JP2017135155A - Substrate for mounting semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to maintain high bonding strength of a light emitting device with respect to a substrate by suppressing stress on the substrate caused by heat generation during light emission of the light emitting device in the substrate on which the light emitting device is mounted by soldering.SOLUTION: The substrate for mounting a semiconductor light emitting device formed by mounting a light emitting device group 6 composed of a plurality of light emitting devices 5 on a line segment L between fixed holes 2 provided at both end portions of a substrate 1 is provided with a pair of stress relief holes 10 on the line segment L between light emitting devices 5a positioned at both ends of the light-emitting device group 6 and the fixed holes 2 located on the respective end sides.SELECTED DRAWING: Figure 14

Description

  The present invention relates to a substrate (semiconductor light emitting device mounting substrate) on which a plurality of semiconductor light emitting devices (for example, LED devices) are mounted.

  Conventionally, as an LED mounting board on which a plurality of LED elements are mounted (particularly mounted in a straight line), for example, Patent Document 1 (name: vehicle lamp) is disclosed as a circuit board constituting a light emitting module.

  The disclosed light emitting module 80 includes a circuit board 81, power feeding connectors 95 and 96, and a semiconductor light emitting element 100, as shown in FIG.

  Among them, the circuit board 81 has two cutout portions 86 formed between the upper side portion 84 and the lower side portion 85 of the right side portion 82 and the left side portion 83, respectively, and 2 formed on the right side portion 82. Two circular holes 87 and 88 penetrating the circuit board 81 are formed between the notch portions 86, and the circuit board 81 is similarly formed between the two notch portions 86 formed on the left side portion 83. Two long holes 89 and 90 penetrating through are formed.

  The power supply connectors 95 and 96 are disposed at the upper end of the upper side portion 84 of the circuit board 81, and a plurality of semiconductor light emitting elements (specifically, 22 semiconductor light emitting elements) 100 are provided on the lower side portion 85 of the circuit board 81. It is arranged linearly in a horizontal row.

  Although not shown in the drawings, the light emitting module 80 is attached to the holding member at the same time when the four notches 86 of the circuit board 81 of the light emitting module 80 are fitted to the screw bosses protruding from the base portion of the holding member. The one circular hole 88 of the circuit board 81 is inserted into one positioning pin protruding from the base portion of the holding member, and the other long hole 90 of the circuit board 81 protrudes from the base portion of the holding member. The other positioning pin is inserted. The other circular hole 87 of the circuit board 81 is fitted into one positioning pin protruding from the back surface side of the fixing part of the reflecting member, and the other long hole 89 of the circuit board 81 is the fixing part of the reflecting member. It is inserted into the other positioning pin protruding from the back side.

  The positioned light emitting module 80 is fastened together with a tapping screw while being sandwiched between the holding member and the reflecting member.

JP 2013-164937 A

  Meanwhile, in the light emitting module 80 having the above configuration, when the semiconductor light emitting element 100 emits light, heat generated from each semiconductor light emitting element 100 is superimposed, so that the amount of heat increases and the temperature of the circuit board becomes extremely high. The circuit board is stretched due to thermal expansion due to temperature rise.

  Then, the circuit board 81 extends in the direction of the long hole 89 and the long hole 90 with the circular hole 87 and the circular hole 88 as fulcrums. Therefore, as the semiconductor light emitting element 100 is located closer to the long hole 89 and the long hole 90, the positional deviation with respect to the holding member and the reflecting member becomes larger, and the semiconductor light emitting element 100 positioned closest to the long hole 89 and the long hole 90 is The largest misalignment occurs.

  As a result, the optical characteristics of the light emitted from the semiconductor light emitting device 100 and emitted from the vehicular lamp may be adversely affected.

  In addition, in order to ensure the holding of the positioning of the circuit board, considering the case where both ends are firmly fixed and supported by means such as screwing, the expansion of the circuit board due to heat generation during light emission of the semiconductor light emitting element Bending stress is generated between the fixed support parts to cause warpage, which causes damage or breakage at the joint part (for example, solder joint part) between the semiconductor light emitting element and the circuit board, thereby ensuring the required joint strength. There is a possibility of disappearing.

  Therefore, the present invention was devised in view of the above problems, and the object of the present invention is to provide a circuit board (LED mounting board) on which a semiconductor light emitting element (LED element) is mounted, when the semiconductor light emitting element emits light. It is intended to maintain a high bonding strength of the semiconductor light emitting element to the circuit board by suppressing the stress on the circuit board caused by the heat generation.

  In order to solve the above problems, the invention described in claim 1 of the present invention is a semiconductor light emitting element mounting substrate on which a semiconductor light emitting element is mounted, and the semiconductor light emitting element mounting substrate penetrates at both ends. A semiconductor light emitting device having a fixing hole made of a hole, and a plurality of semiconductor light emitting device groups made of the semiconductor light emitting devices mounted on a line segment connecting the fixing holes by solder bonding, and positioned at both ends of the semiconductor light emitting device group A pair of stress release holes including through holes are provided on the line segment between the element and the fixed hole located on each end side.

  According to a second aspect of the present invention, in the first aspect, the stress release hole is a rectangle that is long in a direction orthogonal to a direction in which the semiconductor light emitting element group is mounted, or the semiconductor light emitting element group. The central portion in the direction orthogonal to the direction in which the is mounted has a drum shape recessed inward.

  According to a third aspect of the present invention, in the second aspect, the width of the rectangle and the width of the recessed portion of the central portion of the drum shape are both the semiconductor light emitting element of the semiconductor light emitting element. The length of the element group is equal to or shorter than the direction perpendicular to the direction in which the element group is mounted.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the stress relief holes are formed by fixing the semiconductor light emitting elements located at both ends of the semiconductor light emitting element group and the fixing. It is provided at a position away from the vicinity of an intermediate position with respect to the hole in either direction of the semiconductor light emitting element side or the fixed hole side.

  According to the present invention, a semiconductor light-emitting element mounting formed by mounting a semiconductor light-emitting element group composed of a plurality of semiconductor light-emitting elements on a line segment connecting fixed holes provided at both ends of a semiconductor light-emitting element mounting substrate by solder bonding. In the substrate, a pair of stress release holes are provided on the line segment between the semiconductor light emitting elements located at both ends of the semiconductor light emitting element group and the fixing holes located at the respective end parts.

  As a result, the high bonding strength of the semiconductor light emitting element with respect to the semiconductor light emitting element mounting substrate is maintained, and excellent mounting reliability can be ensured.

It is explanatory drawing of the light emitting element mounting board | substrate used for the optimization of the external dimension of a stress release hole. It is the A section enlarged view of FIG. It is explanatory drawing of 1st Example of a stress relief | release hole. Similarly, it is explanatory drawing of 2nd Example of a stress relief | release hole. Similarly, it is explanatory drawing of 3rd Example of a stress relief | release hole. Similarly, it is explanatory drawing of 4th Example of a stress release hole. Similarly, it is explanatory drawing of 5th Example of a stress release hole. Similarly, it is explanatory drawing of 6th Example of a stress release hole. It is a graph of the relative stress added to a light emitting element. Similarly, it is a graph of the relative stress added to a light emitting element. It is explanatory drawing of 7th Example of a stress release hole. Similarly, it is explanatory drawing of 8th Example of a stress relief | release hole. It is a graph of the relative stress added to a light emitting element. It is explanatory drawing of the light emitting element mounting substrate used for optimization of the arrangement | positioning position of a stress release hole. It is a graph which shows the relationship between the position of a stress release hole, and the stress added to a light emitting element. It is explanatory drawing of a prior art example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 15 (the same reference numerals are given to the same portions). 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.

  As shown in FIG. 1, the inventor has fixing through holes (fixing holes) 2 at both ends, and is provided along the line segment L at the center on the line segment L connecting both the fixing holes 2. In the substrate 1 having a plurality of die bonding pads 3, die bonding pads 3 a located at both ends of the die bonding pad group 4 composed of the plurality of die bonding pads 3, and fixing holes 2 located at the respective end portions A pair of stress release through holes (stress release holes) 10 are provided on the line segment L between the two, and as shown in FIG. 2, a plurality of solder joints mounted on adjacent die bonding pads 3 are mounted. It is confirmed that stress applied to the light emitting element 5 caused by heat generation during light emission (lighting) of the light emitting element group 6 including the semiconductor light emitting elements (hereinafter, simply referred to as “light emitting elements”) 5 is relieved by the stress release holes 10. It was optimized geometry of the stress releasing hole 10 by the stress simulation thereon.

  In the simulation of the shape and size of the stress relief hole 10, first, the basic shape of the stress relief hole 10 was made rectangular, and a plurality of stress relief holes having different dimensions were set. In the following, “width” and “height” used in the description of each of the light emitting element and the stress relief hole are “dimension corresponding to the direction in which the light emitting element group is mounted” and “the light emitting element group is mounted, respectively”. Dimension corresponding to the direction orthogonal to the direction indicated.

  The rectangular stress relief hole thus set has a vertically long shape in which the width a is 1/4 (0.25 times) the height d of the light emitting element 5 and the height b is twice the height d of the light emitting element 5. First Embodiment 11 (see FIG. 3), a second embodiment 12 having a horizontally long shape in which the width a is the height d of the light-emitting element 5 and the height b is ½ of the height d of the light-emitting element 5. 4), a third embodiment 13 (see FIG. 5) having a vertically long shape in which the width a is the height d of the light-emitting element 5 and the height b is twice the height d of the light-emitting element 5. A vertically long fourth embodiment 14 (see FIG. 6) in which the height d of the light-emitting element 5 is set to 4 times the height d of the light-emitting element 5, and the width a is set to the height d of the light-emitting element 5. The vertically elongated fifth embodiment 15 (see FIG. 7) in which the height b is 5.25 times the height d of the light emitting element 5, and the width a is twice the height d of the light emitting element 5, The height b is twice the height d of the light emitting element 5 That was the sixth six EXAMPLE 16 (see FIG. 8) of the square.

  In addition, the board | substrate which does not provide a stress relief | release hole was set as the comparative example 20. FIG.

  Therefore, first, regarding the relationship between the width a of each stress release hole and the stress relaxation, the height b (twice the height d of the light emitting element 5) is the same and only the width a is different, the first embodiment 11, The stress was calculated for the third example 13, the sixth example 16, and the comparative example 20. FIG. 9 shows the calculation result on a graph.

  In the graph of FIG. 9, the horizontal axis represents the ratio a / d of the width a of the stress release hole to the height d of the light emitting elements, and the vertical axis represents the maximum stress applied to the light emitting elements when all the light emitting elements are turned on. The ratio is expressed as a ratio (%) when the comparative example having no stress release hole is taken as 100%.

  From FIG. 9, the ratio of the maximum stress [652 MPa] applied to the light emitting device of the first example to the maximum stress [711 MPa] applied to the light emitting device of the comparative example is 91.7%, which is applied to the light emitting device of the third example. The ratio of the maximum stress [642 MPa] is 90.3%, and the ratio of the maximum stress [697 MPa] applied to the light emitting device of the sixth example is 98.0%.

  From this, it was found that the width a of the stress release hole having the greatest stress relaxation effect is the same as the height d of the light emitting element as in the third embodiment.

  Therefore, next, the relationship between the stress relief hole height b and the stress relaxation when the stress relief hole width a is the same as the light emitting element height d obtained as a suitable width in the above stress simulation. The stress was calculated for the second example, the third example, the fourth example, the fifth example, and the comparative example, in which the width a is the same as the height d of the light emitting element and only the height b is different. FIG. 10 shows the calculation result on the graph.

  In the graph of FIG. 10, the horizontal axis represents the ratio b / d of the height b of the stress release hole to the height d of the light emitting elements, and the vertical axis represents the maximum stress applied to the light emitting elements when all the light emitting elements are turned on. Is expressed as a ratio (%) when the comparative example having no stress release holes is taken as 100%.

  From FIG. 10, the ratio of the maximum stress [680 MPa] applied to the light emitting device of the second example to the maximum stress [711 MPa] applied to the light emitting device of the comparative example is 95.6%, which is applied to the light emitting device of the third example. The ratio of the maximum stress [642 MPa] is 90.3%, the ratio of the maximum stress [610 MPa] applied to the light emitting device of the fourth embodiment is 85.8%, and the maximum stress applied to the light emitting device of the fifth embodiment. The ratio of [569 MPa] is 80.0%.

  From this, when the width a of the stress relief hole is made equal to the height d of the light emitting element, the height b of the stress relief hole having the greatest stress relaxation effect is at least the height b of the light emitting element. In the range of 5.25 times d, the higher the effect, the greater the effect.

  Therefore, from the result of the stress simulation described above, the rectangular stress release hole has a width a equal to the height d of the light emitting element and a height b at least in the range of 5.25 times the height d of the light emitting element. The higher the value, the greater the effect.

  Next, based on the simulation results, the seventh embodiment and the eighth embodiment partially have a portion having a width a (the same value as the height d of the light emitting element) obtained by the simulation. Stress simulation was also performed on a stress release hole having a shape other than a rectangle (for example, a drum shape with a central portion in the height direction recessed inward as shown in FIGS. 11 and 12).

From FIG. 11, the seventh embodiment 17 has a height b that is twice the height d of the light emitting element 5, a width a ₁ at the upper end and the lower end that is twice the height d of the light emitting element, and a central portion. The width a ₂ of the recessed portion is the same as the height d of the light emitting element, and the eighth embodiment 18 shows that the height b is four times the height d of the light emitting element from FIG. The width a ₁ was set to be twice the height d of the light emitting element, and the width a ₂ of the recessed portion at the center was the same as the height d of the light emitting element.

The graph of FIG. 13 shows a sixth example of a square in which the width a is twice the height d of the light emitting element 5 and the height b is twice the height d of the light emitting element 5, and the width a is the light emitting element 5. The height d of the light emitting element 5 and the height b of the light emitting element 5 is twice as long as the height d of the light emitting element 5, the width a is the height d of the light emitting element 5, and the height b is Fourth embodiment of a vertically long shape having a height four times the height d, the height b is twice the height d of the light emitting element 5, and the width a ₁ of the upper end portion and the lower end portion is the height d of the light emitting element 5. seventh embodiment of the width a ₂ of recessed portion of the central portion and the same as the height d of the light emitting element 5 with a 2-fold, and the height b and 4 times the height d of the light emitting element 5, the upper end In the eighth embodiment, the width a ₁ of the center portion and the lower end portion is twice the height d of the light emitting element 5, and the width a ₂ of the recessed portion in the center is the same as the height d of the light emitting element 5. When all the light emitting elements are turned on, The maximum stress applied to the light emitting element is expressed as a ratio (%) when the maximum stress applied to the sixth embodiment is 100%.

  From FIG. 13, in contrast to the sixth embodiment in which the width a of the stress release hole is twice the height d of the light emitting element, the entire portion where the width a of the stress release hole is the same as the height d of the light emitting element is shown. The third embodiment, the fourth embodiment, the seventh embodiment, and the eighth embodiment, which are intended or partially included, show that the stress relaxation effect is more effectively exhibited.

Further, each of the third embodiment of the rectangle having the same width a as the height d of the light emitting element, and the height b of the light emitting element, each of which makes the height b of the stress relief hole twice the height d of the light emitting element. the drum-shaped seventh embodiment having the recess of the same width a ₂ and d, it can be seen that substantially the same degree of stress relaxation effect can be obtained.

Similarly, the fourth embodiment in which each of the heights b of the stress relief holes is four times the height d of the light emitting element and has the same width a as the height d of the light emitting element, and the height of the light emitting element is the drum-shaped eighth embodiment having the recess of the same width a ₂ and d, it can be seen that substantially the same degree of stress relaxation effect can be obtained.

  At the same time, it can be seen that the fourth embodiment and the eighth embodiment, in which the height b of the stress release hole is higher, have a higher stress relaxation effect than the third embodiment and the seventh embodiment.

  This result shows that the height b of the stress release hole, which is preferable obtained by the simulation, is higher as long as the height b is at least 5.25 times the height d of the light emitting element. This is in line with the result that the effect is great.

From the above, if the height b of the stress releasing holes are the same, has a rectangular stress releasing hole having the same width a as the height d of the light-emitting element, the same width a ₂ height d of the light-emitting element recesses Even if the shape is different from the drum-shaped stress release hole, it is possible to obtain almost the same stress relaxation effect.

  Further, in any of the stress release holes (rectangle and drum shape), the stress relaxation effect increases as the height b increases.

By the way, the suitable position which provides a stress release hole was also calculated by stress simulation.
As the simulation conditions, as shown in FIG. 14, the stress release hole 10 has a vertically long shape in which the width a is the height d of the light emitting element 5 and the height b is twice the height d of the light emitting element. As a third embodiment, a light emitting element group 6 composed of a plurality of light emitting elements 5 is mounted on a line segment L between fixed holes 2 provided at both ends of the substrate 1, and light emission located at both ends of the light emitting element group 6 is achieved. A pair of stress release holes 10 are provided on the line segment L between the element 5a and the fixing hole 2 located on each end side.

  The distance from the center of the light emitting element 5a located at both ends of the light emitting element group 6 to the center of the stress releasing hole 10 is f, and the distance from the center of the stress releasing hole 10 to the center of the fixing hole 2 is e. .

  The result of the stress simulation is shown in FIG.

  FIG. 15 shows the center of the light emitting element 5a located at both ends of the light emitting element group 6 at a distance f from the center of the light emitting element 5a located at both ends of the light emitting element group 6 to the center of the stress relief hole. Represents the ratio (f / (e + f)) to the distance (e + f) from the center of the fixing hole 2 to the center of the fixing hole 2, and the vertical axis represents the maximum stress [MPa] applied to the light emitting element.

  From FIG. 15, (f / (e + f)) is 0.25, that is, the distance from the center of the light emitting element 5a located at both ends of the light emitting element group 6 to the stress release hole is the both ends of the light emitting element group 6. When the distance from the center of the light emitting element 5a located at the center to the center of the fixing hole 2 is 1/4, the maximum stress applied to the light emitting element is 637 [MPa], and (f / (e + f)) is 0. .5, that is, the distance from the center of the light emitting element 5a located at both ends of the light emitting element group 6 to the stress releasing hole is the center of the light emitting element 5a located at both ends of the light emitting element group 6 The maximum stress applied to the light emitting element is 645 [MPa], and (f / (e + f)) is 0.75, that is, located at both ends of the light emitting element group 6. The distance from the center of the light emitting element 5a to the stress release hole is such that the light emitting element 5a located at both ends of the light emitting element group 6 In the case of 3/4 of the distance from the center to the center of the fixed hole, the maximum stress applied to the light emitting element is 642 [MPa].

  Therefore, when the asymptotic line N is drawn, the range in which the stress relaxation effect is the smallest (near the apex of the asymptotic line) is near the intermediate position between the light emitting elements 5a located at both ends of the light emitting element group 6 and the fixing hole 2. It is shown that.

  Therefore, an effective position of the stress release hole provided for stress relaxation is from the vicinity of the intermediate position between the light emitting element 5a and the fixing hole 2 located at both ends of the light emitting element group 6 to the light emitting element 5a side or the fixing hole 2 side. It can be seen that a position apart in either direction is effective.

  From the above simulation results, the stress release hole may be linear or drum-shaped, so that, for example, any shape other than the example such as a round hole and a rhombus hole may be formed between the light emitting element both ends and the fixed hole. It can be said that the stress relaxation occurs when the stress release hole of the shape is formed, as compared with the case without the stress release hole. Even if the fixing hole and both ends of the light emitting element are not horizontally positioned, for example, even if the fixing hole and the light emitting element are shifted in the vertical direction, a stress release hole is formed between the both ends of the light emitting element and the fixing hole. In this case, it can be said that stress relaxation occurs compared to the case without the stress release hole.

  As described above, in the light emitting element mounting substrate on which the light emitting element is solder-mounted, the stress releasing hole is provided in order to suppress the stress on the substrate caused by the heat generated when the light emitting element emits light, and the shape dimension of the stress releasing hole and By applying the calculation result obtained by the stress simulation to the arrangement position, the high bonding strength of the light emitting element with respect to the light emitting element mounting substrate is maintained, and excellent mounting reliability can be ensured.

1 ... Substrate 2 ... Through hole (fixed hole)
DESCRIPTION OF SYMBOLS 3 ... Die bonding pad 3a ... Die bonding pad 4 ... Die bonding pad group 5 ... Semiconductor light emitting element (light emitting element)
5a ... Light emitting element 6 ... Light emitting element group 10 ... Through hole (stress release hole)
11 ... 1st Example 12 ... 2nd Example 13 ... 3rd Example 14 ... 4th Example 15 ... 5th Example 16 ... 6th Example 17 ... 7th Example 18 ... 8th Example 20 ... Comparative example

Claims (4)

A semiconductor light emitting element mounting substrate for mounting a semiconductor light emitting element,
The semiconductor light emitting element mounting substrate has a fixing hole made of a through hole at both ends, and a semiconductor light emitting element group made of a plurality of the semiconductor light emitting elements is mounted by solder bonding on a line segment connecting the fixing hole,
A pair of stress release holes including through holes is provided on the line segment between the semiconductor light emitting elements located at both ends of the semiconductor light emitting element group and the fixing holes located at the respective end parts. A substrate for mounting a semiconductor light emitting device.   The stress release hole has a rectangular shape that is long in a direction orthogonal to the direction in which the semiconductor light emitting element group is mounted, or a drum shape in which a central portion in a direction orthogonal to the direction in which the semiconductor light emitting element group is mounted is recessed inward. The substrate for mounting a semiconductor light emitting element according to claim 1, comprising:   Both the width of the rectangle and the width of the recessed portion of the central portion of the drum shape are equal to or less than the length of the semiconductor light emitting element in the direction orthogonal to the direction in which the semiconductor light emitting element group is mounted. The substrate for mounting a semiconductor light emitting element according to claim 2.   The stress release hole is located at a position away from the vicinity of an intermediate position between the semiconductor light emitting element located at both ends of the semiconductor light emitting element group and the fixing hole in either the semiconductor light emitting element side or the fixing hole side. The semiconductor light-emitting element mounting substrate according to claim 1, wherein the substrate is mounted.