A preparation fixture for a high-reliability semiconductor laser array packaging structure and a packaging structure preparation method using the same

Abstract

The present invention discloses a fixture for preparing a high-reliability semiconductor laser array packaging structure and a packaging structure preparation method using the same. The fixture is used to install the product module of the packaging structure, and includes a base, a cylindrical pin, a horizontal moving block, a wedge block and a vertical moving block. The center of the base has an indented horizontal groove, and one end of the horizontal groove is provided with an indented inclined groove. The inner side 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 fixture for preparing a high-reliability semiconductor laser array packaging structure in the present invention can ensure that the weld seam is not extruded during the melting process of the solder between the bar and the conductive heat dissipation spacer, and solves the problem of open soldering caused by the height difference at the bottom of the conductive heat dissipation spacer and the problem of excessive solder extrusion, and at the same time avoids the problem of secondary melting of the solder.

Description

Technical Field

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

[0002] Currently, in the high-temperature hard solder semiconductor laser bar stack array packaging structure, generally n bars and n + 1 conductive heat dissipation spacers (such as tungsten copper, copper, diamond copper, etc.) are alternately stacked, and are reflow soldered with a monolithic electrical insulation 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 stack array unit.

[0003] The preparation process of this packaging structure generally includes three steps. The first step is to weld each bar and each conductive heat dissipation spacer with a high-temperature hard solder (such as gold-tin, gold-germanium, etc.) into a module. The second step is to perform a second soldering of the overall module and the electrical insulation heat sink with a high-temperature hard solder (such as gold-tin, gold-germanium, etc.). The third step is to use a soft solder with a relatively low temperature to reflow solder the laser bar stack array unit and the heat sink again to form a shape.

[0004] The above preparation process of the packaging structure mainly includes the following problems:

[0005] 1. During the welding process of the bar and the conductive heat dissipation spacer in the first step, the required welding effect is that there is no void soldering at the welding interface between the bar and the conductive heat dissipation spacer, less solder overflows from the front cavity surface of the bar and the conductive heat dissipation spacer, and there is no solder short circuit overall. However, in the actual product preparation process, if the pressure is too small, it is easy to cause void soldering at the welding interface; conversely, if the pressure is too large, it is easy to cause more solder to overflow from the front cavity surface of the bar and the conductive heat dissipation spacer, or solder to be extruded at other positions resulting in solder short circuit. At the same time, during the welding process of the bar and the conductive heat dissipation spacer in the first step, after the solder melts at high temperature, it will be extruded due to the fixed pressure, and the weld seam will inevitably narrow.

[0006] 2. During the welding process of the bar and the conductive heat dissipation spacer in the first step, the high-temperature hard solder reacts with the metal layers 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. However, during the second reflow packaging process of the module and the electrical insulation heat sink with a high-temperature hard solder in the second step, the usually adopted reflow temperature range is higher than the melting temperature of the high-temperature hard solder between the module and the electrical insulation 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 reflow temperature process window in the second step is small. If the temperature is too low, it will cause insufficient melting of the solder, and then void soldering at the welding interface. If the temperature is too high, it will cause secondary melting of the solder between the bar and the conductive heat dissipation spacer, affecting the performance of the bar.

[0007] 3. During the second reflow encapsulation process of the module and the electrically insulating heat sink using high-temperature hard solder, it is necessary to control the fixture pressure, reflow temperature, and solder thickness to achieve the welding effect of no voids in the welding surface and no solder short circuit in the overall bar array unit. However, in the actual product preparation process, during the welding process of the bar and the conductive heat dissipation block in the first step, the light-emitting surfaces of the bars are generally made flush by an assembly fixture during the welding of each bar and each conductive heat dissipation block. Generally, there are height deviations in the conductive heat dissipation blocks, which will cause height differences in the lower surfaces. In the subsequent welding process, the welding surface of the lower surface is not a flat surface. Then, in the second welding process, when the pressure and reflow temperature are fixed, if the solder is too thin, it is easy to cause voids in the welding interface. On the contrary, if the solder is too thick, it is easy to cause solder extrusion and then 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 voids in the welding interface. On the contrary, if the pressure is too large, it is easy to cause solder extrusion and then solder short circuit. Summary of the Invention

[0008] To solve the above problems, the present invention provides a fixture for preparing a high-reliability semiconductor laser array package structure and a package structure preparation method using the same. It can ensure that the weld seam is not extruded during the melting process of the solder between the bar and the conductive heat dissipation block, resulting in solder extrusion. And by applying a large pressure to the electrically insulating heat sink and using a relatively thick solder, the void welding problem caused by the height difference at the bottom of the conductive heat dissipation block is solved. And by chamfering the conductive heat dissipation block, the problem of excess solder extrusion is solved. In addition, the problem of secondary melting of the solder on both sides of the bar is avoided by melting the solder at two places synchronously.

[0009] According to one aspect of the present invention, there is provided a fixture for preparing a high-reliability semiconductor laser array package structure, which is used to install the product module of the package structure. It includes a base, a cylindrical pin, a horizontal moving block, a wedge block, and a vertical moving block. The center of the base has an indented horizontal groove. One end of the horizontal groove is provided with an indented inclined groove. The inner side 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;

[0010] The product module is composed of multiple bars, multiple conductive heat dissipation blocks, multiple first high-temperature hard solder sheets, multiple second high-temperature hard solder sheets, and an electrically insulating heat sink. Among them, each of the bars is stacked between the conductive heat dissipation blocks, each of the first high-temperature hard solder sheets is located between each of the bars and each of the conductive heat dissipation blocks, each of the second high-temperature hard solder sheets is disposed on the top of each of the conductive heat dissipation blocks, the electrically insulating heat sink is disposed above each of the high-temperature hard solder sheets, and the vertical moving block presses on the top of the electrically insulating heat sink.

[0011] In some embodiments, the inclination angle of the inclined surface is between 5° and 20°, the wedge block is made of aluminum and its surface is subjected to hard anodizing treatment. The advantage is that the suitable angles of the inclined groove and the inclined surface on the wedge block are described, and the rough inclined surface can provide a large frictional force for the wedge block, while the aluminum wedge block has a small weight and is easy to remain fixed after removing the downward thrust.

[0012] 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 surface of the closest conductive heat dissipation block. The advantage is that the relevant dimensions and setting conditions of the cylindrical pin are described, which is convenient for applying appropriate pressure to the conductive heat dissipation block.

[0013] In some embodiments, the surface of the conductive heat dissipation block is polished and a gold plating layer is provided on the outermost layer. The advantage is that a gold plating layer is provided on the surface of the conductive heat dissipation block, making it have a high smoothness, which can facilitate the climbing of the melted solder.

[0014] In some embodiments, chamfers are provided at both corners of the side of the conductive heat dissipation block close to the second high-temperature hard solder sheet, and the height of the conductive heat dissipation block minus the side length of the chamfer is not less than the length of the bar. The advantage is that it is convenient for the melted solder to climb on the conductive heat dissipation block.

[0015] In some embodiments, each of the first high-temperature hard solder sheets and each of the second high-temperature hard solder sheets are made of gold-tin or gold-germanium materials, and each of the second high-temperature hard solder sheets is relatively thick. The advantage is that the suitable materials and thickness conditions of the first high-temperature hard solder sheets and the second high-temperature hard solder sheets are described, and the relatively thick second high-temperature hard solder sheets are convenient for extrusion after melting.

[0016] According to another aspect of the present invention, there is provided a method for preparing a packaging structure using the fixture for preparing a high-reliability semiconductor laser array packaging structure, which includes the following steps:

[0017] S1: Assemble the product module;

[0018] S2: Place the product module in the fixture and fix it using the fixture;

[0019] S3: Place the fixture and the product module in a vacuum reflow oven for heating to melt each solder pad synchronously to achieve soldering;

[0020] Among them, step S2 further includes the following steps:

[0021] A. Place the product module, the cylindrical pin, and the horizontal moving block in the horizontal groove successively;

[0022] 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;

[0023] C. Remove the downward thrust;

[0024] D. Apply a pressure to the vertical moving block in the vertical direction to press the electrical insulation heat sink.

[0025] In some embodiments, in step S3, when each of the first high-temperature hard solder pads melts, there will be no extrusion phenomenon. The advantage is 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 extruded when melting.

[0026] In some embodiments, in step S3, when each of the first high-temperature hard solder pads starts to melt, its edge will shrink. The advantage is that there is some air between the first high-temperature hard solder pad and the two-sided bus bars and the conductive heat dissipation partition blocks on both sides, so that the edge of the first high-temperature hard solder pad shrinks when it starts to melt, further avoiding the extrusion phenomenon.

[0027] In some embodiments, in step S3, when each of the second high-temperature hard solder pads melts, it will be extruded, and the extruded solder will enter between each of the bus bars and each of the conductive heat dissipation partition blocks along each of the conductive heat dissipation partition blocks and intersect with the solder of each of the first high-temperature hard solder pads. The advantage is that this can prevent the situation of solder extrusion and short circuit due to excessive pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of a fixture for preparing a high-reliability semiconductor laser array packaging structure according to an embodiment of the present invention;

[0029] Figure 2 is Figure 1 a schematic exploded view of the packaging structure shown;

[0030] Figure 3 isFigure 2 Partial structural schematic diagram when the solder in the shown encapsulation structure starts to melt;

[0031] Figure 4 For Figure 2 Partial structural schematic diagram after the solder in the shown encapsulation structure melts.

[0032] 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 partition block 12, first high-temperature hard solder sheet 13, second high-temperature hard solder sheet 14, electrical insulation heat sink 15, chamfer 16. Specific implementation manner

[0033] The present invention will be further described in detail below with reference to the accompanying drawings.

[0034] As Figure 1 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, and is used to jointly install and encapsulate the product module 1 of the structure. Among them, 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 are in contact with each other, while the vertical moving block 6 is arranged above the product module 1.

[0035] The center of the base 2 has a sunken horizontal groove 7, the bottom surface of the horizontal groove 7 is horizontal, and an inclined groove 8 is sunken at one end of the horizontal groove 7. Among them, 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.

[0036] The inner side surfaces of the inclined groove 8 away from the horizontal groove 7 are all inclined surfaces, and the inclination angle of this inclined surface is generally between 5° and 20°. One side surface of the wedge block 5 is also correspondingly set to be inclined. Then, 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 frictional force for the wedge block 5, while the bottom surface of the horizontal groove 7 is relatively smooth, which can enable the product module 1 to move smoothly.

[0037] The wedge block 5 is generally made of materials with low density and high temperature resistance such as aluminum, and is subjected to hard anodizing treatment on the surface to increase its surface roughness. The horizontal moving block 4 can only move horizontally by fitting the bottom surface of the horizontal groove 7, and the vertical moving block 6 can only move vertically.

[0038] As Figures 2 - 4As shown in the figure, the product module 1 is composed of multiple bar strips 11, multiple conductive heat dissipation partition blocks 12, multiple first high-temperature hard solder pads 13, multiple second high-temperature hard solder pads 14, and an electrically insulating heat sink 15. Among them, each bar strip 11 is respectively stacked between each conductive heat dissipation partition block 12, each first high-temperature hard solder pad 13 is respectively located between each bar strip 11 and each conductive heat dissipation partition block 12, and each second high-temperature hard solder pad 14 is respectively arranged on the top of each conductive heat dissipation partition block 12, and the electrically insulating heat sink 15 is arranged above each high-temperature hard solder pad.

[0039] 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 partition blocks 12 and the second high-temperature hard solder pads 14 is the same and both are one more than the number of the bar strips 11.

[0040] Both corners of the side of the conductive heat dissipation partition block 12 close to the second high-temperature hard solder pad 14 have chamfers 16. Among them, the height of the conductive heat dissipation partition block 12 is slightly greater than the length of the bar strip 11, and even if the height of the conductive heat dissipation partition block 12 minus the side length of the chamfer 16, it is still not less than the length of the bar strip 11. For example, if the height of the conductive heat dissipation partition block 12 is 2.65 mm and it is matched with the bar strip 11 with a cavity length of 2.5 mm, then the chamfer 16 is preferably set in the range of 0.1 mm to 0.15 mm, and in order to improve the heat dissipation effect, the wider the side length of the chamfer 16 within the adjustable range, the better.

[0041] After the surface of the conductive heat dissipation partition block 12 is polished, a gold plating layer is provided on the outermost layer to make it have a high smoothness.

[0042] Both the first high-temperature hard solder pads 13 and the second high-temperature hard solder pads 14 are 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 partition block 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 solder pad thickness between the conventionally selected conductive heat dissipation partition block 12 and the electrically insulating heat sink 15 as 25 μm, the thickness of the second high-temperature hard solder pad 14 can be selected from 30 μm to 100 μm. In addition, the first high-temperature hard solder pad 13 can also select a slightly thicker solder pad according to the situation.

[0043] In addition, the diameter of the cylindrical pin 3 in the fixture is the same as the length of the bar strip 11, and the cylindrical pin 3 contacts the midpoint of the side of the closest conductive heat dissipation partition block 12, while the vertical moving block 6 presses on the center position of the top of the electrically insulating heat sink 15.

[0044] The present invention also provides a packaging structure preparation method applying the fixture for preparing the above high-reliability semiconductor laser array packaging structure, which includes the following main steps S1 to S14.

[0045] S1: Assemble product module 1.

[0046] As described above, use 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 sink 15 to assemble the product module 1 to be welded and processed.

[0047] S2: Place product module 1 in a fixture and fix it using the fixture.

[0048] In this step, place product module 1, cylindrical pin 3 and horizontal moving block 4 successively in the horizontal groove 7 in the center of the base 2; then, insert the wedge block 5 along the inclined surface of the inclined groove 8, and apply a relatively large downward thrust in the vertical direction to the wedge block 5, which will squeeze horizontal moving block 4, cylindrical pin 3 and product module 1 to fix their positions; then, remove this downward thrust. Due to the frictional force 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 product module 1; finally, apply a vertical pressure to the vertical moving block 6 by stacking pressure blocks or using spring pins, etc., to press the electrically insulating heat sink 15, and then product module 1 can be fixed.

[0049] S3: Place the fixture and product module 1 thereon in a vacuum reflow oven for heating to melt each solder pad synchronously to achieve welding.

[0050] As Figure 3 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 each bar strip 11 and each conductive heat dissipation spacer 12 are fixed and there is no squeezing force on both sides, there will be no extrusion phenomenon when each first high-temperature hard solder pad 13 melts. At the same time, since there is often a little air between the first high-temperature hard solder pad 13 and the bar strips 11 and conductive heat dissipation spacers 12 on both sides, when the first high-temperature hard solder pad 13 starts to melt, its edge will slightly contract.

[0051] At the same time, as Figure 4 shown, during the heating and reflow melting process, since the electrically insulating heat sink 15 is subjected to the pressure applied by the vertical moving block 6, the second high-temperature hard solder pads 14 between each conductive heat dissipation spacer 12 and the electrically insulating heat sink 15 will be squeezed, and when melting, their solder will be extruded and climb along the gold plating layer on each conductive heat dissipation spacer 12 to the chamfer 16, and then enter between each bar strip 11 and each conductive heat dissipation spacer 12 to intersect with the solder of each melted first high-temperature hard solder pad 13.

[0052] In addition, since the heights of the conductive heat dissipation blocks 12 at different positions may be different, the extrusion amounts of the solder will be different, which will further lead to differences in the amount of solder incorporated between each bar 11 and each conductive heat dissipation block 12, and affect the solder morphologies on both sides.

[0053] In addition, since the solder on both sides of the bar 11 is in a liquid phase state, the bar 11 may have a slight degree of freedom in the horizontal direction. Therefore, it can be displaced slightly to adapt to the filling of the solder on both sides.

[0054] In terms of pressure control, since the solder of each extruded second high-temperature hard solder sheet 14 will climb and spread to intersect with the solder of each first high-temperature hard solder sheet 13, there will be no situation where the solder is extruded and short-circuited due to excessive pressure.

[0055] In terms of temperature control, since each first high-temperature hard solder sheet 13 and each second high-temperature hard solder sheet 14 melt synchronously and belong to the same reflow encapsulation, the relative reflow temperature process window range is relatively large.

[0056] In summary, due to the effects in aspects such as solder control, pressure control, and temperature control, the process window of this method is very large, which is convenient for operation and has a high processing yield.

[0057] The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A packaging structure preparation method using a high-reliability semiconductor laser array packaging structure preparation fixture for installing a product module of the packaging structure, characterized in that: The fixture comprises a base, a cylindrical pin, a horizontal moving block, a wedge-shaped block and a vertical moving block. The base has a sunken horizontal groove in the center, one end of the horizontal groove is provided with a sunken inclined groove, the inner side of the inclined groove away from the horizontal groove and the side 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 is composed 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 bars are stacked between the conductive heat dissipation spacers, the first high-temperature hard solder welding sheets are located between the 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 moving block is pressed on the top of the electrically insulating heat dissipation sheet; The method 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.

2. The method for preparing a packaging structure using 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 method for preparing a packaging structure using a 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 method for preparing a packaging structure using a 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 method for preparing a packaging structure using a 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 method for preparing a packaging structure using a 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.

7. The method for preparing a packaging structure using a high-reliability semiconductor laser array packaging structure preparation fixture according to claim 1, characterized in that: In step S3, each of the first high-temperature hard solder pieces will not be squeezed out when melted.

8. The method for preparing a packaging structure using a high-reliability semiconductor laser array packaging structure preparation fixture according to claim 1, characterized in that: In step S3, when each of the first high-temperature hard solder pads is initially melted, its edge shrinks.

9. The method for preparing a packaging structure using a high-reliability semiconductor laser array packaging structure preparation fixture according to claim 1, 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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