JP4058028B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device, and more particularly to a technique effective when applied to prevention of deformation of a lead frame used for assembling a semiconductor device.

In the conventional LSI package, the bonding area between the semiconductor chip and the resin is increased by making the outer diameter of the die pad smaller than the outer diameter of the semiconductor chip mounted thereon (see, for example, Patent Document 1). ).
JP-A-6-216303 (FIG. 1)

  In a semiconductor device configured by sealing a semiconductor chip mounted on a lead frame, a metal (for example, copper) having a relatively high thermal expansion coefficient is used for the lead frame.

  Here, in the semiconductor device, during operation, the semiconductor chip generates heat, and thus, thermal expansion / contraction stress is directly applied to the lead frame.

  Also, in the semiconductor device manufacturing process, the lead frame is often heated to a high temperature.

  For example, at the time of die bonding for fixing a semiconductor chip (curing temperature of silver paste around 325 ° C.), at the time of wire bonding for connecting a gold wire (from 200 ° C.), or at the time of resin sealing (at the curing temperature of the resin) Process of around 180 ° C.).

  A package using a copper material for the lead frame is described in Patent Document 1 (Japanese Patent Laid-Open No. 6-216303).

  Here, the thermal expansion coefficient of the copper material used for the lead frame is about 16.5 micro-in / in / ° C., and the thermal expansion coefficient of the semiconductor chip made of silicon is 2.8 to 7.3 micro-in / in / ° C. It stays at about ℃ (all around 20 ℃).

  Thus, if the thermal expansion coefficient of the lead frame, which is a metal material, is large, a large thermal expansion and contraction stress is directly applied due to heat generated from the semiconductor chip during operation of the semiconductor device. Then, since the tab to which the semiconductor chip is fixed and the tab suspension lead supporting this tab are deformed, the semiconductor chip can be peeled off from the tab without being deformed, or cracked by being dragged by the deformation. There is a concern that it may occur.

  Also, for extremely thin semiconductor devices with a mounting height of about 1mm, such as TSOP (Thin Small Outline Package) and TQFP (Thin Quad Flat Package), the package itself is difficult to ensure mechanical strength. Therefore, it is assumed that the adverse effects due to such thermal expansion and contraction stress become remarkable.

  Furthermore, even in a semiconductor device having a normal thickness such as SOP and QFP, the amount of heat generation increases as the size of the semiconductor chip increases.

  Accordingly, an object of the present invention is to provide a technique capable of relieving thermal expansion and contraction stress of a lead frame.

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

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

That is, a semiconductor device of the present invention is formed integrally with a semiconductor chip on which an integrated circuit is formed, a tab on which the semiconductor chip is smaller than an outer dimension of the semiconductor chip, and the tab. A plurality of supporting tab suspension leads, a plurality of leads formed so as to surround the semiconductor chip and disposed between the plurality of tab suspension leads, and the semiconductor chip and the plurality of leads are electrically connected to each other. a plurality of bonding wires for the semiconductor chip, the tab, the plurality of tab suspension leads, and a sealing resin for sealing the plurality of bonding wires, and the plurality of leads, extending before Symbol tab suspension leads in extending direction, between the tabs and the tab suspension leads are long slits in the width direction of the tab suspension leads are formed, the semiconductor Chips via the plurality of tab suspension die bonding material provided only in the tub surrounded by the slit formed in each of the leads, in which is mounted on the tub.

Furthermore, the semiconductor device of the present invention includes a semiconductor chip on which an integrated circuit is formed, a tab that is smaller than the outer dimensions of the semiconductor chip, on which the semiconductor chip is mounted, and is formed integrally with the tab. A plurality of supporting tab suspension leads, a plurality of leads formed so as to surround the semiconductor chip and disposed between the plurality of tab suspension leads, and the semiconductor chip and the plurality of leads are electrically connected to each other. a plurality of bonding wires for the semiconductor chip, the tab, the plurality of tab suspension leads, and a sealing resin for sealing the plurality of bonding wires, and a plurality of leads, extending before Symbol tab suspension leads in the direction, between the tabs and the tab suspension leads are long slits in the width direction of the tab suspension leads are formed, the tab suspension Li In de, the offset portion is formed at a position distant from said slit than the end of the semiconductor chip, the semiconductor chip, the tab surrounded by the slit formed in each of the plurality of tab suspension leads It is mounted on the tab through a die bonding material provided only on the tab .

  The lead frame used for assembling the semiconductor device is formed at the center of the frame frame, and is formed by extending a tab on which the semiconductor chip is mounted and extending from the periphery of the tab toward the frame frame. A plurality of leads that are electrically connected to the electrodes, a tab suspension lead that is formed to extend from the frame frame so as to be connected to the tab, and a tab suspension lead that holds the tab in a predetermined position. And a stress relieving portion that deforms in response to thermal expansion and contraction of the chip.

  In this lead frame, the stress relieving portion can be formed on at least one of the inside and outside of the chip mounting area, which is the area where the semiconductor chip is mounted. Further, the stress relieving portion may have a structure having a slit that is deformed by displacement in the length direction of the tab suspension lead, or a meandering shape that expands and contracts by displacement in the length direction of the tab suspension lead.

  In the lead frame described above, the stress relief part is formed inside and outside the chip mounting area, which is the area where the semiconductor chip is mounted, and the stress relief part on one side has a slit that is deformed by displacement in the length direction of the tab suspension lead. The stress relief portion on the other side can have a meandering shape that expands and contracts by displacement in the length direction of the tab suspension lead.

  In these lead frames, the tab may have a cross-shaped cross tab structure or a small tab structure having a size smaller than that of the semiconductor chip. Moreover, in the crosstab structure, a crosstab structure including a plurality of locations separated from each other can be used, and the stress relieving portion can be formed at an extended intersection position of these tabs.

  According to the above-described means, the stress relief portion is formed on the tab suspension lead, and the stress relief portion is deformed according to the expansion and contraction of the tab suspension lead, so that the thermal expansion and contraction stress applied to the lead frame due to heat generation of the semiconductor chip is alleviated. The

Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.
(1) According to the lead frame of the present invention, the stress relief portion is formed on the tab suspension lead, and this stress relief portion is deformed according to the expansion and contraction of the tab suspension lead. Thermal expansion and contraction stress is relieved.
(2) According to the above (1), the semiconductor chip may not follow the deformation of the lead frame made of a different material, but may be peeled off from the tab, or may be dragged by the expansion and contraction of the tab suspension lead to generate a crack. Absent.
(3) In particular, in the case of a small package such as TSOP and TQFP, a stronger thermal stress is applied, which is more effective.
(4) According to the above (1) to (3), the reliability of the product can be improved.

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

(Embodiment 1)
FIG. 1 is a plan view showing a lead frame according to one embodiment of the present invention, FIG. 2 is a plan view showing a part of FIG. 1 in an enlarged manner, and FIG. 3 is a semiconductor configured using the lead frame of FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

  In this embodiment, a lead frame 2 that is electrically connected to a semiconductor chip 1 on which an integrated circuit is formed and exchanges input / output signals with the outside is, for example, a TQFP type made of a pressed copper material. As shown in FIG. 1, it has a plurality of leads 3.

  The leads 3 electrically connected to the electrodes of the semiconductor chip 1 extend in different directions for each group, and in the illustrated case, extend in four directions. Therefore, the semiconductor device 4 (FIG. 3) constituted by the lead frame 2 forms a so-called four-direction lead in which the leads 3 protrude from four directions. However, in the present invention, the type of the lead frame 2 is not limited to TQFP. For example, other thin packages such as TSOP, and various other types of leads extending in two directions or a single direction. It can be applied to those of the structure. Moreover, you may manufacture by etching instead of press work.

  The dam bar 5 is formed so as to connect the leads 3 to each other, and this prevents the resin from protruding when the sealing area A indicated by the outer two-dot chain line is molded. However, a damless structure can also be adopted.

  Frame frames 6 are formed on both sides of the lead frame 2 in the length direction. A pilot hole 7 is opened in the frame frame body 6, and the lead frame 2 is sequentially fed by one package as shown in the figure by feed claws that mesh with the pilot hole 7.

  A tab 8 on which the semiconductor chip 1 is mounted is formed at the center of the lead frame 2. The tab 8 is formed on an extension of four tab suspension leads 9 having a substantially cross shape formed so as to extend from the frame body 6. Therefore, the tab 8 also has a substantially cross-shaped structure, that is, a crosstab structure. The lead 3 is formed to extend outward from the tab 8.

  A chip mounting area B, which is an area where the semiconductor chip 1 is mounted, is indicated by an inner two-dot chain line in FIGS. As shown in the figure, the mounted semiconductor chip 1 is relatively small. Therefore, the outside of the tab 8 protrudes from the mounted semiconductor chip 1, and a part thereof becomes an adhesion region C with the semiconductor chip 1. ing. However, as shown in FIG. 5 and the drawings in other embodiments described below, the semiconductor chip 1 may be of a normal size covering the entire tab.

  An offset portion 10 is formed in the middle of the tab suspension lead 9, and the tab 8 is shifted in the vertical direction with respect to the lead 3. Thereby, the upper and lower resin thicknesses in the molded semiconductor device 4 are equalized.

  Here, the shape of the tab suspension lead 9 is shown in detail in FIG. As shown in the figure, stress relaxation portions 12 a and 12 b having slits 11 are formed at the frame frame base portion of the tab suspension lead 9 and at the center crossing position. A slit 11 that is long in the width direction of the tab suspension lead 9 is formed in the stress relaxation portion 12a, and the substantially cross-shaped tab suspension lead 9 is rotated 45 degrees in the plane direction around the crossing position in the stress relaxation portion 12b. A slit 11 is formed in an approximately cross shape.

  The lead frame 2 on which the stress relieving portions 12a and 12b are formed is wire-connected to the lead 3 after the semiconductor chip 1 is mounted on the tab 8. Thereafter, the resin 3 is molded in the sealing area A indicated by the two-dot chain line on the outer side in FIG. 1 and dam bar cutting, tab suspension lead cutting, and burr removal are performed, and then the lead 3 extending in four directions is formed into a gull wing shape. Thus, the semiconductor device 4 is completed.

  An example of the completed semiconductor device 4 is shown in FIG. 3, and a sectional view taken along line IV-IV in FIG. 3 is shown in FIG. In the case of the semiconductor device 4 shown in the figure, for example, the package thickness is 1 mm, the length is 10 mm, and the width is 15 mm. As shown in FIG. 4, the semiconductor chip 1 electrically connected to the lead 3 by the bonding wire 13 is It is sealed.

  Here, as described above, the thermal expansion coefficient of the lead frame 2 made of copper is as large as about 16.5 micro-in / in / ° C. Therefore, when the semiconductor device 4 operates and the semiconductor chip 1 generates heat, the tab suspension lead 9 extends due to thermal expansion. When the operation of the semiconductor device 4 stops, the extended tab suspension lead 9 contracts to its original length due to heat dissipation. At this time, in the lead frame 2 of the present embodiment, the stress relief portions 12a and 12b having the slits 11 are formed in the tab suspension lead 9, so that when the tab suspension lead 9 expands and contracts, the slit 11 deforms and the lead frame 2 The thermal expansion and contraction stress applied to is relieved. Therefore, the semiconductor chip 1 made of silicon cannot follow the deformation of the lead frame 2 made of a different material such as a copper material and peels from the tab 8 or is dragged by the expansion and contraction of the tab suspension lead 9 to generate a crack. There is no.

  Furthermore, according to the lead frame 2 of the present embodiment, not only during the operation of the semiconductor device 4, a die bonding step for fixing the semiconductor chip 1 (silver paste cure temperature around 325 ° C.), or a bonding wire 13 is connected. In the assembly process such as the wire bonding process (from 200 ° C.) or the resin sealing process (around 180 ° C. at the resin curing temperature), the thermal expansion and contraction stress applied to the lead frame 2 can be reduced as described above.

  Thereby, peeling from the tab 8 of the semiconductor chip 1 and crack generation in the assembly process can be prevented.

(Embodiment 2)
FIG. 6 is a plan view showing a main part of a lead frame according to another embodiment of the present invention.

  In the present embodiment, the stress relieving portion 12c is constituted by meandering shapes formed so as to intersect each other inside the four tabs 8 formed on the tab suspension leads 9 that intersect. In addition, a stress relieving portion 12 a having the slit 11 similar to that of the first embodiment is formed at the base portion of the frame body of the four tab suspension leads 9. The bent portion in the meandering shape may be square or round as shown in the figure.

  As described above, even in the meandering stress relieving portion 12c, when the tab suspension lead 9 is extended by thermal expansion, the stress relieving portion 12c is deformed so as to bend, and when it is contracted, the deformation is restored so that the bending is restored. The thermal expansion / contraction stress due to the heat generation of 1 is alleviated.

(Embodiment 3)
FIG. 7 is a plan view showing a main part of a lead frame according to still another embodiment of the present invention.

  In the present embodiment, tabs 8 are formed at a total of five locations, four locations on the intersecting tab suspension leads 9 and one at the central intersecting position, and the meandering stress relieving portion 12 c is formed on the tab suspension leads 9. It is formed between the formed tab 8 and the tab 8 formed in the center.

  As described above, the tab 8 may be formed at the center and the periphery thereof, and the stress relieving portion 12c may be provided between them.

(Embodiment 4)
FIG. 8 is a plan view showing a main part of a lead frame according to still another embodiment of the present invention.

  In the present embodiment, the tab 8 is formed in a substantially cross shape at the intersection of the tab suspension leads 9, and the stress relaxation portion 12 d having the oval slit 11 has four tab suspension leads 9 extending toward the frame outer frame. Each is formed above.

  As described above, the stress relaxation portion 12 d may be formed on the frame outer frame side of the tab suspension lead 9.

(Embodiment 5)
FIG. 9 is a plan view showing a main part of a lead frame according to still another embodiment of the present invention.

  In the present embodiment, a stress relieving portion 12e having a slit 11 is formed around a tab 8 having a circular small tab structure formed in the center portion. The tab suspension lead 9 is formed so as to extend in four directions from the tab 8 through the stress relieving portion 12e.

  Thus, the tab 8 may have a small tab structure.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, the material of the lead frame is not limited to a copper material, and a 42 alloy material can be similarly applied.

  Furthermore, the meandering stress relieving part and the stress relieving part having slits are not limited to use at the positions shown in the present embodiment. It can also be used as appropriate.

  In addition, the stress relief portion can be formed at the base of the frame outer frame, in the middle of the tab suspension lead, at the center position of the semiconductor chip, etc., and at any one or all of these locations. It can also be formed.

  The present invention is suitable for an electronic component and its manufacturing technology.

It is a top view which shows the lead frame by Embodiment 1 of this invention. It is a top view which expands and shows a part of FIG. FIG. 2 is a perspective view showing a semiconductor device configured using the lead frame of FIG. 1. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. FIG. 3 is a plan view showing a case where a normal-size semiconductor chip is mounted on the lead frame shown in FIG. 2. It is a top view which shows the principal part of the lead frame by Embodiment 2 of this invention. It is a top view which shows the principal part of the lead frame by Embodiment 3 of this invention. It is a top view which shows the principal part of the lead frame by Embodiment 4 of this invention. It is a top view which shows the principal part of the lead frame by Embodiment 5 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Lead frame 3 Lead 4 Semiconductor device 5 Dam bar 6 Frame frame 7 Pilot hole 8 Tab 9 Tab suspension lead 10 Offset part 11 Slit 12a-12e Stress relaxation part 13 Bonding wire 14 Mold resin

Claims (4)

A semiconductor chip on which an integrated circuit is formed;
A tab on which the semiconductor chip is mounted, smaller than the outer dimensions of the semiconductor chip;
A plurality of tab suspension leads formed integrally with the tab and supporting the tab;
A plurality of leads formed so as to surround the semiconductor chip and disposed between the plurality of tab suspension leads;
A plurality of bonding wires that electrically connect the semiconductor chip and the plurality of leads, respectively.
Including the semiconductor chip, the tab, the plurality of tab suspension leads, the plurality of bonding wires, and a sealing resin that seals the plurality of leads ,
In the extending direction of the front Symbol tab suspending lead, between the tabs and the tab suspension leads are long slits in the width direction of the tab suspension leads are formed,
The semiconductor chip is mounted on the tab via a die bonding material provided only on the tab surrounded by the slit formed in each of the plurality of tab suspension leads. Semiconductor device. A semiconductor chip on which an integrated circuit is formed;
A tab on which the semiconductor chip is mounted, smaller than the outer dimensions of the semiconductor chip;
A plurality of tab suspension leads formed integrally with the tab and supporting the tab;
A plurality of leads formed so as to surround the semiconductor chip and disposed between the plurality of tab suspension leads;
A plurality of bonding wires that electrically connect the semiconductor chip and the plurality of leads, respectively.
Including the semiconductor chip, the tab, the plurality of tab suspension leads, the plurality of bonding wires, and a sealing resin for sealing the plurality of leads ,
In the extending direction of the front Symbol tab suspending lead, between the tabs and the tab suspension leads are long slits in the width direction of the tab suspension leads are formed,
In the tab suspension lead, an offset portion is formed at a position farther from the slit than the end of the semiconductor chip ,
The semiconductor chip is mounted on the tab via a die bonding material provided only on the tab surrounded by the slit formed in each of the plurality of tab suspension leads. Semiconductor device.   3. The semiconductor device according to claim 1, wherein each of the tab, the plurality of tab suspension leads, and the plurality of leads is made of a copper material.   4. The semiconductor device according to claim 3, wherein the die bonding material is a silver paste.

Images