High-reliability semiconductor laser array packaging structure preparation clamp and packaging structure preparation method using same

Abstract

The invention discloses a high-reliability semiconductor laser array packaging structure preparation clamp and a packaging structure preparation method using the same. The clamp is used for installing a product module of a packaging structure and comprises a base, a cylindrical pin, a horizontal moving block, a wedge-shaped block and a vertical moving block, a sunken horizontal groove is formed in the center of the base, and a sunken inclined groove is formed in one end of the horizontal groove; the inner side face, away from the horizontal groove, of the inclined groove and the side face, away from the wedge-shaped block, of the inclined groove are rough inclined faces, the product module, the cylindrical pin and the horizontal moving block are arranged in the horizontal groove side by side, and the wedge-shaped block is arranged in the inclined groove. According to the high-reliability semiconductor laser array packaging structure preparation clamp, it can be guaranteed that welding seams between the bars and the conductive heat dissipation spacer blocks are not extruded in the welding flux melting process, so that welding flux extrusion is avoided, and the problems of missing welding and excessive welding flux extrusion caused by the influence of the height difference of the bottoms of the conductive heat dissipation spacer blocks are solved; and meanwhile, the problem of secondary melting of the welding flux is avoided.

Description

Technical Field

[0001] The present invention relates to the field of lasers, and in particular to a high-reliability semiconductor laser array packaging structure preparation fixture and a packaging structure preparation method using the same. Background Art

[0002] The current high-temperature hard solder semiconductor laser bar stacking packaging structure generally alternately stacks n bars and n+1 conductive heat dissipation spacers (such as tungsten copper, copper, diamond copper, etc.), and reflow solders them with a whole piece of electrically insulating heat sink (such as gold-plated or copper-clad aluminum nitride / aluminum oxide / beryllium oxide ceramic sheet, etc.) and a heat sink (usually a copper block) to form a laser bar stacking unit.

[0003] The preparation process of the packaging structure generally includes three steps. The first step is to weld each bar and each conductive heat dissipation spacer into a module with high-temperature hard solder (such as gold-tin, gold-germanium and other solders). The second step is to weld the overall module and the electrical insulating heat sink for a second time with high-temperature hard solder (such as gold-tin, gold-germanium and other solders). The third step is to use relatively low temperature soft solder to reflow solder the laser bar stacking unit and the heat sink again.

[0004] The above packaging structure preparation process mainly includes the following issues: 1. In the first step of welding the bar and the conductive heat dissipation spacer, the welding effect to be achieved is that there is no empty solder at the welding interface between the bar and the conductive heat dissipation spacer, less solder overflow between the bar and the front cavity of the conductive heat dissipation spacer, and no solder short circuit as a whole. However, in the actual product preparation process, the pressure is too small, which is easy to cause empty solder at the welding interface; on the contrary, too much pressure is easy to cause more solder overflow between the bar and the front cavity of the conductive heat dissipation spacer, or solder extrusion at other positions, resulting in solder short circuit. At the same time, in the first step of welding the bar and the conductive heat dissipation spacer, after the solder melts at high temperature, it will be squeezed out due to fixed pressure, and the weld will be narrowed uncontrollably.

[0005] 2. In the first step of welding the bar and the conductive heat dissipation spacer, the high-temperature hard solder reacts with the metal layer on the bar and the conductive heat dissipation spacer, and its composition changes after melting. At this time, its solid phase secondary melting temperature usually increases, but in the second step of reflow packaging the module and the electrical insulating heat sink with high-temperature hard solder, the reflow temperature range usually used is higher than the melting temperature of the high-temperature hard solder between the module and the electrical insulating heat sink, and lower than the secondary melting temperature of the high-temperature hard solder between the bar and the conductive heat dissipation spacer. Therefore, the second step reflow temperature process window is small. If the temperature is too low, the solder will not melt fully, and then the welding interface will be empty. If the temperature is too high, the solder between the bar and the conductive heat dissipation spacer will melt for the second time, affecting the performance of the bar.

[0006] 3. In the second step, when the module and the electrical insulation heat sink are reflow packaged for the second time with high-temperature hard solder, it is necessary to control the fixture pressure, reflow temperature and solder thickness to achieve the welding effect of no empty solder joints on the welding surface and no solder short circuit on the whole bar stacking array unit. However, in the actual product preparation process, because in the first step of welding the bar and the conductive heat dissipation spacer, the welding of each bar and each conductive heat dissipation spacer is generally ensured to be flush with the light-emitting surface of the bar by assembling the fixture, and the height of the conductive heat dissipation spacer generally has deviations, which will cause the height of the lower surface to be high and low. In the subsequent step of welding, the welding surface of the lower surface is not a plane. In the second step of welding, when the pressure and reflow temperature are fixed, if the solder is too thin, it is easy to cause empty solder joints on the welding interface. On the contrary, if the solder is too thick, it is easy to cause solder extrusion and then cause solder short circuit. In addition, when the reflow temperature and solder thickness are fixed, if the pressure is too small, it is easy to cause empty solder joints on the welding interface. On the contrary, if the pressure is too large, it is easy to cause solder extrusion and then cause solder short circuit. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a high-reliability semiconductor laser array packaging structure preparation fixture and a packaging structure preparation method using the same, which can ensure that the weld is not squeezed during the melting of the solder between the bar and the conductive heat dissipation spacer, resulting in solder extrusion, and solve the problem of empty solder caused by the height difference at the bottom of the conductive heat dissipation spacer by applying greater pressure to the electrical insulation heat sink and using thicker solder, and solve the problem of excess solder extrusion by chamfering the conductive heat dissipation block. In addition, the problem of secondary melting of solder on both sides of the bar is avoided by melting the solder at two locations simultaneously.

[0008] According to one aspect of the present invention, a high-reliability semiconductor laser array packaging structure preparation fixture is provided, which is used to install a product module of the packaging structure, and comprises a base, a cylindrical pin, a horizontal moving block, a wedge block and a vertical moving block, wherein the base has an inwardly sunken horizontal groove in the center, and an inwardly sunken inclined groove is arranged at one end of the horizontal groove, and the inner side surface of the inclined groove away from the horizontal groove and the side surface of the wedge block are both rough inclined surfaces, the product module, the cylindrical pin and the horizontal moving block are arranged side by side in the horizontal groove, and the wedge block is arranged in the inclined groove; The product module consists of a plurality of bars, a plurality of conductive heat dissipation spacers, a plurality of first high-temperature hard solder welding sheets, a plurality of second high-temperature hard solder welding sheets and an electrically insulating heat dissipation sheet, wherein the bar bars are stacked between the conductive heat dissipation spacers, the first high-temperature hard solder welding sheets are located between the bar bars and the conductive heat dissipation spacers, the second high-temperature hard solder welding sheets are arranged on the top of the conductive heat dissipation spacers, the electrically insulating heat dissipation sheet is arranged above the high-temperature hard solder welding sheets, and the vertical movable block is pressed on the top of the electrically insulating heat dissipation sheet.

[0009] In some embodiments, the inclined surface has an inclination angle of 5° to 20°, and the wedge block is made of aluminum and its surface is hard-oxidized. The advantages thereof are that the appropriate angles of the inclined groove and the inclined surface on the wedge block are described, and the rough inclined surface can provide greater friction for the wedge block, and the aluminum wedge block is light in weight and easy to remain fixed after the downward thrust is removed.

[0010] In some embodiments, the diameter of the cylindrical pin is consistent with the length of the bar, and the cylindrical pin contacts the midpoint of the side of the closest conductive heat dissipation spacer. The benefit is that the relevant size and setting of the cylindrical pin are described, which facilitates the appropriate pressure on the conductive heat dissipation spacer.

[0011] In some embodiments, the surface of the conductive heat dissipation spacer is polished and a gold-plated layer is provided on the outermost layer. The advantage is that the gold-plated layer is provided on the surface of the conductive heat dissipation spacer, so that it has a higher finish and can facilitate the climbing of the melted solder.

[0012] In some embodiments, the conductive heat dissipation spacer has chamfers at two corners on one side close to the second high-temperature hard solder pad, and the height of the conductive heat dissipation spacer minus the length of the chamfer is not less than the length of the bar. The benefit is that the conductive heat dissipation spacer can facilitate the climbing of the melted solder.

[0013] In some embodiments, each of the first high-temperature hard solder pads and each of the second high-temperature hard solder pads are made of gold-tin or gold-germanium material, and each of the second high-temperature hard solder pads is relatively thick. The benefit is that the suitable materials and thicknesses of the first high-temperature hard solder pads and the second high-temperature hard solder pads are described, and the second high-temperature hard solder pads are relatively thick for easy extrusion after melting.

[0014] According to another aspect of the present invention, there is provided a method for preparing a packaging structure using the high-reliability semiconductor laser array packaging structure preparation fixture, which comprises the following steps: S1: assembling the product module; S2: placing the product module in a fixture and fixing it with the fixture; S3: placing the fixture and the product module in a vacuum reflow furnace for heating, so that each solder sheet is melted synchronously to achieve welding; Wherein, step S2 also includes the following steps: A. placing the product module, the cylindrical pin and the horizontal moving block in the horizontal groove in sequence; B. Insert the wedge block along the inclined surface of the inclined groove, and apply a downward thrust to the wedge block in the vertical direction to squeeze the horizontal moving block, the cylindrical pin and the product module to fix their positions; C. Remove the downward thrust; D. Apply a pressure to the vertical moving block in the vertical direction to compress the electrical insulating heat sink.

[0015] In some embodiments, in step S3, each of the first high temperature hard solder pads will not be squeezed out when melted. This is beneficial in that since the fixture does not apply pressure to the product module after being fixed, the first high temperature hard solder pads will not be squeezed out when melted.

[0016] In some embodiments, in step S3, the edges of each of the first high-temperature hard solder pads shrink when they are initially melted. This is beneficial in that there is some air between the first high-temperature hard solder pads and the bars and conductive heat dissipation spacers on both sides, so that the edges of the first high-temperature hard solder pads shrink when they are initially melted, further avoiding extrusion.

[0017] In some embodiments, in step S3, each of the second high-temperature hard solder sheets will be squeezed out when melted, and the squeezed solder will enter between each of the bar strips and each of the conductive heat dissipation spacers along each of the conductive heat dissipation spacers, and will blend with the solder of each of the first high-temperature hard solder sheets. This is beneficial in that there will be no short circuit caused by solder extrusion due to excessive pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a structure of a jig for preparing a high-reliability semiconductor laser array packaging structure according to an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of the exploded structure of the package structure shown; Figure 3 for Figure 2 A schematic diagram of a portion of the package structure shown when the solder begins to melt; Figure 4 for Figure 2 Schematic diagram of a portion of the package structure after the solder melts.

[0019] In the figure: product module 1, base 2, cylindrical pin 3, horizontal moving block 4, wedge block 5, vertical moving block 6, horizontal groove 7, inclined groove 8, bar 11, conductive heat dissipation spacer 12, first high temperature hard solder welding piece 13, second high temperature hard solder welding piece 14, electrical insulating heat sink 15, chamfer 16. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0021] like Figure 1 As shown, the fixture includes a base 2, a cylindrical pin 3, a horizontal moving block 4, a wedge block 5 and a vertical moving block 6, which are used to jointly install and package a product module 1. The product module 1, the cylindrical pin 3, the horizontal moving block 4 and the wedge block 5 are arranged side by side in the center of the base 2 and contact each other, and the vertical moving block 6 is arranged above the product module 1.

[0022] The base 2 has a sunken horizontal groove 7 in the center, the bottom surface of the horizontal groove 7 is horizontal, and a sunken inclined groove 8 is arranged at one end of the horizontal groove 7. The product module 1, the cylindrical pin 3 and the horizontal moving block 4 are all arranged in the horizontal groove 7, and the wedge block 5 is arranged in the inclined groove 8.

[0023] The inner side surface of the inclined groove 8 away from the horizontal groove 7 is an inclined surface, and the inclination angle of the inclined surface is generally between 5° and 20°, and one of the side surfaces of the wedge block 5 is also correspondingly set to be inclined, so when the wedge block 5 descends, it can push the horizontal moving block 4 and the cylindrical pin 3 to squeeze the product module 1. Among them, the inclined surface of the inclined groove 8 is relatively rough, which can provide a large friction force for the wedge block 5, and the bottom surface of the horizontal groove 7 is relatively smooth, which can make the product module 1 move smoothly.

[0024] The wedge block 5 is generally made of low-density, high-temperature resistant materials such as aluminum, and is hard-oxidized on the surface to increase its surface roughness. The horizontal moving block 4 can only move in the horizontal direction in accordance with the bottom surface of the horizontal groove 7, while the vertical moving block 6 can only move in the vertical direction.

[0025] like Figure 2-4 As shown, the product module 1 consists of a plurality of bar bars 11, a plurality of conductive heat dissipation spacers 12, a plurality of first high-temperature hard solder pads 13, a plurality of second high-temperature hard solder pads 14 and an electrically insulating heat sink 15, wherein the bar bars 11 are stacked between the conductive heat dissipation spacers 12, the first high-temperature hard solder pads 13 are located between the bar bars 11 and the conductive heat dissipation spacers 12, the second high-temperature hard solder pads 14 are arranged on the top of the conductive heat dissipation spacers 12, and the electrically insulating heat sink 15 is arranged above the high-temperature hard solder pads.

[0026] The number of the first high temperature hard solder pads 13 is twice that of the bar strips 11 , and the number of the conductive heat dissipation spacers 12 and the second high temperature hard solder pads 14 is the same and each is one more than the bar strips 11 .

[0027] The two corners of the conductive heat dissipation spacer 12 on one side close to the second high temperature hard solder pad 14 are both provided with chamfers 16, wherein the height of the conductive heat dissipation spacer 12 is slightly greater than the length of the bar 11, and even if the height of the conductive heat dissipation spacer 12 minus the side length of the chamfer 16 is not less than the length of the bar 11. For example, assuming that the height of the conductive heat dissipation spacer 12 is 2.65 mm, when it is matched with the bar 11 with a cavity length of 2.5 mm, the chamfer 16 is suitably set within the range of 0.1 mm to 0.15 mm, and in order to improve the heat dissipation effect, the side length of the chamfer 16 is as wide as possible within the adjustable range.

[0028] After the surface of the conductive heat dissipation spacer 12 is polished, a gold-plated layer is provided on the outermost layer to make it have a higher smoothness.

[0029] The first high-temperature hard solder pad 13 and the second high-temperature hard solder pad 14 are both made of materials such as gold-tin and gold-germanium. Among them, the edge of the second high-temperature hard solder pad 14 exceeds the edge of the chamfer 16 of the conductive heat dissipation spacer 12, and the second high-temperature hard solder pad 14 is 1.5 to 4 times thicker than the conventional process. For example, taking the conventionally selected pad thickness between the conductive heat dissipation spacer 12 and the electrical insulation heat dissipation pad 15 as 25μm, the thickness of the second high-temperature hard solder pad 14 can be selected to be 30μm to 100μm. In addition, the first high-temperature hard solder pad 13 can also be selected to be slightly thicker according to the situation.

[0030] In addition, the diameter of the cylindrical pin 3 in the fixture is consistent with the length of the bar 11, and the cylindrical pin 3 contacts the midpoint of the side of the nearest conductive heat dissipation spacer 12, while the vertical moving block 6 presses on the top center position of the electrical insulation heat sink 15.

[0031] The present invention also provides a packaging structure preparation method using the above-mentioned high-reliability semiconductor laser array packaging structure preparation fixture, which includes the following main steps S1~S14.

[0032] S1: Assemble product module 1.

[0033] According to the above, a plurality of bar strips 11, a plurality of conductive heat dissipation spacers 12, a plurality of first high temperature hard solder pads 13, a plurality of second high temperature hard solder pads 14 and an electrically insulating heat dissipation pad 15 are assembled into a product module 1 to be welded.

[0034] S2: Place the product module 1 in the fixture and fix it with the fixture.

[0035] In this step, the product module 1, the cylindrical pin 3 and the horizontal moving block 4 are placed in succession in the horizontal groove 7 in the center of the base 2; then, the wedge block 5 is inserted along the inclined surface of the inclined groove 8, and a relatively large downward thrust is applied to the wedge block 5 in the vertical direction, which will squeeze the horizontal moving block 4, the cylindrical pin 3 and the product module 1 to fix their positions; then, the downward thrust is removed, and due to the friction between the wedge block 5 and the inclined surface of the inclined groove 8, the positions of all the above components can be fixed, and there is no squeezing force on both sides of the product module 1; finally, a vertical pressure is applied to the vertical moving block 6 by stacking pressure blocks or using spring pins, so that it presses the electrically insulating heat sink 15, and the product module 1 can be fixed.

[0036] S3: Place the fixture and the product module 1 thereon in a vacuum reflow furnace for heating so that each solder sheet melts synchronously to achieve welding.

[0037] like Figure 3 As shown, in terms of solder control, during the heating and reflow melting process, since the positions of the first high-temperature hard solder pads 13 between the bar strips 11 and the conductive heat dissipation spacers 12 are fixed and there is no squeezing force on both sides, the first high-temperature hard solder pads 13 will not be squeezed out when they are melted. At the same time, since there is often some air between the first high-temperature hard solder pads 13 and the bar strips 11 and the conductive heat dissipation spacers 12 on both sides, the edges of the first high-temperature hard solder pads 13 will shrink slightly when they are initially melted.

[0038] At the same time, if Figure 4 As shown, during the heating reflow melting process, since the electrically insulating heat sink 15 is subjected to the pressure exerted by the vertical moving block 6, each second high-temperature hard solder pad 14 between each conductive heat sink 12 and the electrically insulating heat sink 15 will be squeezed, and when melted, its solder will be squeezed out and climb along the gold-plated layer on each conductive heat sink 12 to spread to the chamfer 16, and then enter between each bar 11 and each conductive heat sink 12, and blend with the solder of each melted first high-temperature hard solder pad 13.

[0039] In addition, since the heights of the conductive heat dissipation spacers 12 at different positions may be different, the amount of solder extrusion will be different, and thus the amount of solder integrated between each bar 11 and each conductive heat dissipation spacer 12 will be different, affecting the solder morphology on both sides.

[0040] In addition, since the solders on both sides of the bar 11 are in liquid state, the bar 11 may have a slight degree of freedom in the horizontal direction, so it can be slightly displaced to accommodate the filling of solders on both sides.

[0041] In terms of pressure control, since the solder of each extruded second high-temperature hard solder welding piece 14 will climb and spread to blend with the solder of each first high-temperature hard solder welding piece 13, there will be no short circuit caused by solder extrusion due to excessive pressure.

[0042] In terms of temperature control, since each first high-temperature hard solder pad 13 and each second high-temperature hard solder pad 14 are melted synchronously and belong to the same reflow package, the reflow temperature process window range is relatively large.

[0043] In summary, due to the effects in solder control, pressure control and temperature control, this method has a large process window, is easy to operate and has a high processing yield.

[0044] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A high-reliability semiconductor laser array packaging structure preparation fixture, used for installing a product module of the packaging structure, characterized in that: It comprises a base, a cylindrical pin, a horizontal moving block, a wedge-shaped block and a vertical moving block, wherein the base has an inwardly sunken horizontal groove in the center, an inwardly sunken inclined groove is arranged at one end of the horizontal groove, the inner side surface of the inclined groove away from the horizontal groove and the side surface of the wedge-shaped block are both rough inclined surfaces, the product module, the cylindrical pin and the horizontal moving block are arranged side by side in the horizontal groove, and the wedge-shaped block is arranged in the inclined groove; The product module consists of a plurality of bars, a plurality of conductive heat dissipation spacers, a plurality of first high-temperature hard solder welding sheets, a plurality of second high-temperature hard solder welding sheets and an electrically insulating heat dissipation sheet, wherein the bar bars are stacked between the conductive heat dissipation spacers, the first high-temperature hard solder welding sheets are located between the bar bars and the conductive heat dissipation spacers, the second high-temperature hard solder welding sheets are arranged on the top of the conductive heat dissipation spacers, the electrically insulating heat dissipation sheet is arranged above the high-temperature hard solder welding sheets, and the vertical movable block is pressed on the top of the electrically insulating heat dissipation sheet.

2. A high-reliability semiconductor laser array packaging structure preparation fixture according to claim 1, characterized in that: The inclination angle of the inclined surface is between 5° and 20°, and the wedge block is made of aluminum and its surface is hard-oxidized.

3. The high-reliability semiconductor laser array packaging structure preparation fixture according to claim 1, characterized in that: The diameter of the cylindrical pin is consistent with the length of the bar, and the cylindrical pin contacts the midpoint of the side of the nearest conductive heat dissipation spacer.

4. The high-reliability semiconductor laser array packaging structure preparation fixture according to claim 1, characterized in that: After the surface of the conductive heat dissipation spacer is polished, a gold-plated layer is arranged on the outermost layer.

5. The high-reliability semiconductor laser array packaging structure preparation fixture according to claim 1, characterized in that: The two corners of the conductive heat dissipation spacer on one side close to the second high-temperature hard solder pad are chamfered, and the height of the conductive heat dissipation spacer minus the side length of the chamfer is not less than the length of the bar.

6. The high-reliability semiconductor laser array packaging structure preparation fixture according to claim 1, characterized in that: Each of the first high-temperature hard solder pads and each of the second high-temperature hard solder pads are made of gold-tin or gold-germanium material, and each of the second high-temperature hard solder pads is relatively thick.

7. A method for preparing a packaging structure using the high-reliability semiconductor laser array packaging structure preparation fixture according to any one of claims 1 to 6, characterized in that: The following steps are included S1: assembling the product module; S2: placing the product module in a fixture and fixing it with the fixture; S3: placing the fixture and the product module in a vacuum reflow furnace for heating, so that each solder sheet is melted synchronously to achieve welding; Wherein, step S2 also includes the following steps: A. placing the product module, the cylindrical pin and the horizontal moving block in the horizontal groove in sequence; B. Insert the wedge block along the inclined surface of the inclined groove, and apply a downward thrust to the wedge block in the vertical direction to squeeze the horizontal moving block, the cylindrical pin and the product module to fix their positions; C. Remove the downward thrust; D. Apply a pressure to the vertical moving block in the vertical direction to compress the electrical insulating heat sink.

8. The method for preparing a packaging structure using a high-reliability semiconductor laser array packaging structure preparation fixture according to claim 7, characterized in that: In step S3, each of the first high-temperature hard solder pieces will not be squeezed out when melted.

9. The method for preparing a packaging structure using a high-reliability semiconductor laser array packaging structure preparation fixture according to claim 7, characterized in that: In step S3, when each of the first high-temperature hard solder pads is initially melted, its edge shrinks.

10. The method for preparing a packaging structure using a high-reliability semiconductor laser array packaging structure preparation fixture according to claim 7, characterized in that: In step S3, each of the second high-temperature hard solder welding sheets will be squeezed out when melted, and the squeezed solder will enter between each of the bar strips and each of the conductive heat dissipation spacers along each of the conductive heat dissipation spacers, and will blend with the solder of each of the first high-temperature hard solder welding sheets.

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