TWI402460B - LED wick and LED chip and manufacturing method - Google Patents

Description

LED wick and LED chip and manufacturing method

The invention relates to the field of LED technology; in particular to an LED wick and a heat conduction technology in an LED chip.

LED heat dissipation is a key technical issue in the current promotion of LED lighting. Since the LED chip needs to dissipate heat, the LED illuminator should be like a current incandescent lamp and a fluorescent lamp. The wick (bulb) is a standardized component and is easy to install, adding a layer of difficulty. LED lighting, luminaires and wicks have not yet achieved relatively independent, and easy to assemble standardized components, thus making them more costly.

From the simple heat transfer analysis, LED heat dissipation is only a normal temperature heat transfer process, which is not complicated. However, due to the knowledge of heat transfer and mature heat transfer technology, and other basic knowledge related to heat transfer are not fully recognized by the LED industry, the current LED heat dissipation technology and products are complicated, in the initial stage.

The heat transfer process from the LED junction to the air convection heat transfer surface (ie, the heat sink) is a heat conduction process. Since the LED wafer area is small and the heat flux density is very high, the heat conduction process is very important in the heat dissipation of the entire LED. The most effective and simple way to reduce the thermal resistance of the heat conduction process is to use high thermal conductivity materials such as copper and aluminum, high thermal conductivity, low material cost, and easy processing. However, copper and aluminum are metal conductors. As an LED lighting fixture for electrical appliances, electrical safety requirements must be met. A certain high insulation requirement must be achieved between the LED junction and the heat sink (metal exposed component). Generally, the withstand voltage should reach thousands. Volt insulation requirements. Insulation and heat conduction are contradictory. In current products, LED chips are often placed on a ceramic insulating lining, which is solved by using ceramics with high withstand voltage and low thermal conductivity. Although ceramics, such as Al ₂ O ₃ ceramics, have a thermal conductivity of up to 20 W/m‧K, they are ten times smaller than aluminum and nearly twenty times smaller than copper. The heat flux density on LED wafers is as high as 10 ⁶ W/m ² ; The mm ₂ thick Al ₂ O ₃ insulation lining only has a thermal conduction temperature difference of 10 ° C on the insulating lining, and the processing cost of the 0.2 mm thick Al ₂ O ₃ ceramic sheet is not low. It is common to use a low thermal conductivity solid-state adhesive (typically silver paste) to hold the wafer, which in turn results in a very high thermal temperature difference between the wafer and the insulating liner.

The object of the present invention is to address the heat conduction process in the heat dissipation process of the LED. First, to solve the problem of heat conduction in the actual wick standardization; Second, the contradiction between heat conduction and insulation in the LED chip, propose a technical solution with simple structure and low cost.

The technical solution of the present invention: the LED wick mainly comprises a wafer, a heat diffusion sheet and a heat conductive core, and the heat generated by the wafer is transmitted to the heat conductive core through the heat diffusion sheet, and then transferred to the heat sink by the heat core. The invention is characterized in that: the heat conducting core adopts aluminum or copper; the contact heat transfer surface of the heat conducting core and the heat sink (ie, the heat conducting core heats outward) adopts a conical column structure, or a threaded column structure or a tapered stud structure. The wafer is soldered to the heat diffusion sheet; the area of the heat diffusion sheet is more than five times the wafer area, the thickness is not less than 0.5 mm, and the copper or aluminum or copper-aluminum composite material is used; the heat diffusion sheet and the heat conductive core are disposed between The high voltage insulating layer has a thickness of more than 0.1 mm.

The heat conducting core adopts a conical column structure, and the fins also have matching conical holes. As long as the pushing force is small, the contact pressure between the biconducting surface of the heat conducting core and the conical surface of the fin is obtained. The contact thermal resistance is reduced, the tapered hole and the conical column are easy to be formed, the matching precision is easy to ensure, the cost is low, and the installation is convenient. Since the surface area of the threaded cylinder is enlarged, the contact heat transfer area is enlarged, and the thermal resistance between the heat conducting core and the heat sink is reduced. For example, the ordinary 60 ^O triangular thread has a surface area twice that of the cylindrical surface. The LED wick is installed in the heat sink (lamp) by rotating, and the tool can be omitted, and the operation is convenient. The tapered stud structure combines the advantages of a tapered column structure and a threaded column structure: large contact pressure and large contact area for easy installation. By adopting the heat conducting core of the invention, the problem of heat conduction between the LED wick and the heat sink is solved, and the assembly of the LED wick is facilitated, thereby solving the primary problem of the standardization of the actual LED wick.

Although the heat diffusion sheet of the present invention is similar to the heat sink of the current product and the heat transfer process, the present invention firstly clarifies one of the important functions - thermal diffusion, and is called a heat diffusion sheet. Because the LED chip has a small area, such as a 1×1mm wafer, even if the power consumption is 1.2W, the heat density reaches 10 ⁶ W/m ² , which is very high, thus solving the problem of contact thermal resistance between the wafer and the heat diffusion sheet. It became the primary problem, and the problem of electrical insulation between the two was second. The welding process, even with the lowest cost soldering, the thermal conductivity of metallic tin is as much as 60W/m‧K, which is more than ten times higher than that of advanced thermal paste. Therefore, the wafer is soldered and soldered to the heat diffusion sheet. The heat conduction temperature difference between the wafer and the heat diffusion sheet will be effectively reduced. As a heat diffusion sheet, the heat diffusion sheet should not only be made of a material having high thermal conductivity, but also have a large area and thickness. Therefore, the heat diffusion sheet is made of copper and aluminum, and the area of the heat diffusion sheet is required to be more than 5 times the thickness of the wafer. Not less than 0.5mm, the design is preferably to select not less than 10 times the wafer area. If the wafer is 1×1mm, 1W, the thickness of the heat diffusion sheet should be 1.0mm or more. The purpose and function is to make the heat in the heat diffusion sheet. Effective diffusion reduces the heat flux density between the heat diffusion sheet and the heat conductive core. In order to meet the insulation problem required by the electrical safety specification, it can be solved by a high-voltage insulation layer between the heat diffusion sheet and the heat-conducting core.

In the present invention, the high voltage insulating layer is defined as an insulating layer having a DC voltage resistance of 500 V or more.

It is proposed that the thickness of the high-voltage insulating layer between the heat diffusion sheet and the heat-conducting core is greater than 0.1 mm. If an Al ₂ O ₃ ceramic insulating layer is used, the DC voltage of 0.1 mm is up to 1 kV, which is to allow the heat diffusion sheet to The insulating layer between the thermal conductive cores bears the insulation requirements of most or all of the safety regulations, reduces the insulation requirements between the wafer and the heat diffusion sheet, or does not consider the insulation between the two at all, so as to reduce the transmission between the two. The temperature difference is hot.

If soldering is used between the wafer and the heat diffusion sheet, the thickness of the tin between the two is 20 μm. Under the heat flux of 10 ⁶ W/m ^{2 , the} heat transfer temperature difference between the two interfaces can be calculated as Δt=0.32 °C. According to the heat diffusion sheet, if the heat flux density is reduced by 8 times to 1.25×10 ⁵ W/m ² , the high-voltage insulation layer between the heat diffusion sheet and the heat-conducting core is 0.2 mm thick Al ₂ O ₃ ceramic, and the thermal conductivity is 20 W/ m‧K, the heat transfer temperature difference Δt=1.25°C at the high-voltage insulation layer is calculated, that is, the sum of the heat conduction temperature differences of the two interfaces in the LED wick is within 2°C. If a 0.2 mm thick Al ₂ O ₃ ceramic insulating sheet is placed between the wafer and the heat diffusion sheet (heat sink) (a current product structure), only the heat transfer temperature difference between the two sides of the ceramic sheet can be calculated as Δt = 10 ° C, which is As much as five times as described above, it can be seen that the heat conduction temperature difference in the LED wick can be significantly reduced by the invention. In the following specific embodiments, the LED wick of the present invention is further illustrated to facilitate the advantages of waterproof sealing, mass production, and standardization.

For the LED chip component composed of a wafer and a heat diffusion sheet, the present invention also proposes a specific structure and manufacturing method from the viewpoint of reducing thermal resistance, reducing cost, and facilitating manufacturing.

1. The heat diffusion sheet is made of aluminum or copper or copper-aluminum composite material; the solder contact area of the wafer and the heat diffusion sheet is larger than one third of the wafer area; the heat diffusion sheet is provided with a high voltage insulation layer or a low voltage insulation layer; The insulating layer is an aluminum oxide film grown directly from the surface of the metal aluminum on the heat diffusion sheet by anodization, the thickness of the film being greater than 50 μm; the low-voltage insulating layer is formed by a ceramic insulating film formed by vapor deposition, or by anodizing An aluminum oxide film grown directly from the surface of the metal aluminum on the heat diffusion sheet, the film thickness being less than 50 μm.

Second, the pn junction electrode of the wafer is a V-type electrode, and the flip-chip structure is adopted; the heat diffusion sheet is made of copper or aluminum or copper-aluminum composite material; the heat-dissipating pad is disposed on the wafer; the solder joint contact area between the wafer and the heat diffusion sheet is larger than One-third of the wafer area; the outside of the n-junction and the p-junction or part of the p-junction on the wafer is covered by a ceramic insulating film formed by vapor deposition, and the thermal pad is disposed outside the ceramic insulating film.

Third, the LED chip adopts a wafer positioning piece made of an insulating sheet, and the wafer positioning piece is soldered or bonded on the heat diffusion sheet, and the wafer is embedded in the wafer positioning insert in the positioning piece, and the wafer is soldered on the heat diffusion sheet.

A method for manufacturing an LED chip package, characterized in that: a wafer positioning plate is used, a plurality of wafer positioning inserts are opened on the wafer positioning plate, and no less than two positioning holes; corresponding on the heat diffusion sheet Pad and positioning hole; the wafer is first fixedly embedded in the wafer positioning insert, and then attached to the heat diffusion sheet together, and then heated together for the soldering process of the wafer and the heat diffusion sheet; or the wafer positioning board is first attached to the heat diffusion sheet Then, the wafer is embedded in the wafer positioning insert, and then heated together to perform the soldering process of the wafer and the heat diffusion sheet.

As shown in FIG. 1, the heat conducting core 6 adopts a conical column structure, and the conical cylinder surface (ie, the heat transfer surface of the heat conducting core outward) is in close contact with the central tapered hole of the heat sink 3, and heat is passed through the contact surface from the heat conducting core. 6 is transmitted to the heat sink 3, so the gap between the contact faces should be as small as possible, that is, the matching precision is high and the contact pressure is large. The tapered column and the tapered hole are easy to process and the accuracy is easy to ensure. As long as the pushing force is small, the contact pressure can be enlarged by several times. In the figure, the screw 5 is used to tighten the heat conducting core 6 tightly on the heat sink. 3 in the center of the tapered hole. In order to further reduce the thermal contact resistance between the thermal conductive core and the heat sink, a thermal paste such as rouge should be applied to the cylinder or the hole.

Although the thermal conductivity of aluminum is not as good as that of copper, the price of aluminum is low and it is easier to form, for example, by using a hot press injection process to produce an aluminum heat conductive core, which is high in efficiency and low in cost; and because the heat flux density in the heat conductive core has been lowered, In view of cost of manufacture, the heat conductive core is preferably made of aluminum.

As shown in FIG. 1, there is only one heat diffusion sheet 2, and a plurality of wafers 1 are disposed (welded) on the heat diffusion sheet 2, and the heat diffusion sheet 2 is attached to one end surface of the heat conduction core 6 through the high voltage insulation layer 4, and the end surface will be It is called the heat absorbing surface, and the opposite end, that is, the end provided with the screw 5 is called the heat conductive core rear end. The side of the heat diffusion sheet that is in close contact with the heat absorbing surface of the heat transfer core is referred to as the B side of the heat diffusion sheet, and the side on which the wafer is placed is referred to as the A side of the heat diffusion sheet.

The use of ceramic sheets as the high-voltage insulation layer has the following problems: First, the processing cost of the ceramic sheets is not low and brittle; Second, there is a problem of interface contact thermal resistance between the ceramic sheets and the heat diffusion sheets and the heat-conducting core, if a welding process is employed , low efficiency and high cost. If the gluing process is used, the contact thermal resistance is high. The anodization process is used to directly grow an aluminum oxide film from the surface of the metal aluminum on the heat conductive core or the heat diffusion sheet. As the high voltage insulation layer, the contact thermal resistance between the high voltage insulation layer and the heat diffusion sheet or the heat conduction core is eliminated. The anodizing process is low in cost and high in efficiency, and is suitable for mass production. The aluminum oxide film formed by anodization has pores, and the pores are unfavorable for heat conduction and insulation. The sealing treatment should be performed, for example, using insulating varnish or paraffin, preferably using a resin having a high thermal conductivity. The hard anodization process and micro-arc oxidation (also known as micro-plasma oxidation or anode spark deposition) process produce a thicker aluminum oxide film that is more suitable for the fabrication of high-voltage insulation layers.

The LED wick shown in FIG. 2, the heat conducting core 6 adopts a threaded column structure, and also adopts a single piece heat diffusion sheet structure, but the wafer 1 is collectively disposed (welded) at the center of the heat diffusion sheet 2, and in the heat diffusion sheet 2 The A side is provided with a low voltage insulating layer 8. With the insulating layer, a circuit and pads corresponding to the wafer and electrode leads can be disposed on the A side of the heat diffusion sheet, and those auxiliary elements (such as an antistatic protection element) can be disposed together with the wafer in thermal diffusion. On-chip, packaged together, this structure is highly integrated and easy for downstream production. Due to the high heat flux density of the wafer, it is particularly important to reduce the thermal conductivity of the insulating layer. The dielectric strength is not important. It is not necessary to meet the requirements of the electrical safety specification. As long as the highest value of the voltage used is reached, the 220V mains peak voltage can reach 380V. That is to say, the dielectric strength of the insulating layer is up to 450V, which is low-voltage insulation, and the insulating layer is called a low-voltage insulating layer.

Ceramic membranes produced by vapor deposition, such as diamond, SiC, AlN, BN, BeO, Al ₂ O _{3 ,} etc., dense, good insulation, high thermal conductivity, especially diamond, SiC, AlN, BN BeO is a highly thermally conductive ceramic, and can be used not only for the low-voltage insulating layer on the surface of the heat diffusion sheet A in the present invention, but also for the ceramic insulating film on the wafer to be described later. The vapor deposition process includes physical vapor deposition (PVD) and chemical vapor deposition (VCD), both of which can be used to fabricate the low voltage insulating layer of the present invention.

Although the ceramic film produced by the vapor deposition process has high density and high thermal conductivity, it can also produce a highly thermally conductive ceramic film, but the thickness of the ceramic film is thin (several micrometers), and the cost is high, especially to obtain a ceramic with a pressure of several hundred volts. The film (having a film thickness of 10 μm or more) has a higher cost. The aluminum anodizing process can also be used in the manufacture of the low-voltage insulating layer of the heat-dissipating sheet A surface of the present invention, although the thermal conductivity of the produced aluminum oxide film is not as high as that of the vapor deposition process, but the cost is low, and a thick film is easily obtained. The insulation strength reaches 100V or more. When designing, the thickness of the aluminum oxide film of the low-voltage insulation layer should be less than 50μm, and the thermal resistance of the heat conduction should be controlled.

Although copper is more expensive than aluminum, it is not easy to be formed. However, since the amount of the heat diffusion sheet material is very small, the shape is simple (sheet shape), the manufacturing is easy, and more importantly, the heat flux density of the wafer is high, and the material having high thermal conductivity is more important. Therefore, the heat diffusion sheet should first use copper. In order to form an anodized aluminum oxide layer on the surface of the copper heat diffusion sheet, a copper-aluminum composite material should be used, and a layer of aluminum is coated on the surface of the copper plate. The thickness of the aluminum layer on the surface of the heat diffusion sheet A is thin, and the thickness thereof is sufficient for the aluminum thickness required for anodization.

As shown in FIG. 3, according to an LED wick of the present invention, the heat conducting core 6 adopts a tapered stud structure, and is further provided with a lamp cover 12 through which the lead wire 9 passes through the heat conducting core 6 and is led out from the rear end of the heat conducting core. The electrical connection structure is not only compact, easy to assemble, but also easy to achieve a waterproof and insulating seal with high requirements for the wick. As shown in the figure, at the rear end of the heat-conducting core, the lead wire 9 is taken out, and the sealant 10 is provided, which is very easy to realize the lead-out of the lead wire 9 and a reliable waterproof and insulating seal. The waterproof and insulating seal of the front end of the wick can be realized by the lamp cover 12 and the potting sealant. Waterproof insulation is very important for outdoor appliances such as street lamps. The lampshade 12 not only functions as a waterproof insulation for the wick, but also functions as optical reflection, condensing, and the like.

Each of the wafers in FIG. 3 is provided with a heat diffusion sheet, that is, a multi-LED chip structure, and the high voltage insulation layer 4 is provided not only on the heat absorbing surface of the heat conduction core but also on the B surface of the heat diffusion sheet, and thus a single LED chip. With high voltage insulation properties. Such a structure is particularly suitable for forming an aluminum oxide insulating layer by an anodizing process. For example, to achieve an insulation strength of 2 kV, the thickness of the aluminum oxide film is 200 μm, and it is difficult to use single-sided growth, if it is divided into two sides. , respectively, grow 100μm thick, the difficulty is reduced, and the density is higher, and the thermal conductivity is also better. The figure shows a PCB board 11 in which an LED chip is embedded in the PCB board 11. The auxiliary circuit of the LED chip can be placed on the PCB board 11, and the lead wire 9 is also soldered to the circuit on the PCB board 11.

The wick in Figure 3 is connected to the external power supply by lead type. It can also be connected by terminal type or contact or touch pad type. The terminal block or contact (contact pad) is placed at the rear end of the heat conducting core, and the connecting wire (lead wire 9) ) passing through the heat conducting core, ie embedded in the heat conducting core. The LED wick shown in Fig. 4 employs a contact type structure in which the contacts 13 on the wick are in contact with the spring contacts 14 fixed to the heat sink 3, just like the existing bulbs. The plug-in electrical connection structure is a contact type structure.

By using a dedicated heat transfer calculation software, the calculation of nine heat-transfer processes of 1×1mm, 1W heat-generating wafer in a heat sink shows that the junction temperature of the nine wafers is higher than that of the dispersion. Arrangement (when the distance between the two is 5mm) is much higher than 5°C. From the basic knowledge of heat transfer, it can also be analyzed that in order to reduce the thermal resistance of the thermal conduction, the LED chip on the thermal diffusion sheet or the LED chip composed of the wafer and the heat diffusion sheet should be dispersed as much as possible on the heat conduction core, and the power of the single wafer is exhausted. It may be small and the number is as much as possible. Figure 5 is a plan view showing the dispersion of six wafers on a heat diffusion sheet. Fig. 6 shows that four LED chips are arranged on the heat conducting core 6, and each chip has a wafer set of three wafers. In practical design applications, there are multiple wafers that must be grouped together and inseparable. For example, three wafers in a three-color white LED chip cannot be separated. When designing the LED wick, the number of wafers or chipsets should be as large as possible, at least not less than three or three groups, but too much quantity will lead to an increase in production cost; the power of a single wafer should be as small as possible, and the maximum power should not be greater than 4W, but too small a single chip power means that the increase in the number of wafers will likely lead to increased costs. The wafers or wafer sets (chips) of Figures 5 and 6 are all radially dispersed and dispersed, such that the radial dispersion arrangement is most reasonable.

The LED wick shown in Fig. 7 has a central portion of the heat conducting core 6 and is provided with a heat dissipating fin 7. This structure is designed for a high power LED wick because the wick has a large power, a large number of wafers or chips, and a radial direction. The dispersion is arranged in a dispersed manner, so that the outer diameter of the heat conducting core is particularly large, and the central portion is vacant, and the heat dissipating fins 7 are used to increase the heat dissipating area, which not only reduces the volume of the entire fin, but also reduces the aluminum material for heat dissipation.

In the LED chip of FIGS. 3, 4, and 7, a high-voltage insulating layer 4 is disposed on the B surface of the heat diffusion sheet 2. If the high-voltage insulating layer is to be formed by anodization of aluminum, the heat diffusion sheet 2 should be made of aluminum or copper-aluminum composite. Material, preferably copper-aluminum composite material. The wafer is soldered to the heat diffusion sheet, which can effectively solve the problem of high thermal conduction temperature difference caused by high heat flux density, but must ensure sufficient welding contact area. The present invention considers that the solder contact area between the wafer and the heat diffusion sheet should be not less than one third of the wafer area, and the area of the heat diffusion sheet should be greater than 5 times (preferably not less than 10 times) of the wafer area, and the thickness is not Less than 0.5mm.

As shown in FIG. 8 , the pn junction electrode is an L-contact (Laterial-Contact), which is simply referred to as an L-type electrode. The LED wafer of the tantalum carbide substrate is suitable for such an electrode type. Since SiC can be doped into a conductor, the tantalum carbide substrate can serve as an n-junction electrode, and the outer surface of the substrate 15 is provided with a heat-conductive pad 16, that is, an n-pole pad, and the area of the heat-conductive pad is also the wafer 1 The welding contact area with the heat diffusion sheet 2. The A surface of the heat diffusion sheet 2 in FIG. 8 is provided with a low-voltage insulating layer 8 which can be obtained by vapor deposition or aluminum anodization, and a corresponding heat-conductive pad (ie, an n-pole lead) should be provided on the surface of the low-voltage insulating layer 8. Pad) and n-pole leads. The LED chip shown in FIG. 9 is similar to that shown in FIG. 8. The main difference is that, in FIG. 9, the thermal conductive pad 16 on the substrate 15 is directly soldered to the metal on the heat diffusion sheet 2, in the B of the heat diffusion sheet 2. The surface is provided with a high voltage insulating layer 4 which can be obtained by anodizing aluminum.

As shown in FIG. 10, the pn junction electrode is a V-contact (Vertical-Contact), referred to as a V-type electrode, and adopts a flip-chip structure, also called a flip chip structure, and the LED chip of the sapphire substrate is suitable for use. Electrode type. The figure shows that the thermal pad 16 is directly soldered to the metal surface of the thermal diffusion sheet 2, the thermal pad 16 is in communication with the p junction electrode 20, the thermal pad 16 is also the p pad, the thermal pad 16 and the p junction electrode 20 ceramic insulating films 21 are formed by vapor deposition. The heat diffusion sheet 2 is also a p-pole lead, and the p-pole of the chip can be directly soldered to the heat diffusion sheet 2. A high-voltage insulating layer 4 is provided on the surface B of the heat diffusion sheet 2, and can be formed by anodization of aluminum. The A-plane of the heat diffusion sheet 2 is provided with an n-pole lead 18, and an electrode lead insulating layer 19 is interposed therebetween. The n-pole lead 18 has a pad thereon and is directly soldered to the n-pole pad 17 on the wafer 1. The solder contact area between the wafer 1 and the heat diffusion sheet 2 includes the area of the heat conductive pad 16 and the area of the n-pole pad. If the area of the heat conductive pad 16 is sufficiently large, the problem of heat conduction resistance of the electrode lead insulating layer 19 is Not important. As can be seen from FIGS. 11 and 12, the n junction electrode 22 and the partial p junction electrode 20 are covered by the ceramic insulating film 21, and the heat conduction pad 16 is outside the ceramic insulating film 21, so that the ceramic insulating film structure is used as much as possible The area of the thermal pad is increased, that is, the solder contact area between the wafer and the heat diffusion sheet.

The LED chip shown in FIG. 13 is similar to that shown in FIG. 10, and the V-shaped electrode and the flip-chip structure are different in that the n junction electrode 22 and the p junction electrode 20 (excluding the pads) are all covered by the ceramic insulating film 21. The thermally conductive pad 16 is spaced apart from the p-pole pad 23 and is insulated from the two electrodes, see FIGS. 14 and 15. The A surface of the heat diffusion sheet 2 is further provided with a p-pole lead 24 and is provided with an electrode lead insulating layer 19.

A 1×1mm large LED chip is a large-sized wafer. The electrode pad and the thermal pad are disposed on such a small area. As shown in FIGS. 11 and 14, the size of the electrode pad is generally as small as 0.1 mm in diameter. It must be ensured that short-circuit soldering should not occur, so the alignment accuracy of the wafer and the heat diffusion sheet is high. Generally, eutectic soldering is used, and the heating time takes a few seconds. If one-to-one alignment and reheating are used, the required equipment is not only high and expensive, but also has low production efficiency. High-power LED chip package, low efficiency and high cost, is also a major problem in the LED industry.

The present invention provides a method for using a wafer positioning plate to solve the above problems. As shown in FIGS. 16 and 17, a plurality of wafer positioning inserts are opened on a wafer positioning plate 25, and the wafer 1 is embedded in the wafer positioning insert. The wafer positioning plate 25 is also provided with a positioning hole 26, which is illustrated as having six positioning holes 26, and the positioning holes are designed to be at least two. The punching process is used to process the positioning hole 26 and the wafer positioning insert, which has high precision, simple equipment and high efficiency. The heat diffusion sheet 27 is provided with corresponding positioning holes, and the corresponding pads on the wafer are disposed on the basis of the positioning holes. The position of the wafer is determined by the wafer positioning insert on the wafer positioning plate 25, and the wafer positioning plate 25 and the heat diffusion sheet 27 are aligned by the positioning holes 26, thereby ensuring the pads and the heat diffusion sheets on each wafer. The corresponding pad alignment is accurate, and then the whole is heated and soldered together, and several wafers are soldered at one time (55 in the figure). This method is not only efficient but also simple in equipment. When heating and soldering, pressurization is required to force the wafer to be attached to the heat diffusion sheet to ensure the soldering quality. Since the wafer is embedded in the wafer positioning insert, it is easy to ensure that it is not displaced when pressurized. There are two kinds of steps: First, the wafer 1 is firstly embedded and fixed in the wafer positioning plate 25, positioned by the positioning holes 26, and then attached together on the heat diffusion sheet 27, and then heated together to carry out the welding process of the wafer and the heat diffusion sheet. Second, the wafer positioning plate 25 is positioned by the positioning hole 26, first attached to the heat diffusion sheet 27, and then the wafer 1 is embedded in the wafer positioning insert, and then heated together to perform the welding process of the wafer and the heat diffusion sheet. After the soldering is completed, the wafer positioning plate can be removed or retained. As shown in FIGS. 19 and 20, the wafer positioning plate which is slit and left in the LED wafer is referred to as a wafer positioning sheet 28. At this time, the wafer positioning sheet 28 should be Insulating material can be used, and high temperature resistant polyester film can be used.

The above method not only makes the wafer and the heat diffusion sheet have accurate alignment, high welding efficiency, simple equipment, but also is advantageous for the subsequent process efficiency improvement. For example, after the wafer and the heat diffusion sheet are welded, the large sheet is first cut into one piece. The strips, that is, the wafers and the heat diffusion sheets are arranged in a row, and the lead pins of the chip are also processed into corresponding arrangement, so that the electrodes can be welded once and aligned, and the sealant can be filled at once, and then cut into one. LED chip.

Referring to FIG. 18, a method of producing the LED chip of the single heat diffusion sheet multi-wafer structure shown in FIG. 5 by the above process of the present invention is employed. The large wafer positioning plate and the heat diffusion plate are processed by a punching process to process the wafer positioning pieces and the heat diffusion sheets connected in a row. When the processes of the alignment welding and the filling and sealing are completed, the connected parts are cut into one. A LED chip.

As shown in FIG. 19, an LED chip with a wafer positioning piece is provided with an electrode lead and a pad (or circuit) on the wafer positioning piece 28. The wafer in the figure uses an L-shaped electrode, the thermal pad 16 is also an n-pole pad, and the n-pole 18 is led out from above through the wafer positioning piece 28, and the p-pole lead 24 is disposed on the wafer positioning piece 28, p on the wafer The pad pads 23 are soldered to the pads on the p-pole leads 24 by wires 29. In the LED chip shown in Fig. 20, the electrode pads (p-pole pads 23) on the wafer are placed against the edge of the wafer (preferably at the corners), and the electrode leads (p-pole leads 24) on the wafer positioning sheet 28 are provided. The pads are in close proximity to the corresponding pads on the wafer (p-pole pads 23), and the two electrode pads are soldered directly by solder 30 (such as tin).

The LED chip with a wafer positioning piece shown in FIG. 21 adopts a V-shaped electrode and a flip-chip structure. The A surface of the heat diffusion sheet 2 is provided with a low-voltage insulating layer 8, and the B surface is provided with a high-voltage insulating layer 4, and the low-voltage insulating layer 8 is provided. Electrode leads (n-pole leads 18, not shown in the p-pole lead diagram), and thermally conductive pads (also p-lead lead pads) are provided. The LED chip shown in Fig. 22 is similar to that of Fig. 21. The V-shaped electrode and the flip-chip structure are significantly different in that the n-pole pad 17 is disposed on the sidewall of the wafer, and the pad of the n-pole lead 18 on the wafer positioning piece 28 is tight. The pads are soldered directly by solder 30 by pads on the sidewalls of the wafer (n-pole pads 17).

Referring to the LED chip shown in FIG. 23 and FIG. 24, the four corners of the wafer are cut into a quarter circle, and the n-pole pad 17 and the p-pole pad 23 on the wafer are disposed in the four corner-shaped sidewalls. And the diagonal distribution; the ceramic insulating film 21 covers a whole surface of the wafer, the thermal conductive pad 16 is insulated from the two electrodes, the thermal diffusion sheet 2 is a pure metal plate, and the thermal conductive pad 16 on the wafer directly diffuses with the heat. Sheet metal welding. Such a structure is advantageous for increasing the area of the thermal conductive pad (welding contact area) and reducing the alignment accuracy requirement.

As shown in Figures 11, 14, and 24, the electrode pads are all disposed at the corners, and of course, may be disposed near the edge of the wafer, but at the corners, it is more advantageous to make full use of the wafer area to obtain more illuminating regions. The n-pole and p-pole pads shown in Figures 14 and 24 are all at the corners and are diagonally distributed, and the wafer is rectangular. Such a structure is advantageous for preventing alignment errors of the two electrode pads.

In order to increase the light extraction rate, a reflective film should be provided on the outer surface of the wafer positioning piece to reflect the light reflected on the surface of the wafer positioning piece.

(1). . . Wafer

(2). . . Heat diffusion sheet

(3). . . heat sink

(4). . . High voltage insulation

(5). . . Screw

(6). . . Thermal core

(7). . . Heat sink fin

(8). . . Low voltage insulation

(9). . . Lead wire

(10). . . Plastic closures

(11). . . PCB board

(12). . . lampshade

(13). . . Contact

(14). . . Elastic contact

(15). . . Substrate

(16). . . Thermal pad

(17). . . N-pole pad

(18). . . N-pole lead

(19). . . Electrode lead insulation

(20). . . P junction electrode

(twenty one). . . Ceramic insulating film

(twenty two). . . N junction electrode

(twenty three). . . P-pad

(twenty four). . . P pole lead

(25). . . Wafer positioning board

(26). . . Positioning hole

(27). . . Heat diffusion sheet

(28). . . Wafer positioning piece

(29). . . wire

(30). . . solder

1 is a schematic cross-sectional view of a LED wick equipped with a heat sink according to the present invention. The heat conducting core is a conical column structure, showing the cooperation relationship between the wick and the heat sink.

2 is a schematic cross-sectional view of a LED wick according to the present invention, the heat conducting core being a threaded column structure.

3 is a schematic cross-sectional view of a LED wick according to the present invention. The heat conducting core is a tapered stud structure and is provided with a lamp cover, showing the lead wire structure and sealing waterproof features.

4 is a schematic cross-sectional view of a LED wick equipped with a heat sink according to the present invention, showing the electrical connection between the wick and the luminaire (heat sink) using a resilient contact and a contact structure.

5 and 6 are schematic views of wafer distribution on an LED wick in accordance with the present invention, showing that the wafer or wafer set is radially spaced apart and dispersed as uniformly as possible.

7 is a schematic cross-sectional view of a high power LED wick according to the present invention, with a central portion penetrating and provided with heat dissipating fins.

8 and 9 are respectively schematic cross-sectional views of two LED chips according to the present invention, and the pn junction electrode is an L-type electrode, which is particularly suitable for a wafer of a tantalum carbide substrate.

10 is a schematic cross-sectional view of a LED chip according to the present invention. The pn junction electrode is a V-type electrode and is a flip-chip structure. The thermal pad and the p-pole pad are integrated, and are particularly suitable for a wafer of a sapphire substrate.

Figure 11 is a schematic diagram of the wafer according to the chip of Figure 10, showing p, n junction electrodes and their pads, ceramic insulating film, thermally conductive pads, showing n-pole pads at four corners.

Figure 12 is a schematic view of the ceramic insulating film and the thermally conductive pad according to Figure 11.

Figure 13 is a schematic cross-sectional view showing the characteristics of an LED chip according to the present invention.

Fig. 14 is a view showing the characteristics of a wafer in the chip shown in Fig. 13, showing p, n junction electrodes and their pads, a ceramic insulating film, and a thermal pad.

Figure 15 is a schematic view of the ceramic insulating film and the thermally conductive pad according to Figure 14.

16 and FIG. 17 are schematic diagrams showing the features of the wafer positioning plate in accordance with the present invention for ensuring the alignment of the wafer and the heat diffusion sheet, and FIG. 17 is a schematic cross-sectional view of the structure of FIG.

Figure 18 is a schematic view showing the feature of the wafer positioning plate in accordance with the present invention to ensure the wafer and the heat diffusion sheet are aligned and welded.

19 and 20 are respectively schematic cross-sectional views of two LED chips using a wafer positioning sheet according to the present invention, and an L-type pn junction electrode suitable for a wafer of a tantalum carbide substrate.

21, 22, and 23 are respectively schematic cross-sectional views of three types of LED chips using a wafer positioning piece according to the present invention, a V-type pn junction electrode electrode, and a flip-chip structure.

Figure 24 is a schematic illustration of the characteristics of the wafer in the chip shown in Figure 23.

(2). . . Heat diffusion sheet

(4). . . High voltage insulation

(6). . . Thermal core

(9). . . Lead wire

(10). . . Plastic closures

(11). . . PCB board

(12). . . lampshade

Claims (11)

An LED wick comprising: a heat conducting core, a heat diffusion sheet and a wafer attached to the A side of the heat diffusion sheet, wherein the heat conducting core is made of aluminum or copper and the heat transfer surface of the heat conducting core is heat-transferred by a cone a column structure, or a threaded column structure or a tapered stud structure; the heat diffusion sheet is made of copper or aluminum material, or a copper-aluminum composite material, the heat diffusion sheet has a thickness of not less than 0.5 mm and an area larger than 5 times the area of the wafer; A high voltage insulating layer is disposed between the heat diffusion sheet and the heat absorbing surface of the heat conductive core, and the high voltage insulating layer has a thickness greater than 0.1 mm. The LED wick of claim 1, wherein the heat diffusion sheet has an area of not less than 10 times the wafer area. The LED wick according to claim 1 or 2, wherein the high voltage insulating layer employs an aluminum oxide film grown directly from the surface of the heat conductive core or the heat diffusion sheet or both of the metal aluminum by anodization. The LED wick according to claim 1 or 2, wherein the heat diffusing sheet has a low-voltage insulating layer disposed on the surface A, the wafer is attached to the low-voltage insulating layer, and the low-voltage insulating layer is passed through the gas phase. The resulting ceramic insulating film is deposited, or an aluminum oxide film grown directly from the surface of the metal aluminum on the heat diffusion sheet by anodization, the thickness of the aluminum oxide film being less than 50 μm. An LED chip comprising: a wafer and a heat diffusion sheet attached to the A side of the heat diffusion sheet, wherein the heat diffusion sheet is made of copper or aluminum or copper-aluminum composite material; the area of the heat diffusion sheet is greater than 5 times the area of the wafer. The thickness of the heat diffusion sheet is not less than 0.5 mm; the B surface of the heat diffusion sheet is provided with a high voltage insulation layer or the A surface of the heat diffusion sheet is provided with a low voltage insulation layer, or the A surface and the B surface of the heat diffusion sheet are respectively provided with a low voltage insulation layer and a high voltage insulating layer; wherein the high voltage insulating layer has a thickness greater than 0.1 mm; the low voltage insulating layer uses a ceramic insulating film formed by vapor deposition, or alumina grown directly from the surface of the metal aluminum on the heat diffusion sheet by anodization The film has a thickness of less than 50 μm. The LED wafer according to claim 5, wherein the heat diffusion sheet has an area of not less than 10 times the wafer area. The LED chip of claim 5, wherein the pn junction electrode of the wafer is a V-type electrode, and the LED wafer has a flip-chip structure; the wafer is provided with a thermal pad, and is soldered to the heat diffusion sheet. On the A side, the solder contact area between the wafer and the heat diffusion sheet is not less than one third of the wafer area; the n junction electrode and the p junction electrode or part of the p junction electrode on the wafer are deposited by vapor deposition on the outside. The resulting ceramic insulating film is covered, and the thermally conductive pad is outside the ceramic insulating film. An LED chip comprising: a heat diffusion sheet, a wafer and a wafer positioning piece, wherein the heat diffusion sheet is made of copper or aluminum material or copper-aluminum composite material; the heat diffusion sheet has an area larger than 5 times the area of the wafer, and the thickness is not less than 0.5 mm; The positioning piece is made of an insulating sheet material and is soldered or bonded to the A side of the heat diffusion sheet. The wafer positioning piece is provided with a wafer positioning insert, and the wafer is embedded in the wafer positioning insert on the wafer positioning piece. The LED wafer of claim 8, wherein the heat diffusion sheet has an area of not less than 10 times the wafer area. The LED chip according to claim 8 or 9, wherein an electrode pad is disposed on an edge or a corner of the wafer or a sidewall of the wafer, and a corresponding electrode lead is disposed on the wafer positioning piece, The pads on the electrode leads are adjacent to the corresponding electrode pads on the wafer, and the two pads are directly soldered by wires or solder. The LED chip according to claim 10, wherein the corner of the wafer is cut, and an electrode pad is disposed on a side wall of the notched corner of the wafer, and the wafer is positioned on the upper electrode lead of the wafer close to the wafer. The electrode pads on the corners, the two pads are directly soldered by solder.