JPH10261820A - Sub-mount, optical element using it, and manufacture of its wiring section - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sub-mount having a wiring section which is improved in continuity reliability and the manufacturing process of which can be simplified. SOLUTION: A sub-mount 1 is constituted of a ceramic substrate 2 having a first flat surface for placing optical parts and a massive electrode 3 which is buried in the second flat surface of the substrate 2 so that the first surface 3a of the electrode 3 may be exposed on the first flat surface of the substrate 2 in a flushed state and, at the same time, the second surface 3b of the electrode 3 may be flushed with the second flat surface of the substrate 2. An optical element is formed by providing a photodiode or laser diode on the first flat surface of the substrate 2 of the sub-mount 1 as the optical parts. In addition, the wiring section of the sub-mount 1 is formed by forming punoced holes through a ceramic green sheet and filling up the punched holes with printed metallized paste composed of a conductive material, and then, baking the sheet after cutting the sheet into pieces or cutting the sheet into pieces after baking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submount in which a wiring portion is provided on a ceramic substrate, an optical element incorporating a surface-receiving photodiode or a surface-emitting laser diode using the submount, and a sub-mount. The present invention relates to a method for producing a wiring portion of a mount.

[0002]

2. Description of the Related Art Conventionally, a photodiode has been provided on a submount consisting of a ceramic substrate and a wiring portion in order to receive an optical signal on a surface and supply it as an electrical signal to an external circuit.
2. Description of the Related Art Various configurations of a photodiode subassembly as an example of an optical element that supplies a signal of a photodiode to an external circuit via a wiring portion are known. Also, various types of laser diode subassemblies using surface emitting laser diodes instead of photodiodes as optical elements are known.

FIG. 6 is a diagram showing a configuration of an example of a photodiode subassembly as an example of a conventional optical element.
In the example shown in FIG. 6, the photodiode subassembly 51 includes a ceramic substrate 52 and a ceramic substrate 5.
The photodiode 53 provided on the second side surface, the wiring portion 54 formed continuously on the same side surface and the upper surface of the photodiode 53, and the wiring portion 54a on the same side surface as the photodiode 53 and the photodiode 53 are connected. And a wire bonding portion 55. Reference numeral 56 denotes a wire bonding portion that connects the wiring portion 54b on the upper surface of the ceramic substrate 52 to an external circuit (not shown).

[0004]

In the above-described conventional photodiode subassembly 51, in order to connect the photodiode 53 to an external circuit, a wiring portion 54 is formed with a wiring portion 54a formed on the side surface of the ceramic substrate 52. 54b formed on the upper surface. As described above, the wiring portion 54 is connected to a different surface of the ceramic substrate 52, that is, FIG.
In the example shown in (1), since it must be provided over two perpendicular surfaces, there is a problem that the reliability of conduction at the corner 54c is poor.

That is, there is a possibility that the corner portion 54c is chipped during handling or the like, and the wiring portion 54 is disconnected. In addition, in order to form the wiring part 54, usually, first, one wiring part, for example, the wiring part 54a is formed by printing,
The other wiring portion 54b is formed by printing. On this occasion,
Although the above two-step printing is performed in consideration of the corner 54c, the corner 54c is inevitably rounded and thin,
Again, there was a possibility that the wire would break at this corner 54c. Further, as described above, two steps of printing are required to form the wiring part 54, and there is a problem that the wiring part 54 is troublesome in manufacturing.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a submount, an optical element using the submount, and a method of manufacturing the wiring portion, which has high reliability of conduction of the wiring portion and can simplify a manufacturing process.

[0007]

A submount according to the present invention comprises: a ceramic substrate having a first plane on which an optical component is to be mounted; and a submount embedded on a second plane different from the first plane of the ceramic substrate. And the first surface is exposed so as to be flush with the first plane, and the second surface thereof is flush with the second plane. And a massive electrode that is exposed to light.

An optical device using the submount according to the present invention is an optical device using the submount having the above-described structure, and includes a photodiode or a laser diode provided on a first plane of the ceramic substrate. And a wire bonding portion for conducting a photodiode or a laser diode to the first plane of the massive electrode.

Further, according to the method of manufacturing a wiring portion of a submount according to the present invention, the punching hole is formed by punching a ceramic green sheet in the method of manufacturing a wiring portion formed of massive electrodes of the submount having the above-described structure. The metallized paste made of a conductive material is embedded in the punched holes by printing, and (1) the ceramic green sheet and the metallized paste are cut so that the punched holes are divided into two, and then the ceramic green sheet and the metallized paste are simultaneously fired. Alternatively, (2) the ceramic green sheet and the metallized paste are simultaneously fired, and thereafter, the ceramic substrate and the massive electrode are cut so that the punched holes are divided into two.

In the present invention, the wiring portion is formed by embedding the massive electrode in the ceramic substrate, exposing the first surface of the massive electrode to be flush with the first plane of the ceramic substrate, By exposing a second surface different from the first surface so as to be flush with a second plane different from the first plane of the ceramic substrate, there is a corner in a conventional wiring portion. Without this, the reliability of conduction in the wiring portion is increased. Further, in order to form such a block electrode as a wiring portion by embedding it in a ceramic substrate, a punch hole is formed in a ceramic green sheet with a punch as conventionally known for manufacturing a ceramic wiring substrate or the like. A large number of submounts are produced by printing a conductive metallizing paste in the punched holes and then cutting at a predetermined position and firing at the same time or simultaneously firing and cutting at a predetermined position. be able to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a configuration of an example of a submount according to the present invention. In the example shown in FIG. 1, the submount 1 of the present invention includes a ceramic substrate 2 and a semi-cylindrical electrode 3 formed by embedding the upper surface of the ceramic substrate 2 and having a shape obtained by dividing a cylinder in the axial direction. I have.
A feature of the submount 1 of the present invention is that a wiring portion is formed by embedding a semi-cylindrical electrode 3 as a block electrode on the upper surface of a ceramic substrate 2, and at this time, a semi-circular end 3 of the semi-cylindrical electrode 3 is formed.
a is exposed so as to be flush with the side surface of the ceramic substrate 2, and the cylindrical section 3 b of the semi-cylindrical electrode 3 is exposed so as to be flush with the upper surface of the ceramic substrate 2.

In the example shown in FIG.
Is not particularly limited, but for example, AlN or alumina is preferably used. The material of the semi-cylindrical electrode 3 is not particularly limited as long as it has conductivity, but it is preferable to use Mo or W. Further, if necessary, it is preferable that the semicircular end 3a and the cylindrical cross section 3b of the semicylindrical electrode 3 are plated with Ni or Au to improve the conductivity. In addition, in the example shown in FIG. 1, the example of the semi-cylindrical electrode 3 is shown as the massive electrode, but at least one surface of the massive electrode having another shape is exposed to the side surface of the ceramic substrate 2 and the other electrode is formed. Needless to say, as long as the surface is exposed on the upper surface of the ceramic substrate 2, it can be suitably used similarly to the above-described semi-cylindrical electrode 3.

In the submount 1 of the present invention having the above-described structure, the wiring portion is formed by an integral block electrode, that is, the semi-cylindrical electrode 3, so that the corner 3c of the semi-cylindrical electrode 3 is used for handling or the like. Even if it is missing a little, there is no disconnection, and the reliability of conduction of the wiring portion can be increased.

FIG. 2 shows a photodiode subassembly 11 as an example of an optical element using the submount of the present invention.
FIG. 3 is a diagram illustrating an example of a configuration. In the example shown in FIG.
The photodiode subassembly 11 of the present invention includes a ceramic substrate 12, a surface light receiving photodiode 13 provided on a side surface of the ceramic substrate 12, and a ceramic substrate 12.
A semi-cylindrical electrode 14 formed by embedding in the upper surface of a cylinder and having a shape obtained by dividing a cylinder in the axial direction, and a wire bonding portion 15 connecting the photodiode 13 and the semi-cylindrical electrode 14
It is composed of 16 is a semi-cylindrical electrode 14
And a wire bonding portion for connecting the external circuit (not shown).

In the photodiode subassembly 11 of the present invention, similarly to the submount shown in FIG.
The wiring portion is formed by embedding a semi-cylindrical electrode 14 as a block electrode on the upper surface of the ceramic substrate 12, and the semi-circular end 14 a of the semi-cylindrical electrode 14 is flush with the side surface of the ceramic substrate 12. And the cylindrical section 14b of the semi-cylindrical electrode 14 is exposed so as to be flush with the upper surface of the ceramic substrate 12. Then, the wire bonding section 15 is connected to the photodiode 1
3, and a wire bonding portion 16 is formed between the columnar section 14b of the semi-cylindrical electrode 14 and an external circuit.

FIG. 3 is a diagram showing an example of the overall configuration of a photodiode subassembly 11 as an optical element according to the present invention. In the example shown in FIG.
3 are provided in a line on the side surface of the ceramic substrate 12 at equal intervals, and a plurality of semi-cylindrical electrodes 14 are formed on the upper surface of the ceramic substrate 12 at equal intervals corresponding to the respective photodiodes 13. As an example of actual dimensions, the length L of the ceramic substrate 12 is 5 mm, the width W is 1 mm, the height H is 1.5 mm, and the pitch P between the photodiode 13 and the semi-cylindrical electrode 14 is 0.25 mm. .

In the examples shown in FIGS. 2 and 3, the photodiode subassembly 11 has been described as an optical element. However, if a surface emitting laser diode is provided instead of the photodiode 13, the optical element of the present invention can be used. Another example laser diode subassembly can be made. Further, in the example shown in FIGS. 2 and 3, an example in which a plurality of photodiodes 13 are arranged in parallel as a photodiode subassembly 11 to form an array has been described, but each of the photodiode 13 and the semi-cylindrical electrode 14 is one. Needless to say, the present invention can be applied to a single-channel photodiode subassembly provided as well.

FIGS. 4 (a) to 4 (d) are views showing each step of the method for producing the wiring portion of the submount 1 according to the present invention. First,
A ceramic green sheet 21 having the same width as the length L of the submount 1 to be manufactured and having the same thickness as the width W is prepared, and the semi-cylindrical electrode of the ceramic green sheet 21 is formed as shown in FIG. Punch holes 22 are formed by punching at positions where the holes 14 should be formed. Next, FIG.
As shown in (b), the formed punch holes 22 are filled with a metallizing paste 23 made of a conductive material, preferably Mo or W, by printing.

Next, as shown in FIG. 4C, the ceramic green sheet 21 and the metallized paste 23 in the punch holes 22 are cut at the position L1 so that the punch holes 22 are divided into two. In addition, along with the above cutting,
Further cutting is performed at a position L2 having the same width as the length H of the photodiode array 1 from the cutting position L1. Thereafter, by firing the ceramic green sheet 21 and the metallized paste 23 at the same time, the wiring portion of the submount 1 can be manufactured as shown in FIG. In the above-described example, cutting was performed after firing.
3 is filled by printing, the ceramic green sheet 21 and the metallized paste 23 are simultaneously fired first, and then the ceramic substrate and the block electrodes are cut in accordance with the above-described method, and a similar wiring portion of the submount 1 is produced. can do. In each of the examples, Ni plating and Au plating for wire bonding are provided on the surface of the electrode as necessary.

In the example shown in FIG. 4, the example in which the thickness of the ceramic green sheet 21 is the same as the width W of the submount to be produced is shown. It is often difficult to obtain the width W of the submount. In that case, a predetermined number of ceramic green sheets 21 can be laminated to obtain the width W of the submount. In this case, all the ceramic green sheets 21 can be laminated by providing punch holes 22 at predetermined positions as shown in FIG. 4A, but it may be difficult to position the punch holes at the time of lamination. Therefore, it is preferable to provide the punched holes 22 only on one sheet exposed on the surface, and to stack the ceramic green sheets 21 having no punched holes. Then, a portion that is not enough as an electrode can be formed by printing and firing a metallized paste.

FIG. 5 shows an example of such an example. In the example shown in FIG. 5, 31 and 32 are electrodes provided on the first plane and the second plane of the ceramic substrate 2 by printing and firing, respectively. Also in this example, since the semi-cylindrical electrode 3 exists at the corner, disconnection or the like at the corner does not occur. In the example shown in FIG. 5, the electrodes 31 and 32 are provided in common to the two semi-cylindrical electrodes 3 in the case where the electrodes for connecting the grounds of all the photodiodes or laser diodes are formed. This is because a large current flows in that case.

[0022]

As is apparent from the above description, according to the present invention, the wiring portion should be formed by embedding the massive electrode in the ceramic substrate, and the first surface of the massive electrode should be provided with the optical component of the ceramic substrate. Exposed so as to be flush with the first plane, and a second surface different from the first surface of the massive electrode is flush with a second plane different from the first plane of the ceramic substrate. Since there is no corner in the conventional wiring portion, the reliability of conduction in the wiring portion is increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an example of a submount of the present invention.

FIG. 2 shows a photodiode as an example of the optical element of the present invention.
It is a figure showing an example of composition of a subassembly.

FIG. 3 is a diagram showing an example of an overall configuration of a photodiode subassembly of the present invention.

FIG. 4 is a view showing each step of a method for producing a wiring portion of a submount according to the present invention.

FIG. 5 is a diagram showing a configuration of another example of the submount of the present invention.

FIG. 6 is a diagram showing a configuration of an example of a conventional photodiode subassembly.

[Explanation of symbols]

1 Submount, 2, 12 Ceramic substrate, 3,
14 semi-cylindrical electrode, 3a, 14a semi-circular end, 3
b, 14b Cylindrical cross section, 3c, 14c corner, 11 photodiode subassembly, 13 photodiode, 15, 16 wire bonding part, 21 ceramic green sheet, 22 punch hole, 23 metallized paste

Claims (8)

[Claims] 1. A ceramic substrate having a first plane on which an optical component is to be mounted; and a massive electrode embedded on a second plane different from the first plane of the ceramic substrate,
The first surface is exposed so as to be flush with the first plane, and the second surface is composed of a massive electrode exposed so as to be flush with the second plane. A submount characterized by the following. 2. The semi-cylindrical electrode in which the massive electrode is formed by dividing a cylinder in the axial direction, and exposing a semi-circular end of the semi-cylindrical electrode so as to be flush with the first plane.
2. The submount according to claim 1, wherein the cross section of the cylinder is exposed so as to be flush with the second plane. 3. An optical device using the submount according to claim 1 or 2, wherein a photodiode or a laser diode provided on a first plane of the ceramic substrate; An optical element comprising: a wire bonding portion that conducts to a first plane of an electrode. 4. The optical device according to claim 3, wherein a plurality of sets of said photodiode or laser diode and a block electrode are provided. 5. A method of manufacturing a wiring portion comprising a block electrode of a submount according to claim 1, wherein a punched hole is formed by punching a ceramic green sheet, and the formed punched hole is formed of a conductive material. A method for producing a wiring portion, comprising: embedding a metallized paste by printing, cutting a ceramic green sheet and a metallized paste so that a punch hole is divided into two, and then simultaneously firing the ceramic green sheet and the metallized paste. 6. A method for manufacturing a wiring portion comprising a block electrode of a submount according to claim 1 or 2, wherein a punched hole is formed by punching a ceramic green sheet, and the formed punched hole is formed of a conductive material. A method for producing a wiring portion, comprising: embedding a metallized paste by printing, simultaneously firing a ceramic green sheet and a metallized paste, and then cutting the ceramic substrate and the block electrode so that a punch hole is divided into two. 7. The method according to claim 5, wherein said ceramic green sheet is made of alumina, and said metallized paste is Mo or W paste. 8. The method according to claim 5, wherein the first and second surfaces of the fired massive electrode are plated with Ni or Au.