JP5986923B2 - Luminescent display device - Google Patents

Description

  The present invention relates to a light-emitting display device, and more particularly, to a light-emitting display device using a semiconductor light-emitting element as a light-emitting source, such as bar display, level display, numeric display, alphanumeric display, dot matrix display, and surface display.

  Conventionally, as this type of light-emitting display device, one having a structure shown in FIG. 9 has been disclosed (Patent Document 1).

  That is, a lead frame 83 in which the LED chip 82 is mounted (die-bonded) so as to enclose a semiconductor light emitting element (LED chip) 82 in a light guide portion 81 provided at a position corresponding to each display segment of the reflection case 80. , A translucent resin 84 filled in the reflection case 80 is filled in the light guide portion 81 and the lead frame 83 is sealed with resin.

JP 2001-332771 A

  By the way, in the light-emitting display device having the above structure, the translucent resin (for example, epoxy resin) 84 and the lead frame 83 are greatly different in thermal expansion coefficient, and the thermal expansion coefficient of the translucent resin 84 is the thermal expansion of the lead frame 83. It is more than 5 times the coefficient. Therefore, the thermal expansion coefficient difference at the interface between the translucent resin 84 and the lead frame 83 in the cooling process after heat-curing the translucent resin 84 in the manufacturing process of the light-emitting display device or after solder mounting on the mounting substrate of the light-emitting display device. The thermal stress is generated and becomes latent as a residual stress, and the residual stress becomes obvious due to a temperature change due to repeated lighting and extinguishing of the LED chip 82 in an actual use state as a display device, and the translucent resin 84 and the lead frame 83 An abnormal situation such as peeling of the interface between them, peeling of the LED chip 82 or the bonding wire 85 from the lead frame 83, or disconnection of the bonding wire 85 occurs, which causes a problem such as a decrease in luminous intensity or non-lighting.

  In particular, the light guide unit 81 that is surrounded by the lead frame 83 and the reflection case 80 and encloses the LED chip 82 and is filled with the translucent resin 84 does not disperse the actual residual stress to the outside. As the accumulated stress is accumulated, the stress distribution in the light guide portion becomes uneven, and a large concentrated stress is generated locally. As a result, the occurrence of the abnormal situation becomes prominent, leading to a decrease in reliability due to the malfunction.

  In addition, a force acting in the surface direction is applied to the lead frame 83 itself due to the thermal stress of the translucent resin 84 filled in the reflection case 80, and relative to the surface direction at the interface between the translucent resin 84 and the lead frame 83. A gap occurs. When the deviation in the surface direction occurs in the lead frame 83, particularly in the portion where the LED chip 82 is die-bonded, there is a possibility that it becomes a cause of occurrence of the abnormal situation.

  Therefore, the present invention was devised in view of the above problems, and the object of the present invention is to provide a lead frame on which a translucent resin (filling resin) filled in a reflective case and an LED chip (LED element) are mounted. In particular, the thermal stress generated in the light guide part (segment part) containing the LED chip is alleviated due to the difference in thermal expansion coefficient at the interface between the transparent resin and the lead frame, and the LED chip. It is intended to prevent the occurrence of problems such as a decrease in luminous intensity and non-lighting by suppressing the occurrence of abnormal situations such as peeling of the bonding wire from the lead frame or disconnection of the bonding wire. Thus, a highly reliable light-emitting display device is realized.

  In order to solve the above-described problem, the invention described in claim 1 of the present invention includes a case having a light guide hole surrounded by an inner surface and a plurality of cases disposed so as to close the bottom of the light guide hole. A lead frame, a semiconductor light emitting element located in the bottom of the light guide hole and mounted on at least one of the plurality of lead frames, and the case and the lead frame are integrated and filled in the light guide hole And a filling resin for sealing the lead frame, wherein at least one of the plurality of lead frames has a through hole, and the through hole is filled with the filling resin and part of the through hole is formed in the case. The light guide hole is blocked by a portion in the vicinity of the inner surface of the bottom portion of the light guide hole, and the other portion is located in the bottom portion of the light guide hole.

  The light-emitting display device of the present invention includes a case having a light guide hole surrounded by an inner surface and a plurality of light-emitting holes disposed so as to close the bottom of the light guide hole, each having a semiconductor light-emitting element mounted thereon or a bonding wire connected thereto. The lead frame and a filling resin for integrating the case and the lead frame, at least one of the plurality of lead frames has a through hole, and a part of the through hole is the bottom of the light guide hole of the case The portion near the inner surface is closed, and the other portion is located in the bottom of the light guide hole.

  As a result, the portion of the through hole located in the bottom portion of the light guide hole disperses the thermal stress of the filling resin to the outside, and simultaneously reduces and diffuses the thermal stress remaining in the light guide hole, The anchor effect of the filling resin with respect to the lead frame suppresses the deviation between the filling resin and the lead frame. As a result, the interface peeling between the filling resin and the lead frame, the peeling of the semiconductor light emitting element and the bonding wire from the lead frame, or the occurrence of defects such as the disconnection of the bonding wire is prevented, thereby contributing to the improvement of reliability. is there.

It is a top surface explanatory view of a 7 segment number indicator of an embodiment. It is AA cross-section explanatory drawing of FIG. It is an upper surface explanatory view of a lead frame. It is side surface explanatory drawing of a lead frame. It is upper surface explanatory drawing of the lead frame in which the conductor light emitting element was mounted. It is upper surface explanatory drawing of the 7 segment number indicator of the state which removed the filling resin with which the light guide hole was filled. It is BB sectional explanatory drawing of FIG. It is a table | surface of the test result of a light leak test. It is explanatory drawing of a prior art example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 8 (the same portions are given the same reference numerals). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

  1-7 is explanatory drawing which concerns on the 7 segment numerical display of embodiment of a light emission display apparatus, FIG. 1 is a top surface explanatory view of a 7 segment numerical display, FIG. 2 is AA cross-sectional description of FIG. FIG. 3, FIG. 3 is a top view of the lead frame, FIG. 4 is a side view of the lead frame, FIG. 5 is a top view of the lead frame on which the semiconductor light emitting element is mounted, and FIG. FIG. 7 is a cross-sectional explanatory view taken along the line BB in FIG. 6 (a state where the light guide hole is filled with a filling resin).

  A 7-segment numeric display (hereinafter abbreviated as “numerical display”) 1 includes a reflective case 10, a lead frame (hereinafter abbreviated as “lead”) 20, a semiconductor light emitting element (for example, LED element) 30, and bonding. A wire 40 and a filling resin 50 are provided.

  Among them, the reflective case 10 is made of a resin material having reflectivity and light shielding properties, and has a surface (11) display part to a segment (g) display part (hereinafter referred to as “segment (a) to segment”. (G) ”and a decimal point (dp) display section (hereinafter referred to as a decimal point (dp)), and each of the segment (a) to the segment (g) and the decimal point (dp) Light guide holes (A) to (G) and (DP) each including a through hole penetrating from the surface 11 to the back side are provided at corresponding positions, and the back side has an opening 12.

  The inner surface of each of the light guide holes (A) to (G) and (DP) forms a reflection surface by exposing the cloth of the reflection case 10 as it is.

  The lead 20 extends from each of the plurality of divided portions 21 and the plurality of divided portions 21 by a metal plate processing such as punching or bending a metal plate material, and the bonding portions 21 face each other. A plurality of electrode parts 23 bent perpendicularly to the bonding part 22 from both ends are formed into a substantially U shape, and thereafter surface treatment is performed by solder plating or the like. The bonding portion 22 is further provided with a through hole 24 at a predetermined position of a predetermined dividing portion 21 described later (see FIGS. 3 and 4).

  The LED elements 30 are mounted on the divided portions 21 of the bonding portions 22 of the leads 20 through the conductive bonding members 35 at positions corresponding to the respective light guide holes (A) to (G) and (DP) ( (See FIG. 5).

  Returning to FIGS. 1 and 2, the LED element 30 is mounted via the conductive bonding member 35 at a position corresponding to each of the light guide holes (A) to (G) and (DP) of the dividing portion 21. The lower electrode (not shown) of the LED element 30 and the dividing portion 21 on which the LED element 30 is mounted are electrically connected.

  At the same time, an upper electrode (not shown) of the LED element 30 and another divided part 21 electrically separated from the divided part 21 on which the LED element 30 is mounted are electrically connected via a bonding wire 40. ing.

  The lead 20 is disposed in the reflective case 10 in a state where the bonding portion 22 on which the LED element 30 is mounted is located at the bottom of each light guide hole (A) to (G), (DP) of the reflective case 10. ing. The filling resin 50 is filled in the reflection case 10 including the light guide holes (A) to (G) and (DP), and the bonding portion 22 of the lead 20 is buried in the filling resin 50. .

  In the numeric display 1 having the above configuration, when the state in which the filled resin filled in each of the light guide holes (A) to (G) and (DP) is removed is viewed from above, as shown in FIG. At the bottom of (A) to (G) and (DP), two divided portions 21a and 21b of the lead bonding portion are located with a gap 25 of a predetermined distance, and one divided portion 21a has The LED element 30 is mounted, and the other divided portion 21b is connected to the other end portion of the bonding wire 40 having one end portion connected to the upper electrode of the LED element 30.

  Further, at least one of the divided portions 21a and 21b is provided with a through hole 24 that extends to the inner side surface 13 at the bottom of each of the light guide holes (A) to (G) and (DP).

  As shown in FIG. 7, a part of the through hole 24 is blocked by a portion of the back surface 14 of the reflection case 10 in the vicinity of the inner surface 13 at the bottom of each of the light guide holes (A) to (G) and (DP). While being peeled off, the other portions are located in the bottoms of the light guide holes (A) to (G) and (DP).

  Accordingly, each of the gap 25 between the lead divided portion 21a and the divided portion 21b and the partial through hole 24a of the through hole 24 at the bottom of each light guide hole (A) to (G), (DP) is filled resin 50. The filling resin 50 filled in the light guide holes (A) to (G) and (DP) by the filled resin 50 and the filling resin filled on the opening 12 side of the reflective case 10. 50 communicates in the reflection case 10.

  By the way, as described above, the thermal expansion coefficient of the filling resin 50 and the lead 20 is greatly different, and the thermal expansion coefficient of the thermosetting filling resin 50 such as epoxy resin is 5 times or more the thermal expansion coefficient of the lead 20. It has become. Therefore, thermal stress due to a difference in thermal expansion coefficient is generated at the interface between the filling resin 50 and the lead 20 in the cooling process after the heat curing of the filling resin 50 in the manufacturing process of the number display and after the solder mounting on the mounting board of the number display. The residual stress becomes latent, and the residual stress becomes obvious due to temperature changes caused by repeatedly turning on and off the LED element 30 in the actual use state as a numerical display, and the interface peeling between the filling resin 50 and the lead 20, LED Abnormal conditions such as peeling of the element 30 or the bonding wire 40 from the lead 20 or disconnection of the bonding wire 40 occur, which causes a failure such as a decrease in luminous intensity or non-lighting.

  In particular, in each of the light guide holes (A) to (G) and (DP) including the LED element 30 and filled with the filling resin 50, the filling resin 50 is connected to the two divided portions 21 a and 21 b of the lead 20. Since it is surrounded by the side surface 13, the thermal stress in the cooling process after the heat-curing of the filling resin 50 in the manufacturing process and after the solder mounting on the mounting board of the numeric display is accumulated inside as residual stress without being dispersed outside. It is easy to make the stress distribution in the light guide portion of the residual stress non-uniform, and there is a possibility that a large concentrated stress is generated locally.

  In this case, the gap 25 located between the two divided portions 21a and 21b of the lead also exists in a display such as a conventional numeric display, and each light guide hole (A) to (G), ( The thermal stress of the filling resin 50 in the respective cooling processes after the heat curing of the filling resin 50 filled in the DP) and after the solder mounting of the numeric display device is distributed to the opening 12 side through the gap 25 to reduce the stress. It has a mitigating function.

  In the present embodiment, a portion of the through hole 24 provided in each of the lead split portions 21a and 21b, which is applied to the inner side surface 13 at the bottom of each light guide hole (A) to (G) and (DP). (Partial through hole) 24a is located.

  In this partial through hole 24a, the gap 25 located between the two split portions 21a and 21b of the lead is heat applied to the center side of each of the light guide holes (A) to (G) and (DP) of the filling resin 50. While distributing the stress and contributing to stress relaxation, the thermal stress applied to the inner side surface of each of the light guide holes (A) to (G) and (DP) of the filling resin 50 is partially penetrated along the inner side surface. Dispersing on the opening 12 side through the holes 24a contributes to further stress relaxation.

  Therefore, the residual stress of the filling resin 50 accumulated in each of the light guide holes (A) to (G) and (DP) can be further reduced and the stress distribution is made uniform with respect to the conventional display. Can also be planned.

  Furthermore, the filling resin 50 filled in each of the light guide holes (A) to (G) and (DP) is hard to be filled on the side of the filling resin 50 filled on the opening 12 side of the reflection case 10 through the partial through holes 24a. The filling resin 50 filled on the opening 12 side of the reflection case 10 is inserted into the light guide holes (A) to (G), (DP) filled in the respective light guide holes (A) to (DP) via the partial through holes 24a.

  Therefore, the through hole 24 provided in at least one of the two divided portions 21a and 21b of the lead serves as an anchor effect for the divided portions 21a and 21b.

  As a result, the residual stress of the filled resin 50 filled in each of the light guide holes (A) to (G) and (DP) due to the through holes 24 provided in at least one of the two divided portions 21a and 21b of the lead. Due to the reduction effect and the anchor effect on each of the two divided portions 21a and 21b of the lead, the filling resin 50 and the two divided portions 21a and 21b of the lead in each of the light guide holes (A) to (G) and (DP), respectively. It is possible to suppress the occurrence of problems such as peeling at the interface between the LED element 30, peeling from the split part 21 a of the LED element 30, peeling from the split part 21 b of the bonding wire 40, or disconnection of the bonding wire 40. 3 and 5, through holes are provided in all lead frames. However, the present invention is not limited to this, and it is sufficient that at least one lead frame has through holes. The number of lead frames provided with through holes and the number and size of the through holes can be arbitrarily designed according to the target specification and the degree of failure.

  Next, since the state of peeling and light leakage was verified for the numerical display of the present embodiment (example) and the conventional multi-order display (comparative example), the test method and the results will be described below.

  The light leakage is a result of examining the state of leakage light from the partial through hole located at the bottom of the light guide hole with respect to the light from the LED element included in the light guide hole.

  As for the test sample, the numeric display of the example has a lead thickness of 0.25 mm, an external size of 19 mm long × 12.5 mm wide × 12 mm thick, and 0.6 mmφ in each of the two divided portions 21 a and 21 b of the lead 20. And a part of the through hole is blocked by a portion in the vicinity of the inner side surface of the bottom of each light guide hole (A) to (G), (DP) on the back surface of the reflection case. . On the other hand, the numerical display of the comparative example is not provided with a through hole, and other than that is the same as the embodiment.

  As a peeling test method, a thermal shock test was adopted, and -40 ° C. (15 minutes) to + 85 ° C. (15 minutes) was defined as one cycle, and this was repeated for 288 cycles. The number of samples is four for each of the example and the comparative example.

  As a result of the thermal shock test, in Comparative Example, unlit due to peeling occurred in the segment (a) for all four test samples after 22 cycles. In contrast, in the example, peeling and non-lighting did not occur even after 288 cycles.

  Thus, in a display device having a light guide hole structure, by providing a through hole in a lead and arranging the through hole at a position as shown in the present embodiment, the through hole can exhibit a peeling prevention function. Proven.

  In the light leakage test, the same test samples as those used in the thermal shock test were used for both the examples and the comparative examples, and the number of samples was two for each of the examples and the comparative examples.

  In the test method, the current value of the LED element energization current is set so that the luminous intensity of the segment (a) and the segment (d) is 100 mcd, and the surface of the segment (a) and the segment (d) is covered with a light shielding mask. The luminous intensity of the adjacent segment when the segment (a) and the segment (d) were turned on (the LED element was driven with the current value) was measured while blocking the emitted light from the segment (a) and the segment (d).

  The leakage light measurement segments are the segments (b) and (f) when the segment (a) is lit, and the segments (c) and (e) when the segment (d) is lit.

  As shown in FIG. 8, the light leakage test result shows that the average luminous intensity of the leakage light of the segments (b) and (f) when the segment (a) is turned on is 0.38 mcd in the example, and is a comparative example. Was 0.31 mcd, and the difference was as small as 0.07 mcd. Further, the average luminous intensity of the leaked light of the segments (c) and (e) when the segment (d) is turned on is 0.31 mcd in the example and 0.32 mcd in the comparative example, and the difference is 0. It was a slight difference from 01mcd.

  The partial through-hole is formed by blocking a part of the through-hole in the vicinity of the inner side surface of the bottom of each of the light guide holes (A) to (G) and (DP) on the back surface of the reflection case. This is a result of the light leakage of the example being suppressed to a level that is not significantly different from that of the comparative example by reducing the cross-sectional area of the partial through-hole with respect to the through-hole.

  Therefore, in this embodiment, the through-hole formed in the lead suppresses an increase in light leakage and maintains the optical characteristics, while the interface peeling between the filling resin and the lead, the LED element and the bonding wire lead. This contributes to the improvement of reliability by preventing the occurrence of defects such as peeling of the wire or disconnection of the bonding wire.

  As the filling resin, a translucent resin such as an epoxy resin or a silicone resin, or a phosphor dispersion resin in which a phosphor is dispersed in the translucent resin is used.

1 ... 7-segment numeric display (numeric display)
DESCRIPTION OF SYMBOLS 10 ... Reflective case 11 ... Front surface 12 ... Opening 13 ... Inner side surface 14 ... Back surface 20 ... Lead frame (lead)
DESCRIPTION OF SYMBOLS 21 ... Dividing part 21a ... Dividing part 21b ... Dividing part 22 ... Bonding part 23 ... Electrode part 24 ... Through-hole 24a ... Partial through-hole 25 ... Gap 30 ... Semiconductor light emitting element (LED element)
35 ... Conductive bonding member 40 ... Bonding wire 50 ... Filling resin

Claims (1)

A case having a light guide hole surrounded by an inner surface;
A plurality of lead frames arranged to close the bottom of the light guide hole;
A semiconductor light-emitting element located in the bottom of the light guide hole and mounted on at least one of the plurality of lead frames;
The case and the lead frame are integrated and a filling resin that fills the light guide hole and seals the lead frame is provided.
At least one of the plurality of lead frames has a through-hole, and the through-hole is filled with the filling resin, and a part of the through-hole is closed with a portion of the case near the inner surface of the bottom of the light guide hole. The light emitting display device is characterized in that the other portion is located in the bottom of the light guide hole.

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