TWI411183B - Laser diode element - Google Patents

Abstract

Disclosed is a laser diode element wherein the quantity of warpage of an LD array due to the fact that members thermally expand at different thermal expansion coefficients when the members are bonded is suppressed, and increase of thermal resistance due to increase of the thickness of a sub-mount is also suppressed. The laser diode element is provided with a laser diode array (1) having a plurality of light emitting points (11), and a sub-mount (2) having a mounting surface (21) for mounting the laser diode array (1). A protruding section (22) is provided on an end portion within the same mount surface (21) on which no laser diode array (1) is mounted, and the quantity of warpage of the laser diode (1) due to thermal expansion when bonding is performed is reduced.

Description

Laser diode component

The present invention relates to a laser diode element having a stress buffer material (submount).

Conventionally, it has been required to reduce the amount of warpage of a laser diode array (LD array) having a plurality of light-emitting portions in a laser diode (LD) device. Therefore, in order to reduce the thermal deformation of the underlying package board which is one of the causes of the LD array (also referred to as LD bar) warpage, an underlying package board in which a plurality of materials are bonded to each other is used (see, for example, Patent Document 1) .

[Previous Technical Literature] Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2006-344743 (paragraphs [0013] to [0034], Figs. 1 to 3)

In the conventional laser diode element (semiconductor laser element) having the underlying package board, since the underlying package board is formed by bonding the plurality of materials, the price of the underlying package board becomes high.

In addition, since the underlying package board composed of the composite material is disposed at the lower portion of the laser diode array, the thermal resistance increases due to the increase in the thickness of the underlying package board, which may cause an increase in the temperature of the LD element. The problem of deterioration of life performance and low output of laser output.

In addition, there is also a problem that the LD array is warped due to thermal expansion of the bonding members constituting the underlying package sheets having different thermal expansion coefficients.

The present invention has been made to solve the problems as described above, and an object thereof is to obtain an increase in thermal resistance in an underlying package board by providing a convex portion at an end portion of an underlying package board to which an LD array is not bonded. At the same time, the amount of warpage of the LD array due to thermal expansion at the time of bonding is reduced, and the laser diode element which suppresses the overall deformation is suppressed.

The laser diode device of the present invention includes a laser diode array having a plurality of light-emitting portions and a laser diode having an underlying package board for mounting a mounting surface of the laser diode array In the polar body element, a portion where the laser diode array is not mounted on the end portion in the same plane as the mounting surface is provided with a convex portion.

According to the present invention, the amount of warpage of the underlying package board and the LD array can be reduced, and the amount of deviation of the light-emitting point distribution from the design value can be reduced. Moreover, the increase in thermal resistance that occurs with an increase in the thickness of the underlying package board can be reduced.

1 is a perspective view showing a laser diode element (semiconductor laser element) of Embodiment 1 of the present invention, showing a main portion of the laser diode element (LD array and underlying package board) before bonding With the state after the joint.

In addition, Fig. 2 is an exploded side view showing the laser diode element of Fig. 1, and Fig. 3 is a view showing the state after the bonding of the laser diode element of Fig. 2 and the flow of heat (dashed arrow) ) side view.

In the first to third embodiments, the laser diode array (LD array) 1 is, for example, MBE (Molecular Beam Epitaxy) or MOCVD (Metal Organic Chemical Vapor Deposition). By means of a deposition method or the like, a compound of AlGaAs (aluminum gallium arsenide) (or InGaAsP (such as indium gallium arsenide)) is laminated or grown on a GaAs (gallium arsenide) substrate.

The LD array 1, typically has a flat shape having a width (longitudinal direction) of 10 mm, a depth (resonator length) of 1 mm to 3 mm, a thickness of 100 μm to 200 μm, and side by side at the end faces along the long side direction. A plurality of (tens of) light-emitting points (light-emitting portions) 11 are formed.

Further, in the case where GaAs is used as the substrate of the LD array 1, the thermal expansion coefficient of the LD array 1 is about 6.5 × 10 ^-6 (K ^-1 ).

The underlying package board (stress buffer material) 2 is provided to ease the difference in thermal expansion coefficient between the LD array 1 and the heat sink 4 (see FIG. 2), and includes a mounting surface for mounting the LD array 1. 21, and a convex portion 22 formed at the end.

The material of the underlying package board (stress buffer material) 2 may be, for example, CuW (copper-tungsten alloy, thermal expansion coefficient of about 6.5×10 ^-6 (K ⁻¹ )), AlN (aluminum nitride, thermal expansion rate of about 4.6×10). ^-6 (K ^-1 )) and so on.

As the material of the heat sink 4, for example, copper (thermal expansion coefficient of about 1.7 × 10 ^-6 (K ^-1 )) can be used.

A solder material (not shown) such as Au-Sn (gold-tin alloy) is applied to the mounting surface 21 to which the LD array 1 is bonded. The thickness of the consumable is typically 10 μm or less.

The underlying package board 2 and the heat sink 4 are joined by a pellet-shaped solder material 3.

The LD array 1, the underlying package board 2, and the heat sink 4, which are arranged and formed as shown in FIGS. 1 to 3, are heated to a temperature exceeding the solder material between the LD array 1 and the underlying package board 2 (Au-Sn solder material) The melting point of about 280 ° C or higher and the temperature of the melting point of the welding material 3 (which will be described later) between the underlying package board 2 and the heat sink 4 are pressed from above and below.

At this time, the underlying package board 2 is on the side where the mounting surface 21 to which the LD array 1 is bonded, and the end portion of the portion where the LD array 1 is not bonded to the same in the same plane as the mounting surface 21, The convex portion 22 is provided along the longitudinal direction of the LD array 1 (the direction in which the light-emitting points 11 are arranged).

Thereby, the rigidity of the longitudinal direction of the underlying package board 2 is increased by the thickness of the convex portion 22, the occurrence of warpage is reduced, and the warpage of the underlying package board 2 due to the temperature difference between the upper and lower sides is suppressed, and The effect of warpage of the LD array 1 caused by a difference in expansion ratio at the time of heating at the time of joining to the time of cooling after joining.

In addition, in the third figure, the light output direction (thick line arrow) and the heat flow (dashed arrow) when the LD element is oscillated are displayed, and it is understood that the heat sink 4 fully exerts its function when theLD element operates.

In the second and third figures, the pellet-shaped solder material 3 is sandwiched between the underlying package board 2 and the heat sink 4, but the solder may be applied to the underside of the underlying package board 2 before bonding. Material 3.

As the material of the welding material 3, various materials such as In (indium), SnAgCu (tin-silver-copper alloy), and PbSn (lead-tin alloy) can be used, but in order to make the LD array 1 and the underlying package board in consideration of the bonding order, 2 After the integration, the heat sink 4 is joined, and it is preferable to use a material having a lower melting point than the welding material (Au-Sn) used in the joining of the LD array 1 and the underlying package board 2 as the material of the welding material 3.

As shown in FIG. 2, after the LD array 1 is integrated with the underlying package board 2 bonded thereto, the integrated LD array 1 and the underlying package board 2 are bonded to the heat sink 4 through the solder material 3.

When the underlying package board 2 and the LD array 1 are bonded to the heat sink 4, since the heat sink 4, the underlying package board 2, and the LD array 1 are heated to a temperature higher than the melting point of the bonding material 3 for bonding, The heat is expanded, and then, after joining, it is cooled and contracted in a state where the both are fixed.

At this time, warpage occurs due to a difference in thermal expansion coefficient between the heat sink 4, the underlying package board 2, and the consumable material 3. However, when the bonding process is performed, the upper surface of the underlying package board 2 is provided with the convex portion 22 in the longitudinal direction. Therefore, the underlying package board 2 is less likely to warp, and as a result, the effect of reducing the amount of warpage of the LD array 1 is obtained.

Further, as shown in FIG. 3, when laser light is emitted from the LD array 1, heat generated from the LD array 1 (dashed arrow) propagates from the surface joined to the underlying package 2 to the heat sink 4.

At this time, since the thickness of the portion of the underlying package board 2 to which the mounting surface 21 of the LD array 1 is bonded is thin, the thickness of the portion of the LD array 1 to which the convex portion 22 is not bonded is thick, so Even if the convex portion 22 is formed, it does not hinder the propagation of heat from the LD array 1 to the heat sink 4, and has the same heat dissipation performance as the case where the convex portion 22 (the entire underlying package sheet is thin) is not provided.

Therefore, according to the configurations of the first to third embodiments of the first embodiment of the present invention, in particular, the warpage is likely to occur, for example, the width of the LD array 1 is 5 mm or more, and the mounting surface 21 of the LD array 1 is bonded. The thickness of the underlying package board 2 is 300 μm or less, which has a remarkable effect.

The convex portion 22 of the underlying package board 2 is not limited to a shape in which the four corner posts are joined along the end portion of the mounting surface 21 (flat member) (see FIGS. 1 to 3), and the fourth step can also be adopted. Any shape and arbitrary configuration as shown in Fig. 8.

4 to 8 are perspective and plan views showing first to fifth modifications of the underlying package board 2 according to Embodiment 1 of the present invention.

Fig. 4 is a view showing a first variation of the underlying package board 2 in which the upper portion of the convex portion 22 is shown to have a curved shape.

Fig. 5 is a view showing a second variation of the underlying package board 2 in which a groove is formed at the center portion along the extending direction of the convex portion 22. In this case, the deformation resistance strength in the long axis direction of the LD array 1 is increased, and the effect of reducing the deformation can be improved.

Fig. 6 shows a third variation of the underlying package board 2 in which the display projections 22 are not arranged in parallel with respect to the longitudinal direction of the end portion of the underlying package board 2, but are arranged to be inclined. In this case, not only the deformation in the long-axis direction of the LD array 1 but also the deformation in the short-axis direction can be reduced.

Fig. 7 is a view showing a fourth variation of the underlying package board 2 in which the display projections 22 are divided into two in parallel, and a portion in the central portion is disposed in the opposite direction. Also in this case, not only the deformation in the long-axis direction of the LD array 1 but also the deformation in the short-axis direction can be reduced.

Fig. 8 shows a fifth variation of the underlying package board 2 in which the display projections 22 are formed in a U shape and are disposed in three directions of the underlying package board 2 except for the joint portion of the LD array 1.

As shown in Fig. 8, only the joint portion of the underlying package board 2 and the LD array 1 is cut away to form a structure surrounded by the convex portion 22, which not only reduces the amount of warpage in the long-axis direction of the LD array 1, but also reduces the amount of warpage in the long-axis direction of the LD array 1. It is also possible to surely reduce the amount of warpage in the short axis direction.

Next, the effect of reducing the amount of warpage of the laser diode element of the first embodiment of the present invention will be more specifically described with reference to the ninth to eleventh drawings.

Figures 9 through 11 show the results of actual thermal calculations and construction calculations for a laser diode component using a specific LD array 1.

Fig. 9 is an exploded perspective view showing the actual dimensions of the respective portions of the laser diode element used for the calculation of the amount of warpage, showing a specific configuration of the case where the heat calculation and the structural calculation are performed.

Fig. 10 is a view showing the width w [μm] and the deformation (amount of warpage) of the convex portion 22 in the case where the upper and lower temperature gradients are assumed in the configuration of Fig. 9 (and the ordinary underlying package in which no convex portion is provided). Explanation of the relationship (calculation example) of the board ratio). Fig. 11 is an explanatory view showing a relationship (calculation example) of the height h [μm] of the convex portion and the magnitude of the deformation in the case where the upper and lower temperature gradients are assumed in the configuration of Fig. 9.

In Fig. 9, the shape of the LD array 1 is set to a thickness of 100 μm, a width of 10 mm, and a depth of 1 mm.

The mounting surface 21 of the underlying package board 2 on which the convex portion 22 is not formed is set to have a thickness of 320 μm, a length in the longitudinal direction of 11 mm, and a depth (width) of 2.5 mm.

The convex portion 22 is set to have a length of 11 mm in the longitudinal direction, w (μm) in the depth (width), and h (μm) in height (thickness).

Further, the LD array 1 and the underlying package board 2 are bonded by a solder material portion (Au-Sn) as described above.

The calculation results of the 10th and 11th drawings assume that in the configuration of FIG. 9, the upper surface temperature of the LD array 1 is 250 ° C, and the lower surface temperature of the underlying package board 2 is 300 ° C, which indicates the vertical direction of the LD array 1. The magnitude of the deformation of the direction (the amount of warpage of the LD array 1).

As can be clearly seen from the 10th and 11th, it can be seen from the results of the 10th and 11th drawings that the convex portion is provided as compared with the case where the convex portion 22 is not provided (w=0, h=0). In the case of 22, the amount of warpage of the LD array 1 becomes small.

In other words, it can be seen from Fig. 10 that the smaller the value of the width w of the convex portion 22 is, the smaller the deformation is. As is apparent from Fig. 11, the smaller the value of the height h of the convex portion 22, the smaller the deformation.

From the above results, the effects of the first embodiment of the present invention can be confirmed.

Further, a material (not shown) having a Young's modulus (not easily deformed) may be additionally joined to the convex portion 22 to form a structure capable of further suppressing the amount of warpage.

In this case, when the material is additionally joined to the convex portion 22, a hard solder or the like having a higher melting point than the bonding material 3 used in the bonding of the LD array 1 and the bonding of the heat sink 4 may be used.

Thus, when the LD array 1 is bonded to the underlying package board 2, problems such as peeling of the bonding material do not occur.

Further, diffusion bonding may be employed in the additional joining of the additional material to the convex portion 22.

In addition, after the additional material is added to the bonding of the convex portions 22, the underlying package 2 can be cut or polished, and the underlying package 2 having high shape accuracy can be produced.

Further, in the case where the coefficient of thermal expansion of the material constituting the heat sink 4 is larger than the thermal expansion coefficient of the material constituting the mounting surface 21 (flat plate portion) of the underlying package board 2, the heat sink is cooled in the state of thermal expansion, and the heat sink is used. 4 will shrink more than the underlying package board 2, so the underlying package board 2 will warp so that the center portion is shifted upward.

Therefore, in order to offset the warp to reduce the amount of warpage, a member having a thermal expansion coefficient larger than that of the underlying package board 2 can be joined to the upper surface of the convex portion 22 of the underlying package board 2.

On the other hand, in the case where the thermal expansion coefficient of the material constituting the heat sink 4 is smaller than the thermal expansion coefficient of the material constituting the mounting surface 21 (flat plate portion) of the underlying package board 2, conversely, the shrinkage amount of the heat sink 4 is lower than that of the underlying package. Since the board 2 is small, the underlying package board 2 is warped so that both ends become higher.

Therefore, in order to offset this warpage to reduce the amount of warpage, a material having a thermal expansion coefficient smaller than that of the underlying package board 2 may be bonded to the upper surface of the convex portion 22 of the underlying package board 2.

Further, due to the temperature gradient at the time of bonding, the temperature of the lower side of the underlying package board 2 may be higher than that of the upper side, and the amount of thermal expansion of the lower portion may be larger than that of the upper portion. In this case, the coefficient of thermal expansion is relatively small. By forming the convex portion 22 by the member, the amount of warpage can be reduced.

Next, the effect of the laser diode element of the first embodiment of the present invention in the assembly process will be described with reference to FIG.

Fig. 12 is a side view showing a state in which the laser diode element is assembled by solder bonding.

Fig. 12 shows a state in which the LD array 1 held by the collet 6 is bonded to the mounting surface 21 of the underlying package board 2 placed on the stage 5.

When the LD array 1 is bonded to the underlying package board 2, as shown in FIG. 12, the underlying package board 2 is fixedly mounted on the stage 5, and the LD array 1 is held under the collet 6 with respect to the underlying package. After the LD array 1 is positioned, the mounting surface 21 of the board 2 is pressed against the mounting surface 21 to which the solder material (not shown) is applied, and is heated from both sides of the stage 5 and the collet 6. welding.

At this time, since the collet 6 is provided with a mechanism (not shown) that is movable in the vertical direction and the horizontal direction, it is small in size and has a smaller heat capacity than the stage 5.

Further, the collet 6 is smaller than the platform 5 side, and it is difficult to mount a heater having a high output and a large size. Therefore, the main body of the temperature control is often provided in a platform having a large heat capacity and a large heater capable of mounting a high output. On the side, there is a temperature difference between the side of the platform 5 and the side of the collet 6.

However, as described above, even if there is a temperature difference between the collet 6 and the stage 5, because the convex portion 22 of the underlying package board 2, and the joint surface belonging to the LD array 1 (through the LD array 1 and the barrel) Since the flow of the upward heat is smaller than the mounting surface 21 of the clip 6 in contact with each other, the temperature difference between the upper and lower sides of the convex portion 22 is smaller than the mounting surface 21 to which the LD array 1 is bonded, and the difference in thermal expansion amount can be reduced. Caused by the deformation.

As described above, according to the first embodiment (first to twelfth drawings) of the present invention, an LD array (laser diode array) 1 having a plurality of light-emitting points (light-emitting portions) 11 is provided, and In the laser diode element of the underlying package board 2 on which the mounting surface 21 of the LD array 1 is mounted, the convex portion 22 is provided at the end portion of the mounting surface 21 where the LD array 1 is not mounted, so that the underlying package can be reduced. The amount of warpage of the board 2 and the LD array 1 can make the amount of deviation from the design value of the distribution of the light-emitting points 11 small.

At the same time, an increase in thermal resistance which occurs when the thickness of the underlying package board 2 is increased can be avoided.

Further, according to the first embodiment (the ninth and tenth drawings) of the present invention, the length (11 mm) of the convex portion 22 along the arrangement direction (longitudinal direction) of the plurality of light-emitting points 11 is set to be vertical. Since the width w (0.3 to 1.0 mm) of the convex portion 22 in the direction of the alignment direction is long, the direction (arrangement direction) of the underlying package board 2 and the LD array 1 which has a large influence on the distribution of the light-emitting point 11 can be reduced. The amount of warpage.

Thereby, the amount of deviation from the design value of the distribution of the light-emitting points 11 can be made small, and the increase in the thermal resistance can be suppressed.

Furthermore, according to the first embodiment of the present invention, the mounting surface 21 of the underlying package board 2 is constituted by a flat member, and the convex portion 22 is joined by another member having a Young's modulus higher than the flat member. Since the flat member 21 is formed above, the effect of suppressing the amount of warpage becomes larger.

Further, when the second member is joined directly below the mounting surface 21, the coefficient of thermal expansion of the other member constituting the convex portion 22 is set to be larger than the thermal expansion coefficient of the material constituting the mounting surface 21 (flat member). The value of the coefficient of thermal expansion of the second member directly joined to the underlying package board 2 is set to be larger than the coefficient of thermal expansion of the mounting surface 21 (flat member).

Thus, in the case where the thermal expansion coefficient of the second member directly under the underlying package board 2 is larger than the thermal expansion coefficient of the material of the underlying package board 2, it is bonded directly under the underlying package board 2 during cooling after bonding. Although the second member is shrunk larger than the underlying package board 2 and becomes a shape in which the center portion of the underlying package board 2 is shifted upward and warped, the thermal expansion ratio is higher than that of the underlying package by bonding the upper portion of the underlying package board 2. By using the other member of the plate 2 as the convex portion 22, the amount of warpage on the mounting surface 21 can be offset and reduced.

Further, when the second member is joined directly under the mounting surface 21, the coefficient of thermal expansion of the other member constituting the convex portion 22 is set to be smaller than the thermal expansion coefficient of the material constituting the mounting surface 21 (flat member). The value of the thermal expansion coefficient of the second member directly joined to the underlying package board 2 is set to be smaller than the thermal expansion coefficient of the mounting surface 21 (flat member).

Thus, in the case where the thermal expansion coefficient of the second member directly under the underlying package board 2 is smaller than the thermal expansion coefficient of the material of the underlying package board 2, in the case of cooling after bonding, contrary to the above, the underlying package board 2 is The contraction is larger than the second member directly under the underlying package board 2, and the center portion of the underlying package board 2 is shifted downward (the both end portions of the underlying package board 2 are shifted upward), but By bonding the other member having a lower thermal expansion coefficient than the underlying package board 2 to the upper portion of the underlying package board 2 as the convex portion 22, the amount of warpage on the mounting surface 21 can be offset to be eliminated.

1. . . LD array (laser diode array)

2. . . Bottom package board

3. . . Welding consumables

4. . . heat sink

5. . . platform

6. . . Collet

11. . . Luminous point

twenty one. . . Mounting surface

twenty two. . . Convex

Fig. 1 is a perspective view showing respective states before and after joining of a laser diode element (semiconductor laser element) according to Embodiment 1 of the present invention. (Example 1)

Fig. 2 is an exploded side view showing the laser diode element of the first embodiment of the present invention. (Example 1)

Fig. 3 is a side view showing the joined state and heat flow of the laser diode element of the first embodiment of the present invention. (Example 1)

Fig. 4 is a perspective view and a plan view showing a first modification of the convex portion of the underlying package board according to Embodiment 1 of the present invention. (Example 1)

Fig. 5 is a perspective view and a plan view showing a second modification of the convex portion of the underlying package board according to Embodiment 1 of the present invention. (Example 1)

Fig. 6 is a perspective view and a plan view showing a third modification of the convex portion of the underlying package board according to Embodiment 1 of the present invention. (Example 1)

Fig. 7 is a perspective view and a plan view showing a fourth modification of the convex portion of the underlying package board according to Embodiment 1 of the present invention. (Example 1)

Fig. 8 is a perspective view and a plan view showing a fifth modification of the convex portion of the underlying package board according to Embodiment 1 of the present invention. (Example 1)

Fig. 9 is an exploded perspective view showing the actual dimensions of the respective portions of the laser diode element used for the calculation of the amount of warpage according to Embodiment 1 of the present invention. (Example 1)

Fig. 10 is an explanatory view showing a relationship (calculation example) of the relationship between the width of the convex portion and the magnitude of the deformation (the amount of warpage) in the case where the temperature gradient of the upper and lower sides is assumed in the configuration of Fig. 9. (Example 1)

Fig. 11 is an explanatory view showing a relationship (calculation example) of the relationship between the height of the convex portion and the magnitude of the deformation (the amount of warpage) in the case where the temperature gradient of the upper and lower sides is assumed in the configuration of Fig. 9. (Example 1)

Fig. 12 is a side view showing a state in which the laser diode element of the first embodiment of the present invention is assembled by solder bonding. (Example 1)

1. . . LD array (laser diode array)

2. . . Bottom package board

11. . . Luminous point

twenty one. . . Mounting surface

twenty two. . . Convex

Claims (1)

A laser diode device comprising: a laser diode array having a plurality of light emitting portions; and an underlying package board having a mounting surface for mounting the laser diode array, wherein: a portion of the end of the mounting surface on which the laser diode array is not mounted is provided with a convex portion, and the length of the convex portion along the direction in which the plurality of light emitting portions are arranged is set to be perpendicular to the arrangement direction. The width of the convex portion in the direction is also long, and the mounting surface of the underlying package board is composed of a flat member, and the convex portion is joined by another member having a Young's modulus higher than the flat member. After the step of forming the flat member, the step of cutting or polishing the mounting surface is performed, and the laser diode element further includes a second member directly joined to the mounting surface to form the convex portion. The coefficient of thermal expansion of the other member is set to be larger than the coefficient of thermal expansion of the material constituting the mounting surface, and the coefficient of thermal expansion of the second member is set to be larger than the ratio Thermal expansion coefficient of the material of the surface of a large value.