CN103887420A - LED packaging structure and LED manufacturing method - Google Patents

Abstract

An LED packaging structure and an LED manufacturing method, the packaging structure adopts larger metal spacers to fix the LED chip, so as to improve the heat dissipation capability of the LED chip. In addition, the bonding area of the encapsulation adhesive and the substrate is increased by opening a scoop on the surface of the substrate, so as to improve the bonding strength of the encapsulation adhesive and offset the negative impact of enlarging the metal area. At the same time, the present invention also proposes a specific manufacturing method for the above packaging structure.

Description

A kind of LED package structure and LED manufacturing method

technical field

The invention belongs to the field of LED production and manufacture, and in particular relates to a packaging structure and a manufacturing method capable of improving the heat dissipation effect of the LED.

Background technique

Light Emitting Diode (LED) can directly convert electrical energy into light energy. LED chip is made up of two parts, and a part is P-type semiconductor, and inside it occupies an leading position in hole, and the other end is N-type semiconductor, mainly electron. When these two kinds of semiconductors couple together, between them, just form a "P-N junction". When electric current acts on this chip by wire time, electron will be pushed to P district, and in P district, electron is with hole recombination, then will send energy with the form of photon, the principle of LED luminescence that Here it is.

As a new type of light source, LED has been increasingly widely used in the field of lighting due to its characteristics of energy saving, environmental protection, and long life. At present, the luminous efficiency of LED can only reach 10% to 20%, and the remaining 80% to 90% of the energy is converted into heat energy. With the successful development of high-power chips, the application potential of LED in the field of lighting has been greatly improved. But at the same time, more heat is released per unit area. The heat dissipation problem of high-power LED chips has become an obstacle to the application of current LED technology in lighting engineering.

Please refer to Figures 1A-1C, the current LED production process usually includes the following steps: take a base material 10 (the material of the base material is usually resin, ceramics, glass bracket, etc.), fix the chip 11 on the base material 10, the chip After the 11 is fixed, the conductive wire 12 is welded. After the welding is completed, the compression molding is performed. During the compression molding, the phosphor powder and glue mixture 13 is injected into the cavity of the mold to complete the compression molding.

In the above method, when the LED chip is fixed to the base material, a metal spacer is often arranged on the base material to fix the bottom of the LED chip. The area of the metal spacer is generally equivalent to the area of the LED chip. The heat of the LED chip is often conducted to the base material or an external heat dissipation device through the metal pad. However, with the increase of LED power, this packaging structure faces the following problems:

1. The area of the metal gasket in the chip placement area is too small, which reduces the heat conduction rate of the chip and reduces the ability to maintain the light energy;

2. If the area of the metal gasket is increased, the bonding performance of the encapsulant and it will decrease, and it will be easy to delaminate;

3. The positive and negative poles are completely separated by thermoelectricity, and the thermal channels are completely independent and do not communicate with the internal circuit.

Therefore, how to solve the contradiction between the area of the metal pad and the bonding performance of the packaging adhesive in the LED packaging structure has become a difficult problem that the industry urgently needs to improve.

Contents of the invention

In view of this, the purpose of the present invention is to provide a new LED packaging structure and LED manufacturing method. The encapsulation structure can allow the use of a large-area metal gasket while ensuring the bonding performance of the encapsulation glue and the surface of the substrate material.

According to the purpose of the present invention, a LED packaging structure is proposed, which includes a substrate, an LED chip and an encapsulant for packaging the LED chip on the substrate, and the front side of the substrate is provided with a metal gasket for fixing the LED chip , the area of the metal spacer is at least larger than the LED chip, and two conductive pads are arranged on both sides of the metal pad, and the two conductive pads conduct the positive and negative poles on the LED chip to the LED chip on the back of the substrate. The conductive metal lines, the front surface of the substrate is also provided with a number of slots, and these slots are provided to avoid the metal pad and the two conductive solder joints.

Preferably, a concave-convex structure is provided at the edge of the fishing groove.

Preferably, the substrate is one of glass, quartz, resin or ceramics.

Preferably, a heat sink is further provided on the back of the substrate, and the metal pad penetrates through the substrate and is in thermal contact with the heat sink.

Preferably, the two sides of the substrate are also provided with metal electrodes for testing the electrical performance of the LED, and the metal electrodes penetrate the substrate and are connected to the conductive metal lines on the back of the substrate.

Simultaneously, the present invention also proposes a kind of LED manufacturing method with above-mentioned encapsulation structure, comprises steps:

Provide a substrate motherboard, the substrate motherboard includes a plurality of metal pads, the metal pads correspond to the position of an LED chip, each metal pad is provided with conductive solder points on both sides, and on the back of the substrate There are conductive metal lines connected to these conductive solder points;

setting up a fishing groove on the above-mentioned substrate, and the location of the fishing groove avoids the metal gasket and the conductive solder joint;

Fix the LED chip on the metal pad, and then carry out the wire welding process, and connect the positive and negative poles on the LED chip to the two conductive solder points respectively through wires;

Press the encapsulant onto the front of the substrate through a molding process, and perform solidification;

Finally, the above substrate mother board is subjected to a cutting process to form individual LED devices.

Preferably, the fishing grooves are distributed on the edge of each LED and/or in the middle of both sides of the metal spacer.

Preferably, after curing, the encapsulating glue is one of planar or spherical.

Preferably, when there are multiple rows of LEDs on the substrate motherboard, a scooping groove is provided between every two rows of LEDs, and this scooping groove is also used as a cutting groove in the cutting process.

Compared with prior art, the progress of the present invention is reflected in:

1. Increase the metal layer area of the chip heat dissipation area, the chip directly passes through the independent heat dissipation area, and directly dissipates heat from the bottom, and the heat dissipation effect is better;

2. The non-metal area of the substrate is slotted to increase the bonding force between the outer sealant and the substrate, and it is not easy to delaminate when the power is increased.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

1A-1C are schematic flow charts of a conventional LED manufacturing method.

Fig. 2 is a schematic structural view of a single LED package structure in the first embodiment of the present invention.

FIG. 3 is a top view of the substrate of the package structure in the second embodiment of the present invention.

4A-4B are structural schematic diagrams of the substrate mother board in the manufacturing method of the present invention.

Detailed ways

As mentioned in the background technology, in the traditional LED packaging structure, the area of the metal spacer used to fix the LED chip is too small. With the increase of the power of the LED chip, the small area of the metal spacer is not enough to dissipate heat for the LED chip. Eventually lead to the reduction of LED luminous efficiency. However, if the area of the metal pad is simply increased, the contact area between the encapsulant and the metal pad will increase, and the effective bonding area with the substrate will decrease. When the LED is working, the metal gasket is heated and hot, which easily reduces the adhesion of the encapsulation glue on it and leads to degumming.

therefore. The present invention designs a packaging structure that can not only increase the area of the metal gasket under the LED chip, but also solve the problem that the bonding ability of the packaging glue decreases after the metal gasket is enlarged. The main idea is to set up fishing grooves on the packaging surface of the substrate, except for the area where the metal pads and solder joints are located. The role of these grooves is to increase the effective contact area between the encapsulant and the surface of the substrate, thereby improving the bonding force of the encapsulant. In this way, although the area of the metal gasket is increased, the bonding strength of the packaging glue is guaranteed due to the effective contact area between the packaging glue and the base material, which greatly reduces the damage caused by the contact between the packaging glue and the metal gasket. The risk of degumming, and the heat dissipation capacity of the entire LED is improved due to the increase in the area of the metal gasket. At the same time, the present invention also proposes a manufacturing method capable of manufacturing the above-mentioned LED packaging structure.

Next, the technical solution of the present invention will be described in detail.

Please refer to FIG. 2 . FIG. 2 is a schematic structural diagram of a single LED package structure in the first embodiment of the present invention. As shown in the figure, the LED packaging structure includes a substrate 100 , an LED chip 101 and an encapsulation glue 103 for packaging the LED chip 101 on the substrate 100 . The substrate may be a transparent material, such as glass, quartz, resin, etc., or may be a non-transparent material such as ceramics or plastics. A metal spacer 102 for fixing the LED chip 101 is provided on the front side of the substrate 100 (that is, the packaging surface). The area of the metal spacer 102 is at least larger than that of the LED chip 101. Two conductive pads 104 , the positive and negative poles on the LED chip 101 are respectively connected to the two conductive pads 104 through two wires 105 . Conductive metal lines (not shown) are provided on the back side of the substrate 100, and the two conductive pads 104 pass through the substrate 100 and are connected with these conductive metal lines to connect the positive and negative poles on the LED chip 101. connected to the conductive metal lines on the back of the substrate 100 , and finally connected to external circuits through these conductive metal lines.

The metal pad 102 and the conductive pad 104 are preferably made of copper, of course, other metal materials with excellent electrical conductivity are also available, such as gold, silver, iron, aluminum and so on. In one application, the metal spacer 102 may also be a metal block that runs through the entire substrate 100 , and a heat dissipation device specially used for heat dissipation, such as a heat dissipation fin or a heat dissipation metal sheet, is provided on the back of the substrate 100 . The metal spacer 102 passes through the substrate 100 to form a thermal contact with the heat dissipation device, so as to conduct the heat on the LED chip to the heat dissipation device for heat dissipation. It should be noted that contact should be avoided between the conductive metal lines on the back of the substrate 100 and the heat dissipation device or the metal spacer 102 passing through, so as to ensure the separation of the lines between the heat conduction and conduction of the LED and complement each other.

The special feature of the present invention is that several scooping grooves are provided on the front of the substrate 100, such as the scooping grooves 106 and 107 in the figure, wherein the scooping grooves 106 are set on the edge of the substrate 100, and the scooping grooves 107 are set on the edge of the substrate 100. in the middle. There are many ways to limit the opening position of the fishing trough besides the position shown in the figure. For example, the fishing trough set in the middle position can adopt the horizontal bar type parallel to the long side, or even set up multiple parallel and crossing troughs. Or curved slots, as long as these slots avoid the metal pad 102 and the two conductive solder joints 104 . The width of the grooves and the distance between the grooves can be determined according to the size of the metal pads and conductive solder joints. In the case of avoidance, the proportion of the grooves on the entire surface can be increased as much as possible.

These grooves opened on the surface effectively increase the surface area of the entire substrate 100. In this way, when the packaging glue 103 is bonded to the front of the substrate, the effective contact area with the substrate 100 increases, which can not only compensate for the The reduced area between the encapsulant 103 and the substrate due to the increase in the area of 102, and by properly setting the width and number of the slots, can increase the contact area more than before, so that the encapsulant 103 and the substrate 100 Bond strength is improved. The thus obtained LED packaging structure, when the LED chip is working, due to the increase in the area of the bottom metal pad 102, its heat dissipation capability is also increased, ensuring a heat dissipation environment for the high-power LED chip, and improving the LED luminous efficiency.

Preferably, on both sides of the substrate, a metal electrode 108 for testing the electrical performance of the LED is provided. The metal electrodes 108 also penetrate the front and back of the substrate 100 and are connected to the conductive metal traces on the back of the substrate 100 . In the way shown in the figure, the two metal electrodes 108 are designed in a semi-circular arc shape, and only need to clamp out the metal electrodes on both sides with the test clip during testing. Of course, the metal motor can also be in any other shape, as long as it can meet the testing requirements of the LED.

Please refer to FIG. 3 . FIG. 3 is a top view of the substrate of the package structure in the second embodiment of the present invention. In this embodiment, in addition to opening grooves on the surface of the substrate, a concave-convex structure is added at the edge of the groove. These concave-convex structures can also be wavy, square or other in addition to the zigzag shape shown in the figure. Regular or irregular concave-convex graphics. By providing these concave-convex structures, the effective contact area provided by the slot can be further increased, so that the bonding performance of the encapsulant can be improved.

Next, the manufacturing method of the LED of the present invention will be described in detail.

Firstly, a substrate motherboard is provided, on which a plurality of LED light-emitting devices can be fabricated. As shown in FIGS. 4A-4B , a plurality of metal spacers have been fabricated on the substrate motherboard, and these metal spacers correspond to the position of an LED chip. Both sides of each metal pad are provided with conductive pads, and conductive metal lines connected with these conductive pads are provided on the back of the substrate. The manufacturing process of these metal pads, conductive solder joints and conductive metal lines is the existing technology in the field of LED manufacturing, and will not be repeated here.

A fishing groove is provided on the above-mentioned substrate, and the location of the fishing groove can avoid the prepared metal gasket and conductive solder joint. As shown in FIG. 4B , the grooves are mainly distributed on the edge of each LED and/or in the middle of both sides of the metal spacer. When there are multiple rows of LEDs on the substrate motherboard, a fishing groove can be provided between every two rows of LEDs, and this fishing groove can be used as a cutting groove in a subsequent cutting process. For example, the substrate motherboard shown in the figure can produce two rows of 4 LED light-emitting devices. It can be seen that one of the slots is located in the middle of the two rows of LED devices. However, it should be understood that after the subsequent cutting process, the The bar gutter will be split in half and each be a gutter for the edge of the LED device. Similarly, if the number of LED devices increases, the opening of corresponding slots will also increase, but a single LED device formed after cutting will roughly have the distribution of slots as shown in Figure 2. Specifically, the opening of the fishing groove can be formed by a molding process, a stamping process, or a casting process.

The LED chip is fixed on the metal pad, and then the wire welding process is performed, and the positive and negative poles on the LED chip are respectively connected to two conductive solder points through wires. After the wire bonding is completed, the current direction is isolated from the metal area of the chip, and there is no general-purpose electric circuit, so that the area under the chip is completely used for heat dissipation, improving heat dissipation performance. Then the encapsulation glue is pressed to the front of the substrate through a molding process. During the press molding, all other non-metallic areas on the front are combined with the encapsulation glue to increase the bonding force and prevent delamination when the power is increased. Then the encapsulation glue is solidified, and the encapsulation glue can be flat or spherical after curing, which is usually selected according to different applications. These chip fixing processes, wire bonding processes, and molding and curing of packaging adhesives are all prior art, and will not be repeated here.

Finally, the above substrate mother board is cut to form individual LED devices. When cutting, you can follow the special cutting line and avoid the already opened fishing groove. And on some substrate motherboards with multiple rows of LEDs, the slots made in the middle of each row of LEDs can also be used as cutting slots. After cutting, the slots in this part become "half slots" and are distributed in the edge of the device, as shown in Figure 2.

To sum up, the present invention proposes an LED packaging structure and a manufacturing method of the LED. The packaging structure adopts a larger metal spacer to fix the LED chip, so as to improve the heat dissipation capability of the LED chip. In addition, the bonding area of the encapsulation adhesive and the substrate is increased by opening a scoop on the surface of the substrate, so as to improve the bonding strength of the encapsulation adhesive and offset the negative impact of enlarging the metal area.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. the encapsulating structure of a LED, comprise substrate, LED chip and be used for LED chip to be encapsulated in the packaging plastic on substrate, it is characterized in that: the front of described substrate is provided with the metallic gasket that fixing described LED chip is used, the area of this metallic gasket is at least greater than described LED chip, be provided with two conductive welding spots in the both sides of this metallic gasket, these two conductive welding spots are conducting to the both positive and negative polarity on LED chip in the conducting metal lines that is positioned at substrate back, the front of described substrate is also provided with some grooves that drag for, and these drag for groove and avoid described metallic gasket and two conductive welding spots and establish.

2. encapsulating structure as claimed in claim 1, is characterized in that: described in drag for groove marginal position be provided with concaveconvex structure.

3. encapsulating structure as claimed in claim 1, is characterized in that: described substrate is the one in glass, quartz, resin or pottery.

4. encapsulating structure as claimed in claim 1, is characterized in that: the back side of described substrate is also provided with heat abstractor, and described metallic gasket runs through described substrate and contacts with described heat abstractor heat conduction.

5. encapsulating structure as claimed in claim 1, is characterized in that: the both sides of described substrate are also provided with the metal electrode for doing electrical LED electric performance test, and this metal electrode runs through substrate and is connected with the conducting metal lines that is positioned at substrate back.

6. a LED manufacture method with the encapsulating structure described in claim 1-5 any one, is characterized in that, comprises step:

One substrate motherboard is provided, on described substrate motherboard, comprise multiple metallic gaskets, the position at the corresponding LED chip place of metallic gasket described in each, the both sides of every metallic gasket are all provided with conductive welding spots, are provided with the conducting metal lines being connected with these conductive welding spots at substrate back;

On aforesaid substrate, offer and drag for groove, drag for the position of groove and avoid described metallic gasket and conductive welding spots;

LED chip is fixed on metallic gasket, then carries out wire bonds technique, the both positive and negative polarity on LED chip is connected with two conductive welding spots respectively by wire;

Packaging plastic is pressed into substrate front side by mould pressing process, and carries out solid type;

Finally, aforesaid substrate motherboard is carried out to cutting technique, form a LEDs device.

7. LED manufacture method as claimed in claim 6, is characterized in that: described in drag for groove and be distributed in the marginal position of every LEDs and/or the centre position of metallic gasket both sides.

8. LED manufacture method as claimed in claim 6, is characterized in that: Gu after type, described packaging plastic be planar shaped or spherical in one.

9. LED manufacture method as claimed in claim 6, is characterized in that: in the time having many row LED on substrate motherboard, arrange one and drag for groove, cutting groove when this drags for groove simultaneously as cutting technique between every two row LED.

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