KR102348352B1 - Light-emitting device - Google Patents

Abstract

The light emitting device 100 in which the light emitting element 10 is to be flip-chip mounted using an anisotropic conductive adhesive paste 30 on the n-type and p-type electrode pads 21 and 22 formed on the substrate 20 in a bump-free manner. In this, it is possible to simultaneously solve the two problems of suppression of short circuit and improvement of heat dissipation efficiency. The light emitting device 10 is flip-chip mounted in a bumpless manner using an anisotropic conductive adhesive paste 30 on the n-type and p-type electrode pads 21 and 22 formed on the substrate 20 to the light emitting device 100 . In this case, the widths of the n-type and p-type electrode pads 21 and 22 are made equal to or narrower than the width of the light emitting element 10 .

Description

Light-Emitting Device {LIGHT-EMITTING DEVICE}

The present invention relates to a light emitting device in which a light emitting element such as a light emitting diode (LED) chip is flip-chip mounted on a substrate with an anisotropic conductive adhesive paste.

When a light emitting device such as a light emitting diode (LED) chip is mounted on a substrate, compared to the Au wire bonding method, the flip chip method, which can be expected to improve light extraction efficiency and heat dissipation characteristics, has been widely applied (Patent Document 1). By the way, light emitting devices such as LED chips are usually cut in a dicing process after making a large number of light emitting devices on a large-diameter semiconductor wafer to become a semiconductor chip that is a light emitting device, and an anisotropic conductive adhesive containing conductive particles is a semiconductor chip When attached to the side surface of the conductive particles, there is a problem that the semiconductor layer and the electrode are electrically connected by the mass of the conductive particles, resulting in a short circuit failure.

For this reason, the generation|occurrence|production of a short circuit was prevented by forming a bump in a light emitting element or a board|substrate, and performing flip-chip mounting. Specifically, as shown in Figs. 3A (a plan view of the light emitting device) and Fig. 3B (a side view of the light emitting device viewed from the direction A in Fig. 3A ), the n-type side of the back surface of the chip body 131 of the light emitting device 110 . The device electrode 111 and the p-type device electrode 112 are applied to the n-type electrode pad 121 and the p-type electrode pad 122 on the surface of the substrate 120 on which the gold bump Bp is formed, respectively, with an anisotropic conductive adhesive paste 130 . ) by thermocompression, flip-chip mounting is performed. In this case, the width L1 of the n-type electrode pad 121 and the width L2 of the p-type electrode pad 122 are configured to be larger than the width L0 of the chip body 131 to ensure conduction reliability, and further, It is common to set the widths L1a, L2a, L1b, and L2b of the protruding portion to be about 30 µm or more and 50 µm or less.

Japanese Patent Laid-Open No. 2007-123613

However, in the case of a light emitting device constructed using bumps as shown in FIG. 3A, although short circuits can be suppressed, the cost of forming gold bumps is very high, and the distance between the light emitting layer and the substrate of the light emitting device that emits light and heat is spaced apart, There was a problem that the heat dissipation characteristics were lowered (in other words, the heat resistance was increased). For this reason, it is also conceivable that the light emitting device has a bumpless structure, which has the advantage that the cost of forming gold bumps becomes unnecessary and the heat dissipation characteristic is improved. As described above, the current situation is that there is a demand for a light emitting device having a bumpless structure that simultaneously solves the two problems of suppression of short circuit and improvement of heat dissipation characteristics.

An object of the present invention is to solve the problems of the prior art. The goal is to solve the two problems of improving heat dissipation characteristics at the same time.

The present inventors have found that in a light emitting device in which a light emitting element is flip-chip mounted on an electrode pad formed on a substrate in a bumpless manner using an anisotropic conductive adhesive paste, the width of the electrode pad on the substrate is equal to or greater than that of the light emitting element. By narrowing, the anisotropic conductive adhesive paste protruding from between the electrode pad and the light emitting element on the substrate is held in the gap between the light emitting element and the substrate surface wider than the gap between the electrode pad and the light emitting element, so the P layer and the N layer It is possible to prevent short-circuiting between the came to complete.

That is, the present invention is a light emitting device in which a light emitting element having a semiconductor chip body is flip-chip mounted using an anisotropic conductive adhesive paste on an electrode pad formed on a substrate in a bumpless manner, wherein the width of the electrode pad is the width of the chip body It is a light emitting device characterized in that it is equal to or narrower than that.

Further, the present invention is a light emitting device, wherein the chip body is a light emitting diode chip.

Further, the present invention is a light emitting device, wherein when the width of the chip body is 100, the width of the electrode pad is 80% or more and 100% or less.

Further, the present invention is a light emitting device, wherein the distance between the edge of the electrode pad in the width direction and the edge of the chip body in the width direction is 10 µm or more and 40 µm or less.

Further, the present invention is a light emitting device in which an anisotropic conductive adhesive paste containing conductive particles is disposed between a light emitting element and a mounting device, and the light emitting device is installed in the mounting device by the anisotropic conductive adhesive paste, the mounting device comprising: a substrate, and an n-type electrode pad and a p-type electrode pad disposed on the substrate; A p-type region and an n-type region are provided inside the chip body to form a pn junction, and the p-type device electrode is electrically connected to the p-type region through the conductive particles, and the n The type-side element electrode is electrically connected to the n-type region through the conductive particles, and the surface of the p-type electrode pad and the surface of the n-type electrode pad are located above the substrate surface, and the p-type electrode pad and The n-type electrode pad is formed in a band shape having a predetermined width, and the tip of the p-type electrode pad and the tip of the n-type electrode pad are located in a region directly below the chip body, and the p-type electrode pad The portion opposite to the tip and the portion opposite to the tip of the n-type electrode pad are located outside the direct region, and the width of the p-type electrode pad is the p-type electrode pad of the chip body. light emission whose length is less than or equal to the length of the first side positioned directly above of it is a device

In addition, the present invention is a light emitting device, wherein the width of the p-type electrode pad is shorter than a length of a first side of the chip body located directly above the p-type electrode pad, and the width of the n-type electrode pad is shorter than the length of the second side of the chip body positioned directly above the n-type electrode pad, the light emitting element and the substrate outside the p-type electrode pad and the n-type electrode pad in the region directly below the Between the light emitting devices, the anisotropic conductive adhesive paste protruding from between the light emitting device and the p-type electrode pad and the anisotropic conductive adhesive paste protruding from between the light emitting device and the n-type electrode pad are disposed. it is a device

In addition, the present invention is a light emitting device, wherein the first side and the second side are arranged in parallel with the same length, and both ends of the first side are located outside the p-type electrode pad immediately above the second side Both ends of the light emitting device are positioned on the outside just above the n-type electrode pad.

According to the light emitting device of the present invention in which the light emitting element is flip-chip mounted on an electrode pad formed on a substrate in a bumpless manner using an anisotropic conductive adhesive paste, the width of the electrode pad is configured to be equal to or narrower than that of the light emitting element, have. For this reason, generation|occurrence|production of a short circuit can be suppressed and the improvement (reduction of thermal resistance) of a heat dissipation characteristic can be implement|achieved simultaneously.

In addition, since the anisotropic conductive adhesive paste does not adhere to the side surface of the light emitting element, it does not interfere with the emission of light emitted from the side surface of the light emitting element.

1A is a plan view of a light emitting device of the present invention.
Fig. 1B is a side view of the light emitting device of the present invention as seen from the direction A in Fig. 1A.
2A is a partially enlarged cross-sectional view for explaining a state in which a light emitting element is disposed on an anisotropic conductive adhesive paste on a mounting substrate.
Fig. 2B is a partially enlarged cross-sectional view for explaining a state when the light emitting element is being pressed.
Fig. 2C is a partially enlarged cross-sectional view for explaining a state in which the p-type side and n-type element electrodes and the p-type side and n-type side substrate electrodes are electrically connected with conductive particles.
2D is an enlarged view for explaining the anisotropic conductive adhesive paste attached to the side surface of the element body of the light emitting device of the prior art.
3A is a plan view of a conventional light emitting device.
3B is a side view of a conventional light emitting device viewed from the direction A of FIG. 3A .

Hereinafter, the light emitting device of the present invention will be described in detail with reference to the drawings.

Fig. 1A is a plan view of the light emitting device 100 of the present invention, and Fig. 1B is a side view of the light emitting device 100 of the present invention as seen from the direction A in Fig. 1A. The light emitting device 100 of the present invention is a light emitting device in which the light emitting element 10 is flip-chip mounted on a substrate 20 in a bumpless manner. Specifically, the light emitting element 10 has a chip body 31 , an n-type element electrode 11 , and a p-type element electrode 12 , and an n-type element electrode 11 and a p-type element electrode 12 . ) is disposed on the chip body 31 .

An n-type electrode pad 21 and a p-type electrode pad 22 are disposed on the substrate 20 , and the substrate 20 , the n-type electrode pad 21 , and the p-type electrode pad 22 are mounted on the substrate 20 . (18) is formed. The n-type element electrode 11 and the p-type element electrode 12 are formed by applying a cured anisotropic conductive adhesive paste 30 to the n-type electrode pad 21 and the p-type electrode pad 22 of the mounting device 18, respectively. It is connected through anisotropic conduction.

The manufacturing process of the light emitting device 100 is demonstrated.

The anisotropic conductive adhesive paste 30 contains conductive particles 36, and when the uncured anisotropic conductive adhesive paste is called a stock solution, a light emitting element ( 10) After disposing the stock solution on the n-type electrode pad 21 and the p-type electrode pad 22 positioned immediately after the The surface on which (12) is formed is made to face the stock solution disposed on the substrate 20, the n-type device electrode 11 of the light-emitting device 10 is brought into contact with the stock solution on the n-type electrode pad 21, and the p-type side The element electrode 12 is brought into contact with the stock solution on the p-type electrode pad 22 .

2A shows the state, reference numeral 28 denotes the stock solution, and the conductive particles 36 are dispersed in the adhesive component 29 of the stock solution 28 . The substrate 20 is mounted on the pedestal 51 .

Here, when the light emitting element 10 is placed on the stock solution 28, assuming that the bottom surface of the chip body 31 and the surface of the substrate 20 are parallel to each other, the reference symbol H ₁ in Fig. 2A denotes the substrate ( The height of the bottom surface 38 of the chip body 31 which is the distance from the front surface 39 of 20 to the bottom surface 38 of the chip body 31 is shown. Reference numerals Wa and Wb denote distances between the n-type electrode pad 21 and the p-type electrode pad 22 in a direction parallel to the substrate 20 from the edge of the chip body 31 .

The thickness of the n-type element electrode 11 and the p-type element electrode 12 are equal, and the thickness of the n-type electrode pad 21 and the p-type electrode pad 22 are also equal, and the chip body 31 _{), the height H 1} of the bottom surface 38 is the thickness P ₁ of the n-type electrode pad 21 and the p-type electrode pad 22, and the n-type or p-side electrode pads 21, 22 and the n-type or p It is the sum total _{of the thickness Q 1} of the stock solution 28 sandwiched between the _{type-side element electrodes 11 and 12 and the thickness E 1} of the n-type element electrode 11 and the p-type element electrode 12 .

The n-type element electrode 11 and the p-type element electrode 12 are formed by etching a conductive thin film formed on the surface of the chip body 31 , and the n-type element electrode 11 and the p-type element electrode 12 are formed by etching. The thickness E ₁ of is thinner than _{the thickness P 1} of the n-type electrode pad 21 and the p-type electrode pad 22. 39) to the surface of the n-type element electrode 11 or the p-type element electrode 12 (H ₁ -E ₁ ) is, from the surface 39 of the substrate 20 to the bottom surface of the chip body 31 ( 38) is the same as the height H _{1 .}

Further, the stock solution 28 is disposed on the n-type device electrode 11 and the p-type device electrode 12 of the light emitting device 10, and the undiluted solution 28 on the n-type device electrode 11 is placed on the n-type electrode. The pad 21 may be brought into contact, and the p-type electrode pad 22 may be brought into contact with the stock solution 28 on the p-type device electrode 12 .

Next, the light emitting device 10 and the substrate 20 are pressed against each other. Here, as shown in Fig. 2B, the light emitting element 10 is pressed against the substrate 20 by a pressing member 52, and at that time, the n-type element electrode 11 and the n-type electrode pad ( 21) and between the p-type element electrode 12 and the p-type electrode pad 22, the undiluted solution 28 is extruded, while the n-type element electrode 11 and the p-type element electrode 12 are They approach the n-type electrode pad 21 and the p-type electrode pad 22, respectively. The height H _{2 at this time is lower than the height H 1} when the light emitting element 10 is mounted, _{and the thickness Q 2} of the stock solution 28 on the n-type electrode pad 21 and the p-type electrode pad 22 is the original thickness. It decreases than Q _1.

Then, as shown in FIG. 2C , the n-type device electrode 11 contacts the n-type electrode pad 21 through the conductive particles 36 , and the p-type device electrode 12 includes the conductive particles 36 . through the p-type electrode pad 22.

At this time, since the size of the conductive particles 36 is negligibly small, the n-type or p-side device electrodes 11 and 12 and the n-type or p-side electrode pads 21 and 22 pass through the conductive particles 36 . In the case of connection, it is the same as in the case of direct contact, and it can be considered that _{the thickness Q 3 of the stock solution 28 is zero. Ignoring the thickness E 1} of the n-type or p-type element electrodes 11 and 12 _{, the height H 3 , which} is the distance between the light emitting element 10 and the substrate 20 , is the n-type electrode pad 21 and the p-type electrode The thickness of the pad 22 is P ₁ .

The adhesive component 29 of the stock solution 28 contains a thermosetting component, and the n-type element electrode 11 and the p-type element electrode 12 are connected to the n-type electrode pad 21 through the conductive particles 36 . and the p-type electrode pad 22, when the light emitting element 10 and the substrate 20 are heated and the undiluted solution 28 is heated, a cured anisotropic conductive adhesive paste 30 is formed, and light is emitted The device 10 and the substrate 20 are fixed to each other, and the n-type or p-side device electrodes 11 and 12 and the n-type or p-side electrode pads 21 and 22 are electrically connected by the conductive particles 36, respectively. A connected light emitting device 100 is obtained.

The chip body 31 is a semiconductor chip in which a semiconductor wafer having an N-type semiconductor region and a P-type semiconductor region provided therein is divided into a plurality of pieces by cutting, and inside each chip body 31, an N-type semiconductor region and P-type semiconductor regions in contact with the N-type semiconductor regions are respectively provided, and pn junctions are respectively formed.

The n-type element electrode 11 on each chip body 31 is electrically connected to the n-type semiconductor region, and the p-type element electrode 12 is electrically connected to the p-type semiconductor region, and the anisotropic conductive adhesive paste 30 ), the n-type element electrode 11 is electrically connected to the n-type electrode pad 21 through the conductive particles 36 , and the p-type element electrode 12 is electrically connected to the p-type element electrode 12 through the conductive particles 36 . Since it is electrically connected to the type side electrode pad 22, when a voltage is applied between the p type side electrode pad 22 and the n type side electrode pad 21, the p type side device electrode 12 and the n type side device electrode ( 11), when a voltage is applied between the p-type semiconductor region and the n-type semiconductor region, the pn junction is forward biased and a current flows through the pn junction, the vicinity of the pn junction emits light.

The substrate 20 is, for example, a plate-shaped resin, and the n-type electrode pad 21 and the p-type electrode pad 22 are conductive films such as a metal film disposed on the surface of the substrate 20, and the n-type side electrode pad 22 The surface of the electrode pad 21 and the surface of the p-type electrode pad 22 are positioned higher than the surface of the substrate 20 by the film thickness P ₁ of the n-type electrode pad 21 and the p-type electrode pad 22 . will be located

When the size of the conductive particles 36 is neglected, the n-type device electrode 11 comes into contact with the n-type electrode pad 21 , and the p-type device electrode 12 comes into contact with the p-type electrode pad 22 . _{, since the film thicknesses P 1} of the n-type electrode pad 21 and the p-type electrode pad 22 are not zero, the front surface 39 of the substrate 20 and the bottom surface 38 of the chip body 31 have a height H _A gap 13 is formed to be spaced apart by 3, and a gap is also formed between the surface 39 of the substrate 20 and the surface of the n-type element electrode 11 or the surface of the p-type element electrode 12 has been That is, the surface of the light emitting element 10 and the surface 39 of the substrate 20 are spaced apart, and a gap is formed.

As described above, when the n-type element electrode 11 and the p-type element electrode 12 are conductive thin films disposed on the surface of the chip body 31, for example, a metal thin film, the thickness E _{1 The value of is smaller than the value of the film thickness P 1} of the n-type electrode pad 21 and the p-type electrode pad 22 , and the bottom surface 38 of the chip body 31 and the n-type electrode pad 21 or the p-type side The distance between the surface of the n-type element electrode 11 or the surface of the p-type element electrode 12 and the surface 39 of the substrate 20 is larger than the distance between the electrode pads 22 (Fig. 2C). ).

In contrast, as shown in FIG. 2D , in the light emitting device of the prior art, the n-type electrode pad 121 and the p-type electrode pad 122 protrude outward from the outer periphery of the light emitting element 110, _{The height H 4} from the front surface 139 of the mounting device 180 to the bottom surface 138 of the chip body 131 is equal to the _{thickness P 1} of the n-type electrode pad 121 and the p-type electrode pad 122 . It is made smaller than _{the height H 3} of the present invention.

And, since the height H ₄ is low, the stock solution 128 is extruded outward from the outer periphery of the light emitting element 110 from between the light emitting element 110 and the n-type or p-side electrode pads 121 and 122 .

Since the viscosity of the stock solution 128 is high, among the extruded stock solutions 128, the later extruded stock solutions 128 rise on the first extruded stock solutions 128, and the extruded stock solutions 128 are light emitting devices 110. When it rises higher than the bottom surface 138 of the chip body 131 and adheres to the side surface of the chip body 131, the lump of the conductive particles 136 after curing the adhesive component 129 causes a short circuit.

In the present invention, the height H _{3 is higher than the height H 4} of the light emitting device of the prior art, between the n-type element electrode 11 and the n-type electrode pad 21, the p-type element electrode 12 and the p-type electrode The undiluted solution 28 extruded from between the pads 22 is accommodated in the gap 13 and does not rise on the side surface of the light emitting element 10 .

The planar shape of the chip body 31 is a quadrangle in which four sides intersect at right angles, and when two sides of the four sides are set as a set, the lengths of the two sides of the set are equal.

In addition, among the two sides of the pair, the n-type electrode pad 21 is located just below one side, and the p-type electrode pad 22 is located just below the other side, so that the n type electrode pad 21 ) and the p-side electrode pad 22 enter the region directly below the chip body 31 from the position immediately below the two sides of the pair, and extend linearly within the region directly below.

The p-type electrode pad 22 and the n-type electrode pad 21 are not located under the two sides of the other set.

Here, the length in a direction perpendicular to the extending direction of the n-type electrode pad 21 is the width L1 of the n-type electrode pad 21, and the direction perpendicular to the extending direction of the p-type electrode pad 22 is defined as Let the length be the width L2 of the p-type electrode pad 22, and the length of the side of the chip body 31 located directly above the n-type electrode pad 21 or directly above the p-type electrode pad 22 is emitted. Let the element width L0.

In the light emitting device 100 of the present invention, the width L1 of the n-type electrode pad 21 and the width L2 of the p-type electrode pad 22 are equal to or shorter than the width L0 of the chip body 31 . . As a result, the anisotropic conductive adhesive paste 30 protruding from between the n-type and p-type electrode pads 21 and 22 and the light emitting element 10 on the substrate 20 is applied to the n-type and p-type electrode pads 21 . . Furthermore, since it is flip-chip mounted in bumpless, manufacturing cost can be compressed, and heat dissipation efficiency can be improved (in other words, thermal resistance is reduced).

Next, the A-direction described above is a direction in which either one of the n-type electrode pad 21 and the p-type electrode pad 22 extends inward from a position just below the side of the chip body 31 .

Here, the width direction of the n-type and p-type electrode pads 21 and 22 in FIGS. 1A and 3A is a direction transverse to the A direction. In other words, the width direction of the n-type and p-type electrode pads 21 and 22 is a direction perpendicular to the A direction in a plane parallel to the surface of the substrate 20 .

Accordingly, the A direction in FIGS. 1A and 3A can be defined as a direction crossing the gap between the n-type electrode pad 21 and the p-type electrode pad 22 . 1A and 3A, since rectangular p-type electrode pads 22 and n-type electrode pads 21 are formed adjacent to each other at predetermined intervals on the substrate 20, the n-type side electrode pads 22 , the width direction of the p-type electrode pads 21 and 22 is substantially orthogonal to the A direction, but the shape of the n-type and p-type electrode pads 21 and 22 is not a rectangle, but a parallelogram, trapezoid, triangle, etc. In the case of the shape of , the width directions of the n-type and p-type electrode pads 21 and 22 are not necessarily substantially perpendicular to the A direction, but may be a direction transverse to the A direction at an inclined angle.

In addition, the width L1, L2 of the n-type electrode pad 21 and the p-type electrode pad 22 is configured to be shorter than the width L0 of the chip body 31. If it is too short, the heat dissipation characteristic tends to decrease. When the length of the width L0 of the chip body 31 is 100, the length of the width L1 of the n-type electrode pad 21 and the width L2 of the p-type electrode pad 22 is preferably 80 or more and 100 or less, More preferably, it is set as 90 or more and 99 or less.

In this case, the chip body 31 of the light emitting element 10 is overhanged on one or both sides of the n-type electrode pad 21 and the p-type electrode pad 22 in the width direction, but the amount of overhang (L1a in FIG. 1A , L1b, L2a, L2b), that is, the gap between the edge of the width direction of the n-type and p-side electrode pads 21 and 22 and the edge of the chip body 31 in the width direction) is too small. ) since the amount of creep of the conductive adhesive paste 30 on the side tends to increase, preferably 0 or more and 120 μm or less, more preferably 5 μm or more and 80 μm or less, particularly preferably 10 μm or more and 40 μm or less to be.

The width L1 of the n-type electrode pad 21 and the width L2 of the p-type electrode pad 22 are usually the same length, but may be different lengths. Also, the overhang amounts L1a, L1b, L2a, and L2b may have the same length, but may be different from each other. Usually, it is preferable to make these overhang amounts into mutually the same amount from the point which improves the precision of operation, such as position alignment at the time of manufacture, and relieves the difficulty of operation.

The width L1 of the n-type electrode pad 21 and the width L2 of the p-type electrode pad 22 are equal to or less than the length of the side of the chip body 31 positioned directly above the n-type electrode pad 21 , as described above. It becomes a length, and it is set to become the length less than the side length of the chip body 31 located directly above the p-type side electrode pad 22. As shown in FIG.

The tips of the n-type electrode pad 21 and the p-type electrode pad 22 are disposed to be spaced apart from each other in a region directly below the chip body 31 .

Here, as described above, the width L1 of the n-type electrode pad 21 and the width L2 of the p-type electrode pad 22 are the sides of the chip body 31 positioned directly above the n-type electrode pad 21 . It is preferable to be shorter than the length and shorter than the length of the side of the chip body 31 positioned just above the p-type electrode pad 22, and located just above the width L1 of the n-type electrode pad 21 The sides of the chip body 31 protrude on both sides of the width L1, and the sides of the chip body 31 positioned just above the width L2 of the p-type electrode pad 22 are empty on both sides of the width L2. It is preferable to go out.

In this case, on the outside of the tip portion of the n-type electrode pad 21 and the p-type electrode pad 22 located in the region directly under the chip body 31 , the side of the chip body 31 is located directly below the A gap formed between the light emitting element 10 and the substrate 20 is disposed except for the portion, and the distance between the substrate 20 and the light emitting element 10 is the light emitting element 10 and the n-type electrode pad ( 21) or the distance between the p-type electrode pads 22 and the n-type electrode pad 21 or the p-type electrode pad 22 by the film thickness P ₁ .

Accordingly, the light emitting element 10 is pressed, the n-type element electrode 11 is brought into contact with the n-type electrode pad 21 through the conductive particle 36 , and the p-type element electrode 12 is connected to the conductive particle 36 . When in contact with the p-type electrode pad 22 through ) is extruded from between the light emitting element 10 and the n-type or p-side electrode pads 21 and 22, and the extruded amount is between the light emitting element 10 and the substrate 20 ) is accommodated in the gap 13 between them, and the stock solution 28 does not rise around the light emitting element 10 .

In the light emitting device 100 of the present invention, in addition to configuring the widths of the n-type and p-side electrode pads 21 and 22 to be equal to or narrower than the width of the chip body 31, the conventional light emitting device Component (for example, the type and size of the light emitting element, the type and size of its connection pad, the type and size of the substrate, the material and thickness of the wiring pattern thereon, the type and viscosity of the anisotropic conductive adhesive paste, It can be set as the structure similar to the kind of electrically-conductive particle 36, average particle diameter, etc.).

Moreover, as the light emitting element 10 which is one of the components of the light emitting device 100 of this invention, an LED chip, an organic EL chip, an inorganic EL chip element, etc. are mentioned, Among them, a LED chip is mentioned preferably. . These are, of course, bumpless.

[Example]

Hereinafter, the present invention will be described by way of more specific examples.

Examples 1 to 7

As an example in which an LED chip is flip-chip mounted on a substrate so that it is bumpless and the width of the electrode pad is equal to or narrower than that of the light emitting element, the light emitting device having the structure shown in Figs. It produced using the LED chip and anisotropic electrically conductive adhesive paste. Specifically, a predetermined amount of anisotropic conductive adhesive paste is supplied from a dispenser on a substrate corresponding to the central portion of the LED element, and an LED chip is loaded on the anisotropic conductive adhesive paste, temperature 230°C, pressure 3N/chip, 30 seconds. A light emitting device was manufactured by thermocompression under the conditions of

In addition, the width from the edge in the width direction of the LED element to the edge in the width direction of the electrode pad (in other words, the amount of overhang of the LED element with respect to the electrode pad (L1a = L1b = L2a = L2b)) is shown in Table 1. In Table 1, it is described as ΔLD. In Examples 1 to 7, the numerical value of ΔLD is 0 or a positive number.

<substrate>

Base Material: Alumina 0.6mm thick

Electrode pad: copper 10㎛ thickness

Electrode pad surface treatment: Ni plating 3㎛ thickness / Au 0.3㎛ thickness

<LED chip>

Product name: DA3547, manufactured by Cree (Cree.Inc., USA)

Size: 350㎛ × 470㎛ × 155㎛t

<Anisotropic conductive adhesive paste>

Product name: SLP-04, manufactured by Decuceria Rouge Co., Ltd.

Comparative Examples 1 to 2

As a comparative example in which an LED chip is flip-chip mounted on a substrate, bumps are formed on electrode pads, and the width of the electrode pad becomes wider than the width of the light emitting element, a light emitting device having the structure shown in FIGS. 3A to 3B is described below. A light emitting device was produced by repeating the same operation as in Example 1 using the same LED chip and anisotropic conductive adhesive paste as in Example 1 except for using the substrate.

<Substrate used in Comparative Example 1>

Base Material: Alumina 0.6mm thick

Electrode pad: copper 10㎛ thickness

Au bump: diameter 80㎛, height 15㎛

Number of Au bumps: 3 on each electrode pad

Au bump pitch: 500㎛

<Substrate used in Comparative Example 2>

Base Material: Alumina 0.6mm thick

Electrode pad: copper 10㎛ thickness

Au bump: diameter 80㎛, height 15㎛

Number of Au bumps: 6 on each electrode pad

Au bump pitch: 200㎛

Table 1 shows the width from the edge of the LED element in the width direction to the edge in the width direction of the electrode pad (in other words, the amount of the electrode pad protruding from the width direction of the LED element (L1a = L1b = L2a = L2b)). is shown in In Table 1, it is described as ΔLD. In Comparative Examples 1 and 2 and Comparative Example 3 below, the numerical value of ΔLD is always a negative number.

Comparative Example 3

A light emitting device was produced in the same manner as in Comparative Example 1, except that, as a substrate, a substrate subjected to electrode pad surface treatment in the same manner as in Example 1 without forming Au bumps was used.

(evaluation)

About the light emitting element produced by the Example and the comparative example, "short-circuit failure" and "heat dissipation characteristic" were tested and evaluated as demonstrated below. The obtained result is shown in Table 1.

<short failure>

100 light emitting devices of each Example and each comparative example were produced, respectively, and whether a short circuit occurred between the P-pole side and the N-pole side was checked using a tester (Curve Tracer TCT-2004, Kokuyo Denki Kogyo Co., Ltd.) was confirmed, and the ratio (short-circuit occurrence rate) of the light emitting elements in which a short circuit occurred was calculated|required. It is preferable that it is 1 % or less, as for the short circuit incidence rate, it is more preferable that it is 0.5 % or less, It is especially preferable that it is 0 %.

<Heat dissipation characteristics>

In order to evaluate the heat dissipation characteristics, the thermal resistance value of each light emitting element is measured in accordance with "JE-DEC standard, JESD51-14", and the light emission of Examples or Comparative Examples when the thermal resistance value of Comparative Example 1 is used as a control The decrease rate (thermal resistance decrease rate) of the element thermal resistance value was calculated. The reduction rate is preferably 25% or more, more preferably 30% or more, and particularly preferably 35% or more.

As can be seen from Table 1, when a light emitting device is produced by flip-chip mounting the LED chip on the electrode pad formed on the substrate by bump-free using an anisotropic conductive adhesive paste, the width of the electrode pad is the width of the light emitting element. When it is equal to or narrower than that, it turns out that the short circuit occurrence rate will be 1 % or less, and the thermal resistance decrease rate will be 20 % or more. In particular, when the amount of overhang of the substrate of the light emitting element with respect to the electrode pad is set to 10 µm or more and 40 µm or less, the short circuit occurrence rate is 0% and the thermal resistance decrease rate is 35% or more, which is preferable.

On the other hand, it can be seen that in the case of the light emitting devices of Comparative Examples 1 and 2 using the substrate provided with bumps, the short circuit defect is improved, but the heat dissipation characteristic is not improved. In the case of the light emitting device of Comparative Example 3, although the heat dissipation characteristic is improved, it turns out that a short circuit defect will exceed 1 %.

The light emitting device of the present invention in which the light emitting element is flip-chip mounted using an anisotropic conductive adhesive paste on an electrode pad formed on a substrate is configured such that the width of the electrode pad is equal to or narrower than that of the light emitting element. . For this reason, generation|occurrence|production of a short circuit is suppressed and it is useful as a light emitting device which further improved the heat dissipation characteristic (reduction of thermal resistance).

100: light emitting device
10: light emitting element
11: n-type device electrode
12: p-type device electrode
20: substrate
21: n-type electrode pad
22: p-type electrode pad
30: anisotropic conductive adhesive paste
31: chip body
Bp: gold bump
L0: width of the light emitting element
L1: Width of the n-type electrode pad
L2: Width of the p-type electrode pad

Claims (7)

A light emitting device in which a light emitting device having a semiconductor chip body is flip-chip mounted on an electrode pad formed on a substrate in a bumpless manner using an anisotropic conductive adhesive paste,
The width of the electrode pad is equal to or narrower than the width of the chip body,
The light emitting device according to claim 1, wherein a distance between the edge of the electrode pad in the width direction and the edge of the chip body in the width direction is 10 µm or more and 40 µm or less. The light emitting device according to claim 1, wherein the chip body is a light emitting diode chip. The light emitting device according to claim 1 or 2, wherein when the width of the chip body is 100, the width of the electrode pad is 80% or more and 100% or less. delete An anisotropic conductive adhesive paste containing conductive particles is disposed between the light emitting device and the mounting device, and the light emitting device is provided in the mounting device with the anisotropic conductive adhesive paste,
The mounting device is
board and
an n-type electrode pad and a p-type electrode pad disposed on the substrate;
The light emitting element includes a chip body having a planar shape of a quadrilateral;
having a p-type element electrode and an n-type element electrode installed in the chip body;
A p-type region and an n-type region are provided inside the chip body to form a pn junction;
the p-type device electrode is electrically connected to the p-type region through the conductive particles, and the n-type device electrode is electrically connected to the n-type region through the conductive particles;
a surface of the p-type electrode pad and a surface of the n-type electrode pad are located above the substrate surface;
The p-type electrode pad and the n-type electrode pad are formed in a band shape having a predetermined width,
The tip of the p-type electrode pad and the tip of the n-type electrode pad are located in a region directly below the chip body, the portion opposite to the tip of the p-type electrode pad, the tip of the n-type electrode pad, The part on the opposite side is located outside the area directly under the
The width of the p-type electrode pad is less than or equal to the length of the first side of the chip body positioned directly above the p-type electrode pad,
The width of the n-type electrode pad is less than or equal to the length of the second side of the chip body positioned directly above the n-type electrode pad,
A gap between the edge of the p-type electrode pad in the width direction and the edge in the width direction of the chip body is 10 μm or more and 40 μm or less,
The light emitting device according to claim 1, wherein an interval between an edge of the n-type electrode pad in the width direction and an edge of the chip body in the width direction is 10 µm or more and 40 µm or less. The space between the p-type electrode pad in the direct region and the light emitting element outside the n-type electrode pad and the substrate protrudes from between the light emitting element and the p-type electrode pad and the anisotropic conductive adhesive paste and the anisotropic conductive adhesive paste protruding from between the light emitting element and the n-type electrode pad are disposed. The method according to claim 6, wherein the first side and the second side are arranged in parallel with the same length, and both ends of the first side are located outside the p-type electrode pad immediately above,
and both ends of the second side are positioned outside and directly above the n-type electrode pad.

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