JP2006210796A - Circuit device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit device including external electrodes with high connection reliability against a thermal stress. <P>SOLUTION: The circuit device 10A is provided with circuit elements 12, pads 23A electrically connected to the circuit elements and each exposed from each exposed part 18, and cover resins 16 each covering each pad 23A on the rear side of the device. Further, each of projected parts 23C integrally and externally extended from each pad 23A is covered by each cover resin 16. Moreover, the width between the end of each exposed part 18 and each pad 23A at each of the projected part 23C is formed narrower than that of the other parts. Consequently, since the area of each projected part 23C exposed from each exposed part 18 is limited, the amount of solder soldered to each projected part 23C is limited when each external electrode 15 made of solder is attached to each pad 23A. Thus, the circuit device 10A including each bumped-up external electrode 15 can be provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a circuit device and a manufacturing method thereof, and more particularly to a circuit device including an external connection electrode on a lower surface of the device and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, a circuit device set in an electronic device is used in a mobile phone, a portable computer, and the like. Recently, a wafer scale CSP called a CSP (chip size package) equivalent to the chip size has been developed.

  FIG. 12A shows a CSP 66 that employs a substrate 65 as a support substrate and is slightly larger than the chip size. Here, description will be made assuming that the transistor chip T is mounted on the substrate 65.

  A first electrode 67, a second electrode 68, and a die pad 69 are formed on the surface of the substrate 65, and a first back electrode 70A and a second back electrode 70B are formed on the back surface. The first electrode 67 and the first back electrode 70A are connected via the through hole TH. Further, the second electrode 68 and the second back electrode 70B are electrically connected through the through hole TH.

  The transistor chip T is fixed to the die pad 69, and the emitter electrode of the transistor and the first electrode 67 are connected through the thin metal wire 72. Further, the base electrode of the transistor and the second electrode 68 are connected through a thin metal wire 72. A resin layer 73 is provided on the substrate 65 so as to cover the transistor chip T.

  Further, in the circuit device such as the CSP as described above, an external electrode 76 made of solder or the like is formed on the back surface of the device in order to exchange electric signals with the outside (see, for example, Patent Document 1 below). .

  Referring to FIG. 12A, external electrode 76 is formed on first back electrode 70A and second back electrode 70B formed on the back surface of substrate 65. Further, the back surface of the substrate 65 in a region excluding the external electrode 76 is covered with a resist 74.

  There are two structures for regulating the shape of the external electrode 76. The first structure is a solder mask defined (hereinafter referred to as SMD structure), and the second structure is a non solder mask defined (hereinafter referred to as NSMD structure).

  Referring to FIG. 12B, in the SMD structure, the shape and position of the external electrode 76 are regulated by the exposed portion 75 provided in the resist 74. In this structure, the back electrode 70 to which the external electrode 76 is attached is covered with the resist 74, and the adhesion strength between the back electrode 70 and the substrate 65 is reinforced.

With reference to FIG. 12C, in the NSMD structure, the exposed portion 75 provided in the resist 74 is formed larger than the back electrode 70. Therefore, the shape and position of the external electrode 76 are regulated by the wettability of the back electrode 70. In this structure, the side surface of the back electrode 70 is also covered with the external electrode 76, so that the adhesive strength between the two is strong. Further, in the NSMD structure, when the external electrode 76 made of solder is formed by screen printing, the distance L5 from the back surface of the resist 74 to the top of the external electrode 76 is about 0.1 mm.
JP-A-11-274361

  However, the above CSP 66 has a problem that the height of the external electrode 76 cannot be sufficiently secured, and the connection reliability when the CSP 66 is mounted on a mounting board such as a mother board is not sufficient. Specifically, referring to FIG. 12D, the CSP 66 is fixed to a conductive path 74A formed on the front surface of the mounting substrate 74 through external electrodes 76 formed in a matrix on the back surface. . Further, if the thermal expansion coefficients of the CSP 66 and the mounting substrate 74 are different, the expansion amounts of the two differ depending on the temperature change under the usage condition, and therefore the external electrode 76 is subjected to stress. In order to reduce this stress, it is effective to form the external electrode 76 high. However, since the external electrode 76 is formed by melting the printed solder paste, it is difficult to form the external electrode 76 at, for example, 0.1 mm or more. Further, by placing solder balls, it is possible to form the external electrode 76 having a height of about 0.15 mm, for example. However, the manufacturing method of the external electrode 76 using solder balls has a problem that the cost becomes high.

  Furthermore, since the external electrode 76 is formed low, a sufficient gap is not ensured between the back surface of the CSP 66 and the mounting substrate 74. For this reason, there is a problem that voids are generated in the external electrode 76 in the reflow process in which the external electrode 76 is melted and the CSP 66 is mounted.

  The present invention has been made in view of the above problems, and a main object of the present invention is to provide a circuit device having an external electrode formed high in order to increase a connection reliability line, and a method for manufacturing the circuit device.

  The circuit device of the present invention includes a circuit element, a conductive pattern that is electrically connected to the circuit element to form a pad, and a coating resin that covers the conductive pattern by exposing the pad from an exposed portion. In addition, the protrusion extending integrally from the pad to the outside is covered with the coating resin, and the width of the outer peripheral end portion of the exposed portion and the pad is larger than that of the other portion at the position where the protrusion is formed. It is characterized by narrowing.

  Furthermore, in the circuit device of the present invention, an external electrode is connected to the pad, and the external electrode is in contact with a back surface and a side of the pad.

  Furthermore, in the circuit device of the present invention, the pad has a rotationally symmetric shape.

  Furthermore, in the circuit device of the present invention, the plurality of protrusions are provided at positions symmetrical with respect to the center of the pad.

  Furthermore, in the circuit device according to the present invention, the exposed portion includes a curved portion surrounding a peripheral portion of the pad and a linear portion provided corresponding to the protruding portion.

  Furthermore, in the circuit device of the present invention, the conductive pattern has a multilayer wiring structure.

  The method for manufacturing a circuit device according to the present invention includes a step of forming a conductive pattern including a pad electrically connected to a circuit element and a projecting portion integrally extending from the pad to the outside, and the conductive pattern as a coating resin. And by partially removing the coating resin to form an exposed portion larger than the pad to expose the pad from the exposed portion, and at the place where the protruding portion is provided, The step of narrowing the width between the outer peripheral end of the exposed portion and the pad than other portions, and printing the solder paste using a metal screen having an opening having the same size as the exposed portion, Filling the exposed portion with the solder paste, and heating and melting the solder paste to form external electrodes covering the upper and side surfaces of the pad. And wherein the door.

  Furthermore, in the circuit device manufacturing method of the present invention, the pad has a rotationally symmetric shape.

  Furthermore, in the method for manufacturing a circuit device according to the present invention, the exposed portion includes a curved portion surrounding a peripheral portion of the pad and a linear portion provided corresponding to the protruding portion.

  In the circuit device according to the present invention, the protruding portion integrally extending from the pad to the outside is provided, and the pad is exposed from the exposed portion provided in the coating resin. Moreover, in the location where the protrusion is provided, the distance between the outer peripheral end of the exposed portion and the pad is formed to be narrower than other locations. Therefore, when the external electrode made of solder is attached to the pad, it is possible to reduce the amount of solder attached to the protruding portion, and it is possible to form a high external electrode having a height of 0.15 mm or more, for example. It becomes. Therefore, it is possible to provide a circuit device having excellent connection reliability when mounted on a mounting board or the like.

  Furthermore, according to the method for manufacturing a circuit device of the present invention, a sufficiently high circuit device can be obtained. Therefore, when the circuit device is mounted on a mounting substrate by melting the external electrode by reflow, it occurs in the external electrode. Voids to be reduced can be reduced.

  With reference to FIG. 1, the configuration of the circuit device 10A of the present embodiment will be described. 1A is a cross-sectional view of the circuit device 10A, FIG. 1B is a plan view of the circuit device 10A viewed from the back side, and FIG. 1C is an enlarged perspective view of the pad 23A.

  Referring to FIGS. 1A and 1B, a circuit device 10A according to the present embodiment has a multilayer conductive pattern. Further, the semiconductor element 12 </ b> A and the chip element 12 </ b> B are electrically connected as circuit elements to the upper first wiring layer 22 and are covered with the sealing resin 13. On the back surface of the circuit device 10A, pads 23A made of the second wiring layer 23 are arranged in a matrix. In this embodiment, the pad 23 </ b> A is exposed to the outside from the exposed portion 18 provided in the coating resin 16. Components constituting the circuit device 10A will be described below.

  In the present embodiment, a conductive pattern is constituted by the first wiring layer 22 and the second wiring layer 23 stacked via the insulating layer 21. The first wiring layer 22 and the second wiring layer 23 are connected at a desired location by a connecting portion 19 that penetrates the insulating layer 21. Here, a two-layer wiring structure is shown, but a three-layer or more wiring structure may be formed.

  The first wiring layer 22 is a wiring layer provided at the top of the wiring structure, and is electrically connected to circuit elements such as the semiconductor element 12A and the chip element 12B. Specifically, a die pad to which the semiconductor element 12 or the like is fixed, a bonding pad to which the thin metal wire 14 is connected, or the like is formed by the first wiring layer 22. Further, the wiring connecting them may be constituted by the first wiring layer 22. Further, the surface of the first wiring layer 22 is covered with a metal coating 26 in order to improve the bonding property of the circuit element. Further, the first wiring layer 22 may be covered with a resin material except for a portion where a circuit element is connected.

  The second wiring layer 23 is a conductive pattern provided at the lowermost part of the wiring structure, and forms a pad 23A to which the external electrode 15 is attached. Further, a wiring 23D that connects the connecting portion 19 and the pad 23A may be configured. Further, a metal film 26 made of a plating film is formed on the surface of the pad 23A.

  As the material of both the wiring layers described above, the material is selected in consideration of the adhesion of the brazing material, the bonding property, and the plating property. Specifically, a conductive foil containing Cu as a main material, a conductive foil containing Al as a main material, or a conductive foil made of an alloy such as Fe-Ni can be adopted as a material for the wiring layer.

  The circuit elements include semiconductor elements 12A such as transistors, diodes, and IC chips, and chip elements 12B such as chip capacitors and chip resistors. These circuit elements are fixed to the surface of the first wiring layer 22 through a fixing material 20 such as solder or conductive paste. Although the thickness is increased, face-down semiconductor elements such as CSP and BGA can also be mounted. Here, a system including a plurality of circuit elements 12 may be configured.

  The sealing resin 13 has a function of covering circuit elements such as the semiconductor element 12A, and a thermosetting resin or a thermoplastic resin is used as the material thereof.

  The coating resin 16 is formed so as to cover the back surface of the circuit device 10A. The coating resin 16 is provided with an exposed portion 18, and the pad 23 </ b> A is exposed from the exposed portion 18. The pad 23A and the exposed part 18 are formed in a substantially circular shape, and the exposed part 18 is formed larger than the pad 23A. Therefore, the side surface of the pad 23 </ b> A is exposed without being covered with the coating resin 16.

  The external electrode 15 is made of solder or the like and is attached to the pad 23A. In this embodiment, the back surface and the side surface of the pad 23 </ b> A are covered with the external electrode 15. Accordingly, since the area where the pad 23A and the external electrode 15 are in contact with each other is large, the adhesive force between them is improved. Here, in addition to solder, a silver paste, a copper paste, or the like may be employed as the material of the external electrode 15. Furthermore, here, a BGA (Ball Grid Array) is formed by the external electrodes 15, but a configuration in which the external electrodes 15 are omitted may be employed. When the external electrode 15 is omitted, an LGA (Land Grid Array) is formed by the pads 23A exposed on the back surface.

  With reference to FIG. 1B, the shape of the pad 23A formed of the second wiring layer 23 will be described. The pad 23A is integrally provided with a protruding portion 23C that protrudes to the periphery. The tip portion of the protruding portion 23C is covered with the coating resin 16, and the portion where the protruding portion 23C and the pad 23A are connected is exposed from the exposed portion 18.

  Furthermore, the shape of the protrusion 23C is provided at a position symmetrical with respect to the center of the pad 23A. Specifically, referring to the pad 23A located in the upper part of FIG. 1B, the two protrusions 23C are arranged symmetrically with respect to the center point of the pad 23A. Thereby, the improvement of the adhesive force by the protrusion part 23C can be enlarged. Furthermore, three or more protrusions 23C may be provided at positions symmetrical with respect to the center point of the pad 23A.

  In addition, referring to the pad 23B located on the lower right side of FIG. 1B, one protrusion 23C is provided, and the wiring 23D is drawn out so as to face the protrusion 23C.

  With reference to FIG. 1C, the configuration of the pad 23A will be further described. The projecting portion 23C is a portion projecting to the outside continuously with the pad 23A, and the tip portion thereof is covered with the coating resin 16. In this figure, the protruding portion 23C of the portion covered with the coating resin 16 is indicated by a dotted line. The length that the protruding portion 23C protrudes to the periphery is, for example, about 0.1 mm. A portion of about 0.05 mm from the base of the protruding portion 23C is exposed from the exposed portion 18. Then, the protruding portion 23 </ b> C in the other region is covered with the coating resin 16. In this way, the protrusion 23C is partially covered with the coating resin 16, thereby preventing the pad 23A from being peeled off.

  With reference to FIG. 2, the configuration of the pad 23A and the exposed portion 18 will be further described.

  The outer peripheral end portion of the exposed portion 18 includes a curved portion 18A that extends in a circle so as to surround the peripheral portion of the pad 23A, and a linear portion 18B that is linearly provided corresponding to the protruding portion 23C. Further, as is apparent from the figure, the exposed portion 18 provided in the coating resin 16 is formed to be larger in plan than the pad 23A.

  The curved portion 18A draws an arc similar to the shape of the pad 23A. As an example, the diameter D1 of the pad 23A is 0.5 mm, and the diameter D2 of the curved portion 18A is 0.65 mm. Accordingly, the distance L1 between the outer peripheral end of the pad 23A and the curved portion 18A is about 0.075 mm. Usually, the distance L1 is about the same as the tolerance (for example, about 0.05 mm) when the exposed portion 18 is formed in order to make the pad 23A fine pitch. On the other hand, in this embodiment, the distance L1 is set larger than this tolerance to about 0.075 mm. As a result, the gap between the curved portion 18A and the pad 23A can be increased, and a larger amount of solder paste can be printed in the step of printing the solder paste. Therefore, it is possible to obtain an external electrode having a larger protruding amount. Details of the solder paste printing process will be described later.

  The straight portion 18B is linearly provided so as to straddle the protruding portion 23C, and here, two straight portions 18B are formed in parallel corresponding to the protruding portions 23C positioned symmetrically. By providing the straight portion 18B, the planar shape of the exposed portion 18 becomes a circle that is partially cut linearly. By providing this linear portion 18B, the length (L2) of the protruding portion 23C exposed to the exposed portion 18 is shortened. For example, the length of L2 is about 0.05 mm. Thus, by shortening the length (L2) of the protruding portion 23C exposed at the exposed portion 18, the amount of solder adhering to the protruding portion 23C can be reduced in the step of forming the external electrode made of solder on the pad 24A. Can be reduced.

  With the above configuration, when it is assumed that a solder paste having a certain thickness is applied by screen printing, a large amount of solder used for forming the external electrode can be secured, so that the external electrode can be made high. Further, by shortening the distance L2, the area of the protrusion 23C covered with the coating resin 16 can be increased. Accordingly, the bonding strength between the pad 23A and the coating resin 16 is increased, and the peeling of the pad 23A is suppressed.

  A structure in which the circuit device 10A is mounted on the mounting substrate 24 will be described with reference to FIG. 3A is a cross-sectional view of the circuit device 10A mounted on the mounting substrate 24, and FIG. 3B is a plan view of a region where the pad 23A is formed.

  Referring to FIG. 3A, here, circuit device 10A is mounted on conductive path 24A formed on the surface of mounting substrate 24 through external electrode 15 melted by the reflow process.

  In this embodiment, the external electrode 15 having a height of, for example, about 0.15 mm is formed by the configuration of the circuit device 10A described above. Therefore, even when the circuit device 10 </ b> A is mounted, the circuit device 10 </ b> A and the mounting substrate 24 are sufficiently separated by the external electrode 15. Therefore, even if a thermal stress acts on the external electrode 15 due to a change in the temperature of the outside air due to a difference in thermal expansion coefficient between the circuit device 10 </ b> A and the mounting substrate 24, the stress is absorbed by the external electrode 15. This improves the connection reliability of the external electrode 15 against thermal stress.

  Referring to FIG. 3B, external electrode 15 is formed to cover the back surface and side surface of pad 23A. Further, the back and side surfaces of the protruding portion 23 </ b> C exposed to the exposed portion 18 are also covered with the external electrode 15. In this embodiment, the protruding portion 23C exposed from the exposed portion 18 is limited, so that a higher external electrode 15 can be formed.

  With reference to FIG. 4, the configuration of another form of circuit device 10B will be described. 4A is a cross-sectional view of the circuit device 10B, and FIG. 4B is a plan view of the circuit device 10B as viewed from the back surface. The basic configuration of the circuit device 10B is the same as that of the circuit device 10A described above, and the difference is that the circuit device 10B has a single-layer conductive pattern 11.

  4A and 4B, in circuit device 10B, single-layer conductive pattern 11 is formed, and semiconductor element 12A is electrically connected to conductive pattern 11. Further, the semiconductor element 12 </ b> A and the conductive pattern 11 are sealed with the sealing resin 13 with the back surface of the conductive pattern 11 exposed.

  The conductive pattern 11 has a structure in which the back surface is exposed and is embedded in the sealing resin 13, and is electrically separated by the separation groove 17. The conductive pattern 11 is formed by etching, and its side surface is formed as a curved surface.

  Further, the conductive pattern 11 includes a die pad 11B disposed near the center and a plurality of bonding pads 11A disposed so as to surround the die pad 11B. The semiconductor element 12A is fixed to the upper surface of the die pad 11B via a fixing material 20 such as solder. The electrode provided on the surface of the semiconductor element 12 </ b> A and the bonding pad 11 </ b> A are connected through a thin metal wire 14.

  The bonding pad 11A is provided with a protruding portion 11C protruding to the periphery, and the configuration of the protruding portion 11C is the same as that of the circuit device 10A described with reference to FIG.

  An external electrode 15 made of a brazing material such as solder is provided on the back surface of the conductive pattern 11 exposed from the sealing resin 13. Further, the portion where the external electrode 15 is not provided on the back surface of the apparatus is covered with a coating resin 16.

  The sealing resin 13 covers the semiconductor element 12 </ b> A, the fine metal wires 14, and the conductive pattern 11 by exposing the back surface of the conductive pattern 11. Further, the separation grooves 17 that separate the conductive patterns 11 are filled with a sealing resin 13.

  Referring to FIG. 4B, a protrusion 11C that protrudes toward the periphery is integrally formed with bonding pad 11A. The configuration of the exposed portion 18 is the same as that of the circuit device 10A described above. Therefore, also in the circuit device 10B, the height of the external electrode 15 is formed to be higher than 0.15 mm, for example.

  Next, the test results using the circuit device 10A of the present embodiment will be described with reference to FIG. 5A is a cross-sectional view of the circuit device 10A of the present embodiment, FIG. 5B is a cross-sectional view of the circuit device 10C of the comparative example, and FIG. 5C is a circuit diagram of the circuit devices 10A and 10C. It is a graph which shows the result of the conducted heat cycle test.

  In the heat cycle test, the temperature of the atmosphere surrounding the circuit elements mounted on the mounting substrate is changed, for example, between −40 ° C. and 125 ° C. As a result, thermal stress is intentionally applied to the external electrode for fixing the circuit device and the mounting substrate. Then, the number of circuit devices in which connection failure occurs in the external electrode is measured. By performing the heat cycle test, the connection reliability of the circuit device with respect to the temperature change becomes clear.

  Referring to FIG. 5A, in circuit device 10A of the present embodiment, distance H1 from the tip of external electrode 15 to coating resin 16 is formed as high as about 0.15 mm. Here, after 20 circuit devices 10A were mounted on a mounting substrate, a heat cycle test was performed on each.

  With reference to FIG. 5B, in the circuit device 10C to be compared, the distance H2 from the tip of the external electrode 15 to the coating resin 16 is formed as low as about 0.10 mm. Other configurations are the same as those of the circuit device 10A of the present embodiment. Similarly to the circuit device 10A of the present embodiment, 20 circuit devices 10C were prepared and fixed to the mounting substrate, and then a heat cycle test was performed.

  The only difference between the circuit device 10A of the present application and the circuit device 10C to be compared is the height of the external electrode 15. Therefore, the relationship between the height of the external electrode 15 and the connection reliability can be known by conducting a heat cycle test on both of them and comparing the results.

  The result of the heat cycle test will be described with reference to the graph in FIG. The graph shown in this figure is a log-log graph, the horizontal axis indicates the number of heat cycles, and the vertical axis indicates the cumulative failure rate. In this graph, the test results by the circuit device 10A of the present embodiment are indicated by black circles, and the test results by the circuit device 10C to be compared are indicated by “x”. A line approximating the test result by the circuit device 10A of the present embodiment is indicated by A1, and a line approximating the test result by the circuit device 10B to be compared is indicated by A2.

  As is apparent from the results shown in the graph, the circuit device 10A according to the present embodiment is less likely to cause a failure in the cycle test than the circuit device 10C to be compared. Specifically, when the number of cycles is about 1000 times, both the circuit device 10A and the circuit device 10C start to have defects. Then, when the number of cycles reaches about 1100, a failure occurs in both of the circuit device 10A and the circuit device 10C. However, the approximate line A1 that approximates the cumulative failure rate of the circuit device 10A of the present invention is located on the right side of the approximate line A2 that approximates the cumulative failure rate of the circuit device 10C to be compared. That is, the circuit device 10A of this embodiment can withstand a larger number of cycle tests. Since the graph shown in FIG. 4C is a logarithmic graph, the difference between the approximate line A1 and the approximate line A2 seems to be insignificant, but in reality, they differ by several tens of cycles. . Further, the only difference between the circuit device 10A of the present application and the circuit device 10C to be compared is the height of the external electrode 15. From this, it has been clarified that the connection reliability against thermal stress can be improved by forming the external electrode 15 high by the configuration of the circuit device 10A of the present invention.

  Next, a method for manufacturing the circuit device 10A shown in FIG. 1 will be described with reference to FIGS.

  With reference to FIG. 6A, first, the conductive foil laminated through the insulating layer 21 is patterned to form the first wiring layer 22 and the second wiring layer 23. Specifically, the first wiring layer 22 and the second wiring layer 23 are obtained by performing wet etching through the resist PR patterned into a desired shape. In this step, a pad 23A provided with a protruding portion 23C as shown in FIG. 1B is formed. After the patterning is completed, the first wiring layer 22 and the second wiring layer 23 may be covered with a plating film.

  Next, referring to FIG. 6B, circuit elements are electrically connected to the first wiring layer 22. Here, the semiconductor element 12 </ b> A and the chip element 12 </ b> B are electrically connected to the first wiring layer 22. The electrode of the semiconductor element 12 </ b> A and the first wiring layer 22 are connected via the fine metal wire 14. Further, a sealing resin 13 is formed so as to cover the semiconductor element 12A and the chip element 12B. The second wiring layer 23 is entirely covered with the coating resin 16.

  Referring to FIG. 7, next, exposed portion 18 is formed by exposing and developing coating resin 16. FIG. 7A is a cross-sectional view in this step, and FIG. 7B is a plan view of the pad 23A and the like as viewed from below.

  With reference to FIG. 7A, the exposed portion 18 is formed larger than the pad 23 </ b> A, and the side surface of the pad 23 </ b> A is exposed from the exposed portion 18. Further, the protruding portion 23 </ b> C formed integrally with the pad 23 </ b> A is partially covered with the covering resin 16.

  With reference to FIG. 7B, as described above, the exposed portion 18 has a shape including a curved portion 18A and a straight portion 18B. The width L1 between the curved portion 18A and the pad 23A is formed larger than the tolerance (0.05 mm) when the exposed portion 18 is formed. For example, the width L1 is about 0.075 mm. Thus, by forming the exposed portion 18 large, a large amount of solder paste can be stored in the exposed portion 18 in a later step.

  Referring to FIGS. 8 and 9, next, external electrode 15 is attached to pad 23A. In this step, the external electrode 15 is formed by printing a solder paste using a metal screen.

  FIG. 8A shows a metal screen 25 used in this step. The screen 25 is made of a metal film having a thickness (T1) of about 0.1 mm, for example, and is provided with an opening 25A that is partially opened at a location corresponding to the exposed portion 18 provided in the coating resin 16. Yes. The position of the opening 25 </ b> A exactly corresponds to the exposed portion 18, and the shape and size thereof are the same as those of the exposed portion 18.

  With reference to FIG. 8B, the screen 25 is placed on top of the coating resin 16. As described above, the positions of the exposed portions 18 provided in the coating resin and the openings 25A provided in the screen 25 correspond exactly. Further, in the present application, since the exposed portion 18 is formed sufficiently large with respect to the pad 23A, the opening 25A formed in the same size as the exposed portion 18 is also formed large. Accordingly, a space composed of the exposed portion 18 and the opening portion 25A is also formed large.

  With reference to FIG. 8C, the exposed portion 18 and the opening portion 25 </ b> A are filled with the solder paste 26 by printing the solder paste 26 using a squeegee (not shown). Here, the solder paste is a powder in which powdered solder is mixed.

  Referring to FIG. 8D, screen 25 is removed after printing is completed. By this step, the applied solder paste 26 protrudes to the outside according to the thickness of the screen 25.

  Referring to FIG. 9, next, solder paste 26 is heated and melted in a reflow process, thereby forming external electrode 15 made of solder. FIG. 9A is a cross-sectional view showing a state after the external electrode 15 is formed, FIG. 9B is an enlarged plan view showing one external electrode 15, and FIG. FIG. 9B is a cross-sectional view taken along line CC ′ of FIG. 9B, and FIG. 9D is a cross-sectional view taken along line DD ′ of FIG.

  Referring to FIG. 9A, the external electrode 15 is formed by heating and melting the solder paste applied in the previous step. Each pad 23A is formed with a nearly spherical external electrode 15 due to the surface tension of the solder when melted.

  Referring to FIG. 9B, the external electrode 15 is formed so as to cover the protruding portion 23C of the exposed portion and the upper surface and side surfaces of the pad 23A. In this embodiment, the exposed portion 18 includes a curved portion 18A and a straight portion 18B, and the straight portion 18B is positioned so as to straddle the protruding portion 23C. As described above, the width L2 between the pad 23A and the straight portion 18B is shorter than the width L1 between the curved portion 18A and the pad 23A. Specifically, the width L1 is about 0.075 mm while the width L2 is about 0.05 mm. Therefore, by forming the straight portion 18B, the amount of the protruding portion 23C exposed to the exposed portion 18 is reduced. Therefore, in this step, the amount of solder adhering to the protruding portion 23C is reduced, and the external electrode 15 is formed higher upward accordingly.

  Referring to FIG. 9C, in this cross section, the external electrode 15 is in contact with the upper surface and the side surface of the pad 23A, and the connection between them is strengthened. In addition, a groove 18C is formed between the terminal end of the exposed portion 18 and the pad 23A. This groove 18C is filled with solder paste in the previous step. Then, the solder component filled in the groove 18 </ b> C is sucked upward in the reflow process to form the external electrode 15. In this embodiment, the width L1 of the groove 18C (the width at which the curved portion 18A and the pad 23C are separated) L1 is set to be as wide as about 0.075 mm. Accordingly, a large amount of solder component filled in the groove 18C is sucked upward, so that the high external electrode 15 is formed.

  Referring to FIG. 9D, in the cross section provided with the protrusion 23C, the external electrode 15 is also attached to the upper surface of the protrusion 23C. In this embodiment, since the protruding portion 23C exposed to the exposed portion 18 is made as narrow as possible, the amount of solder attached to the protruding portion 23C is small. As a result, a higher external electrode 15 can be formed. Through the above steps, the circuit device 10A as shown in FIG. 1 is manufactured.

  Next, a method for manufacturing the circuit device 10B having the single-layer wiring structure shown in FIG. 4 will be described with reference to FIGS.

  Referring to FIG. 10A, first, separation grooves 17 are provided on the surface of a conductive foil 40 made of a metal such as copper, and the conductive pattern 11 is formed in a convex shape. Here, the separation groove 17 is formed so that the conductive pattern 11 including the bonding pad 11A and the die pad 11B has a convex shape. The separation groove 17 is formed by wet etching through the patterned resist PR. In this step, the bonding pad 11A is formed to have a protruding portion as shown in FIG.

  Referring to FIG. 10B, next, the semiconductor element 12A is fixed to the die pad 11B, and the semiconductor element 12A and the bonding pad 11A are electrically connected through the fine metal wires 14. Further, the sealing resin 13 is formed so that the semiconductor element 12A is covered and filled in the separation groove 17.

  Referring to FIG. 10C, next, the conductive foil 40 is removed from the back surface until the sealing resin 13 filled in the separation groove 17 is exposed. Here, the conductive foil is removed from the back surface by wet etching.

  Referring to FIG. 10D, next, a coating resin 16 is formed so as to cover the exposed conductive pattern 11. Further, the exposed portion 18 is formed so that the back surface of the bonding pad 11A is exposed by exposing and developing the coating resin 16. Here, the exposed portion 18 is formed larger than the bonding pad 11A. Further, the protruding portion 11C (see FIG. 4B) formed integrally with the bonding pad 11A is covered with the coating resin 16.

  Referring to FIGS. 11A to 11C, next, solder paste 26 is printed using screen 25. FIG. First, the screen 25 is placed on the upper surface of the coating resin 16 so that the opening 25A provided in the screen 25 and the exposed portion 18 are accurately superimposed. Next, the solder paste 26 is printed using a squeegee (not shown), and the solder paste 16 is filled in the space formed by the opening 25 </ b> A and the exposed portion 18. After printing the solder paste 26, the screen 25 is removed.

  Finally, referring to FIG. 11D, the solder paste 26 is heated and melted to form the external electrode 15. Through the above steps, a circuit device 10B as shown in FIG. 4 is manufactured.

It is a figure which shows the circuit apparatus of this invention, (A) is sectional drawing, (B) is a top view, (C) is a perspective view. It is a top view which shows the circuit apparatus of this invention. It is a figure which shows the circuit apparatus of this invention, (A) is sectional drawing, (B) is a top view. It is a figure which shows the circuit apparatus of this invention, (A) is sectional drawing, (B) is a top view. (A) is sectional drawing which shows the circuit apparatus of this invention, (B) is sectional drawing which shows the circuit apparatus of a comparison object, (C) is a graph which shows a test result. It is a figure which shows the manufacturing method of the circuit apparatus of this invention, (A) And (B) is sectional drawing. It is a figure which shows the manufacturing method of the circuit apparatus of this invention, (A) is sectional drawing, (B) is a top view. It is a figure which shows the manufacturing method of the circuit apparatus of this invention, (A) is a perspective view, (B)-(D) is sectional drawing. It is a figure which shows the manufacturing method of the circuit apparatus of this invention, (A) is sectional drawing, (B) is a top view, (C) And (D) is sectional drawing. It is a figure which shows the manufacturing method of the circuit apparatus of this invention, (A)-(D) is sectional drawing. It is a figure which shows the manufacturing method of the circuit apparatus of this invention, (A)-(D) is sectional drawing. It is a figure which shows the conventional circuit apparatus, (A)-(D) is sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10A Circuit apparatus 10B Circuit apparatus 11 Conductive pattern 11A Bonding pad 11B Die pad 12A Semiconductor element 12B Chip element 13 Sealing resin 14 Metal fine wire 15 External electrode 16 Covering resin 17 Separation groove 18 Exposed part 19 Connection part 20 Adhesive material 21 Insulating layer 23A pad 23C Protruding part 24 Mounting board 25 Opening part

Claims (9)

A circuit element, a conductive pattern electrically connected to the circuit element to form a pad, and a coating resin that covers the conductive pattern by exposing the pad from an exposed portion,
Protruding portions extending integrally from the pad to the outside are covered with the coating resin,
The circuit device according to claim 1, wherein a width between the outer peripheral end portion of the exposed portion and the pad is narrower than that of the other portion at the portion where the protruding portion is formed. An external electrode is connected to the pad,
The circuit device according to claim 1, wherein the external electrode is in contact with a back surface and a side edge of the pad.   The circuit device according to claim 1, wherein the pad has a rotationally symmetric shape.   The circuit device according to claim 1, wherein the plurality of protrusions are provided at positions symmetrical with respect to the center of the pad.   The circuit device according to claim 1, wherein the exposed portion includes a curved portion surrounding a peripheral portion of the pad and a linear portion provided corresponding to the protruding portion.   The circuit device according to claim 1, wherein the conductive pattern has a multilayer wiring structure. Forming a conductive pattern including a pad electrically connected to a circuit element and a protrusion integrally extending from the pad to the outside;
Coating the conductive pattern with a coating resin;
By partially removing the coating resin, an exposed portion larger than the pad is formed to expose the pad from the exposed portion, and an outer peripheral end portion of the exposed portion is provided at the place where the protruding portion is provided. And a step of making the width of the pad narrower than other parts,
Filling the exposed portion with the solder paste by printing a solder paste using a metal screen having an opening having the same size as the exposed portion;
And a step of heating and melting the solder paste to form external electrodes that cover the upper and side surfaces of the pad.   8. The method of manufacturing a circuit device according to claim 7, wherein the pad has a rotationally symmetric shape. 8. The method of manufacturing a circuit device according to claim 7, wherein the exposed portion includes a curved portion surrounding a peripheral portion of the pad and a linear portion provided corresponding to the protruding portion.

Images