JP4778627B2 - Laser diode submount and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser diode submount and a method for manufacturing the same.
[0002]
[Prior art]
Laser diodes are widely used as light sources of optical sensors for various precision length measuring instruments, remote control, information recording / reproduction, and automatic machine positioning. Since the laser diode has a high current density of 1 to 4 kA / cm 2 during operation, if the heat generated by the operating current is efficiently transmitted to the outside and not dissipated, the light emission efficiency of the laser diode is reduced by heat and the amount of light is reduced. Therefore, in order to maintain the light amount, the operating current is further increased. Since the operating current increases from this repetition and the life of the laser diode becomes extremely short, it is important to efficiently dissipate heat. Therefore, the laser diode is mounted on the heat dissipation block (heat sink) having high thermal conductivity, the electrode wiring is made, and the product is housed in a package. One such conventional laser diode mounting structure has been filed by the present applicant as Japanese Patent Application No. 2000-048375.
[0003]
The laser diode mounting structure will be described with reference to the drawings. FIG. 5 is a perspective view showing a submount which is a mounting member of a conventional laser diode. FIG. 6 is a perspective view showing a laser diode mounting structure using the submount of FIG. In FIG. 5, 65 is a submount and 51 is a rectangular parallelepiped heat radiation block made of a metal material having high thermal conductivity such as copper or copper alloy. At least the front surface (the front side in the figure) of the block 51 is plated with metal such as gold, and is in a surface state capable of wire bonding that is prevented from oxidation and corrosion. Reference numeral 52 denotes a rectangular parallelepiped ceramic piece joined to one corner of the front surface of the block 51. The two adjacent side surfaces of the block 51 and the two adjacent side surfaces of the ceramic piece 52 coincide with each other.
[0004]
On the front surface of the ceramic piece 52, a metallized pattern 52a such as gold is formed in a limited range, similar to the one disclosed in the application of Japanese Patent Application No. 2000-046649 by the applicant of the present application. Reference numeral 53 denotes a rectangular parallelepiped ceramic piece joined to the other corner of the block 51 opposite to the one corner. Two adjacent side surfaces of the block 51 and two adjacent side surfaces of the ceramic piece 53 are flush with each other. I'm doing it. The ceramic pieces 52 and 53 have the same thickness, and the front surface of the ceramic piece 53 is subjected to metallization as an electrode. The rear surfaces of the ceramic pieces 52 and 53 are all subjected to gold-tin metallization.
[0005]
Next, a laser diode mounting structure using the submount 65 will be described. In FIG. 6, reference numeral 54 denotes a laser diode element. The laser diode element 54 is positioned with high accuracy so as to match the metallized pattern 52a of the ceramic piece 52 so that the light emitting portion 54a faces upward in order to emit laser light from a desired position in the package. The anode electrode side is joined with a high thermal conductive adhesive. 55 is a wiring wire that connects the anode electrode of the laser diode element 54 and the front surface of the ceramic piece 53, and 56 is a wiring wire that connects the cathode electrode of the laser diode element 54 and the front surface of the block 51. 57 and 58 are wiring patterns on the package on which the submount 65 is mounted, and 59 and 60 are conductive fixing materials for connecting and fixing the ceramic pieces 53 and the block 51 and the wiring patterns 57 and 58, respectively. The front lower end of the ceramic piece 53 and the lower surface of the block 51 serve as connection terminals for the wiring patterns 57 and 58.
[0006]
Next, a method for manufacturing the submount will be described. In FIG. 7A, 61 has an outer peripheral shape from which tens to hundreds of blocks 51 can be taken out (represented in a simplified manner in the figure), and the thermal conductivity of copper, copper alloy or the like having a thickness of about 1 mm. It is a block aggregate made of a high metal material, and at least one surface of the front and back is subjected to surface treatment by gold plating or the like. Reference numeral 62 denotes a ceramic plate made of a high thermal conductive ceramic material such as aluminum nitride having the same outer peripheral shape as the block aggregate 61, and a pattern 62a which is a pair of large and small patterns whose surface (upper surface in the figure) is subjected to metallization of gold tin. Are arranged vertically and horizontally. Then, a metallization process such as gold is applied to the back surface (the lower surface in the drawing) in a pattern shape (not visible in the drawing) facing the pattern 62a, and the metallization pattern corresponding to the pattern 52a is applied to the larger pattern. ing.
[0007]
Reference numeral 64 denotes a jig plate having the same outer peripheral shape made of the same material as that of the block aggregate 61 or a material having the same thermal expansion coefficient. First, as shown in FIG. 7A, after the jig plate 64 and the ceramic plate 62 are bonded so that the pattern 62a faces outward, the ceramic plate 62 is cut along the A line and preliminarily divided. . Here, the A line is a cutting center line that divides a pair of patterns 62a included in the same block 51 when the submount is completed. At this time, the jig plate 64 may be partly cut, but not cut off. Next, the surface treated surface of the block aggregate 61 is superposed on the surface of the ceramic plate 62 where the pattern 62a is provided, and is pressed and heated, whereby a ceramic plate 62 to which a jig plate 64 as shown in FIG. And a block plate 61 are formed. During this time, the adhesive between the ceramic plate 62 and the jig plate 64 has lost its adhesive force. Next, as shown in FIG. Peel off. Thereafter, when the bonding plate 63 is cut by the B line, the portion of the ceramic substrate 62 that is in contact with the block aggregate 61 and not subjected to metallization is dropped, and the submount 65 as shown in FIG. 5 is completed. . Here, the B line is a cutting center line that divides the blocks 51 from each other when the submount is completed.
[0008]
[Problems to be solved by the invention]
However, in the conventional manufacturing method of such a submount, in the process of forming the joining plate by stacking the block assembly on the ceramic plate bonded to the jig plate, the gold-tin solder for joining to the copper plate is heated. Before the melt bonding, the adhesive between the jig plate and the ceramic plate loses its fixing force, so that the aligned ceramic pieces may move. Then, using the specified position of the pattern on the freely moving ceramic pieces as a reference, the average outer cutting position of the submount is determined and cut into individual pieces. In FIG. 5, L1, L2, and L3) vary, and the mounting yield of the laser element is deteriorated. Moreover, in this manufacturing method, there are many parts where ceramics are discarded, and the material yield is as low as about 50%. From the above, facilities, man-hours, and material costs are large.
[0009]
The present invention has been made to solve such a conventional problem, and its object is to contribute to a reduction in equipment cost and man-hours, and to improve a material yield and a laser diode submount and a method for manufacturing the same. Is to provide.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is composed of a heat dissipation block made of a high heat conductive metal material for mounting a laser diode, and both surfaces of the block are metallized. was at a plurality of ceramic pieces is laser diode submount joined, the piece one ceramic of said plurality of ceramic pieces metallized pattern to be a fixed position reference of the laser diode is formed, the ceramic The pieces are joined to the top front center upper end of the block so that the upper surfaces thereof are coincident with each other, and the other ceramic pieces are joined to the lower corners of the front face of the block with the lower surface and side surfaces of the block being coincident with each other. It is characterized by.
[0012]
The invention of claim 2, wherein, among the invention of claim 1 Symbol placement, the surface of the ceramic pieces are joined in the block, characterized in that are plated with gold.
[0013]
The invention described in claim 3 is a method of manufacturing a formed laser diode submount with heat radiating block of high thermal conductivity metal material for mounting the laser diode, the size of the high heat that can be extracted a number sub-mount the conductive metal substrate is subjected to the entire surface metallization with solder gold-tin on one side, forming a block aggregates stuck in the desired sequence ceramic piece gold-metallized on the entire surface on the back surface, the ceramic And the step of cutting the assembly so that all the pieces are cut in at least one direction and a part is cut in two directions, and the submount is taken out as a single piece.
[0014]
According to a fourth aspect of the present invention, the metal substrate is bonded to a jig plate before the assembly is cut out of the third aspect of the invention, and then the laser diode is fixed to the ceramic piece as a reference position for the laser diode. It has the process of forming a metallization metallization pattern.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a laser diode submount according to an embodiment of the present invention, FIGS. 2 and 3 are perspective views or plan views showing a method of manufacturing the submount, and FIG. It is a top view which shows the pattern shape of the laser element mounting part of the submount which is this embodiment.
[0016]
First, the configuration of the laser diode submount according to the embodiment of the present invention will be described. In FIG. 1, reference numeral 15 denotes a submount, and reference numeral 1 denotes a rectangular parallelepiped heat dissipation block made of a metal material having high thermal conductivity such as copper or copper alloy which is a base of the submount 15. At least one surface (the front side of the figure) of the block 1 is plated with metal such as gold, and is in a surface state capable of wire bonding that is prevented from oxidation and corrosion. 2, 3, 4 are rectangular parallelepiped high thermal conductive ceramic pieces having the same thickness, and the ceramic piece 2 is bonded to the upper center of the front surface of the block 1 with the upper surfaces aligned with each other. A laser diode element mounting pattern 2a is formed. The ceramic pieces 3 and 4 are joined to both adjacent corners of the block 1 such that the lower surface and side surfaces of the block 1 and each other coincide with each other. The front surface of the ceramic pieces 3 and 4 is subjected to a metallization process in a surface state capable of wire bonding. The rear surfaces of the ceramic pieces 2, 3, 4 are metalized with gold-tin solder on the entire surface.
[0017]
Next, a method for manufacturing the submount will be described. In FIG. 2 (a), 11 is a block aggregate having an outer peripheral shape from which a large number of blocks 1 can be taken out and having a thickness of about 1 mm, and at least one surface is in a surface state capable of preventing oxidation / corrosion and wire bonding by gold plating or the like. Process it. In FIG. 2 (b), the surface 12 is metallized on the entire surface with high heat conductive solder such as gold tin, and further metallized on the back surface with gold or the like in consideration of solder wettability and wire bonding property. A large ceramic plate is cut into pieces that take into account the mounting accuracy of a transfer machine, a chip mounter, etc., which will be described later. As shown in FIG. 2C, a ceramic piece 12 is placed on a copper plate 1 in a checkered pattern with a general positional accuracy of about ± 100 μm with a gold tin side down using a transfer machine, a chip mounter, etc. By joining in a low oxygen atmosphere such as pressurization heating and cooling, 13 joining plates in which a large number of ceramic pieces 12 are joined are formed.
[0018]
In FIG. 3, reference numeral 14 denotes a jig plate having the same outer peripheral shape made of the same material as the block aggregate 11 or a material having a thermal expansion coefficient comparable to that of the block aggregate 11. As shown in FIG. 3A, the block assembly 11 side of the joining plate 13 is flatly adhered to the jig plate 14 in order to reduce the warpage of the joining plate 13. Next, as shown in FIG. 3 (b), a desired metallized pattern is masked on a part of the ceramic pieces 12, and the metallized portion other than the desired pattern is removed using an etching apparatus to complete the completed submount. Thus, a desired metallized pattern 12a having a size capable of obtaining two metallized patterns 2a is obtained.
[0019]
The joining plate 13 on which the pattern 12a is formed is cut using a cutting device such as a multi-wire saw so as to cut a part of the jig plate 14 along the C line shown in FIG. Here, the C line is a cutting center line that determines the outer shape of each submount 15 including the bisector of the pattern 12a. By this method, the positional accuracy of the pattern 2a with respect to the outer shape of the submount 15 is improved. However, in order to further increase the positional accuracy of the pattern 2a, the joining plate 13 on the jig plate 14 is cut by the C line before the pattern 12a is formed. Then, by forming the metallized pattern 2a with respect to the intersection of the C line in FIG. 3C on the joining plate 13 that is separated into pieces together with the jig 14, the cutting position error is reduced. You may make it obtain the removed submount.
[0020]
Next, the effect of this embodiment will be described. Since the ceramic piece 12 has been divided into small pieces in advance, the influence of the difference in thermal expansion coefficient between the two materials due to pressurization, heating, and cooling remains in the small area of the ceramic piece 12 when being fixed to the block assembly 11. The warp of the plate 13 can be reduced. Further, when the jig plate 14 is bonded to the joining plate 13 later, the adhesion between the block assembly 11 and the ceramic piece is not loosened. In addition, since the outer shape of the submount 15 is cut based on the metallized pattern 2a which is a reference position for fixing the laser diode element, the position accuracy of the laser diode element is determined with high accuracy regardless of the bonding position accuracy of the ceramic piece 12. It becomes like this. Moreover, since many pieces are processed by batch processing, man-hours can be reduced.
[0021]
Further, when the submount 15 is formed, six ceramic pieces are required for two finished products by arranging as shown in FIG. 3, but in the case of a large number of pieces, about two pieces are calculated. Therefore, equipment costs such as a transfer machine and a chip mounter can be kept low. In addition, since it is a method using individual ceramic pieces, an inexpensive insulating material such as alumina, zirconia, glass or the like can be substituted for the ceramic pieces that become the electrodes, in which case the manufacturing cost is further reduced. Can be reduced. In addition, a partial metallization pattern such as gold-tin solder on the back surface of the ceramic, which was necessary in the conventional method, is unnecessary, and the equipment costs related to patterning can be reduced. Since both electrodes are drawn out on the lower surface of the submount 15, it is easy to bond the substrate to the wiring pattern.
[0022]
Although the metallized pattern 2a described in the above embodiment is for a two-wavelength laser, it can be applied to a single-wavelength laser as it is by simply forming the pattern as shown in FIG. In this case, one of the electrode ceramic pieces is not necessary, but a cost merit can be obtained as compared with a case where a submount for a single wavelength laser is prepared by another design.
[0023]
【The invention's effect】
As described above, according to the present invention, a block assembly in which a large number of ceramic pieces divided into individual pieces are joined is formed on a block substrate made of a metal material having a high thermal conductivity in advance, and a laser diode is fixed to the assembly. Since a pattern serving as a position reference is formed and the outer shape of the submount is cut using this pattern as a reference, the laser diode fixing position accuracy is improved, which contributes to man-hour reduction and yield improvement.
[0024]
Further, by performing pattern formation as a reference position for fixing the laser diode after cutting the outer shape of the bonding plate, an error in the outer cutting position was removed, and a more accurate submount was obtained. Since the individual pieces cut out from the ceramic plate are used, the material yield is improved and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a laser diode submount according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a method for manufacturing a laser diode submount according to an embodiment of the present invention.
FIG. 3 is a perspective view (partially plan view) showing a method for manufacturing a laser diode submantle according to an embodiment of the present invention.
FIG. 4 is a plan view of a laser diode element fixing pattern according to another embodiment of the present invention.
FIG. 5 is a perspective view of a conventional laser diode submount.
FIG. 6 is a perspective view showing a laser diode mount mounting structure using a conventional laser diode submount.
FIG. 7 is a perspective view showing a conventional method of manufacturing a laser diode submount.
[Explanation of symbols]
1 Block 2, 3, 4 Ceramic piece 2a Metallized pattern 11 Block assembly 12 Ceramic piece 12a Pattern 13 Bonding plate 14 Jig plate 15 Submount

Claims (4)

A laser diode submount comprising a heat dissipation block made of a highly thermally conductive metal material for mounting a laser diode , wherein a plurality of ceramic pieces metallized on both sides are bonded to one surface of the block . A metallized pattern serving as a reference for fixing the laser diode is formed on one of the ceramic pieces, and the ceramic piece is bonded to the upper center of the front surface of the block so that the upper surfaces coincide with each other. A ceramic diode submount, wherein the ceramic piece is joined to both lower corners of the front face of the block such that the lower face and side faces of the block coincide with each other . The laser diode submount according to claim 1, wherein the surface that is bonded to the ceramic piece of the block are plated with gold. The method of manufacturing a laser diode submount composed of radiating block of high thermal conductivity metal material for mounting the laser diode, the high thermal conductivity metal substrate size can be extracted a number sub-mount, gold on one side A step of forming a block aggregate by applying ceramic metallization to the entire surface with tin solder and fixing a metal piece with gold metallization treatment on the back surface in a desired arrangement, and cutting the ceramic piece at least in one direction And a step of cutting the block assembly so that a part thereof is cut in two directions and taking out the submount as a single unit. 4. The method according to claim 3, further comprising the step of forming a metallized pattern serving as a laser diode fixing position reference on the ceramic piece after the metal substrate is bonded to a jig plate before cutting the assembly. Of manufacturing a laser diode submount.

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