CN1145225C - Chip type light emitting diode and manufacturing method thereof - Google Patents

Abstract

The invention relates to a chip type light emitting diode and a manufacturing method thereof, wherein silver is plated on the surface of a metal substrate, a plurality of wire frames are formed after etching, one end of each wire frame is bonded with a chip and is connected to the other end through a routing, the wire frames are sealed and cut to form the chip type light emitting diode, and the wire frames exposed at the bottom of the chip type light emitting diode form electrical contacts. The invention does not need to use a printed circuit board as a base material, can greatly reduce the volume, and can improve the routing efficiency and facilitate the operation because the metal substrate has the characteristics of heat conduction and magnetic attraction.

Description

Chip type light emitting diode and its manufacturing method

The invention relates to a chip type light emitting diode and a manufacturing method thereof.

As is generally known, light-emitting diodes (LEDs) have the advantages of long life, low power consumption, and low heat generation. Development and advent, such as light-emitting diodes for side light sources of mobile phone displays, are different from traditional light-emitting diodes in form. As shown in FIG. 10 , the figure shows the appearance of a traditional chip-type light-emitting diode before it is packaged and not divided. The structure of the chip-type light-emitting diode is that several parallel copper lines are formed on the surface of a printed circuit board 80 90, the adjacent inner sides of each copper circuit 90 are respectively extended to form several chip pads 91 and copper contacts 92, as shown in Figure 11, wherein the chip pads 91 are fixed with a chip 93 by silver glue, the chip 93 is the copper contact 92 that is punched to the opposite end with a gold wire by a wire bonding machine.

The bottom surface of the printed circuit board 80 is formed with several copper contacts, and each copper contact corresponds to the chip pad 91 and the copper contact 92 respectively, and the electrical connection is formed by through-hole electroplating; and the copper circuit on the bottom surface of the printed circuit board 80 for future welding.

The printed circuit board 80 is sealed after completing the steps of die bonding and bonding. As shown in FIG. The joint 92, the die bonding pad 91 and the die 93 thereon are completely sealed. Subsequent division is carried out in a cross-cutting manner perpendicular to the sealant layer 94. Since adjacent chip pads 91 and copper contacts 92 are connected to each other through copper lines 90, there is a series effect between adjacent light-emitting diodes, so it can be seen It is practical to separate into LED module assemblies with the right amount of light emitting chips.

Although the chip-type light-emitting diode is suitable for the side light source of the mobile phone display, the manufacturing process is too complicated, and the product qualification rate is low and the finished product is bulky.

First of all, in terms of manufacturing process, in the past, the circuit was first made on the printed circuit board 80, that is, the copper circuit 90, the chip pad 91 and the copper contact 92 were formed, and the surface of the copper contact 92 was sequentially plated with nickel oxide and Gold layer, during wire bonding, the gold wire is respectively punched on the chip 93 and the copper contact 92 by means of ultrasonic processing. Since there are nickel oxide and gold layers on the surface of the copper contact 92, a higher melting point is necessary to make the gold wire stable. However, due to the high speed of bonding, without the assistance of other heating measures, the stability of bonding cannot be improved. And after sealing glue and being divided into finished product, under working state, can make the epoxy resin that constitutes sealing glue layer 94 expand to the gold between chip 93 and copper contact 92 because of heat will be generated when wafer 93 shines. The line forms a pull. In the original design, this kind of thermal expansion and contraction has been estimated, so the gold wire will be given a tensile strength of at least 10g during wire bonding. However, as mentioned above, due to the lack of heating measures in the wire bonding step Auxiliary, so it is difficult to strengthen the bonding strength of the gold wire with a higher melting point. In this case, the chance of the gold wire being torn due to thermal expansion and contraction of the sealant layer 94 will be greatly increased, resulting in a decrease in the qualified rate of the finished product. Increased costs.

In addition, in terms of volume, as shown in FIG. 12 , since the light-emitting diode is based on a printed circuit board 80 as a base material, after the packaging is completed and divided, the printed circuit board 80 is also used as a part of the light-emitting diode. It has a considerable thickness, so it will increase the volume of the light emitting diode, which is not conducive to the miniaturization of products.

Therefore, the purpose of the present invention is to provide a chip-type light-emitting diode with small volume, low cost, high manufacturing efficiency and high yield of finished products and its manufacturing method.

In order to achieve the above object, according to one aspect of the present invention, the manufacturing method of the chip-type light-emitting diode of the present invention includes the following steps: using a metal substrate as a base material, and plating a silver layer on the surface and bottom surface of the metal substrate to improve its electrical connection. performance; image transfer and circuit etching are performed on the metal substrate to form several parallel wire frames on the metal substrate, and extend on the opposite sides of each wire frame to form chip pads and wiring parts; on the wire frame Chips are installed on the pads of the chips, and wires are bonded to connect the chips with the corresponding wiring parts; sealing is carried out on the metal substrate; and the metal substrate is divided to form a chip-type light-emitting diode.

In order to achieve the above object, according to another aspect of the present invention, the chip type light emitting diode of the present invention comprises a chip pad, a wiring portion positioned at the opposite direction of the chip pad, a chip fixed on the chip pad, a The gold wire connecting the chip and the wiring part and a sealant layer located on the surface of the chip pad and the wiring part; the chip pad and the wiring part are made of a metal substrate, and silver is formed on the surface and bottom of the metal substrate. layer, the bottom surface of which is used directly for contacts.

A blind hole is formed on the surface of the chip welding pad on the wire frame, and the chip is fixed therebetween by silver glue in the blind hole.

Adopt above-mentioned method of the present invention to make the advantage of wafer-type light-emitting diode as follows:

1. Significantly improve the pass rate of finished products: the present invention utilizes a sheet-like metal substrate as a base material, and directly forms a chip pad and a wiring part with a contact function on it for the purpose of installing crystal bonding wires; Since the metal substrate can be heated on the machine using the thermal conductivity characteristics during operation to improve the melting degree of the gold wire and the electrical connection ability, in this case, it can fully meet the requirement of 10g tensile strength, and the gold wire will not be damaged due to sealing. The adhesive layer expands with heat and contracts with cold and is torn off, so a very high pass rate of finished products can be obtained, which in turn can greatly reduce costs.

2. The volume is greatly reduced: because the present invention directly forms chip pads and wiring parts on the metal substrate, and makes it have the function of contacts, so it is not necessary to form copper circuit contacts on the surface and bottom respectively like printed circuit boards, As a result, the element has considerable thickness, so the volume of the light-emitting diode produced by the invention is greatly reduced, which is beneficial to the miniaturization of electronic products.

3. The manufacturing process is simple: Compared with the manufacturing method of the traditional chip-type light-emitting diode using the printed circuit board as the base material, the manufacturing process has been significantly simplified, and the efficiency and the qualified rate of the finished product can be improved.

4. Ideal heat dissipation effect: the chip pad and wiring part of the light-emitting diode produced by the present invention are used as contacts at the same time. When the chip is energized to generate heat, it can be directly dissipated through the chip pad and wiring part, so it has an ideal heat dissipation effect .

5. Low cost: The traditional production process is to sequentially plate nickel oxide and gold layers on the surface of the copper circuit of the printed circuit board. Among them, gold is a precious metal, and its manufacturing cost is naturally high. However, the present invention is to plate silver on the surface of the metal substrate, and its cost is much lower than that of the gold layer, so the cost is significantly reduced.

In order to further understand the purpose, features and advantages of the present invention, the present invention will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is the exterior view before metal substrate etching of the present invention;

Fig. 2 is the exterior view of the metal substrate of the present invention after the circuit is formed;

Fig. 3 is a partial plan view of the metal substrate of the present invention;

Fig. 4 is a sectional view of the metal substrate of the present invention;

Fig. 5 is an appearance diagram of the metal substrate of the present invention after crystal bonding;

Fig. 6 is an appearance diagram of the metal substrate of the present invention after sealing;

Fig. 7 is a cross-sectional view of the metal substrate of the present invention after sealing;

Fig. 8 is a sectional view of the divided metal substrate of the present invention;

FIG. 9 is an equivalent circuit diagram of the LED module assembly of the present invention.

Fig. 10 is the external view of the printed circuit board that adopts the manufacturing process of prior art to make;

Fig. 11 is a partial appearance view of a printed circuit board made by a manufacturing process in the prior art;

Figure 12 is a cross-sectional view of a printed circuit board produced using a prior art manufacturing process.

The method for making the wafer-type light-emitting diode of the present invention comprises the following steps:

"Substrate making": select a sheet-like metal substrate 10 as the base material, as shown in Figure 1, in order to improve the electrical connection effect on the surface of the metal substrate 10, a metal layer of an ideal conductor is plated on it, in this embodiment , is to plate the silver layer of appropriate thickness on the surface and the bottom surface of this metal substrate 10 respectively, to improve its electrical connection;

"Formation of lines": steps such as image transfer and line etching are carried out on the metal substrate 10, and several parallel wire frames 11 are formed on the metal substrate 10, as shown in Figures 2 and 3, adjacent wire frames 11 The space between them is hollow, and several chip pads 12 and connection parts 13 are respectively extended on the opposite sides of each wire frame 11. In this embodiment, the several chip pads 12 formed on the sides of each wire frame 11 and the wiring portions 13 are arranged equidistantly, and each chip pad 12 corresponds to a wiring portion 13;

A blind hole 120 is formed on each of the chip bonding pads 12 , as shown in FIG. 4 , for accommodating the chip; a tiny hole 130 is also formed on the wiring portion 13 for enhancing the electrical connection ability of wire bonding.

"Installation and wire bonding": install the chip 14 on each chip pad 12 of the wire frame 11 as shown in the fifth figure. Specifically, it is fixed in the blind hole 120 on the chip pad 12 by silver glue The wafer 14; after the crystal loading is completed, wire bonding is performed immediately, and the wafer 14 is connected to the opposite wiring portion 13 by the gold wire 15;

Since the metal substrate 10 is made of metal flakes, it has ideal heat conduction and magnetic properties, so during operation, the machine carrying the metal substrate 10 can be heated, and the wire bonding can be performed under the heated state, and the gold wire 15 can be provided. The melting degree and the electrical connection strength with the chip 14 and the wiring part 13. In addition, if an electromagnet is installed on the machine table, it can generate a magnetic attraction effect on the metal substrate 10 on it, so that the metal substrate 10 can be flatly fixed on the machine table to facilitate operation.

"Sealing": sealing on the metal substrate 10, in this embodiment, using a mold to form a strip-shaped sealing layer 16 between adjacent wire frames 11, as shown in Figures 6 and 7, so that Enclose the chip pads 12, wiring parts 13 and the chips 14, gold wires 15, etc. on the adjacent wire frame 11;

"Segmentation": Divide the metal substrate 10 to form an independent single light-emitting diode or several series-connected modular light-emitting diodes; Divide in the direction of the light emitting diode, since the chip bonding pad 12 of each light emitting diode is connected to the wiring part 13 of another light emitting diode through the wire frame 11, so the light emitting diodes in the horizontal direction already have a series form, which can be seen Actually, it is necessary to divide and obtain the required number of LED module assemblies; as shown in FIG. 8 , the figure shows the structure of a module assembly with two LEDs, and its equivalent circuit is shown in FIG. 9 . Because the present invention utilizes the metal substrate 10 as the base material, it constitutes the chip pad 12 and the wiring portion 13 respectively through the circuit forming steps. The bottom of portion 13 naturally constitutes an electrical connection point for soldering to the circuit board.

A chip type LED of the present invention comprises a chip pad 12, a wiring portion 13 positioned on the opposite direction of the chip pad 12, a chip 14 fixed on the chip pad 12, a connection chip 14 and wiring The gold wire 15 of the part 13 and a sealant layer 94 located on the surface of the chip pad 12 and the connection part 13; the chip pad 12 and the connection part 13 are composed of a metal substrate 10, and its bottom surface is directly used for the contact 92. Silver layers are respectively formed on the surface and the bottom surface of the metal substrate 10 . A blind hole 120 is formed on the surface of the chip bonding pad 12 , and the chip 93 is fixed therebetween by silver glue in the blind hole 120 . Minute pores are formed in the connecting portion 13 . Several parallel wire frames 11 are formed on a sheet-like metal substrate, and the space between adjacent wire frames 11 is hollow, and the chip pads 12 and wiring parts 13 are respectively extended along the opposite sides of each wire frame 11 form.

Claims (13)

1. A method for manufacturing a wafer-type light-emitting diode, characterized in that it comprises the following steps: Using a metal substrate as a base material, and plating a silver layer on the surface and bottom surface of the metal substrate; Carrying out image transfer and line etching on the metal substrate to form several parallel wire frames on the metal substrate, and extending respectively on the opposite sides of each wire frame to form chip pads and wiring parts; Installing a chip on the chip bonding pad of the wire frame, and performing wire bonding, so that the chip is connected to the opposite wiring part; Carrying out glue sealing on the metal substrate; and The metal substrate is divided to form a chip-type LED. 2 . The method for manufacturing a chip-type light-emitting diode according to claim 1 , wherein the metal substrate is plated with silver layers on the surface and the bottom surface respectively, so as to improve its electrical connection. 3 . 3 . The method for manufacturing a chip-type LED according to claim 2 , wherein blind holes are formed on the surface of the chip bonding pads on the wire frame, and the chip is fixed in the blind holes with silver glue. 4 . 4. The method of manufacturing a chip-type light-emitting diode according to claim 3, wherein tiny pores are formed on the connection portion of the wire frame. 5 . The method for manufacturing a chip-type light-emitting diode according to claim 1 , wherein the wire bonding step is to connect the chip to the opposite wiring portion through a gold wire while the metal substrate is heated. 6 . 6. A chip-type light-emitting diode, characterized in that it includes a chip pad, a wiring portion positioned at the opposite direction of the wafer pad, a chip fixed on the wafer pad, a gold wire connecting the chip and the wiring portion and a sealant layer positioned on the surface of the chip pad and the wiring portion; the chip pad and the wiring portion are made of a metal substrate, and a silver layer is formed on the surface and bottom of the metal substrate, and the bottom surface is directly used for the contact . 7 . The chip-type light emitting diode as claimed in claim 6 , wherein silver layers are respectively formed on the surface and the bottom surface of the metal substrate. 8 . The chip-type light-emitting diode as claimed in claim 7 , wherein blind holes are formed on the surface of the bonding pads of the chip, and the chip is fixed therebetween by silver glue in the blind holes. 9. The chip-type light-emitting diode as claimed in claim 8, wherein tiny pores are formed on the connecting portion. 10. A metal substrate for making light-emitting diodes, which is characterized in that several parallel wire frames are formed on a sheet-shaped metal substrate, and the adjacent wire frames are hollow, and the relative distance between each wire frame is Wafer pads and connection parts are respectively extended on the sides, and silver layers are respectively formed on the surface and the bottom surface of the metal substrate. 11. The metal substrate for making light-emitting diodes according to claim 10, characterized in that, the surface and the bottom surface of the metal substrate are plated with a silver layer respectively. 12 . The metal substrate for making light-emitting diodes as claimed in claim 11 , wherein blind holes are formed on the surface of the chip bonding pads of the wire frame, and the chip is fixed therebetween by silver glue in the blind holes. 13 . 13. The metal substrate for manufacturing light-emitting diodes according to claim 12, wherein tiny pores are formed on the connection portion of the wire frame.

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