JP2006229030A - Lead frame and semiconductor device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead frame which is capable of restraining cracking from occurring in the sealing resin of a semiconductor device, and to provide the semiconductor device using the same. <P>SOLUTION: The lead frame A1 includes die bonding pads 1A and 1B where semiconductor chips 5A and 5B are mounted respectively; a lead 3A electrically connected to the die bonding pads 1A and 1B; and frames 4A and 4B connected to the lead 3A. A bridging unit 2 is provided between the die bonding pads 1A and the lead 3A containing inclined parts 22a, 22b, 22c, and 22d that are inclined at an angle with the direction in which the die bonding pad 1A extends toward the lead 3A. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lead frame used for manufacturing a semiconductor device such as a diode, a transistor, and an LSI, and a semiconductor device using the lead frame.

  An example of this type of conventional lead frame is shown in FIG. The lead frame X shown in the figure includes a bonding pad 91, a frame 94, and leads 93, and is made of, for example, copper. A semiconductor chip 95 is mounted on the bonding pad 91 in the manufacturing process of the semiconductor device. The leads 93 are connected to each other by a frame 94. In the manufacturing process of the semiconductor device, the semiconductor chip 95 and a part of the lead 93 are covered with a sealing resin 97 such as an epoxy resin. Thereafter, a predetermined portion (broken line in the figure) of the frame 94 is cut to separate the leads 93. The semiconductor device is mounted on, for example, a circuit board using the leads 93. Power is supplied from the circuit board to the semiconductor chip 95 via the leads 93. Thereby, a function corresponding to the configuration of the semiconductor chip 95 is exhibited.

  However, a semiconductor device manufactured using the lead frame X has a problem that cracks are likely to occur in the sealing resin 97. For example, when the semiconductor chip 95 is energized, the semiconductor chip 95 generates heat. This heat is transferred from the semiconductor chip 95 to the sealing resin 97 and raises the temperature of the entire semiconductor device. The lead 93 and the sealing resin 97 have different linear expansion coefficients depending on the material. Since the epoxy resin has a larger linear expansion coefficient than copper, the sealing resin 97 has a larger expansion amount than the lead 93. The expansion of the sealing resin 97 is hindered by the leads 93, and stress is generated in the sealing resin 97. This stress is intensively generated in the sealing resin 97 every time the semiconductor device is used repeatedly. In the manufacturing process of the semiconductor device, the sealing resin 97 is often formed using a relatively high temperature resin paste. In this case, the resin paste shrinks with cooling. The lead 93 cannot sufficiently follow this contraction, and stress remains in the sealing resin 97. Furthermore, the semiconductor device is generally often mounted using a so-called reflow soldering process. Since this method raises the temperature of the semiconductor device, there is a possibility that thermal stress is also generated in the sealing resin 97. The stress as described above has caused the sealing resin 97 to crack.

JP-A-9-246451

  The present invention has been conceived under the circumstances described above, and provides a lead frame capable of suppressing the occurrence of cracks in a sealing resin of a semiconductor device and a semiconductor device using the same. It is an issue.

  In order to solve the above problems, the present invention takes the following technical means.

  A lead frame provided by the first aspect of the present invention is a lead frame comprising a die bonding pad on which a semiconductor chip is mounted, a lead conducting to the die bonding pad, and a frame connected to the lead. A bridge portion including an inclined portion that is inclined with respect to a direction from the die bonding pad to the lead is provided between the die bonding pad and the lead.

  According to such a configuration, the bridge portion is easily elastically bent. This facilitates relative displacement between the die bonding pad and the lead. For example, when manufacturing a semiconductor device using the lead frame, a sealing resin may be formed. The sealing resin is contracted because it is formed by cooling a relatively high temperature resin paste. At this time, the die bonding pad and the lead can be appropriately displaced relative to the shrinkage of the sealing resin. Thereby, it can be avoided that excessive stress remains in the sealing resin. Further, in a semiconductor device using the lead frame, stress generated in the sealing resin can be relieved even if it is repeatedly used. Therefore, it can suppress that a crack arises in the above-mentioned sealing resin.

  In a preferred embodiment of the present invention, the bridging portion includes a continuous inclined portion in which a plurality of the inclined portions are arranged in series via bent portions. According to such a configuration, the bridging portion has a so-called spring structure. Therefore, the relative displacement between the die bonding pad and the lead can be further promoted, which is suitable for preventing cracking of the sealing resin.

  In a preferred embodiment of the present invention, the bridge portion includes a plurality of the continuous inclined portions arranged in parallel. According to such a configuration, the support of the die bonding pad can be ensured.

  In a preferred embodiment of the present invention, the bridging portion has a line-symmetric shape about an axis extending in a direction from the die bonding pad toward the lead. According to such a configuration, the die bonding pad can be easily displaced along the direction from the die bonding pad to the lead.

  In a preferred embodiment of the present invention, the bridging portion includes a plurality of inclined portions that are inclined in the same side with respect to the direction from the die bonding pad toward the lead and are arranged in parallel. According to such a configuration, the die bonding pad can be easily displaced in a direction intersecting with a direction from the die bonding pad toward the lead.

  In a preferred embodiment of the present invention, an additional die bonding pad is further provided between the lead and the bridge portion. According to such a configuration, it is possible to mount a plurality of semiconductor chips, and it is possible to prevent the plurality of semiconductor chips from unduly hindering the contraction and expansion of the sealing resin.

  A semiconductor device provided by the second aspect of the present invention includes a semiconductor chip, a die bonding pad on which the semiconductor chip is mounted, a lead conducting to the die bonding pad, and a sealing resin that covers the semiconductor chip. Is manufactured using the lead frame according to any one of claims 1 to 6, so that the die bonding pad and the lead are connected to each other from the die bonding pad. A bridge portion including an inclined portion inclined with respect to a direction toward the lead is provided. According to such a configuration, it is possible to reduce the stress generated in the sealing resin and suppress the generation of cracks.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 1 shows an example of a lead frame according to the present invention. As shown in FIG. 1, the lead frame A1 of the present embodiment includes two die bonding pads 1A and 1B, a bridge portion 2, three leads 3A, 3B, and 3C, and frames 4A and 4B. For example, it is formed by punching or etching a copper or iron metal plate.

  Of the two die bonding pads 1A, 1B, the bridging portion 2, the three leads 3A, 3B, 3C, and the frames 4A, 4B, the portion inside the mold line 7a is sealed with a sealing resin. Thus, it is a unit that can constitute one semiconductor device. The lead frame A1 is provided with a plurality of units other than those shown in the drawing, and these units are connected by frames 4A and 4B. Thereby, the lead frame A1 can make a plurality of semiconductor devices.

  The two die bonding pads 1A and 1B are both rectangular and are arranged side by side in the x direction. The x direction represents the direction from the die bonding pad 1A toward the lead 3A. These die bonding pads 1A and 1B are portions to which the semiconductor chips 5A and 5B are die bonded when a semiconductor device is manufactured using the lead frame A1.

  The bridge portion 2 includes two continuous inclined portions 21A and 21B, and connects the two die bonding pads 1A and 1B. The two continuous inclined portions 21A and 21B are arranged in parallel in a direction orthogonal to the x direction. The continuous inclined portion 21A includes two inclined portions 22a and 22b, and the continuous inclined portion 21B includes two inclined portions 22c and 22d. The inclined portions 22a, 22b, 22c, and 22d are all inclined with respect to the x direction. The inclined portion 22a and the inclined portion 22b are opposite to each other in inclination in the x direction. The same applies to the inclined portions 22c and 22d. The inclined portions 22a and 22b and the inclined portions 22c and 22d are arranged in series in the x direction via the bent portions 23a and 23b. The bridging portion 2 has a line-symmetric shape about an axis O that passes through the vicinity of the centers of the die bonding pads 1A and 1B and extends in the x direction.

  The three leads 3A, 3B, 3C are arranged in parallel in a direction orthogonal to the x direction, and each has a strip shape extending substantially in the x direction. The lead 3A connects the die bonding pad 1B and the frame 4A and is electrically connected to the die bonding pad 1A. The leads 3B and 3C are connected to the frame 4A, but are not directly connected to the die bonding pad 1B. Wire bonding pads 31b and 31c used for wire bonding of the semiconductor chips 5A and 5B in the manufacture of the semiconductor device are formed at the tips of the leads 3B and 3C, respectively.

  The two frames 4A and 4B each have a strip shape extending in a direction orthogonal to the x direction, and are arranged in parallel in the x direction. The two frames 4A and 4B are connected by a plurality of subframes 41. In the manufacturing process of the semiconductor device, the frames 4A and 4B and the subframe 41 are cut along the virtual line C.

  FIG. 2 shows an example of a manufacturing process of a semiconductor device using the lead frame A1.

  In this figure, semiconductor chips 5A and 5B are mounted on die bonding pads 1A and 1B, respectively. The semiconductor chips 5A and 5B are mounted by, for example, a resin bonding method using a paste. The upper surfaces of the semiconductor chips 5A and 5B in the drawing and the wire bonding pads 31b and 31c are electrically connected by wires 6.

  The mold line 7a indicates a region where the sealing resin is formed. The sealing resin is formed by, for example, a transfer mold method using an epoxy resin. After the sealing resin is formed, the frames 4A and 4B and the subframe 41 are cut along the virtual line C. As a result, the leads 3A, 3B, and 3C and the portions that remain connected to them become leads 3A ', 3B', and 3C 'shown in FIG.

  3 and 4 show an example of a semiconductor device manufactured using the lead frame A1 shown in FIG. The illustrated semiconductor device B undergoes the manufacturing process shown in FIG. 2 so that two die bonding pads 1A and 1B, a bridging portion 2, three leads 3A ′, 3B ′ and 3C ′, and a semiconductor chip 5A. , 5B and a sealing resin 7 for sealing them. All of the three leads 3A ', 3B', 3C 'are exposed from the sealing resin 7 near one end thereof. These exposed portions are used for electrical connection of the semiconductor device B. That is, the lead 3A 'is electrically connected to the lower surface of the semiconductor chips 5A and 5B in the drawing, and the leads 3B' and 3C 'are electrically connected to the upper surface of the semiconductor chips 5A and 5B in the drawing.

  Next, operations of the lead frame A1 and the semiconductor device B will be described.

  As shown in FIG. 1, the bridging portion 2 has a structure that is easily elastically bent as compared with the die bonding pads 1A and 1B and the leads 3A, 3B, and 3C. With such a structure, when the die bonding pads 1A and 1B, the bridging portion 2, the lead 3A, and the sealing resin 7 expand and contract, the stress is generated in the sealing resin 7 in a concentrated manner. Can be suppressed.

  As a case where the die bonding pads 1A and 1B and the sealing resin 7 expand and contract, for example, there is a manufacturing process of the sealing resin 7. When the sealing resin 7 shown in FIG. 3 is formed, a resin paste having a relatively high temperature is used. For this reason, the lead frame A1 is temporarily heated, and then cooled together with the resin paste. At this time, the resin paste becomes the sealing resin 7 with shrinkage. A metal material such as copper or iron, which is the material of the lead frame A1, and an epoxy resin, etc., which is the material of the sealing resin 7, generally have different linear expansion coefficients. Therefore, the lead frame A1 and the sealing resin 7 contract. A difference in quantity occurs. Due to the difference in contraction amount, an external force is generated in the lead frame A1. When an external force is applied to the bridging part 2, the bridging part 2 is elastically bent. This can prevent the sealing resin 7 from contracting. Therefore, it is possible to avoid the stress due to the manufacturing process remaining in the sealing resin 7 and to prevent the sealing resin 7 from being cracked.

  Further, the semiconductor device B is generally often mounted using a so-called reflow soldering process. In this mounting method, the temperature is raised to a temperature at which the solder paste can be melted in a state where the semiconductor device B is inserted into a reflow furnace, and then cooled to room temperature. For this reason, the sealing resin 7 expands and contracts. Even in this case, since the bridging portion 2 is easily elastically bent, it is possible to avoid an inappropriate thermal stress from being generated in the sealing resin 7. Therefore, it is possible to prevent cracks from occurring in the sealing resin 7.

  Furthermore, when the semiconductor device B is repeatedly used, the sealing resin 7 may expand and contract. That is, when the semiconductor chips 5A and 5B are energized, the semiconductor chips 5A and 5B generate heat. In repeated use of the semiconductor device B, the energization is intermittently performed. For this reason, the temperature of the semiconductor device B repeatedly rises and falls. Thereby, the sealing resin 7 repeats expansion and contraction. At this time, if the thermal stress generated in the sealing resin 7 is large, it causes a crack. In the present embodiment, the die bonding pads 1 </ b> A and 1 </ b> B can easily follow the expansion and contraction of the sealing resin 7 because the bridging portion 2 is elastically bent. Therefore, even when the semiconductor device B is repeatedly used, it is possible to prevent generation of cracks by avoiding generation of undue thermal stress in the sealing resin 7.

  The continuous inclined portions 21A and 21B have so-called spring structures because the inclined portions 22a and 22b and the inclined portions 22c and 22d are arranged in series, respectively. For this reason, the elastic bending mentioned above is promoted and it is suitable for protection of the sealing resin 7. Further, since the die bonding pads 1A and 1B are connected by the two continuous inclined portions 21A and 21B, the support of the die bonding pad 1A is ensured. Thereby, in the manufacturing process of the semiconductor device B, it can suppress that the die bonding pad 1A is torn off.

  As shown in FIG. 4, the semiconductor chips 5 </ b> A and 5 </ b> B are covered with a sealing resin 7 except for the lower surface in the figure. Thus, the die bonding pads 1A and 1B and the sealing resin 7 are firmly bonded. For this reason, when the sealing resin 7 expands and contracts in the x-direction, a force tends to be generated to greatly displace the die bonding pads 1A and 1B. In the present embodiment, since the bridging portion 2 is formed between the die bonding pads 1A and 1B, it is suitable for preventing the stress in the x direction from being generated in the sealing resin 7.

  FIG. 5 shows another example of the lead frame according to the present invention. In this figure, elements similar to those in the above embodiment are given the same reference numerals, and description thereof will be omitted as appropriate.

  In the illustrated lead frame A2, the bridging portion 2 is composed of two inclined portions 22e and 22f. The two inclined portions 22e and 22f are arranged in parallel in a direction orthogonal to the x direction, and are inclined to the same side with respect to the x direction.

  Even in such an embodiment, the effect of suppressing the stress of the sealing resin can be exhibited as in the above-described embodiment. Further, since the inclined portions 22e and 22f are inclined to the same side with respect to the x direction, the die bonding pads 1A and 1B in the present embodiment are, for example, in a direction orthogonal to the x direction compared to the above-described embodiment. Relative displacement is easy. Therefore, when a semiconductor device is manufactured using the lead frame A2, stress in a direction orthogonal to the x direction can be suppressed among stresses generated in the sealing resin.

  The lead frame and the semiconductor device according to the present invention are not limited to the above-described embodiments. The specific structure of each part of the lead frame and the semiconductor device according to the present invention can be varied in design in various ways.

  The inclination direction and the inclination angle of the inclined portion are not limited to the above-described embodiment, and can be set as appropriate. Further, the continuous inclined portion is not limited to one having two inclined portions, and three or more inclined portions may be arranged in series. Of course, the number of the inclined portions or the continuous inclined portions arranged in parallel is not limited to the number of the embodiments described above.

  As a semiconductor device, for example, if a light-emitting chip is used as a semiconductor chip, it can be configured as a light-emitting device, but can be configured to exhibit various functions other than this. The mounting structure of the semiconductor chip is not limited to the structure described above, and may be, for example, a flip chip format.

1 is an overall plan view showing an example of a lead frame according to the present invention. It is a whole perspective view which shows the manufacturing process of the semiconductor device using an example of the lead frame which concerns on this invention. 1 is an overall perspective view showing an example of a semiconductor device according to the present invention. It is sectional drawing which follows the IV-IV line of FIG. It is a whole top view which shows the other example of the lead frame which concerns on this invention. It is a whole perspective view of an example of the conventional lead frame.

Explanation of symbols

A Lead frame B Semiconductor device 1A, 1B Die bonding pad 2 Bridge part 3A, 3B, 3C Lead 4A, 4B Frame 5A, 5B Semiconductor chip 6 Wire 7 Sealing resin 7a Mold line 22a, 22b, 22c, 22d Inclined part 21A , 21B Continuously inclined part 41 Subframe

Claims (7)

A die bonding pad on which a semiconductor chip is mounted;
A lead conducting to the die bonding pad;
A lead frame comprising: a frame connected to the lead;
A lead frame, comprising a bridge portion including an inclined portion inclined with respect to a direction from the die bonding pad toward the lead between the die bonding pad and the lead.   The lead frame according to claim 1, wherein the bridging portion includes a continuous inclined portion in which a plurality of inclined portions are arranged in series via bent portions.   The lead frame according to claim 2, wherein the bridging portion includes a plurality of the continuous inclined portions arranged in parallel.   The lead frame according to claim 3, wherein the bridging portion has a line-symmetric shape about an axis extending in a direction from the die bonding pad toward the lead.   2. The lead frame according to claim 1, wherein the bridging portion includes a plurality of inclined portions that are inclined in the same side with respect to a direction from the die bonding pad toward the lead and are arranged in parallel.   6. The lead frame according to claim 1, further comprising an additional die bonding pad provided between the lead and the bridging portion. A semiconductor chip;
A die bonding pad on which the semiconductor chip is mounted;
A lead conducting to the die bonding pad;
A semiconductor device comprising: a sealing resin that covers the semiconductor chip,
It is manufactured using the lead frame according to any one of claims 1 to 6, and is inclined with respect to a direction from the die bonding pad to the lead between the die bonding pad and the lead. A semiconductor device, wherein a bridging portion including an inclined portion is provided.

Images