompanying the temperature change (15 ° C. to 80 ° C.). By the resistance measurement, a contact failure between the LGA connector and the LGA package and / or the system board was observed. On the other hand, when the connector 1 is used, the load on the column is controlled within a range of 30 g to 60 g. The deformation of the column can be reduced, and a change in the separation distance between the LGA package and the system board accompanying a temperature change (15 ° C. to 80 ° C.) can be followed. As a result, it was not observed that the column collapsed and caused poor contact with the LGA package and / or system board.

(Second Embodiment)
Next, the configuration of the LGA connector 230 according to the second embodiment will be described with reference to FIG. The LGA connector 230 can be used in place of the LGA connector 130 in the electronic device 100 shown in FIG. 9 corresponds to FIG. 5 and shows a part of the connector 230 and a part of the semiconductor device (referred to as LGA package) 110 and the wiring board (referred to as system board) 120 connected by the connector. Yes. In addition, about the element which is common in the connector 130 and the connector 230, the same referential mark is attached | subjected and detailed description about the function and material is abbreviate | omitted.

  The LGA connector 230 includes an electrically insulating frame 231 that is a support member, and a plurality of conductive connection terminals (columns) 240 that penetrate the frame and protrude from both sides of the frame. The column 240 is sandwiched between the land 112 of the LGA package 110 and the electrode pad 122 of the system board 120 by external pressure, and can electrically connect the opposing land 112 and the electrode pad 122.

  Each column 240 includes a metal part 243 inserted through the through-hole 232 of the frame 231, a first conductive spring 244 provided on the LGA package 110 side, and a second conductive provided on the system board 120 side. And a spring 245. The metal part 243 has a length larger than the thickness of the frame 231 and protrudes from both the LGA package side and the system board side of the frame 231. The first spring 244 is wound around the protruding portion of the metal portion 243 on the LGA package side, and the second spring 245 is wound around the protruding portion of the metal portion 243 on the system board side. As the conductive springs 244 and 245, for example, metal wires such as copper, phosphor bronze, stainless steel, beryllium copper, and piano wire can be used, and for example, plating such as gold plating may be performed.

  Each column 240 further includes a first conductive pad 246 attached to the tip of the first spring 244 (the end on the LGA package 110 side) and the tip of the second spring 245 (the end on the system board 120 side). ) Attached to the second conductive pad 247. The conductive pads 246 and 247 each include a conductive elastomer such as a conductive rubber in which a conductive filler is dispersed, at least on the contact surface with the LGA package 110 and the system board 120. The first conductive pad 246 and the second conductive pad 247 may be attached to the first spring 244 and the second spring 245 using a conductive adhesive, respectively. Instead of or in addition to bonding, other connection means may be used, such as, for example, the conductive pads 246 and 247 have molded portions that fit into the tips of the springs 244 and 245, respectively.

  Preferably, the LGA connector 230 has a metal film 233 formed on the inner wall of the through hole 232 of the frame. The metal film 233 can be, for example, a Cu plating film. The LGA connector 230 further has metal pads (see 234 in FIG. 11) formed around each through hole 232 on at least one surface of the frame 231 on the LGA package 110 side and the system board 120 side. May be. When this metal pad exists, the metal film 233 and the metal pad communicate with each other and surround each through hole 232. Base ends (end portions on the frame 231 side) of the first and second conductive springs 244 and 245 can be electrically connected to the metal film 233 or the metal pad. This electrical connection can be performed, for example, by bringing the base ends of the conductive springs 244 and 245 into contact with the metal film 233 or a metal pad, or by bonding with a conductive adhesive. The metal film 233 contributes to conduction between the land 112 of the LGA package and the electrode pad 122 of the system board.

  Thus, each column includes a metal portion 243 including a shape memory alloy, first and second conductive springs 244 and 245, and first and second conductive pads 246 and 247 including a conductive elastomer. It can be configured as a composite member including As described above with respect to the metal part 143 of the first embodiment, the shape memory alloy of the metal part 243 can be various, such as a Ni—Ti alloy, a copper alloy, and an iron alloy in consideration of the transformation point temperature and the like. Can be selected from these shape memory alloys. Based on the phase transformation principle, the shape memory alloy can be shrunk with a small load when in the martensite phase, and when the shape memory alloy returns to the parent phase at a temperature equal to or higher than the transformation point temperature, it exhibits a shape memory effect and recovers its shape.

  FIG. 10 schematically shows the effect of using the column 240 configured as such a composite member. FIG. 10 shows a part of the electronic device 100 in two temperature ranges (a) near room temperature and (b) when the temperature rises (for example, near 80 ° C.), as in FIG.

  In the vicinity of room temperature, the metal part 243 including the shape memory alloy is in a state of being compressed in accordance with a load received from the LGA package 110 and the system board 120 by an external pressure. The length of the metal part 243 at this time is L3. The springs 244 and 245 are also compressed according to the load received from the LGA package 110 and the system board 120. Of course, a load is also applied to the conductive pads 246 and 247 including the conductive elastomer, and the pads 246 and 247 are in pressure contact with the land 112 of the LGA package and the electrode pad 122 of the system board, respectively.

  When the electronic device 100 is in operation, the temperature of the LGA package 110, the system board 120, and the LGA connector 130 rises due to heat generated by the semiconductor chip 113 included in the LGA package 110, and these elements may be warped. Normally, as shown in the figure, the LGA package 110 tends to warp upward and the system board 120 tends to warp downward, and therefore the distance between the LGA package 110 and the system board 120 increases. At this time, the metal portion 243 including the shape memory alloy extends to the length L4 following the increased separation distance due to the shape memory effect (L4> L3), and the conductive pads 244 and 245 are respectively connected to the land 112 and the electrode. It acts to press against the pad 122. The springs 244 and 245 also act to press the conductive pads 244 and 245 against the land 112 and the electrode pad 122, respectively, due to their own thermal expansion and elasticity.

  The behavior shown in FIGS. 10 (a) and 10 (b) is selected from the shape and composition of the shape memory alloy so that it is in the martensite phase near room temperature and in the parent phase when the temperature rises to cause warpage. This can be realized. For example, the transformation point temperature of the shape memory alloy used for the metal part 243 may be selected as a temperature between room temperature and the maximum operating temperature in the device design.

  Thus, the height of the column 240 including the metal portion 243 follows the thermal deformation of the LGA package 110 and the system board 120 both near room temperature and at the time of temperature rise using the phase transformation of the shape memory alloy. Can change. Therefore, the column 240 prevents a gap from being formed between the land 112 and the electrode pad 122, and can maintain good electrical connectivity between the LGA package 110 and the system board 120.

  Also, each column 140 abuts the conductive elastomers 141 and 142 to the corresponding lands 112 and pads 122, thus preventing damage to the Au plating on the land surface and the pad surface seen when directly contacting the metal. can do. Therefore, it can be avoided that Cu is exposed and oxidized, and also from this point, it can contribute to maintaining good electrical connectivity.

  Further, since the load on the column 240 is distributed to the metal portion 243 and the springs 244 and 245, the metal portion 243 suppresses the disappearance of elastic force and / or the occurrence of creep due to an excessive load on the springs 244 and 245. It works like this. Therefore, even if the LGA package 110 and / or the system board 120 is warped unexpectedly, the column 240 is electrically connected between the LGA package and the system board by the extension of the springs 244 and 245. Can be maintained.

  Furthermore, since each column 240 makes the pads 246 and 247 including at least the surface of the conductive elastomer contact the corresponding lands 112 and pads 122, damage to the Au plating on the land surface and the pad surface can be prevented. Therefore, it can be avoided that Cu is exposed and oxidized, and also from this point, it can contribute to maintaining good electrical connectivity.

  Also in the present embodiment, various modifications mentioned in relation to the first embodiment can be applied as necessary. For example, a configuration in which only the inner peripheral portion or the outer peripheral column includes a shape memory alloy, a configuration in which a shape memory alloy and another metal are connected to form a metal portion, and / or a metal portion is a coil shape or a corrugated plate You may use the structure which has shapes other than rod shape, such as.

  Next, an example of a method for manufacturing the LGA connector 230 will be described with reference to FIG.

  The steps of FIGS. 11A to 11C can be performed in the same manner as the steps of FIGS. 8A to 8C. First, as shown in FIG. 11A, through holes 232 are formed in a frame 231 having an insulating material in a pattern corresponding to the land pattern of the LGA package. Next, as shown in FIG. 11B, a metal plating film 233 is formed on the inner wall of the through hole 232 of the frame. Further, a pad 234 may be formed around the plated through hole 232. Next, as shown in FIG. 11 (c), the metal part 243 including the shape memory alloy is inserted into the through hole 232.

  Next, as shown in FIG. 11 (d), springs 244 and 245 are inserted into the metal part 243 protruding from the frame 231 from both sides of the frame 231. The springs 244 and 245 can be formed in advance from a fine metal wire such as copper. Further, the base ends of the springs 244 and 245 can be fixed on the pad 234 with, for example, a conductive adhesive. When there is no pad 234 or when direct conduction with the metal plating film 233 is possible, the base ends of the springs 244 and 245 may be fixed to the metal plating film 233. Further, this electrical connection may be performed by other methods without using a conductive adhesive.

  Finally, as shown in FIG. 11E, conductive pads 246 and 247 containing a conductive elastomer are attached to the tips of the springs 244 and 245, respectively. The conductive elastomer may be a conductive rubber containing a conductive filler such as a conductive silicone rubber. The conductive pads 246 and 247 can be fixed to the tips of the springs 244 and 245 using, for example, a conductive adhesive. Here, only the proximal ends and the distal ends of the springs 244 and 245 are fixed, but an intermediate portion of the springs may be fixed to the metal portion 243 as necessary. When the metal plating film 233 and the metal pad 234 surrounding the through hole 232 of the frame are not formed, the base ends of the springs 244 and 245 may be fixed to the metal portion 243.

(Example 2)
Through holes having a pitch of 1.27 mm and a diameter of about 0.75 mm are formed in a frame having a thickness of about 1.95 mm. Cu plating is performed on the inner wall of the through hole to form an Au pad around the through hole. A rod-shaped NiTi alloy having a composition ratio of Ni: 49% and Ti: 51% is inserted through the through hole. On both the LGA package side and the system board side of the frame, a spring having a length of about 0.18 mm is disposed by winding a copper wire of 30 μm to 70 μmφ at a pitch of 50 μm so as to surround the NiTi alloy protruding from the frame. The base end of each spring is fixed to the Au pad with a conductive adhesive. For example, a conductive silicone rubber pad is fixed to the tip of each spring with a conductive adhesive.

  The case of using the LGA connector having the column manufactured as described above (hereinafter referred to as connector 2) is compared with the case of using the above-described conventional connector (the LGA connector having a column made of only conductive rubber). went.

  When the contact state between the LGA package and the column of the LGA connector was observed at room temperature and 80 ° C., a gap of 10 μm to 30 μm was generated in the conventional connector at 80 ° C. as described above. I couldn't. A rod-shaped NiTi alloy having a length of about 2.17 mm can be extended by about 65 μm due to a phase transformation when the temperature rises, and acts to touch the conductive silicone rubber pad and push up the pad. Thereby, generation | occurrence | production of a gap can be prevented.

  In addition, when the conventional connector is used, as described above, the column is extremely deformed by an excessive load and follows the change in the separation distance between the LGA package and the system board due to the temperature change (15 ° C.-80 ° C.). And contact failure occurred. On the other hand, when the connector 2 is used, the load on the column is controlled within the range of 30 g to 60 g as in the case of using the connector 1 described above. The deformation of the column can be reduced, and a change in the separation distance between the LGA package and the system board accompanying a temperature change (15 ° C. to 80 ° C.) can be followed. As a result, it was not observed that the column collapsed and caused poor contact with the LGA package and / or system board. Further, the connector 2 can realize both electrical connection via the spring and the conductive silicone rubber pad and electrical connection via the NiTi alloy and the conductive silicone rubber pad, thereby further improving the electrical connectivity.

  Although the embodiment has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and changes can be made within the scope of the gist described in the claims.

100 Electronic device 110 Semiconductor device (LGA package)
111 Package substrate 112 Pad (land)
113 Semiconductor chip 120 Wiring board (system board)
122 Electrode pad 130, 230 Connector (LGA connector)
131, 231 Frame 132, 232 Through hole 133, 233 Metal film 134, 234 Metal pad 140, 240 Column 141, 142 Conductive elastomer 141a, 142a Insertion hole 141b, 142b Contact surface 143, 243 Metal part (shape memory alloy)
151 Bolster plate 152 Heat spreader 153 Heat sink base 154 Screw with spring 244, 245 Conductive spring 246, 247 Conductive pad

Claims (7)

An electrically insulating frame;
A through hole provided in the frame;
A connector comprising: a connection terminal disposed in the through hole and projecting from the frame, the connection terminal having a metal part including a shape memory alloy.   The connector according to claim 1, wherein the connection terminal has a conductive elastomer at a tip of a protruding portion from the frame.   The connector according to claim 1, wherein the metal part has a length larger than a thickness of the frame and protrudes from both sides of the frame.   The connector according to claim 3, wherein a spring is wound around a protruding portion of the metal portion from the frame.   The connector according to claim 1, wherein a metal film is formed on an inner wall of the through hole. A wiring board;
A semiconductor device provided above the wiring board;
An electronic device comprising: a metal terminal including a shape memory alloy; and a connection terminal for electrically connecting the wiring board and the semiconductor device. A connector having a frame, a through hole provided in the frame, and a connection terminal disposed in the through hole and projecting from the frame, the connection terminal having a metal part including a shape memory alloy Placing on the wiring board;
A method of manufacturing an electronic device, comprising: disposing a semiconductor device on the connector and electrically connecting the connection terminal to the wiring board and the semiconductor device.

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