A projection light source module

Abstract

The application discloses a projection light source module, which comprises a light-emitting chip group composed of a plurality of LED light-emitting chips, a plate-shaped backing plate and a heat spreading device inlet, the heat spreading device inlet is a phase change heat transfer element and is provided with a plane bearing surface; the top surface of the backing plate is provided with a die bonding part, and the chip is die-bonded to the die bonding part through a die bonding layer; the bottom surface of the backing plate is provided with an integral fixing bonding layer, and the backing plate is fixed on the plane bearing surface through the fixing bonding layer. The material of the backing plate is heat-conducting ceramic, diamond copper, diamond aluminum or diamond; the temperature of die bonding is higher than the temperature of fixing the backing plate. The module passes through the straight-through structure of the chip-backing plate-heat spreading device inlet, and the thermal resistance layers such as the copper substrate and the heat-conducting interface layer in the prior art are omitted, meanwhile, the backing plate introduces a new material with high heat conductivity, so that the total resistance value of the thermal resistance cascade is greatly reduced, the junction temperature of the chip can be effectively controlled under the working condition of an ultrahigh driving current, and a more reliable solution is provided for exerting the high performance of the LED chip and improving the brightness of the projector.

Description

Technical Field

[0001] This invention relates to the field of semiconductor solid-state light source packaging technology, and more particularly to a light source module for a projector, specifically a through-type high thermal conductivity projection light source module that achieves ultra-high heat flux density heat dissipation by optimizing the heat conduction path. Background Technology

[0002] For the key thermal resistance cascading of the light source in most domestically produced LCD projectors, please refer to [link / reference needed]. Figures 1-2 As shown in the diagram: 1′ represents the LED chip, typically a blue LED chip with a size of 40-45 mil. The number of chips ranges from 5 strings of 3 parallel to 14 strings of 10 parallel, with hundreds of variations. The chips are closely spaced with a spacing of 5-8 mil, and the spaces between them are filled with white glue. The top surface of the entire chip area is covered with yellow phosphor to emit white light; 2′ represents the substrate (currently, aluminum nitride ceramic plates are commonly used in the industry), with a total thickness of approximately 0.35-0.45 mm and a thermal conductivity of approximately 170 W / (m·K). LED chip 1 The eutectic bonding is performed on the eutectic pad 21' on the front side (or top surface, top layer, TopLayer in Protel99 software, etc., without distinction) of the substrate 2'; 6' is a copper substrate, typically 1.5-1.6mm thick. The front side of the copper substrate 6' has thermoelectric separation pads corresponding to the bottom (or bottom layer) pad 22' of the substrate 2'. The substrate 2' is soldered onto the copper substrate 6'. Of course, connectors, NTCs, and other components are also mounted on the copper substrate 6', which is common knowledge and will not be elaborated upon. The back side of the copper substrate 6' is flush with the entrance for mounting the heat dissipation device (or heat dissipation channel, without distinction), such as... Figure 1 The aluminum block 34', solder layer 35', and heat pipe 3' are sequentially arranged in series. Figure 2 The aluminum block 38′ and heat pipe 3′ are placed side by side in the middle.

[0003] In the past two years, the industry has gradually and completely phased out conventional wafers. Currently, the vast majority of projection light sources are flip-chip wafers, with a small number using single-electrode (vertical electrode) wafers. Therefore, this invention does not involve conventional wafers.

[0004] The main difference between the thermal models of flip-chip and single-electrode chips lies in the thermal resistance Rj from the MQW layer to the die-bonding layer (or "die-bonding layer," which is not distinguished). This difference includes, but is not limited to, differences in mechanical stacking models, materials (such as the thermal conductivity difference of some materials by 4-5 orders of magnitude), optical models, and current congestion. Currently, the most widely used chips in the industry, such as Sanan's (e.g., model S-40CBFSD-B) or Jucan's 40mil flip-chip, or Sanan's 41mil (e.g., S-47ABPSD-C) single-electrode chip, all have excellent performance. However, after packaging and installing a heat dissipation system, their light-emitting characteristics are far from the original chip specifications. The fundamental reason is that the heat dissipation of the chip is significantly insufficient during the design and manufacturing of the packaging and the entire system.

[0005] The critical thermal resistance of the chip's heat dissipation channel consists of two parts connected in series. The first part is the thermal resistance Rj from the MQW layer to the die-bonding layer, which is an inherent property of the chip. The second part is the thermal resistance from the die-bonding layer to the inlet of the heat dissipation device, such as... Figure 10 as well as Figure 1 , Figure 2 The thermal resistance Ra (for aluminum nitride in liner 2) or Rd (for diamond copper in liner 2), R', and R" from the solidified layer to the inner wall of the heat pipe are innovative issues that projector manufacturers need to understand deeply and effectively improve.

[0006] Insufficient heat dissipation is mainly manifested in the fact that for chips of the above size (40-45mil), such as each flip chip after the driving current is ≥0.8-0.85A, and each single electrode chip after the driving current is ≥1.05-1.1A (efficiency inflection point), the light emission characteristics of the light source and the original characteristics provided in the chip datasheet gradually deviate as the current increases.

[0007] The optical spread (or "optical expansion") of an LED light source, determined by the aperture of the projection lens, is fixed. Once the optical spread area of ​​the light source is exhausted, increasing the drive current of the light source module is the simplest and most direct way to improve the output brightness of the projector. However, after the current reaches the efficiency inflection point mentioned above, further increases are unreasonable and futile. Therefore, using scientifically sound methods to significantly improve the current R' and R" is a problem that the industry urgently needs to solve. Summary of the Invention

[0008] In view of this, the present invention provides a projection light source module, which aims to solve the above-mentioned technical problems, including:

[0009] A light-emitting chip assembly, comprising a plurality of LED light-emitting chips; the bottom of each LED light-emitting chip is provided with a die bonding layer; The liner is a plate-shaped body; the liner has a top surface and a bottom surface opposite each other; the top surface of the liner is provided with a die bonding connection part, and the LED light-emitting chip is die bonded to the die bonding connection part through the die bonding bonding layer, and the die bonding temperature is t1; the bottom surface of the liner is provided with a full-surface fixed bonding layer; the material of the liner is any one of thermally conductive ceramic, diamond / copper composite material, diamond / aluminum composite material, or diamond. And the inlet of the heat expansion device, wherein the inlet of the heat expansion device is a phase change heat transfer element; The phase change heat transfer element has a planar bearing surface for supporting the liner; the liner is fixed on the planar bearing surface by the fixed bonding layer, and the temperature of the fixed liner is t2; The t1 is greater than the t2.

[0010] Through the above technical solution, the present invention directly fixes the LED light-emitting chip onto the planar bearing surface of the phase change heat transfer element via a high thermal conductivity substrate, eliminating the need for materials such as copper substrate and thermal interface layer in traditional solutions. This significantly shortens the heat transfer path and reduces the cascaded thermal resistance value. At the same time, the substrate is made of thermally conductive ceramic, diamond copper, diamond aluminum, or diamond, and the substrate itself has extremely low thermal resistance. Thus, it can control the junction temperature of the chip within a safe and efficient range under ultra-high power conditions where the driving current of each chip is greatly increased, significantly breaking through the heat dissipation bottleneck of projector brightness improvement.

[0011] Preferably, in the above-mentioned projection light source module, the material of the liner is diamond / copper composite material or diamond / aluminum composite material, and an anti-oxidation protective layer is provided on the side of the liner.

[0012] Preferably, in the above-mentioned projection light source module, the total thickness of the substrate, including the die bonding portion on its top surface and the fixed bonding layer on its bottom surface, is 0.3mm-0.8mm.

[0013] Preferably, in the above-mentioned projection light source module, the phase change heat transfer element is a heat pipe, and a flat surface is processed on the outer cylindrical surface of the heat pipe as the flat bearing surface. The width of the flat surface is not less than the width of the liner plate, and the length of the flat surface is greater than the length of the liner plate.

[0014] Optionally, in the above-mentioned projection light source module, the heat pipe blank is extruded and the flat surface is extruded simultaneously. The surface of the heat pipe is provided with a nickel plating layer. The area on the flat surface where the liner is fixed is provided with a solder resist window and at least three machine vision marks. The wall thickness of the area on the flat surface where the liner is fixed is 0.4mm-0.8mm after secondary processing.

[0015] Preferably, in the above-mentioned projection light source module, the phase change heat transfer element is a heat column, the heat column includes a base and a tube, the outer end face of the base is the planar bearing surface, and the base covers one end of the tube.

[0016] Furthermore, in the aforementioned projection light source module, the hot column further includes an end cap, an exhaust pipe, and a capillary structure layer; the end cap covers the end of the tube body away from the base, and a through hole is provided in the center of the end cap, into which the exhaust pipe is inserted; the joint between the base and the tube body, the joint between the tube body and the end cap, and the joint between the end cap and the exhaust pipe are all connected by fusion welding of the base material; the capillary structure layer is located inside the hot column and is arranged on the inner wall surface of the base and the inner wall surface of the tube body; the outer end of the exhaust pipe is sealed after the inside of the hot column is evacuated and liquid is injected.

[0017] Preferably, in the above-mentioned projection light source module, the local peak-to-valley difference in the area where the liner is fixed on the planar bearing surface is not greater than 0.04 mm, and the overall peak-to-valley difference is not greater than 0.06 mm.

[0018] Preferably, in the above-mentioned projection light source module, the die bonding temperature t1 is at least 40°C higher than the temperature t2 of the substrate.

[0019] Preferably, in the above-mentioned projection light source module, the top surface of the substrate is further provided with at least one lead pad, which is used to connect to an external driving circuit.

[0020] As can be seen from the above technical solution, compared with the prior art, the projection light source module provided by the present invention has the following beneficial effects: 1. Significantly shortens the heat transfer path and reduces the total thermal resistance: This invention eliminates the copper substrate and thermal interface layer in traditional solutions, allowing the heat generated by the LED light-emitting chip to be directly transferred to the planar bearing surface of the phase change heat transfer element through the substrate. This reduces the cascading of multiple thermal resistance layers and fundamentally solves the problems of long heat dissipation paths, excessive thermal resistance, and low driving current in existing technologies.

[0021] 2. Fully utilize the heat dissipation potential of high thermal conductivity new material substrates, especially diamond copper, diamond aluminum or diamond as substrates. The substrates themselves have extremely low thermal resistance or even negligible thermal resistance, which allows the excellent thermal conductivity of advanced heat sink materials to be effectively utilized, thereby significantly increasing the driving current while maintaining high luminous efficiency.

[0022] 3. Supports ultra-high current drive, breaking through the bottleneck of brightness improvement: The combined effect of the above measures enables each 40-45mil chip to work stably and with high light output efficiency under a drive current of 2A, 3A or even greater. The chip junction temperature is controlled within the ideal range, maintaining high luminous efficiency while significantly improving the total luminous flux, providing a practical heat dissipation solution for projectors to output higher brightness. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a commonly used thermal resistance cascade in the prior art; Figure 2 This is a schematic diagram of another commonly used thermal resistance cascade in the prior art; Figure 3 This is a cross-sectional schematic diagram of Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the heat pipe shape in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the LED chip and substrate after die bonding in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the heat column in Embodiment 2 of the present invention; Figure 8 This is a cross-sectional view of the heat column in Embodiment 2 of the present invention; Figure 9 This is a schematic diagram of Embodiment 2 of the present invention; Figure 10 This is a schematic diagram of the thermal resistance cascade in Embodiment 1 of the present invention.

[0025] in: 1—LED light-emitting chip; 2—backing plate; 3—heat pipe; 4—heat column; 5—support; 21—Eutectic pad or electrode; 22—Pad or electrode; 23—Solder layer; 31—Plane; 32—Capillary layer; 41—Base; 411—Outer end face; 42—Pipe body; 43—End cap; 44—Exhaust pipe; 45—Capillary layer; 461—First weld; 462—Second weld; 463—Third weld. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1: See Figures 3 to 6 , Figure 10 As shown, this embodiment provides a projection light source module, including a light-emitting chip group, a substrate 2, and a heat expansion device inlet.

[0028] The light-emitting chipset includes several LED light-emitting chips 1. As is known, the bottom of the LED light-emitting chip 1 is provided with a die bonding layer 12. Currently, the die bonding layer 12 usually has two structures: one is a flip chip with two eutectic pads; the other is a single electrode chip with one eutectic pad (for eutectic bonding) or a metal electrode that does not support eutectic bonding (for silver paste sintering for die bonding).

[0029] The liner 2 is a plate-shaped body; the liner 2 has a top surface and a bottom surface, the top surface of the liner 2 is provided with a die bonding part 21, the LED light-emitting chip 1 is die bonded to the die bonding part 21 through the die bonding layer 12, and the die bonding temperature is t1 (Note: t1 is not necessarily a specific value, but a temperature change curve over a period of time); the bottom surface of the liner 2 is provided with a full-surface fixed bonding layer 22.

[0030] The material of the liner 2 is any one of thermally conductive ceramic, diamond / copper composite material, diamond / aluminum composite material, or diamond.

[0031] The inlet of the heat expansion device is a phase change heat transfer element; the phase change heat transfer element has a planar bearing surface for supporting the liner 2; the liner 2 is fixed to the planar bearing surface by a fixed bonding layer 22, and the temperature of the fixed liner 2 is t2. Similarly, depending on the process, t2 is not necessarily a specific value, but rather a temperature change curve over a period of time.

[0032] The constraint t1 is greater than t2, and the preferred condition t1-t2≥40℃ can be understood as follows: First, the minimum value of t1 must be greater than the maximum value of t2; second, if the minimum value of t1 minus the minimum value of t2 is ≥40℃, and the maximum value of t1 minus the maximum value of t2 is ≥40℃, then the subsequent process of fixing the bonding substrate 2 will have no quality risk to the preceding die bonding process; third, if the difference (taken as a positive number) between the die bonding time ω1 and the time ω2 for fixing the bonding substrate 2 is less than the smaller of ω1 and ω2, then certain points on the temperature change curve can be used as a criterion for whether a 40℃ difference exists. The above are all based on actual process control and are unrelated to this invention, so they will not be elaborated upon.

[0033] When the liner 2 is made of diamond / copper composite material or diamond / aluminum composite material, an anti-oxidation protective layer needs to be made on the four sides of the liner 2, because the copper or aluminum elements contained in the liner 2 are reactive and easily oxidized and corroded. At present, the protective film layer can be achieved by methods such as nickel plating, while techniques such as depositing silicon dioxide thin films can also achieve the protective function.

[0034] The total thickness of the liner 2, including the die bond connection 21 on its top surface and the fixed bonding layer 22 on its bottom surface, is 0.3mm-0.8mm. Currently, the material for the liner 2 in the industry is all aluminum nitride ceramic plate, with a thickness of 0.38mm being the most common. This is the preferred choice considering comprehensive factors such as post-eutectic stress, bending stiffness, thermal expansion, thermal resistance, and cost. This size is also widely used in other industries, and a certain standardization has naturally formed due to market demand. The thermal conductivity is approximately 170W / (m·K). See also Figure 1 , Figure 2As shown, the process of combining LED chip 1′, aluminum nitride ceramic plate (2′) and copper substrate 6′ is very mature and inexpensive; while the diamond copper material body is usually 0.5mm thick; diamond (polycrystalline) thickness is more common at 0.4-0.8mm, but cost is more sensitive to thickness.

[0035] In this embodiment, the phase change heat transfer element is a heat pipe 3. A plane 31 is machined on the outer cylindrical surface of the heat pipe 3 as a plane bearing surface. The width of the plane 31 is not less than the width of the liner plate 2, and the length of the plane 31 is greater than the length of the liner plate 2.

[0036] The heat pipe 3 preform is extruded and a blank plane 31 is extruded simultaneously. The surface of the heat pipe 3 is coated with a nickel layer (this process is carried out after the secondary processing of the plane 31). Solder mask windows and at least three machine vision marks are provided in the area on the plane 31 where the liner 2 is fixed. The wall thickness of the area on the plane 31 where the liner 2 is fixed after secondary processing is 0.4mm-0.8mm. If the thickness is too thin, it will affect the strength, making it difficult to complete the efficient and low-cost secondary processing while ensuring accuracy. It will also cause the liner 2 to bear unnecessary stress after reflow soldering, which is difficult to release and may affect the life of the chip. If it is too thick, it will not only increase the cost, but also affect the normal heat transfer (thermal resistance R3, see below). The 0.8mm thickness limit is the upper limit summarized in practice, and 0.45-0.55mm thickness is usually preferred.

[0037] Before or after the bonding of the liner 2 and the heat pipe 3 in this embodiment is completed, see [reference needed]. Figure 6 Depending on the situation, it may be necessary to first fix the heat pipe 3 to the bracket 5, and then automatically bond the liner 2 to the heat pipe 3 (at this time, the bracket 5 acts as a fixture for reflow soldering). Alternatively, after the bonding is completed, the light source module needs to be fixed to the bracket 5 and installed onto the required position on the projector's optical system via the bracket 5. The structure, material, and shape of the bracket 5 are common structural features, and it only serves a structural function, so they are not limited. The connection between the heat dissipation facilities of the heat expansion device, such as fins, fins, etc. (not shown in this invention, and not limited thereto), and the heat pipe 3 may also need to be achieved through the cooperation of the bracket 5.

[0038] The local peak-to-valley difference in the area where the liner 2 is fixed on the planar bearing surface (planar surface 31) of the heat pipe 3 is no greater than 0.04 mm, and the overall peak-to-valley difference is no greater than 0.06 mm. This is to ensure the quality of the fit with the liner 2. Specifically, after the heat pipe 3 completes the sealing process, this dimensional specification is obtained through a secondary machining method of milling or grinding. After completing the above processing steps, the surface of the heat pipe 3 is nickel plated, and then solder resist windows and machine vision marks are made in the area where the liner 2 is fixed on the planar surface 31 for subsequent automated production processes.

[0039] The top surface of the substrate 2 is also provided with at least one lead pad for connecting external driving circuits, such as the specific light source of a "serial" or "parallel" chip, which will lead out two pads, "+" and "-" (e.g. Figure 5 P1 and P2 (shown) are connected to the external driving circuit. However, this invention can input a much larger current to the LED light-emitting chip 1 than in the prior art, for example, 3A per chip, then 5 groups in parallel would be 15A, which is more complicated to handle in terms of both wire diameter and cost for the leads and pads. An alternative approach is to only bring out one of the "+" or "-" terminals on the lead pads on the substrate 2, and the other terminal is energized by processing the substrate 2 (for aluminum nitride or diamond materials, a guide post needs to be made to pass through the body of the substrate 2 to the bottom fixed bonding layer 22; for diamond copper, a certain part of the top insulating layer needs to be etched away), and the other terminal is connected to the heat pipe 3 or a heat expansion device at the same potential as the heat pipe 3. This is more practical and flexible. Therefore, there is no limitation on the number of lead pads connected to the external circuit, as long as they can handle large currents and the hardness of the leads does not cause mechanical peeling damage to the pads.

[0040] The following explanations are provided for this embodiment: "Diamond / copper composite material" and "diamond / aluminum composite material," abbreviated in the industry as "diamond copper" and "diamond aluminum" respectively (the same throughout), are new materials that have been widely used in some highly popular industries in recent years. The "plate-like body" mentioned in this invention refers to a cuboid, where the length and width dimensions are much larger than the thickness. For example, a common aluminum nitride substrate 2 with 11 strings of 7 parallel-arranged 43mil wafers has dimensions of 15mm in length, 9mm in width, and 0.38mm in thickness; a diamond copper substrate 2 with 9 strings of 5 parallel-arranged 41mil wafers, fabricated with a lead pad, has dimensions of 12.5mm in length, 6.02mm in width, and 0.5mm in thickness. Clearly, the length and width dimensions are an order of magnitude larger than the thickness.

[0041] For projector applications, taking the Sanan S-47ABPSD-C single-electrode chip, with an average spacing of 8 mil and a quantity of 9 strings and 5 parallel die bonded onto a 12.5mm × 6.02mm diamond-copper substrate 2 as an example, in 2023, the price of diamond-copper of this size was not yet affordable, but by 2026, its procurement price would be completely acceptable for high-end domestic LCD projectors. Currently, different suppliers of diamond-copper use slightly different manufacturing methods, while the back-end PCB processes are largely similar, resulting in slightly different cost-effectiveness and thermal conductivity. For example, one currently available diamond-copper has a thermal conductivity of 723 W / (m·K), which represents a revolutionary advancement for LED packaging heat sink materials.

[0042] The diamond substrate 2, such as a sandwich structure currently available from the supply chain, consists of double-sided copper clad plates (approximately 55μm thick copper on one side) sandwiching a (polycrystalline) diamond plate (475μm thick). The diamond plate has a thermal conductivity of 1320W / (m·k), and according to the calculation conditions in the table below, its thermal resistance is <0.009℃ / W, which is negligible for the projection light source. It is well-suited for small-sized LCD light valves (e.g., 2-2.7 inches) because it uses fewer chips, resulting in a smaller die-bonding area and relatively lower cost for substrate 2. It can drive a larger current to achieve the desired luminous flux. For example, replacing the existing 6-series 4-parallel chips driving 0.8A current with 4-series 2-parallel chips driving 3A can maintain the overall cost without increasing the projector's image quality (allowing for a larger F# for the projection lens), thus enhancing product competitiveness.

[0043] The LED chip 1 is die-bonded to the die-bonding connection portion 21 of the substrate 2 via a die-bonding bonding layer 12. Specifically, the LED chip 1 and the substrate 2 are die-bonded by eutectic bonding or silver paste sintering. If the die-bonding bonding layer 12 of the LED chip 1 is a eutectic pad, the die-bonding connection portion 21 of the substrate 2 is preferably a eutectic pad, and the two are die-bonded by eutectic bonding. If the die-bonding bonding layer 12 of the LED chip 1 is a metal electrode that does not support eutectic bonding, then the die-bonding connection portion 21 of the substrate 2 is also a metal electrode, and die-bonding is achieved by filling with silver paste. The choice of die-bonding method is determined by the structural characteristics of the die-bonding bonding layer 12 of the LED chip 1, and both die-bonding methods have extremely low thermal resistance.

[0044] The fixed bonding layer 22 on the bottom surface of the backing plate 2 is specifically made into a full-surface solder pad or electrode, and is connected, fixed or bonded to the plane 31 by filling low-temperature solder paste reflow soldering or silver paste sintering.

[0045] The advantages of this embodiment will now be quantitatively explained: Since the thermal resistance model of a single-electrode chip (Rj=Rsi+R12) is relatively simple, we will take the Sanan S-47ABPSD-C chip (bottom P electrode is the eutectic pad), 8mil spacing, and 9 series and 5 parallel components as an example for illustration: Figure 10 In this context, Ra or Rd represents the thermal resistance from the die-bonding layer to the inlet of the heat expansion device. It is formed by the following thermal resistances in series: R21 (the thermal resistance of the die-bonding connection 21 at the top of the substrate 2, which is the eutectic pad in this case); R2 (the thermal resistance of the substrate 2 body itself); R22 (the thermal resistance of the bonding layer 22 at the bottom of the substrate 2, which is the pad in this case); R23 (the thermal resistance of the bonding layer 23 between the substrate 2 and the heat pipe 3, which is the solder in this case); and R3 (the thermal resistance of the wall thickness at the plane 31 of the heat pipe 3). Ra (or Rd) = R21 + R2 + R22 + R23 + R3. For closely packed wafers, the lateral diffusion of each thermal resistance level is not detailed.

[0046] Figure 1 In the prior art, the thermal resistance R′ from the die-bonding layer to the inlet of the heat expansion device is composed of R21′, R2′, R22′, R26′, R6′ (thermal resistance of copper substrate 6′), R7′ (thermal resistance of interface layer), R34′ (thermal resistance of aluminum block), R35′ (thermal resistance of solder layer), and R3′ (thermal resistance of heat pipe 3′ thickness) connected in series: R′=R21′+R2′+R22′+R26′+R6′+R7′+R34′+R35′+R3′.

[0047] Figure 2 In the prior art, R″ is composed of R21′, R2′, R22′, R26′, R6′, R7′, and R3′ connected in series: R″ = R21′ + R2′ + R22′ + R26′ + R6′ + R7′ + R3′.

[0048] We can set R21=R21′, R2 (aluminum nitride material)=R2′, R22=R22′, and R23=R26′ to perform calculations under the same conditions.

[0049] therefore, Figure 10 The thermal resistance from the MQW layer to the inlet of the heat expansion device in this invention is R8 = Rj + Ra (or Rd); Prior art Figure 1 The thermal resistance from the MQW layer to the inlet of the heat expansion device is R9′=Rj+R′; Existing technology Figure 2 The thermal resistance from the MQW layer to the inlet of the heat expansion device is R10′=Rj+R″.

[0050] Figure 1 , Figure 2 , Figure 10 The quantitative thermal resistance of a specific LED light source thermal model is shown in the table below:

[0051] In the table above, the thickness of the diamond copper is 0.5 mm, which is the body thickness, and the thermal conductivity is 723 W / (m·k); the thickness of the copper-clad insulation facility (die bonding part 21) is 5.5 μm, and the thermal conductivity is ≥10 W / (m·k). Since the projection light source does not require a dielectric strength greater than 3KV, the thickness of the insulation facility can be flexibly adjusted. For example, if a breakdown voltage greater than 86V is sufficient (when the chip has 11 series and 7 parallel, and the current is 3A and the voltage is about 3.9V), the thermal conductivity can be significantly improved. These are specific engineering aspects and will not be discussed further.

[0052] The conditions for the subsequent analysis in this embodiment are as follows: ambient temperature 25°C, temperature difference between the two ends of the heat pipe 2°C, and temperature difference between the heat dissipation facility of the heat expansion device and the environment 15°C (after considering the aesthetics of the projector casing opening and fan noise).

[0053] The following explanations are provided based on the actual situation in the industry: Figure 2 The thermal resistance cascade model shown is theoretically superior to... Figure 1 (R9′ is 1.27 times larger than R10′), but in reality... Figure 2 However, this structural configuration is designed for mid-to-low-end products. Its advantages are low cost, but its disadvantages include poor thermal conductivity and inconsistent quality. Figure 1 For high-end products, the advantages are stable and reliable structure and good quality consistency, while the disadvantage is complicated manufacturing. The thermal interface layer 7′ also shows a similar situation, that is, the use of products with high thermal conductivity is often seen in mid- and low-end products. High-end products generally prefer entry-level Shin-Etsu 746 and 776, with thermal conductivity ranging from 0.92 to 1.2 W / (m·k).

[0054] According to the S-47ABPSD-C chip's datasheet, when the drive current is 1.1A (tube voltage approximately 3.3V), since the packaged light source module outputs white light instead of blue light, the heat generation can be indirectly measured by subtracting the integrating sphere's optical power from the electrical power, or by using other methods to directly measure the heat source's heating power. The measured heat generation is approximately 120W. Figure 1 The existing technology chip has an MQW layer temperature of 101°C and a luminous efficiency of about 84%. At this point, the chip's operating conditions can no longer meet the quality requirements of the projector.

[0055] When the S-47ABPSD-C wafer of this invention is operating at a current of 2A (tube voltage approximately 3.6V), the measured heat dissipation power is approximately 255W. This indicates that the temperature of the wafer's MQW layer is either 58.5℃ (substrate 2 is aluminum nitride) or 55℃ (substrate 2 is diamond copper). If 255W of heat is applied to... Figure 1 , Figure 2 The existing technology shown has an MQW layer temperature of 167℃ and 140℃, at which point the wafer can no longer function properly. The advantages of this invention compared to the existing technology are self-evident. In addition, the thermal resistance at each level above does not account for the impact of cavitation (or voids, without distinction). In reality, cavitation is a process-related issue that can be optimized and improved to reasonable specifications.

[0056] In the application of diamond copper in this invention, the thermal resistance difference ΔR8 is reduced by approximately 1.3 times compared to aluminum nitride, demonstrating its value as an advanced material. Diamond, on the other hand, can reduce ΔR8 by 1.9 times compared to aluminum nitride. Regarding existing technologies, [the following is a more detailed description of the technology:] Figure 1 If R2′ in R9′ is changed from 0.03 (aluminum nitride) to 0.0165 (diamond copper), the thermal resistance difference ΔR9′ will only decrease by about 2.7%, and the iterative value of advanced materials is not obvious.

[0057] Example 2: See Figures 7 to 9 As shown, this embodiment provides a projection light source module, including: a light-emitting chip group, a substrate 2, and a heat dissipation device inlet.

[0058] The light-emitting chip group includes several LED light-emitting chips 1, and the bottom of the LED light-emitting chips 1 is provided with a die bonding layer.

[0059] The liner 2 is a plate-shaped body; the liner 2 has a top surface and a bottom surface opposite each other. The top surface of the liner 2 is provided with a die bonding connection part. The LED light-emitting chip 1 is die bonded to the die bonding connection part through the die bonding bonding layer. The die bonding temperature is t1. The bottom surface of the liner 2 is provided with a full-surface fixed bonding layer.

[0060] The material of the liner 2 is any one of thermally conductive ceramic, diamond / copper composite material, diamond / aluminum composite material, or diamond.

[0061] The inlet of the heat amplification device is a phase change heat transfer element.

[0062] The phase change heat transfer element has a planar bearing surface for supporting the liner 2; the liner 2 is fixed to the planar bearing surface by a fixed bonding layer, and the temperature of the fixed liner 2 is t2.

[0063] t1 is greater than t2, and t1 is at least 40°C higher than the temperature t2 of the fixed liner plate 2. For a detailed understanding, please refer to Example 1.

[0064] The liner 2 is made of diamond / copper composite material or diamond / aluminum composite material, and an anti-oxidation protective layer is provided on the side of the liner 2.

[0065] The total thickness of the liner 2, including the die bond connection on its top surface and the fixed bonding layer on its bottom surface, is 0.3mm-0.8mm.

[0066] In this embodiment, the phase change heat transfer element is a heat column 4, which includes a base 41 and a tube 42. The outer end face 411 of the base 41 is a planar bearing surface, and the base 41 covers one end of the tube 42.

[0067] The hot column 4 also includes an end cap 43, an exhaust pipe 44, and a capillary structure layer 45; the end cap 43 covers the end of the tube body 42 away from the base 41, and a through hole is provided in the center of the end cap 43, into which the exhaust pipe 44 is inserted; the joint between the base 41 and the tube body 42, the joint between the tube body 42 and the end cap 43, and the joint between the end cap 43 and the exhaust pipe 44 are all connected by fusion welding of the base material; the capillary structure layer 45 is located inside the hot column 4 and is arranged on the inner wall surface of the base 41 and the inner wall surface of the tube body 42; the outer end of the exhaust pipe 44 is sealed after the inside of the hot column 4 is evacuated and liquid is injected, such as by pressure welding.

[0068] The local peak-to-valley difference in the area where the liner 2 is fixed on the planar bearing surface (outer end face 411) is no greater than 0.04 mm, and the peak-to-valley difference in the overall area is no greater than 0.06 mm.

[0069] The top surface of the liner 2 is also provided with at least one lead pad, which is used to connect to an external drive circuit, as described in Embodiment 1.

[0070] The following are necessary additions to the specific implementation of this embodiment: The base 41, tube 42, end cap 43, exhaust pipe 44, and capillary layer 45 are made of copper, crystalline copper, or copper alloy; the outer diameter of tube 42 is Ψ; the base 41 is preferably, but not limited to, a cuboid or a cylinder, the length and width of the cuboid and the outer diameter of the cylinder are ≥Ψ; preferably, but not limited to, if Ψ < 18 mm, the thickness of the base 41 is 0.6 mm-1 mm, if Ψ ≥ 18 mm, the thickness of the base 41 is 1 mm-1.5 mm; preferably, but not limited to, Ψ ≥ the diagonal length of the top surface of the liner 2.

[0071] The joint between the base 41 and the tube 42 (first weld 461), the joint between the tube 42 and the end cap 43 (second weld 462), and the joint between the end cap 43 and the exhaust pipe 44 (third weld 463) are connected by base material fusion welding (such as automatic laser shielded welding) to ensure weld quality and welding efficiency. The capillary structure layer 45 (such as copper powder sintering process) is located inside the heat column 4 and is evenly distributed on the inner wall surfaces of the base 41 and the tube 42. The manufacturing process and special functions of the heat column 4 can be found in Chinese Patent Publication No. CN101846472A. As a standard material in the heat dissipation industry, this embodiment combines the characteristics of the domestic projector industry and the LED packaging conditions of this industry to make it better suited to the needs of this industry.

[0072] In this embodiment, various installation structures (such as through holes, snap-fit, etc.) can be easily made on the base 41. Heat expansion devices can be installed on the condensing end of the tube body 42 and the end cap 43. One option is to tightly connect the heat column 4 with the heat dissipation facility of the heat expansion device, for example, by pressing the heat column 4 into the central hole of the hollow sunflower profile.

[0073] In the consumer electronics industry, the maximum diameter of heat pipes is typically 10mm-12mm. Excessively large diameters not only take up more space but also make them unsuitable for the cost-effectiveness of domestically produced LCD projectors. Referring to the structural differences between the sintered capillary structure 32 of heat pipe 3 and the capillary layer 45 of heat column 4, it can be seen that the heating efficiency (including contact area and method) and circulation efficiency of the working fluid in heat pipe 3 are far lower than those in heat column 4. If the power density of the LED light source further increases, for example, 12 series 7 parallel, 2A current per crystal, or 9 series 5 parallel, 3A current per crystal, then heat pipe 3 in Example 1 (e.g., 10mm in diameter) will enter a saturated state and struggle to efficiently complete heat transfer. Even if the liner 2 is fixed in the middle of heat pipe 3 and both ends of heat pipe 3 are connected to heat dissipation facilities, heat column 4 of this embodiment is necessary to achieve efficient and low-loss heat transfer.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0075] The above description of the disclosed embodiments enables those 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 invention is not to 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

1. A projection light source module, characterized in that, include: The light-emitting chip group includes a plurality of LED light-emitting chips (1), and the bottom of the LED light-emitting chips (1) is provided with a die bonding layer; The liner (2) is a plate-shaped body; the liner (2) has a top surface and a bottom surface opposite each other; the top surface of the liner (2) is provided with a die bonding connection part; the LED light-emitting chip (1) is die bonded to the die bonding connection part through the die bonding layer; the die bonding temperature is t1; the bottom surface of the liner (2) is provided with a full-surface fixed bonding layer; the material of the liner (2) is any one of thermally conductive ceramic, diamond / copper composite material, diamond / aluminum composite material or diamond; And the inlet of the heat expansion device, wherein the inlet of the heat expansion device is a phase change heat transfer element; The phase change heat transfer element has a planar bearing surface for supporting the liner (2); the liner (2) is fixed on the planar bearing surface by the fixed bonding layer, and the temperature of the liner (2) is fixed at t2; The t1 is greater than the t2.

2. The projection light source module according to claim 1, characterized in that, The liner (2) is made of diamond / copper composite material or diamond / aluminum composite material, and an anti-oxidation protective layer is provided on the side of the liner (2).

3. A projection light source module according to claim 1, characterized in that, The total thickness of the liner (2), including the die bond connection on its top surface and the fixed bonding layer on its bottom surface, is 0.3 mm to 0.8 mm.

4. A projection light source module according to claim 1, characterized in that, The phase change heat transfer element is a heat pipe (3). A plane (31) is machined on the outer cylindrical surface of the heat pipe (3) as the plane bearing surface. The width of the plane (31) is not less than the width of the liner (2), and the length of the plane (31) is greater than the length of the liner (2).

5. A projection light source module according to claim 4, characterized in that, The tube blank of the heat pipe (3) is extruded and the blank plane of the plane (31) is extruded simultaneously. The surface of the heat pipe (3) is provided with a nickel plating layer. The area on the plane (31) where the liner (2) is fixed is provided with a solder resist window and at least three machine vision marks. The wall thickness of the area on the plane (31) where the liner (2) is fixed is 0.4mm-0.8mm after secondary processing.

6. A projection light source module according to claim 1, characterized in that, The phase change heat transfer element is a heat column (4), which includes a base (41) and a tube (42). The outer end face (411) of the base (41) is the planar bearing surface, and the base (41) covers one end of the tube (42).

7. A projection light source module according to claim 6, characterized in that, The hot column (4) also includes an end cap (43), an exhaust pipe (44), and a capillary structure layer (45); the end cap (43) covers the end of the tube body (42) away from the base (41), and a through hole is provided in the center of the end cap (43), and the exhaust pipe (44) is inserted into the through hole; the joint between the base (41) and the tube body (42), the joint between the tube body (42) and the end cap (43), and the joint between the end cap (43) and the exhaust pipe (44) are all connected by fusion welding of the base material; the capillary structure layer (45) is located inside the hot column (4) and is arranged on the inner wall surface of the base (41) and the inner wall surface of the tube body (42); the outer end of the exhaust pipe (44) is sealed after the inside of the hot column (4) is evacuated and liquid is injected.

8. A projection light source module according to any one of claims 1-7, characterized in that, The local peak-to-valley difference in the area where the liner (2) is fixed on the planar bearing surface is no greater than 0.04 mm, and the overall peak-to-valley difference is no greater than 0.06 mm.

9. A projection light source module according to claim 1, characterized in that, The solidification temperature t1 is at least 40°C higher than the temperature t2 at which the liner (2) is fixed.

10. A projection light source module according to claim 1, characterized in that, The top surface of the liner (2) is also provided with at least one lead pad, which is used to connect an external drive circuit.

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