High-power bar laser and manufacturing method thereof

Abstract

The invention discloses a high-power bar laser which comprises a bar stack array, an electrode plate, a thermistor, a transition heat sink, a TEC refrigerator and a base from top to bottom. The invention also discloses a manufacturing method, which comprises the following steps of: firstly, welding the bars and the heat sinks A into one light-emitting unit by using a primary solder, arranging a plurality of light-emitting units, then welding the bars of the adjacent light-emitting units and the heat sinks A together by using a secondary solder, welding the bar of the tail light-emitting unit and the heat sinks B, and packaging to obtain a bar stack array. And finally, sintering the base, the TEC refrigerator, the transition heat sink, the electrode plate and the bar stack array together from bottom to top by using a three-stage solder, packaging a surface-mounted thermistor on the transition heat sink after welding is completed, and bonding a gold wire to obtain the high-power bar laser. According to the invention, the diamond is selected to replace the existing tungsten copper, so that the light-emitting bending phenomenon of the bar can be effectively relieved, the problem of short circuit of the bar stack array due to the fact that the solder is connected with the stack array heat sink in the subsequent packaging process is solved, and the single light-emitting unit in the bar stack array has replaceability in combination with the process design of the multi-stage solder.

Description

Technical Field

[0001] The present invention belongs to the technical field of lasers, and in particular relates to a high-power bar laser and a manufacturing method thereof. Background Art

[0002] Semiconductor laser is a type of laser developed in the 1960s. Its working principle is to use the excitation method of injecting current to convert the electrical energy of the injected current into electro-optical through semiconductor materials and output laser.

[0003] Semiconductor lasers can be used as pump sources for fiber lasers and solid-state lasers. They can also be used to make direct semiconductor lasers and used as light sources in material processing, laser medical treatment, lidar and other fields.

[0004] With the increase in application requirements, there are higher requirements for the optical power and working stability of semiconductor lasers. In order to obtain higher output power, the most direct and effective way is to package multiple single-tube lasers into bars, and then package multiple bar array light sources side by side into a surface array light source to form a high-power bar stacked array semiconductor laser.

[0005] In the prior art, tungsten copper is commonly used as the heat sink material for clamping the bars in the stacked array, and the stacked array is sintered with gold, tin and Korean materials; then the packaged stacked array is first welded on the transition heat sink, and then welded on the metal base. This has at least the following problems: 1. The thermal expansion coefficients of the tungsten copper heat sink and the bar do not match. The thermal stress is concentrated on the bar, causing the bar to deform in the direction parallel to the slow axis. The force on each single-tube laser on the bar is uneven, causing the light to bend. Even excessive thermal stress can cause the bar to tear.

[0006] 2. When using tungsten copper heat sinks, solder may overflow and connect two or more heat sinks, causing a short circuit during the subsequent packaging and sintering process of the packaged bar stack.

[0007] 3. Due to its characteristics, Kim, Tin and Korean materials cannot be dissolved and reworked. The stacked array is usually composed of multiple bars. Once one of the bars fails during the packaging process, the entire stacked array will fail, increasing production costs and human resource investment.

[0008] 4. The power and wavelength of the bar are highly correlated with the operating temperature. At present, the electro-optical conversion efficiency of the domestic bar chip is about 50%. The continuous operation of the stacked array composed of multiple bars will generate a large amount of heat energy. The traditional solution connects the bar laser to an external temperature control system. The temperature modulation of the bar light-emitting area must pass through the metal base of the bar laser, the transition heat sink and the tungsten-copper heat sink before reaching the bar chip, which results in a long temperature control delay. Summary of the invention

[0009] In order to solve the above problems in the prior art, one of the objectives of the present invention is to provide a high-power bar laser.

[0010] The technical solution adopted by the present invention to solve its technical problems is: a high-power bar laser, including a base and a transition heat sink fixed on the base through a TEC cooler, the transition heat sink is respectively provided with a bar stack array and electrode sheets located on the left and right sides of the bar stack array, the transition heat sink is also provided with a chip thermistor and a gold wire located on the front and back sides of the bar stack array, the bar stack array is formed by a plurality of light-emitting units connected laterally, each light-emitting unit is composed of a diamond A heat sink with an "L"-shaped cross section and a bar welded on the inner side of the A heat sink, and a diamond B heat sink with an "I"-shaped cross section is welded to the outermost bar of the bar stack array.

[0011] In the high-power bar laser, the surface part of the A heat sink other than the bottom boss is plated with a metal layer; the surface part of the B heat sink is plated with a metal layer.

[0012] In the high-power bar laser, the thickness of the heat sink A and the heat sink B is 200-1000 μm, and the metal layer is a copper-clad gold-plated layer with a total thickness of 25-50 μm.

[0013] The transition heat sink of the high-power bar laser can be made of diamond or aluminum nitride, and has a copper-plated gold-plated pattern layer with a total thickness of 25 to 50 μm on its upper surface.

[0014] The base and electrode sheet of the high-power bar laser are both made of copper, and the surface is provided with a copper-plated gold layer with a total thickness of 25 to 100 μm.

[0015] The second object of the present invention is to provide a method for manufacturing a high-power bar laser, the steps of which are as follows: Step S1, using a first-level solder to weld the bar and the A heat sink together to form a light-emitting unit, and connecting and arranging a plurality of light-emitting units along a first direction to form a light-emitting unit array; Step S2, using secondary solder to weld the bars of adjacent light-emitting units in the light-emitting unit array and the outer side surface of the A heat sink along the first direction, and also using the secondary solder to weld the bars of the last light-emitting unit to the inner side surface of the B heat sink, and encapsulating to obtain a bar stack array; Step S3, using three-level solder to sinter the base, TEC cooler, transition heat sink, electrode sheet and bar stack array together from bottom to top, after welding, encapsulate the SMD thermistor on the transition heat sink and make gold wire to obtain a high-power bar laser.

[0016] Furthermore, in step S1, the primary solder is gold-tin solder, and its melting point is about 300°C.

[0017] Furthermore, in step S2, the secondary solder may be lead-tin or tin-silver solder, with a melting point between 200 and 250°C.

[0018] Furthermore, in step S3, the tertiary solder may be selected from indium-based alloy, bismuth-based alloy or tin-bismuth alloy, and the melting point is between 120 and 150°C.

[0019] The beneficial effects of the present invention are: 1. The heat sink material in the present invention uses diamond to replace the existing tungsten copper. The thermal expansion coefficient of diamond is 6×10 -6 m / mK and bar 5.9×10 -6 The thermal expansion coefficient of the m / mK is matched, which can effectively alleviate the luminous bending phenomenon of the bar.

[0020] 2. The present invention utilizes the insulating property of diamond to design the structure of the diamond heat sink used in the present invention, which can effectively solve the problem of short circuit caused by solder connection to the stacked array heat sink during the subsequent packaging process of the bar array, and combines the process design of multi-level solder to make the single light-emitting unit in the bar array replaceable.

[0021] 3. In the present invention, multiple light-emitting units are sintered together by secondary solder. If a problem occurs in the subsequent stacking due to failure of the bar in a single light-emitting unit, the secondary solder can be dissolved at a temperature that does not affect the primary solder to replace the single light-emitting unit, thereby avoiding replacement of the entire bar stacking array and saving production costs.

[0022] 4. Diamond has an ultra-high thermal conductivity of up to 2000W / (m*K), which can quickly transfer the heat energy generated by the light-emitting area of ​​the bar to the transition heat sink. The heat energy of the transition heat sink is then transferred to the base through the TEC cooler. The entire cooling system has the advantages of high cooling power and low temperature delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the high-power bar laser of the present invention; Figure 2 for Figure 1 A partial enlarged schematic diagram of the S part; Figure 3 It is a schematic diagram of the structure of heat sink A and heat sink B of the present invention; Figure 4 It is a structural schematic diagram of the light-emitting unit of the present invention; Figure 5 It is a schematic diagram of the structure of the transition heat sink, TEC cooler and base of the present invention; Figure 6 It is a schematic diagram of the process of manufacturing a high-power bar laser according to the present invention.

[0024] The reference numerals of the figures are: 01—bar stack array, 10—bar, 11—heat sink A, 111—metal layer, 112—boss, 12—heat sink B, 121—metal layer, 13—secondary solder layer, 14—tertiary solder layer, 20—transition heat sink, 21—rectangular plating layer, 22—electrode welding area, 23—chip area, 30—chip thermistor, 31—gold wire, 40—TEC cooler, 50—electrode sheet, 60—base, 61—fixing groove. DETAILED DESCRIPTION

[0025] The following describes in detail embodiments of the present invention. Examples of the embodiments are shown in the attached Figures 1 to 6 It is shown in the figure, it should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and thus the figures only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout type may also be more complicated. Example 1

[0026] Reference Figure 1 , Figure 2 As shown, a high-power bar laser proposed in this example includes a base 60 with a fixing groove 61 and a transition heat sink 20 fixed on the base 60 through a TEC cooler 40, and the transition heat sink 20 is respectively provided with a bar stack array 01 and electrode sheets 50 located on the left and right sides of the bar stack array 01. The transition heat sink 20 is also provided with a chip thermistor 30 and a gold wire 31 located on the front and back sides of the bar stack array 01. The bar stack array 01 is formed by a plurality of light-emitting units connected laterally, and each light-emitting unit is composed of an A heat sink 11 with an "L"-shaped cross section and a bar 10 welded to the inner side of the A heat sink 11, and a B heat sink 12 with an "I"-shaped cross section is welded to the outermost bar 10 of the bar stack array 01.

[0027] The structures of the heat sink A 11 and the heat sink B 12 proposed in this embodiment are as follows: Figure 3 As shown, heat sink A 11 is in an "L" shape, and the metal layer 111 on the surface of heat sink A 11 partially covers heat sink A, distinguishing between a conductive area and an insulating area; there is a boss 112 covered by a metal layer at the bottom of the inner side of heat sink A 11, and the lower end of boss 112 is 25 to 50 μm higher than the bottom surface of heat sink A 11. Heat sink B 12 is in an "I" shape, and the metal layer 121 of heat sink B 12 partially covers heat sink B 12, distinguishing between a conductive area and an insulating area. Heat sink A 11, heat sink B 12 and bar 10 have equal sizes in the second direction.

[0028] The light emitting unit structure proposed in this embodiment is as follows Figure 4As shown, each light-emitting unit is packaged by a bar 10 and an A heat sink 11, and the P surface of the bar 10 and the surface metal layer 111 on the inner side of the A heat sink 11 are sintered together by a primary solder. Note that the light-emitting cavity surfaces of the A heat sink 11 and the bar 10 are positively aligned in the third direction. The bar stack array 01 is composed of a plurality of light-emitting units arranged in a positive periodic manner along a first direction, wherein the bar 10 in each light-emitting unit is sintered together with the outer side surface of the A heat sink 11 in another light-emitting unit on the N surface by a secondary solder, and the bar 10 in the last light-emitting unit along the first direction is also welded to the inner side surface of the B heat sink 12 by a secondary solder on the N surface to form a secondary solder layer 13, completing the packaging of the bar stack array 01.

[0029] In this embodiment, the number of the bars 13 is n, the number of the A heat sinks 11 is n, and the number of the B heat sinks 12 is 1, where n is a positive integer greater than or equal to 2.

[0030] In this embodiment, heat sink A 11 and heat sink B 12 are both made of diamond material with a thickness of 200 to 1000 μm, and the metal layer 111 and metal layer 121 on the surface are copper-clad gold-plated layers with a total thickness of 25 to 50 μm. The main body material of the transition heat sink 20 can be selected from diamond or aluminum nitride, and the upper surface has a copper-clad gold-plated graphic layer with a total thickness of 25 to 50 μm. The copper-clad gold-plated graphic layer has a plurality of rectangular plating layers 21 and a patch area 23 in the middle, and large electrode welding areas 22 on both sides. The base 60 and the electrode sheet 50 are both made of copper, and the surface has a copper-clad gold-plated layer with a total thickness of 25 to 100 μm. The structures of the transition heat sink 20, the TEC cooler 40 and the base 60 are as shown in FIG. Figure 5 shown. Example 2

[0031] Reference Figure 6 As shown, this example proposes a method for manufacturing a high-power bar laser, and the steps are as follows.

[0032] Step S1, using a primary solder to solder the bar 10 and the A heat sink 11 together to form a light-emitting unit, and connecting and arranging multiple light-emitting units along a first direction to form a light-emitting unit array. The primary solder is gold-tin solder, which has high welding strength, good oxidation resistance and thermal fatigue resistance, can ensure the reliability of the package, and has a melting point of about 300°C.

[0033] The bar 10 has a P surface and an N surface. The P surface is welded to the inner s side surface of the A heat sink 11 by primary solder to form a light-emitting unit. The specific model of the bar 10 is selected according to demand, and the model of the bar 10 is not limited in the present invention.

[0034] Step S2, use secondary solder to weld the bar 10N surface of each adjacent light emitting unit in the light emitting unit array and the outer side surface of the A heat sink 11 together along the first direction, and also use secondary solder to weld the bar 10 of the last light emitting unit to the inner side surface of the B heat sink 12 to complete the packaging of the bar stack array 01. The secondary solder can be lead-tin or tin-silver solder, with a melting point between 200 and 250°C.

[0035] Step S3, use the tertiary solder to package the base 60, TEC cooler 40, transition heat sink 20, electrode sheet 50 and bar stack array 01 together in a sintering process in the third direction. After the welding is completed, the SMD thermistor 30 is packaged on the transition heat sink 20 and the gold wire 31 is punched to obtain a high-power bar laser. In this embodiment, the bar stack array 01 uses a tertiary solder sheet with a size equivalent to the rectangular coating 21 on the surface of the transition heat sink 20 to sinter with the transition heat sink 20 to form a tertiary solder layer 14. During the sintering process, the boss 112 at the bottom of the inner side of the A heat sink 11 can prevent the molten tertiary solder from overflowing to the adjacent light-emitting unit, effectively preventing the metal layers of the adjacent light-emitting units from being short-circuited by the tertiary solder. The tertiary solder can be selected from indium-based alloys, bismuth-based alloys or tin-bismuth alloys, and the melting point is between 120 and 150°C.

[0036] In this embodiment, if the bar stack array 01 fails during the laser packaging process due to problems including damage to the bar 10 itself, contamination or damage to the cavity surface, etc., the secondary solder layer 13 and the tertiary solder layer 14 are melted at a temperature slightly higher than the melting point of the secondary solder, the failed light-emitting unit is removed and replaced as a whole, the secondary solder is used to sinter the bar stack array 01 again, and the tertiary solder is used to weld the repaired bar stack array 01 back to the transition heat sink 20. In this process, because the melting point of the primary solder is high enough, the connection between the P surface of the bar 10 and the A heat sink 11 on a single light-emitting unit is not affected, and because the active area of ​​the bar 10 is close to the P surface, the active area of ​​the bar 10 is relatively safe and not easily damaged during the entire repair process.

[0037] In this embodiment, Figure 5 As shown, the chip thermistor 30 is pasted on the patch area 23 on the left side of the upper surface of the transition heat sink 20 along the first direction using conductive silver paste, and the patch area 23 on the right side is connected to the upper surface of the chip thermistor 30 by a gold wire 31 through a wire bonding machine. Subsequently, a thermistor loop can be formed by connecting an external wire to the blank part of the patch area 23 to monitor the working temperature of the high-power bar laser, and the temperature can be controlled in conjunction with the TEC cooler 40.

[0038] The high-power bar laser manufactured in this embodiment is connected to the external circuit through the electrode sheets 50 on both sides for operation, and the current flow path is: the positive electrode sheet 50 on the right side of the first direction - the electrode welding area 22 on the surface of the transition heat sink 20 - the metal layer 111 - the bar 10 - circulates in the same way to the metal layer 121 - the transition transition heat sink 20 surface electrode welding area 22 - the negative electrode sheet 50 on the left side of the first direction.

[0039] When the high-power bar laser manufactured in this embodiment is working, the heat generated by the bar 10 is quickly transferred to the transition heat sink 20 through the diamond material A heat sink 11 and B heat sink 12 with high thermal conductivity, and then transferred to the rest of the lower end through the TEC cooler, thereby realizing fast and low-latency temperature control of the bar 10.

[0040] The TEC cooler 40 and the SMD thermistor 30 used in this example are directly purchased mature commercial products, and the models are not specified in the present invention. The base 60 is made of copper and can be connected and fixed to the outside through the fixing grooves 61 on both sides. In other embodiments, the specific structure of the base 60 can be designed by yourself. The external system connected to the high-power bar laser made in this embodiment can consider specific structures such as water cooling and metal conduction heat dissipation, which are not specifically described in this embodiment.

[0041] All processes involving solder sintering described in this example are performed using a eutectic reflow furnace, which can provide an inert reducing atmosphere for solder sintering and has high reliability.

[0042] The above embodiments are only illustrative of the principles and effects of the present invention, as well as some embodiments of its application. For those skilled in the art, several modifications and improvements may be made without departing from the creative concept of the present invention, and all of these belong to the protection scope of the present invention.

Claims

1. A high-power bar laser, characterized in that: The invention comprises a base (60) and a transition heat sink (20) fixed on the base (60) via a TEC cooler (40), wherein the transition heat sink (20) is provided with a bar array (01) and electrode sheets (50) located on the left and right sides of the bar array (01), and the transition heat sink (20) is also provided with a chip thermistor (30) and a gold wire (31) located on the front and rear sides of the bar array (01). The bar array (01) is formed by a plurality of light-emitting units connected transversely, and each light-emitting unit is composed of a diamond A heat sink (11) with an "L"-shaped cross section and a bar (10) welded to the inner side of the A heat sink (11), and a diamond B heat sink (12) with an "I"-shaped cross section is welded to the outermost bar (10) of the bar array (01).

2. A high power bar laser according to claim 1, characterized in that: The surface of the A heat sink (11) other than the bottom boss (112) is plated with a metal layer (111); and the surface of the B heat sink (12) is partially plated with a metal layer (121).

3. A high power bar laser according to claim 2, characterized in that: The A heat sink (11) and the B heat sink (12) have a thickness of 200 to 1000 μm, and the metal layer (111) and the metal layer (121) are copper-plated gold layers with a thickness of 25 to 50 μm.

4. A high-power bar laser according to claim 1, 2 or 3, characterized in that: The transition heat sink (20) is made of diamond or aluminum nitride, and has a copper-plated gold layer with a thickness of 25 to 50 μm on its upper surface.

5. A high-power bar laser according to claim 1, 2 or 3, characterized in that: The base (60) and the electrode sheet (50) are both made of copper, and have a copper-plated gold layer with a thickness of 25 to 100 μm on the surface.

6. A method for manufacturing a high-power bar laser as claimed in claim 1, characterized in that: Here are the steps: Step S1, using a first-level solder to weld the bar (10) and the A heat sink (11) into a light-emitting unit, and arranging a plurality of light-emitting units; Step S2, using secondary solder to weld the bars (10) of adjacent light-emitting units and the A heat sink (11), and weld the bar (10) of the last light-emitting unit to the B heat sink (12), and encapsulate to obtain a bar stack array (01); Step S3, using a three-level solder to sinter the base (60), the TEC cooler (40), the transition heat sink (20), the electrode sheet (50) and the bar stack array (01) together from bottom to top, and after the welding is completed, the surface-mounted thermistor (30) is packaged on the transition heat sink (20) and a gold wire (31) is punched to obtain a high-power bar laser.

7. The method for manufacturing a high-power bar laser according to claim 6, characterized in that: In step S1, the primary solder is gold-tin solder with a melting point of 300°C.

8. The method for manufacturing a high-power bar laser according to claim 7, characterized in that: The secondary solder in step S2 is lead-tin or tin-silver solder with a melting point of 200-250°C.

9. The method for manufacturing a high-power bar laser according to claim 8, characterized in that: In step S3, the tertiary solder is an indium-based alloy, a bismuth-based alloy or a tin-bismuth alloy with a melting point of 120-150°C.

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