JP7113608B2 - LED module - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED module in which wiring of a circuit board on which a plurality of LEDs are mounted is straddled by a resistor or the like.

On a printed circuit board with various electronic components mounted on it, in order to prevent the two wires from short-circuiting, surface-mounted resistors (hereafter referred to as "jumper resistors") are used, and one wire may straddle the other wire. . Similarly, even in a circuit board for an LED module on which a large number of LEDs are mounted, has high heat dissipation, and wiring is provided only on the light emitting surface side, the wiring may be straddled with a jumper resistor (for example, in Patent Document 1 Figure 2).

Japanese Patent Application Laid-Open No. 2017-130496 (Fig. 2)

Since the circuit board of the LED module becomes hot due to the heat generated by the LED, operating conditions tend to be more severe than those of a normal printed circuit board. Under such circumstances, when an LED module equipped with a jumper resistor was subjected to a temperature cycle test, cracks appeared in the solder joints of the jumper resistor, resulting in non-lighting.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an LED module that is less likely to fail to light even if cracks occur in solder joints of some jumper resistors.

In order to achieve the above object, the LED module of the present invention comprises: an LED row in which a plurality of LEDs are connected in series; wiring connecting the plurality of LEDs in the LED row and having both ends connected to power supply terminals; a pair of jumper resistors inserted between two adjacent LEDs in an LED row and connected in parallel, each of the pair of jumper resistors being formed in a rectangular shape and having its longitudinal direction perpendicular to each other ; It is characterized in that it is arranged across the wiring .

A plurality of LEDs are mounted on the upper surface of the circuit board included in the LED module of the present invention. Each LED is connected to wiring formed on the upper surface of the circuit board. Further, a first jumper resistor and a second jumper resistor are mounted on the upper surface of this circuit board. The first jumper resistor and the second jumper resistor are connected in parallel, straddle one wiring, and have their longitudinal directions perpendicular to each other when viewed from above.

When the coefficient of thermal expansion is different between the vertical direction and the horizontal direction of the circuit board, for example, the longitudinal direction of the first jumper resistor is parallel to the direction with the small thermal expansion coefficient, and the longitudinal direction of the second jumper resistor has the large thermal expansion coefficient. Assuming that it is parallel to the direction, when thermal expansion and thermal contraction are repeated as in a temperature cycle test, cracks are more likely to occur in the solder joints of the second jumper resistor than the first jumper resistor. In other words, in a temperature cycle test or the like, even if connection failure occurs in the second jumper resistor, a state in which connection failure does not occur in the first jumper resistor occurs.

The circuit board may be made of metal or ceramic.

The circuit board may have a wiring having a one-layer structure formed on the upper surface thereof.

The plurality of LEDs may comprise a first LED row and a second LED row not electrically connected to the first LED row.

The first LED row and the second LED row may have different emission colors.

In the LED module of the present invention, when the coefficient of thermal expansion of the circuit board is different in the vertical direction and the horizontal direction, as a result of repeated thermal expansion and thermal contraction, one of the two jumper resistors connected in parallel and arranged orthogonally Even if only one connection of the jumper is cracked, there is a high probability that the connection of the other jumper will not fail. Therefore, the LED module of the present invention is less likely to turn off even if thermal expansion and thermal contraction are repeated.

1 is a plan view of an LED module shown as an embodiment of the present invention; FIG. FIG. 2 is a plan view of a circuit board included in the LED module shown in FIG. 1; 2 is a circuit diagram of the LED module shown in FIG. 1; FIG. 2 is a plan view of an LED included in the LED module shown in FIG. 1; FIG. 5 is a cross-sectional view of the LED shown in FIG. 4; FIG. FIG. 4 is a plan view of an LED module shown as a comparative example;

Preferred embodiments of the present invention will now be described in detail with reference to FIGS. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and overlapping descriptions are omitted. ( ) indicates matters specifying the invention described in the claims.

FIG. 1 is a plan view of an LED module 10 shown as an embodiment of the invention. On the circuit board 11 included in the LED module 10, there are eight LEDs 12, eight LEDs 13, jumper resistors 14a (first jumper resistor), 14b (second jumper resistor), 15a ( third jumper resistor), 15b. ( fourth jumper resistor) is mounted. Further, on the circuit board 11, connection electrodes 12a, 12b, 13a, 13b, power supply electrodes 16a, 16b, 17a, 17b, and wiring 18 are formed as electrode patterns.

Before detailed description of FIG. 1, the electrode pattern and circuit of the circuit board 11 and the LEDs 12 and 13 included in the LED module 10 will be described with reference to FIGS.

FIG. 2 is a plan view of the circuit board 11 included in the LED module 10 shown in FIG. Square power supply electrodes 16 a , 16 b , 17 a and 17 b are formed on the periphery of the circuit board 11 . Connection electrodes 12a and 13a connected to the anodes of the LEDs 12 and 13 (see FIG. 1) and connection electrodes 12b and 13b connected to the cathodes of the LEDs 12 and 13 are formed in the central portion. The connection electrodes 12a, 12b are rectangular, paired and arranged in parallel. Similarly, the connection electrodes 13a and 13b are also rectangular, paired, and arranged in parallel.

FIG. 3 is a circuit diagram of the LED module 10. As shown in FIG. In the figure, (a) shows an LED row 16 (first LED row) in which eight LEDs 12 are connected in series, and (b) shows an LED row 17 (second LED row) in which eight LEDs 13 are connected in series. ing. In the first LED row 16, the anode of the LED 12 in the first stage is connected to the power terminal 16a, and the cathode of the LED 12 in the last stage is connected to the power terminal 16b. A first jumper resistor 14a and a second jumper resistor 14b connected in parallel are inserted between the LED 12 in the seventh stage and the LED 12 in the eighth stage. Similarly, in the second LED row 17, the anode of the LED 13 in the first stage is connected to the power terminal 17a, and the cathode of the LED 13 in the last stage is connected to the power terminal 17b. A third jumper resistor 15a and a fourth jumper resistor 15b connected in parallel are inserted between the LED 13 in the fourth stage and the LED 13 in the fifth stage.

The first jumper resistor 14a and the second jumper resistor 14b are surface-mounted resistors having terminals at both ends, and may be 0Ω (with negligible resistance) if used only as wiring. When the first jumper resistor 14a and the second jumper resistor 14b are used to limit the current, even if a connection failure occurs in one of the jumper resistors (for example, the second jumper resistor 14b), the LED 12 only becomes dark and does not light up. Otherwise, you can see that it is broken. The same applies to the third jumper resistor 15a and the fourth jumper resistor 15b.

FIG. 4 is a plan view of the LED 12 included in the LED module 10. FIG. As shown in FIG. 4, when the LED 12 is viewed from above, a square sealing resin 41 and a frame-shaped white reflective resin 42 surrounding the sealing resin 41 are observed. The sealing resin 41 is a silicon resin containing phosphor, and the white reflective resin 42 is a silicon resin containing titanium oxide particles. In addition, in FIG. 4, for reference, the anode 12c and the cathode 12d formed on the back surface of the LED 12 are drawn with broken tips. Since the LED 13 differs from the LED 12 only in the phosphor contained in the sealing resin 41, the corresponding members are shown in parentheses in the drawing.

FIG. 5 is a cross-sectional view of the LED 12 taken along line AA' in FIG. As shown in FIG. 5, the LED 12 has an LED die 43 mounted on the upper surface of a submount substrate 44, and an anode 12c and a cathode 12d, which are projecting electrodes, formed on the lower surface. A sealing resin 41 covers the top surface of the submount substrate 44 and the LED die 43 , and the white reflective resin 42 surrounds the sealing resin 41 . As for the cross-sectional view, since the LED 13 differs from the LED 12 only in the phosphor contained in the sealing resin 41, the corresponding members and the like are shown in parentheses in the drawing.

As described above, the LEDs 12 and 13 differ only in the phosphor contained in the sealing resin 41 . The LED 12 wavelength-converts part of the blue light emitted by the LED die 43 and emits light in a warm color (approximately 2000 K° to 3000 K°). The LED 13 wavelength-converts part of the blue light emitted by the LED die 43 and emits light in a cool color (generally above 5000 K°).

Returning to FIG. 2 again, the electrode pattern formed on the upper surface of the circuit board 11 will be described. As described with reference to FIG. 3, eight LEDs 12 are connected in series on the circuit board 11 . Correspondingly, in FIG. 2 as well, the connection electrode 12a connected to the anode 12c of the LED 12 in the first stage is connected to the power supply electrode 16a via the wiring 18, and the connection electrode 12b connected to the cathode 12d of the LED 12 in the final stage is connected to , are connected to the power supply electrode 16b via the wiring 18. FIG. Similarly, the connection electrode 13a to which the anode 13c of the LED 13 in the first stage is connected is connected to the power supply electrode 17a via the wiring 18, and the connection electrode 13b to which the cathode 13d of the LED 13 in the final stage is connected is connected to the power supply via the wiring 18. It is connected to electrode 17b.

In the portion where the LEDs 12 are connected in series (the portion constituting the first LED row 16 in FIG. 3), in principle, the connection electrode 12b to which the cathode 12d of one LED 12 is connected through the wiring 18 is connected to the LED 12 in the next stage. is connected to the connection electrode 12a to which the anode 12c of is connected. However, corresponding to FIG. 3A, even on the circuit board 11, the connection electrode 12b connected to the cathode 12d of the LED 12 on the sixth stage is connected to the connection electrode 12a connected to the anode 12c of the LED 12 on the seventh stage. 1 jumper resistor 14a and 2nd jumper resistor 14b are connected. That is, a first jumper resistor 14a and a second jumper resistor 14b are mounted between the connection electrode 12b connected to the cathode 12d of the sixth LED 12 and the connection electrode 12a connected to the anode 12c of the seventh LED 12. lands 14c, 14d, 14e and 14f are formed.

Similarly, in the portion where the LEDs 13 are connected in series (the portion constituting the second LED row 17 in FIG. 3), in principle, the connection electrode 13b to which the cathode 13d of one LED 13 is connected via the wiring 18 is connected to the following It is connected to the connection electrode 13a to which the anode 13c of the LED 13 in the row is connected. However, corresponding to FIG. 3B, even on the circuit board 11, the connection electrode 13b connected to the cathode 13d of the LED 13 on the fourth stage is connected to the connection electrode 13a connected to the anode 13c of the LED 13 on the fifth stage. 3 jumper resistor 15a and 4th jumper resistor 15b are used for connection. That is, between the connection electrode 13b connected to the cathode 13d of the fourth LED 13 and the connection electrode 13a connected to the anode 13c of the fifth LED 13, the third jumper resistor 15a and the fourth jumper resistor 15b are mounted. lands 15c, 15d, 15e and 15f are formed.

Returning to FIG. 1 again, the LED module 10 will be described in more detail. The circuit board 11 included in the LED module 10 is based on Al and has an insulating layer on its upper surface. As the insulating layer, there are a layer having an oxidized Al surface, a layer having a printed insulating member, and a layer having a thin resin substrate attached. In the center of the circuit board 11, the LEDs 12 emitting warm color light and the LEDs 13 emitting cold color light are arranged in a checkered pattern. The wiring 18 is formed in a single layer structure on the upper surface of the circuit board 11 .

When trying to connect the LEDs 12 and 13 in series (see FIG. 3) while forming a checkered pattern, since the wiring has a single-layer structure, the wiring 18 of the series circuit consisting of the LEDs 12 and the wiring 18 consisting of the LEDs 13 are connected. crosses. Therefore, in the LED module 10, jumper parts ( first jumper resistor 14a, second jumper resistor 14b, third jumper resistor 15a, fourth jumper resistor 15b) are arranged at two locations on the surface of the circuit board 11, and wiring 18 avoids the crossing of That is, the first jumper resistor 14a and the second jumper resistor 14b straddle the wiring 18 constituting the series circuit ( the second LED row 17 in FIG. 3B) composed of the LEDs 13, and the third jumper resistor 15a and the fourth jumper The resistor 15b straddles the wiring 18 forming the series circuit ( the first LED row 16 in FIG. 3A) composed of the LEDs 12 .

At this time, the first jumper resistor 14a and the second jumper resistor 14b forming the series circuit of the LED 12 are connected in parallel, and their longitudinal directions are perpendicular to each other when viewed from above. Similarly, the third jumper resistor 15a and the fourth jumper resistor 15b forming a series circuit of the LED 13 are connected in parallel and their longitudinal directions are perpendicular to each other when viewed from above.

For example, if the coefficient of thermal expansion in the vertical direction of the circuit board 11 (in FIG. 1, the direction diagonally upward to the right) is smaller than the coefficient of thermal expansion in the lateral direction (the direction diagonally upward to the left in FIG. 1), the first jumper resistor 14a, the longitudinal direction of the third jumper resistor 15a is parallel to the direction of small thermal expansion coefficient, and the longitudinal direction of the second jumper resistor 14b, fourth jumper resistor 15b is parallel to the direction of large thermal expansion coefficient. As a result, even if the LED module 10 is subjected to a temperature cycle test, the solder joints between the first jumper resistor 14a, the third jumper resistor 15a and the circuit board 11 are less likely to crack. That is, even if connection failure occurs in the second jumper resistor 14b and the fourth jumper resistor 15b in the temperature cycle test, the first jumper resistor 14a and the third jumper resistor 15a can maintain a state in which poor connection is unlikely to occur. . Therefore, the LED module 10 is unlikely to lead to a fatal situation of non-lighting even in a severe environment where thermal expansion and thermal contraction are repeated.

For comparison, FIG. 6 shows an LED module 60 with jumper resistors only in the high coefficient of thermal expansion direction. FIG. 6 is a plan view of an LED module 60 shown as a comparative example. The LED module 60 has one fifth jumper resistor 64 as a jumper component forming a series circuit of the LEDs 12, and one sixth jumper resistor 65 as a jumper component forming a series circuit of the LEDs 13. It has the same structure as the LED module 10 except for the above.

Also in the LED module 60, as in the case described above, the circuit board 11 has a large coefficient of thermal expansion in the horizontal direction (in FIG. 6, the direction diagonally upward to the left). At this time, the longitudinal directions of the fifth jumper resistor 64 and the sixth jumper resistor 65 are parallel to the direction in which the coefficient of thermal expansion is large. That is, when the LED module 60 is subjected to the temperature cycle test, cracks occur in the solder joints between the fifth jumper resistor 64 and the sixth jumper resistor 65 and the circuit board 11 due to the large coefficient of thermal expansion in the longitudinal direction. easier. That is, compared with the LED module 10, the LED module 60 does not have bypass means ( the first jumper resistor 14a and the third jumper resistor 15a parallel to the direction in which the coefficient of thermal expansion is small), so non-lighting is more likely to occur in the temperature cycle test.

As described above, since the LED module 10 is provided with the first jumper resistor 14a and the third jumper resistor 15a parallel to the direction of the small thermal expansion coefficient as a detour means, the LED module 60 is more susceptible to temperature cycle tests than the LED module 60. Fatal connection failure is less likely to occur in a harsh environment where thermal expansion and contraction are repeated. In other words, since the magnitude relationship of the coefficient of thermal expansion according to the direction is usually not clarified (not managed), in the LED module 10, at least one of the first jumper resistor 14a or the second jumper resistor 14b has a connection failure. The first jumper resistor 14a and the second jumper resistor 14b are arranged orthogonally in order to prevent the occurrence of

In addition, in the LED module 10, the circuit board 11 is a metal base, and the coefficient of thermal expansion varies depending on the extending direction. Generally, however, the circuit board included in the LED module does not necessarily have to be a metal base as long as it has high thermal conductivity. For example, the substrate material may be ceramics. As with metal bases, circuit boards made of ceramics are also difficult to form through holes, so jumper parts (resistors) are effective. That is, when the coefficient of thermal expansion is different between the vertical direction and the horizontal direction of the circuit board made of ceramics as in the case of the circuit board 11, by connecting the jumper resistors in parallel and arranging them orthogonally, it is possible to prevent non-lighting as in the case of the LED module 10. becomes possible.

Also, in principle, jumper resistors can be eliminated by using multilayer wiring technology. Similarly, it is also possible to form through holes in the base portion made of metal or ceramics. Even with such techniques, jumper resistors may be required depending on the specific design. However, when a single-layer wiring is provided only on one surface like the circuit board 11, the structure of the circuit board 11 and its manufacturing process are significantly simplified. In other words, the significance of applying the present invention to the circuit board 11 having such a configuration increases.

Further, even if the LED module of the present invention has only one LED row, a jumper resistor may be required when a driving circuit or the like is mounted on the circuit board. In this case, too, if a pair of jumper resistors are connected in parallel and crossed, it is possible to prevent non-lighting. On the other hand, the LED module 10 is provided with a toning function in addition to measures against non-lighting. That is, in the LED module 10, the LEDs 12 that emit warm colors constitute the first LED row 16, the LEDs 13 that emit cold colors constitute the second LED row 17, and the LEDs 12 and 13 are arranged in a checkered pattern. , jumper resistors, etc. With this structure, the LED module 10 can adjust the emission color by adjusting the emission intensity of the first LED row 16 and the second LED row 17, and can improve the color mixing property at this time.

10, 60...LED module,
11... circuit board,
12, 13... LEDs,
12a, 12b, 13a, 13b... connection electrodes,
12c, 13c... anode,
12d, 13d... cathode,
14a ... first jumper resistor,
14b ... second jumper resistor,
15a... third jumper resistor,
15b... fourth jumper resistor ,
14c to 14f, 15c to 15f... land,
16 ... the first LED row,
17 ... second LED row ,
16a, 16b, 17a, 17b... power electrodes,
41 ... sealing resin,
42... White reflective resin,
43 LED die,
44... submount substrate,
64 ... fifth jumper resistor,
65... Sixth jumper resistor .

Claims (5)

an LED row in which a plurality of LEDs are connected in series;
a wiring that connects between the plurality of LEDs in the LED row and has both ends connected to power supply terminals;
a pair of jumper resistors inserted between two adjacent LEDs in the LED row and connected in parallel;
In the LED module, the pair of jumper resistors are each formed in a rectangular shape, and arranged across the wiring so that their longitudinal directions are orthogonal to each other. 2. The LED module according to claim 1, wherein the plurality of LEDs are mounted on a circuit board having the wiring formed thereon, and the circuit board is made of metal or ceramic. 3. The LED module according to claim 2, wherein the wiring having a one-layer structure is formed on the upper surface of the circuit board. the LED array comprises a first LED array and a second LED array that are not electrically connected to each other;
The pair of jumper resistors includes a first jumper resistor and a second jumper resistor inserted between two adjacent LEDs in the first LED row, and a third jumper resistor inserted between two adjacent LEDs in the second LED row. a jumper resistor and a fourth jumper resistor;
The first jumper resistor and the second jumper resistor are arranged across the wiring connecting the second LED row, and the third jumper resistor and the fourth jumper resistor are arranged across the wiring connecting the first LED row. 2. The LED module according to claim 1, wherein the LED module is arranged at . 5. The LED module according to claim 4, wherein the first LED row and the second LED row have different emission colors.

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