JP2511717B2 - LED module - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an LED (light emitting diode) module used for a high mount stop lamp, a tail lamp, etc. of an automobile, or a light source for a bar code reader, an LED display, etc. It is a thing.

(Prior art and problem to be solved) Attach electric lead and small reflector to LED chip,
So-called resin-molded LEDs that are resin-molded with these
Since the LED module in which a large number of the above are arranged on the board is troublesome to manufacture and costly, the inventors of the present invention have proposed, for example, a metal substrate layer made of aluminum, an insulating layer thereover, and electrodes provided thereon. A large number of dents are provided on an insulating metal substrate consisting of a circuit pattern, an LED chip is installed on the bottom of the dent, and the side wall surface of the dent is used as a reflecting surface, and the front surface of the insulating metal plate is made of, for example, epoxy resin. LE with a lens plate equipped with a lens so that the lens position corresponds to the LED chip position, suitable for mass production and low cost
A D module was proposed in Japanese Patent Application No. 62-328018.

The present invention relates to an improvement of this LED module.

In the above LED module, the difference in the coefficient of thermal expansion between the metal substrate layer of the insulating metal substrate and the lens plate made of epoxy resin or the like is large, and the thickness of the metal substrate layer is provided with a depression (usually a squeezing process) It is usually chosen to be relatively thin to facilitate
It is about 1 mm, and the lens plate is thicker than this, for example, 1.9 mm in the non-lens part and 4.0 mm in the lens part, so the expansion coefficient and the contraction force of the lens plate have a large expansion coefficient when the temperature of the module rises or falls. Insulated metal substrate bends, LED
The entire module is deformed, its light emission pattern is changed,
Getting worse. Also, during repeated bending due to temperature cycling, the adhesion between the lens plate and the insulating substrate may peel off,
In some cases, the bonding wire that connects the electrode and the electrode circuit pattern is rubbed under the lens plate to cut the bonding wire.

The present invention aims to eliminate these disadvantages.

(Means for Solving the Problems) The LED module of the present invention is an insulating metal substrate 1 in which an electric insulating layer 3 and an electrode pattern 4 are sequentially provided on a metal substrate layer 2.
A concave portion 7 is formed leaving the peripheral edge portion 6 in the bottom, a large number of depressions 8 are provided at the bottom thereof, and an LED 11 is provided at the bottom of the depression 8,
The side wall surface 10 of the recess 8 is used as a reflecting surface, and the lens plate 16 is coupled to the front surface of the insulating metal substrate 1.
Is composed of a plurality of lenses 17 positioned so as to correspond to the central positions of the LEDs 11, respectively, and a non-lens portion having a thickness larger than that of the metal substrate layer 2 of the insulating metal substrate 1, and the lens plate 16 further includes Is directly bonded to the peripheral edge portion 6 of the insulating metal substrate 1.

(Function) In the present invention, since the bending resistance of the insulating metal substrate is improved by forming the concave portion in the insulating metal substrate, the bending of the insulating metal substrate due to the expansion and contraction of the lens plate when the temperature rises or falls is prevented. Therefore, the radiated light pattern does not change due to the bending deformation of the module and is not deteriorated. There is no fear of peeling the adhesion between the lens plate and the insulating metal substrate or cutting the bonding wire due to repeated bending.

(Example) The structure and example of the LED module of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an example of the LED module of the present invention,
FIG. 2 shows a top view of an insulating metal substrate on which the LED is arranged.

In the figure, an insulating metal substrate 1 is made of a metal substrate layer 2 made of a metal such as aluminum, copper, iron or stainless steel and an epoxy resin, epoxy resin containing glass fiber, polyethylene, crosslinked polyethylene, polyimide, polyamide imide, polyester, polyurethane or the like. An electrical insulating layer 3 made of an electrically insulating material, an electrode pattern 4 made of a conductive metal such as aluminum, copper, gold and nickel, and a lead circuit pattern 5. The insulating metal substrate 1 is formed with a recessed concave portion 7 leaving the peripheral edge portion 6 thereof, and a large number of recesses 8 are provided in the bottom portion of the concave portion 7. The depth of the concave portion 7 that imparts a desired bending resistance to the insulating metal substrate 1 is determined by the metal substrate layer 2
First, depending on the type of metal constituting the layer, it depends on the thickness, etc., but when the metal substrate layer is made of aluminum with a thickness of 0.5 mm to 2.0 mm, the depth of the recess is 0.5 mm to 1.5 mm. The size and depth of the recess 8 depend on the size of the LED to be installed, but normally the bottom diameter is 0.4 mm to 1.0 mm, and the opening diameter at the top of the recess is 1.0 mm.
~ 2.0 mm, depth 0.2 mm ~ 0.5 mm. These recesses 7 and depressions 8 can be simultaneously formed by pressing or the like.

The bottom 9 of the recess and the side wall 10 of the recess are the electrode pattern 4
The electrode pattern has a tail-shaped extension 41 extending to the outside of the recess 8 as shown in the drawing. The electrode pattern 4 covering the side wall surface 10 of the recess 8 functions as a light reflecting surface. Therefore, if necessary, gloss polishing or gloss plating of nickel, chromium, gold or the like is performed to enhance the light reflection efficiency.

The LED 11 is installed on the electrode pattern 4 on the bottom 9 of the recess and is adhered thereto by, for example, a conductive adhesive (such as silver paste), and the surface electrode 12 of the LED is extended to the extension 41 of the electrode pattern of the adjacent recess. It is connected by a bonding wire 13. As shown in the figure, a large number of LEDs are connected in series between the lead circuit patterns 5, and a series of LEDs connected in series is connected in parallel by the lead circuit patterns 5. The lead circuit pattern 5 is connected to a power supply circuit (not shown). Reference numeral 14 is a resistor connected between the lead circuit pattern 5 and the LED 11 for limiting the current flowing through the LEDs connected in series.

Reference numeral 15 is a sealing resin for sealing the entire concave portion 7 of the insulating metal substrate 1, or at least the recess 8 and the bonding wire 13,
For example, it is made of a light-transmitting organic polymer such as a silicone resin, an epoxy resin, and a polymer bonate resin.

Reference numeral 16 is a lens plate provided with a large number of lenses 17, and the lens 17 is positioned so that the position of the lens 17 corresponds to the center of the recess 8 and the LED 11 and is coupled to the front surface of the insulating metal substrate 1. In the figure, the lens plate 16 is adhered to the peripheral edge portion 6 of the insulating metal substrate 1 with an adhesive material 18. The lens plate 16 is a single plate composed of a large number of lenses 17 and a non-lens portion, and the non-lens portion needs to have a corresponding thickness in order to provide the lens plate 16 with a considerable mechanical strength. The insulating metal substrate 1 is thicker than the metal substrate layer 2. For example, if the metal substrate layer 2 has a thickness of about 1 mm, the non-lens portion has a thickness of about 1.9 mm. Since the difference in expansion coefficient between the lens plate 16 and the metal substrate layer 2 is large as described above, the insulating metal substrate 1 and the lens plate 16 are
In order to strengthen the bond with the lens board 16, an adhesive may be applied to the entire surface of the sealing resin filling the entire concave portion 7 of the insulating metal substrate and the peripheral edge portion 6, and the lens plate 16 may be adhered. Care must be taken not to impair the light transmission by applying the material. Lens plate 16 is polycarbonate, polyimide, epoxy resin, acrylic resin, polypropylene, nylon polyethylene terephthalate, vinylidene chloride resin, trifluoroethylene chloride resin, tetrafluoroethylene-ethylene copolymer resin, tetrafluoroethylene-hexafluoropropylene It is composed of a light-transmitting organic photomolecule such as a copolymer resin.

The light emitted from the LED 11 is reflected and condensed by the side wall surface 10 of the recess 8 and the lens 17, and is emitted forward.

The LED module of the present invention described above can be variously modified (but not limited to) as described below.

The insulating metal substrate 1 may be provided with a concave portion 7 and a bending rib 19 on an edge thereof as shown in a perspective view of FIG. 3 (however, an electrode pattern and a lead circuit pattern are not shown).
In this case, the twist resistance and bending resistance of the insulating substrate are further improved. The shape of the recess 7 is not limited to the recessed recess shown in FIGS. 1 to 3, and various modifications are possible as long as desired flex resistance can be imparted. Also regarding the formation of the reflection surface on the side wall surface 10 of the electrode pattern 4 and the depression 8, the electrode pattern covers only the bottom 9 of the depression, and the tail-like extension 41 of the electrode pattern extends along the sidewall surface 10 of the depression to the outside of the depression. The side wall surface of the recess of the metal substrate layer 2 itself may form a light reflecting surface. In this case, it is needless to say that the insulating layer 3 is made of a light-transmissive insulating material, and it is desirable that the surface of the metal substrate layer 2 has a high gloss. In contrast to the lens plate 16 shown in FIG. 1, the lens plate 16 may be such that the lens 17 is convex toward the insulating metal substrate side, or has convex portions on both the insulating metal substrate side and the opposite side. It may be one. In short, LED1
In combination with the light reflection pattern of 1 and the shape of the reflection surface formed on the side wall surface 10 of the recess 8, the emitted light of the LED can be efficiently concentrated and emitted in the forward direction.

Regarding the connection between the lens plate and the insulating metal substrate, in addition to the connection by the adhesive material as described above, mechanical engagement fixing to prevent the displacement of the lens and the LED due to expansion and contraction due to temperature change It is desirable to add means. According to a study by the inventor of the present application,
Due to the expansion and contraction of the LED module, the position of the lens on the lens plate is displaced with respect to the recess of the insulating metal substrate and the LED, which reduces the amount of light emitted forward by the module, which reduces the amount of light. Cannot be sufficiently suppressed only by improving the bending strength of the insulating metal substrate having the recessed portion on the insulating metal substrate. In order to sufficiently suppress this, it is necessary to provide an engaging and fixing means capable of sufficiently suppressing the displacement of the arrow tension position. FIGS. 4 (a) and 4 (b) are perspective views of an insulating metal substrate and a lens plate provided with such engaging and fixing means. Of the reference numerals in the drawings, the same reference numerals as those in FIGS. 1 to 3 represent the same parts. The insulating metal substrate 1 is provided with a tooth-shaped groove 20 on its peripheral edge portion 6. On the other hand, the lens plate 15 is provided with legs 21 that fit snugly into the tooth-shaped groove 20 described above. The insulating metal substrate 1 and the lens plate 16 are engaged and fixed by fitting the groove 20 and the leg 21, and the positional displacement due to expansion and contraction due to temperature change is suppressed, and the amount of light due to the positional displacement is suppressed as shown in an experimental example described later. The drop is almost completely prevented. As such an engaging and fixing portion, a large number of holes may be provided in the peripheral portion 6 of the insulating metal substrate, and the lens plate may be provided with legs or pins to be inserted into the holes, or the insulating metal substrate It is also possible to provide holes at corresponding positions of both the lens plate and the lens plate and insert the lock pin into them. These engaging and fixing portions bring about an advantage that the recess of the insulating metal substrate and the alignment of the LED with the lens of the lens plate can be easily performed when the LED module is assembled.

(Experimental Example 1) An LED module of the present invention having a structure as shown in FIG. 1 and FIG. 2 has a similar structure except for a sample having different recess depths and having no recess. For the conventional LED module sample, the sample was stored at -40 ° C for 30 minutes and then stored at 100 ° C for 30 minutes as one cycle, and a heat shock test was repeated for 10 cycles.
Table 1 shows the results of observing the condition of bending or warpage occurring in the D module.

In each sample, the metal substrate layer is made of aluminum, the thickness is about 1.0mm, the lens plate is made of epoxy resin, the plate thickness is about 1.9mm, it has 8 lenses, and the lens plate is from the top of the lens. The thickness up to the bottom surface was 4.0 mm. The vertical and horizontal dimensions of the LED module were 80 mm and 10 mm, respectively.

(Experimental Example 2) The same heat shock test as in Experimental Example 1 was performed on the following Samples 1 to 4 having the same structure and dimensions as those in Experimental Example 1 but different in presence / absence of concave portions, presence / absence of engaging / fixing portions, and positions. Was carried out and the change in the amount of light emitted by the module was measured. Table 2 shows the results. In Table 2, the reduction rate of the light amount is shown in% when the light amount before the heat shock test is 100%.

Specimen 1: No recess and engaging and fixing part.

Specimen 2: Depth of recess is 1.0 mm, no engaging and fixing part.

Specimen 3: Depth of recessed part was 1.0 mm, and engaging and fixing part was formed by a tooth-shaped groove at an intermediate position between lenses.

Specimen 4: Depth of the recess is 1.0 mm, and the engaging and fixing part is a tooth-shaped groove just beside the lens.

(Advantages of the Invention) In the LED module of the present invention, the mechanical strength of the lens plate can be increased by making the thickness of the non-lens portion thicker than the metal substrate layer, and the lens plate and the peripheral edge of the substrate can be increased. There is an advantage that the optical axis of the lens and each LED can be easily aligned by directly connecting the parts. The problems of concern due to the adoption of these configurations are the increase in thermal expansion / contraction force due to the thickening of the lens plate, the deformation of the module due to the direct coupling between the lens plate and the substrate, etc. As is clear from the above, by forming a recess of sufficient depth in the insulating metal substrate, the bending resistance of the insulating metal substrate is improved, and bending of the LED module due to expansion and contraction of the lens plate due to temperature changes can be suppressed. , The pattern of light emitted from the module changes due to the bending of the module,
It doesn't get worse. Further, there is no fear that the bending of the lens plate and the insulating metal substrate may be peeled off due to ON / OFF of heat and the bonding wire may be cut. Moreover, it is possible to simultaneously form the concave portion provided on the insulating metal substrate and the large number of depressions provided at the bottom portion of the insulating metallic substrate by squeezing processing or the like, and impart the necessary bending strength without impairing the mass productivity of the LED module. be able to.

Further, in the LED module of the present invention, when the concave portion is provided in the insulating metal substrate and the engaging fixing portion that engages the insulating metal substrate and the lens plate is provided, it is clear from Experimental Example 2 that the temperature change Lens and LED based on expansion and contraction
It is possible to almost completely eliminate the inconvenience that the amount of radiated light of the LED module decreases due to the misalignment between and. Further, these engaging and fixing portions also bring an advantage in mass production in which the lens plate can be easily positioned in the assembly of the LED module of the present invention.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an example of an LED module of the present invention, FIG. 2 is a top view of an insulating metal substrate on which the LED is arranged, and FIG.
FIG. 4 is a perspective view of another example of the insulating metal substrate according to the present invention, and FIGS. 4 (a) and 4 (b) are perspective views of the insulating metal substrate and the lens plate of still another example. (Explanation of symbols) 1: Insulating metal substrate, 2: Metal substrate layer, 3: Insulating layer, 4: Electrode pattern, 5: Lead circuit pattern, 7: Recess, 8: Dimple, 10:
Side wall surface, 11: LED, 13: bonding wire, 16: lens plate, 17: lens, 19: bending rib, 20: toothed groove, 21: leg

Claims (3)

(57) [Claims] 1. A recess 7 is formed in an insulating metal substrate 1 in which an electric insulating layer 3 and an electrode pattern 4 are sequentially provided on a metal substrate layer 2 while leaving a peripheral edge portion 6 and a large number of recesses 8 are provided in the bottom portion thereof. ,
The LED 11 is installed on the bottom of the depression 8 and the side wall surface 1 of the depression 8
In addition to 0 as a reflecting surface, a lens plate 16 is coupled to the front surface of the insulating metal substrate 1, and the lens plate 16 has a plurality of lenses 17 positioned so as to correspond to the center positions of the LEDs 11, respectively. An LED module comprising a non-lens portion having a thickness larger than that of the metal substrate layer 2 of the insulating metal substrate 1, and further being directly coupled to the peripheral portion 6 of the insulating metal substrate 1 to the lens plate 16. . 2. The metal substrate layer 2 of the insulating metal substrate 1 has a thickness of 0.5 m.
Made of an aluminum plate of m ~ 2.0 mm, the depth of the recess 7 is 0.5 mm ~
The LED module according to claim 1, wherein the LED module has a size of 1.5 mm. 3. The LED module according to claim 1, wherein the insulating metal substrate 1 and the lens plate 16 are provided with engagement fixing portions which are engaged with each other.