JP2017079228A - Terminal for semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal which prevents a semiconductor element from being inclined due to contractive force during cooling of a solder fillet part when soldering is performed.SOLUTION: In a semiconductor element in which a base plate, a semiconductor element, and a terminal connection part are connected in this order by solder, the terminal connection part has a bent part whose one end part protrudes upward and a protrusion formed by protruding the other end part different from one end part upward, and the bent part is connected to a terminal.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a semiconductor element terminal.

  In the process of soldering the semiconductor element and the terminal using a solder reflow furnace or the like, the component elements such as the semiconductor element and the terminal are aligned in the horizontal direction using self-alignment using a solder resist pattern or a jig.

  However, since the solder itself melts in the soldering process, the vertical alignment of the component elements becomes uncertain depending on the melting state.

  Therefore, in order to solve the above problem, by making the electrode area of the upper chip component smaller than the electrode area of the lower electrode, the uniformity of the solder distribution during soldering is ensured, thereby Proposals have been made to ensure vertical alignment (Patent Document 1).

JP2015-39028A

  However, the structure of the prior art can ensure the soldering of the upper and lower component elements, but this structure corresponds only to the soldering of the upper and lower two component elements, and the vertical direction The vertical alignment cannot be ensured for the semiconductor element that solders the three component elements.

  Hereinafter, this will be described with reference to FIG.

  FIG. 1 shows a state in which a diode 2 and a terminal as an example of a semiconductor element are mounted on a base plate 1, FIG. 1A shows an ideal soldering state, and FIG. 1B shows a problem during soldering. This shows a state in which has occurred. Here, the diode 2 is a semiconductor chip having a PN junction, and is a chip-like component having an anode electrode 2A on the front surface and a cathode electrode 2K on the back surface. In this example, the base plate 1 is sufficiently larger than the area of the cathode electrode 2 </ b> K of the diode 2, and the terminal connection portion 4 is smaller than the area of the anode electrode 2 </ b> A of the diode 2. The terminal connecting portion 4 includes a bent portion 40 whose right end is bent upward, and the terminal 6 is connected to the bent portion 40.

  In the soldering process, plate solder or solder pellets may be used as the solder material, but in this example, solder paste is used. Hereinafter, for convenience of explanation, the solder material before melting and the melted solder material and the solidified material are all called solder. Solders 3 and 5 are applied between the base plate 1 and the cathode electrode 2K of the diode 2 and between the anode electrode 2A of the diode 2 and the terminal connection portion 4 and soldered in a solder reflow furnace. At this time, the terminal 6 is fixed and positioned by a jig. Then, the solders 3 and 5 are melted in the solder reflow furnace, and then the solders 3 and 5 are solidified by cooling. At this time, when the solders 3 and 5 are uniformly distributed in the vertical direction, as shown in FIG. Furthermore, the diode 2 does not tilt in the vertical direction.

  However, in practice, as shown in FIG. 1B, when the solder is solidified, the right end portion of the diode 2 may be inclined upward. The reason why this phenomenon occurs is as follows.

  In order to connect the terminal connecting portion 4 to the terminal 6, the right end portion of the terminal connecting portion 4 is bent to constitute the bent portion 40. In the process of melting and solidifying the solder 5, the bent portion The solder in the vicinity of 40 crawls upward along the right end surface of the bent portion 40, and the scooped solder is solidified to form a solder fillet 50. And just before this solder fillet 50 is formed, the solder fillet contracts toward the bent portion 40, and a force is generated that pulls the solder in the direction indicated by the arrow F in the figure. At this time, since the solder 5 located between the right end portion of the diode 2 and the terminal connection portion 4 is pulled toward the bent portion 40, the thickness of the solder between the right end portion of the diode 2 and the terminal connection portion 4 is reduced. Since the position of the terminal 6 is fixed with a jig, the bent portion 40 side of the diode 2 is pulled in the direction toward the bent portion 40 indicated by the arrow F, and the right end portion of the diode 2 is shown in FIG. Tilt upwards.

  Thus, if the right end of the diode 2 is tilted upward, the distribution of the solders 3 and 5 becomes non-uniform, so that the thermal conductivity in the solders 3 and 5 becomes non-uniform, and the heat dissipation is poor overall. In addition, solder deterioration due to thermal stress is accelerated, and cracks are likely to occur inside the solders 3 and 5.

  An object of the present invention is to provide a semiconductor element terminal in which a semiconductor chip does not tilt due to a force of pulling solder due to a contraction force of a solder fillet 50 during soldering.

The semiconductor element terminal of the present invention is a semiconductor element in which a base plate, a chip-like semiconductor element, and a terminal connection portion are connected by solder in this order.
The terminal connecting portion has a bent portion protruding upward at one end portion thereof and a protruding portion protruding upward at the other end portion different from the one end portion, and the bent portion is connected to the terminal. It is characterized by.

  Since the terminal connecting portion has a bent portion and a protruding portion protruding upward, the solder rises at the bent portion and the protruding portion during soldering. For this reason, during soldering, the distribution of solder in the vertical direction between the semiconductor element and the terminal connection portion becomes uniform, and the semiconductor element does not tilt. If the bent part and the protruding part are provided on the terminals facing the terminal connection part, the distribution of the solder becomes more uniform, but different ends of the terminal connection part, for example, so as to prevent the solder distribution from being significantly different, for example, You may provide in an adjacent edge part.

  In the terminal for a semiconductor element according to the present invention, the terminal connection portion has a bent portion protruding upward at one end portion and a protruding portion protruding upward at the other end portion different from the one end, so that the solder rises during soldering. Therefore, the distribution of the solder in the vertical direction at both ends becomes uniform at the time of soldering. For this reason, the inclination of the semiconductor chip can be prevented.

The figure for demonstrating the malfunction of the mounting state of the conventional semiconductor element The figure which shows the mounting state of the semiconductor element which employ | adopted the terminal of embodiment of this invention The figure which shows the mounting state of the semiconductor element which employ | adopted the terminal of other embodiment of this invention. The figure which shows the terminal of further another embodiment of this invention.

  FIG. 2A is a diagram showing a mounting state of a semiconductor element employing the terminal for an embodiment of the present invention. Here, a diode 2 is shown as an example of the semiconductor element.

  The mounting state of the diode 2 is the same as the mounting state of the diode 2 shown in FIG. 1 as a whole, and the difference is the configuration of the terminal connection portion 4.

  That is, the terminal connection portion 4 has a bent portion 40 protruding substantially vertically upward at one end portion and a protruding portion 41 protruding substantially vertically upward at the other end portion different from the one end portion. In the drawing, the right bent portion 40 is connected to the terminal 6. Actually, the terminal 6 and the terminal connection portion 4 are formed by bending one Cu plate.

  The mounting method of the diode 2 is the same as the mounting method of the diode 2 shown in FIG. That is, solders 3 and 5 are applied between the base plate 1 and the cathode electrode 2K of the diode 2 and between the anode electrode 2A of the diode 2 and the terminal connection portion 4 and soldered in a solder reflow furnace. At this time, the terminal 6 is fixed and positioned by a jig. Then, the solders 3 and 5 are melted in the solder reflow furnace, and then the solders 3 and 5 are solidified by cooling. At this time, the bent portion 40 that protrudes substantially vertically upward at one end portion of the terminal connection portion 4. And the other end portion different from the one end portion has a protruding portion 41 protruding substantially vertically upward, so that solder scooping occurs on the outer surface of the bent portion 40 and the protruding portion 41 during soldering. As shown in the drawing, the same solder fillets 50 and 51 are formed on both sides.

  In the present embodiment, the solder fillets 50 and 51 are formed on the outer surfaces of the bent portions 40 and the protruding portions 41 at both ends of the terminal connection portion 4 in the soldering process, and the terminal connection is performed in the process in which the solder fillets 50 and 51 are solidified. A force is generated that each part is pulled in the opposite direction. For this reason, as in the prior art (FIG. 1B), the force of pulling the solder does not act only on one side of the diode 2, and as a result, the diode 2 does not tilt in the vertical direction.

  As shown in FIG. 2B, the anode electrode 2A and the cathode electrode 2K of the diode 2 can be mounted in reverse. A breakdown voltage maintaining structure is formed around the anode electrode 2A of the diode 2, and the area of the anode electrode 2A is smaller than that of the cathode electrode 2K. In such a structure of the diode 2, since the area of the anode electrode 2A soldered with the solder 3 is small, the stability of the diode 2 is poor, and the diode 2 tends to be inclined more easily during the soldering process. However, when the terminal connection portion 4 having the bent portion 40 and the protruding portion 41 is soldered on the cathode electrode 2K as in this example, the force that pulls the diode 2 acts evenly and the distribution of the solder becomes uniform. In addition, the inclination of the diode 2 can be prevented.

  FIG. 3 shows another embodiment. In this example, a bent portion 40 that protrudes upward at one end of the terminal connection portion 4 and a protruding portion 41 that protrudes upward at the other end different from the one end are provided. It protrudes diagonally upward on the outside. In this way, by making the bent portion 40 and the protruding portion 41 obliquely protrude outward and upward, the solder 5 is likely to crawl along the bent portion 40 and the solder fillets 50 and 51 are easily formed. When the solder fillets 50 and 51 solidify and contract, a uniform pulling force acts on the diode 2, and the terminal connection portion 4 is firmly connected to the cathode electrode 2 </ b> K of the diode 2 without tilting the diode 2. .

  In the above example, it is desirable that the inclination angles θ1 and θ2 of the bent portion 40 and the protruding portion 41 are the same angle. By doing so, the sizes of the solder fillets 50 and 51 become the same, and the force with which the solder fillets 50 and 51 pull the solder in opposite directions along the bent portion 40 and the protruding portion 41 becomes the same, and the diode The tilt prevention effect of 2 is further increased.

  In the above example, it is desirable that the bent portion 40 and the protruding portion 41 are provided at opposite ends of the terminal connecting portion 4. In this way, when soldering, the same solder fillets 50 and 51 are formed to face each other on the outer surface of the bent portion 40 and the protruding portion 41 where the rising of the solder 5 faces, so that the solder fillet 50, Since 51 pulls the solder 5 in opposite directions, the distribution of the solder 5 can be made uniform. For this reason, the tilt prevention effect of the diode 2 is further increased.

  In the above example, the bent portion 40 and the protruding portion 41 may be provided at the adjacent end portions of the terminal connecting portion 4. By providing the protruding portion 41 adjacent to the bent portion 40, the solder fillets 50 and 51 are arranged in a plurality of directions as compared with the conventional embodiment in which the solder 5 is pulled only in one direction along the bent portion 40. Since the solder is pulled, it is possible to prevent the solder distribution from becoming uneven. In this case, the protruding portion 41 may be formed at a position adjacent to both sides of the bent portion 40. Even when the planar shape of the terminal connection portion 4 is substantially triangular, if the protruding portion 41 is provided adjacent to the bent portion 40, the distribution of the solder can be prevented from becoming uneven in the same manner.

  FIG. 4 shows yet another embodiment. FIGS. 4A and 4B are a plan view and a perspective view, respectively, of the terminal connection portion 4. Except for the terminal connection portion 4, the present embodiment is the same as the above embodiments.

  In this example, the terminal connection portion 4 has a bent portion 40 and protruding portions 41, 42, 43 formed at the same inclination angle on the side portions of the terminal connection portion 4 on the left and right sides of the rectangular soldering portion 44. . In the example shown in FIGS. 2 and 3, the bent portion 40 and the protruding portion 41 are formed only in the left-right direction, but in FIG. 4, the protruding portions 42 and 43 are further formed in the front-rear direction. By forming the protrusions 41 at the respective end portions in this way, the solder fillet 50 pulls the solder in a plurality of positions and directions, so that the distribution of the solder 5 is made uniform and contributes to the tilt prevention effect of the diode 2.

  In each embodiment, although the planar shape of the terminal connection part 4 was shown by the example of the substantially rectangular shape, the planar shape of the terminal connection part 4 is made into a polygon, and it protrudes in the arbitrary edge parts in which the bending part 40 is not formed. It is also possible to install. For example, the planar shape of the terminal connection portion 4 may be a pentagon, the bent portion 40 may be formed at one end of the end portion, and the protruding portion 41 may be formed at an end portion not adjacent to the end portion. Also, by setting the widths of the bent part and the protruding part to be appropriately different and changing the widths of the solder fillets 50 and 51, the force with which the solder fillets 50 and 51 pull the solder 5 is adjusted, and the inclination of the diode Can also be prevented. Furthermore, the inclination of the diode 2 can be prevented by adjusting the force with which the solder fillets 50 and 51 pull the solder 5 by selecting the angle between the bent portion and the protruding portion, and the combination of the angle and the width. it can.

  In the above embodiment, the diode 2 having a PN junction surface is exemplified as the semiconductor element. However, the present invention can also be applied to other semiconductor elements such as a thyristor.

1-base plate 2-diode 3, 5-solder 4-terminal connecting portion 40-bending portion 41-projecting portion 6-terminal

Claims (6)

In the semiconductor element in which the base plate, the chip-like semiconductor element, and the terminal connection portion are connected by solder in this order,
The terminal connecting portion has a bent portion protruding upward at one end portion thereof and a protruding portion protruding upward at the other end portion different from the one end portion, and the bent portion is connected to the terminal. A terminal for a semiconductor element.   The terminal for a semiconductor element according to claim 1, wherein the bent portion and the protruding portion protrude obliquely outward and upward from the terminal connection portion.   The semiconductor element terminal according to claim 2, wherein the bent portion and the protruding portion have the same inclination angle.   The terminal for a semiconductor element according to claim 1, wherein the bent portion and the protruding portion are provided at opposite ends of the terminal connection portion.   The terminal for a semiconductor element according to claim 1, wherein the bent portion and the protruding portion are provided at adjacent ends of the terminal connection portion.   The said terminal connection part is a terminal for semiconductor elements in any one of Claims 1-3 which has the protrusion part which protrudes upwards in all the edge parts except the edge part in which the said bending part is provided.

Images