JP4649172B2 - Manufacturing method of stem for semiconductor package - Google Patents

Description

  The present invention relates to a semiconductor package stem on which a laser element is mounted, a manufacturing method thereof, and an optical semiconductor device in which a laser element is mounted on a semiconductor package stem.

Several different structures of products are provided for semiconductor package stems on which laser elements are mounted. FIG. 5 shows a basic structure of a semiconductor package stem 10 on which a laser element is mounted. The semiconductor package stem 10 includes an eyelet body 12, a heat radiator 14 provided on the eyelet body 12, and a lead 15 sealed on the eyelet body 12.
In this semiconductor package stem 10, a laser element 16 is bonded to a side surface of a heat dissipation body 14, the laser element 16 and a lead 15 are connected by wire bonding, and a cap 18 having a light transmission window 17 is welded to the eyelet body 12. As a result, the optical semiconductor device is assembled.

The eyelet body 12 of the semiconductor package stem 10 is usually formed of an iron-based material. This is because the iron-based material is suitable for sealing the lead 15 with the glass, and the cap 18 is joined to the eyelet body 12 by resistance welding, so that the eyelet body 12 needs a certain amount of electrical resistance. However, since a recent optical semiconductor device has been equipped with a laser element having a large calorific value, a semiconductor package stem 10 having a larger heat dissipation property has been demanded.
FIG. 6 shows a semiconductor package stem 11 formed using a clad material having a two-layer structure of iron and copper (see Patent Document 1). This semiconductor package stem 11 is formed by pressing a clad material and forming a heat radiator 14a in a raised shape from a copper material portion by pressing, and the eyelet body 12 includes an iron material portion 12a and a copper material portion 12b.

The semiconductor package stem 11 shown in FIG. 6 has the advantage of being excellent in terms of heat dissipation because the heat radiator 14a is formed of a copper material and a copper material is used for a part of the eyelet body 12. is there. However, since the upper part of the eyelet body 12 to which the cap is joined is made of copper, there is a problem that it is difficult to join the cap by resistance welding. Instead of a clad material having a two-layer structure of iron and copper, a pair of It has been considered that a semiconductor package stem is formed using a clad material having an iron-copper-iron three-layer structure in which a copper layer is sandwiched from both sides by an iron layer (see Patent Document 2). The semiconductor package stem formed using this three-layer clad material is excellent in heat dissipation by using a copper material for the clad material, and the upper surface of the eyelet body 12 is made of iron material. It has the advantage that it can be reliably resistance welded.
JP-A-6-291224 JP-A-11-186649

As described above, the semiconductor package stem formed by using a material (cladding material) having a three-layer structure of iron-copper-iron is excellent in heat dissipation and can be reliably attached to the cap by resistance welding. However, since the heat dissipator is formed integrally with the eyelet by pressing, there is a problem that the arrangement position of the heat dissipator and the shape of the heat dissipator are restricted.
That is, in the case where the heat radiator is formed integrally with the eyelet, a through hole for sealing the lead to the glass is punched after pressing the workpiece in the processing step. In actual products, this through-hole is often provided very close to the outer surface of the heat sink. If the hole shape cannot be processed, it may cause defects.

For this reason, depending on the positional relationship between the heat dissipating member and the sealing hole, processing becomes difficult, the defect rate becomes high, and processing as designed becomes difficult.
The present invention has been made to solve these problems, has excellent heat dissipation, and can perform assembly work such as joining caps by resistance welding without any trouble. An object of the present invention is to provide a stem for a semiconductor package and a method for manufacturing the same, which are not restricted in shape, arrangement, or the like.

The present invention has the following configuration in order to achieve the above object.
That is, a method for manufacturing a stem for a semiconductor package comprising an eyelet body, a heat dissipator provided in the eyelet body, and a lead sealed to the eyelet body, wherein a copper layer is sandwiched between a pair of iron layers 3 For the clad material composed of a layer structure, a step of roughing to a larger diameter than the outer shape of the eyelet body, and a concave portion is formed in accordance with the area where the copper layer is exposed in the roughened clad material. Using the pressed die, the region where the iron layer part is pressed from the surface side forming the stepped portion and the heat sink of the iron layer formed on one side of the clad material is joined to the clad. A step of pressing so that the iron layer portion in the region protrudes in a step shape from the surface of the material, and removing the iron layer portion protruding in a step shape from the surface of the cladding material to make the surface of the cladding material flat When formed into In addition, a step of performing a flattening process for exposing the copper layer under the iron layer part and a through hole for inserting and sealing a lead in the clad material subjected to the flattening process are formed. A step of performing a punching process, a step of separating the eyelet main body from the clad material subjected to the hole punching process, and an outer shape punching process to match the outer shape of the eyelet main body, and the eyelet main body of the individual piece Brazing a heat-dissipating member formed by a step of sealing the lead to the glass and a step separate from the individual eyelet body to the exposed surface of the copper layer of the individual eyelet body having the lead sealed with glass And a step of performing.

Further, the pressing process causes the iron layer portion to protrude in a step shape from the surface of the clad material to a thickness equal to or more than the thickness of the iron layer partially including the lower copper layer, and the shaving process is performed as the flattening process. By removing the iron layer portion protruding from the surface of the clad material stepwise from the copper layer, the surface of the copper layer is exposed to the same height as the surface of the iron layer .

In addition, after the radiator is brazed to the exposed surface of the copper layer of the eyelet body of the individual piece, the side surface serving as the laser element mounting surface of the radiator is flattened and positioned. .

  According to the semiconductor package stem and the manufacturing method thereof according to the present invention, the eyelet body is made of a clad material provided with a copper layer, and the radiator is directly bonded to the copper layer having excellent thermal conductivity. It can be provided as a semiconductor package stem having excellent heat dissipation, and can be suitably used as a semiconductor package stem on which a laser element with a large amount of heat generation is mounted. In addition, since the eyelet main body and the heat radiating body are separated from each other, the shape and arrangement position of the heat radiating body are not subject to processing restrictions, and various products can be handled.

FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a stem for a semiconductor package according to the present invention. The semiconductor package stem 20 of the present embodiment is formed by using a clad material having an iron-copper-iron three-layer structure in which the eyelet body 21 is sandwiched between a pair of iron layers and the eyelet body 21 is separated from the eyelet body 21. The heat radiator 25 made of copper formed on the body is brazed to the eyelet body 21.
The eyelet body 21 has a three-layer structure in which a first iron layer 22, a copper layer 23, and a second iron layer 24 are laminated in order from the surface opposite to the surface to which the heat radiator 25 is bonded. The eyelet body 21 is formed so that the upper and lower surfaces of the eyelet main body 21 are covered with an iron material.

Further, the second iron layer 24 is removed and the copper layer 23 is exposed on the upper surface of the eyelet body 21 in the bonding region where the heat radiator 25 is brazed on the upper surface of the eyelet body 21. A radiator 25 is joined to the exposed surface 23a.
The eyelet body 21 is formed by pressing or shaving a clad material having a three-layer structure of iron-copper-iron so that the surface of the second iron layer 24 and the exposed surface 23a of the copper layer 23 are flush with each other. It is formed to be a flat surface. The radiator 25 is brazed to the exposed surface 23a.

An inclined recess 26 is formed on the upper surface of the eyelet body 21 in the vicinity of the base of the radiator 25 to mount an element for monitoring light emission (monitoring element). The inclined recess 26 is formed when the clad material having the three-layer structure is pressed.
Further, a through hole for sealing the lead 15 to the eyelet body 21 is formed, and the lead 15 is glass sealed in the through hole. In FIG. 1, a lead 15 a is a ground lead, and is joined to the lower surface of the eyelet body 21 by resistance welding.

  In the semiconductor package stem 20 of the present embodiment, the eyelet body 21 has a three-layer structure in which the first iron layer 22, the copper layer 23, and the second iron layer 24 are laminated. When the cap 18 is resistance-welded, the required electrical resistance is obtained and the cap 18 can be reliably welded. Moreover, since the heat radiating body 25 is made of a copper material, the heat dissipating property of the heat radiating body 25 is good, and since the heat radiating body 25 is brazed to the copper layer 23 of the eyelet body 21, the heat dissipation of the entire stem is achieved. As a result, it becomes possible to obtain heat dissipation equivalent to that of a product in which the copper material of the eyelet is pressed and the heat radiator and the eyelet are integrally formed.

  In addition, since the semiconductor package stem 20 of the present embodiment has a configuration in which the heat radiating body 25 is formed separately from the eyelet body 21, a process for processing a through hole for sealing the lead 15 to the eyelet body 21. Therefore, it is possible to perform the drilling process without being influenced by the shape and arrangement position of the heat radiating body 25, and thus it is possible to reliably and accurately form the through hole in the eyelet body 21. In addition, since the radiator 25 is brazed and joined to the eyelet body 21 after drilling, the shape of the radiator 25 is not restricted by the drilling (hole position), and the radiator 25 is more free as the radiator 25. A large degree of design becomes possible, and it becomes possible to deal with products of various uses.

2 to 4 show a processing process of the eyelet body 21 which is characteristic in the manufacturing process of the semiconductor package stem 10 described above.
FIG. 2A shows a state in which a clad material 30 having a three-layer structure of iron-copper-iron that forms the eyelet body 21 is roughly drawn to a larger diameter than the outer diameter of the eyelet body 21. The clad material 30 is formed by laminating a first iron layer 22, a copper layer 23, and a second iron layer 24. In the clad material 30 used in this embodiment, the thickness of the first iron layer 22 is 0.75 mm, the thickness of the copper layer 23 is 0.7 mm, and the thickness of the second iron layer 24 is 0.15 mm. Is. Actually, the clad material 30 is provided as a long belt-like body, and is processed by being sequentially fed between processing stages on which a required pressing is performed.

2 (b) and 2 (c) show a process of subjecting the roughly blanked clad material 30 to press working to expose the copper layer 23 in accordance with the region where the radiator 25 is brazed.
FIG. 2 (b) shows a step of aligning and pressing the press die 40 in which the concave portion 42 is formed in accordance with the portion where the copper layer 23 is exposed, with the roughly blanked clad material 30. The recess 42 has a circular planar shape, and an inner bottom surface (ceiling surface) is formed as a flat surface. The depth of the recess 42 is set to such a depth that the copper layer 23 under the second iron layer 24 slightly enters. The pressing surface 44 of the press die 40 other than the recess 42 is formed as a flat surface.

FIG. 2 (c) shows a state in which the press die 40 is pressed onto the clad material 30. The lower surface of the clad material 30 is supported by a support die, and the clad material 30 is sandwiched between the press die 40 and the support die. By pressing the press die 40 to a depth substantially equal to the thickness of the second iron layer 24, the second iron layer 24 and the copper layer 23 enter the recess 42, and the clad material corresponding to the recess 42 has the first portion. The copper layer 23 below the second iron layer 24 has a raised shape.
FIG. 2 (d) shows a state after the clad material 30 is pressed using the press die 40. On the upper surface of the clad material 30, the iron layer portion 24 a (including a part of the lower copper layer) corresponding to the concave portion 42 is stepped from the upper surface of the clad material 30 by a thickness greater than the thickness of the second iron layer 24. Protrusively. The portion of the copper layer 23 that supports the iron layer portion 24a has a shape that rises in a trapezoidal shape.

FIG. 3 shows a flattening process in which the iron layer portion 24a protruding in a step shape on the upper surface of the clad material 30 is removed by shaving, and the upper surface of the clad material 30 is flattened.
FIG. 3A shows a state in which the cutting position of the cutting blade 50 is aligned with the lower portion of the side surface of the iron layer portion 24a, that is, the surface of the second iron layer 24, and FIG. The state which moves so that it may protrude along the surface of the 2nd iron layer 24 and the iron layer part 24a is cut from the clad material 30 is shown.
FIG. 3C shows the clad material 30 obtained by cutting and removing the iron layer portion 24a. By moving the cutting blade 50 along the surface of the second iron layer 24, the iron layer portion 24 a is cut and removed from the copper layer 23, and the surface of the copper layer 23 is the surface of the second iron layer 24. The exposed surface 23a is formed on the same height surface and the copper layer 23 is exposed.

In the present embodiment, the iron layer portion 24a is removed by shaving using the cutting blade 50. However, the iron layer portion 24a may be exposed by other machining such as drilling instead of shaving. Is possible. It is also possible to remove only the iron layer portion 24a using chemical etching without using machining.
In the step of removing the iron layer portion 24a, the exposed surface 23a of the copper layer 23 is flat in order to expose the copper layer 23 below the iron layer portion 24a and to accurately braze the radiator 25. There is a purpose of exposing the surface. Therefore, it is more advantageous to use mechanical processing means such as shaving than chemical etching, including processing time.

  As shown in FIG. 3 (c), after exposing the copper layer 23 to the portion to which the radiator 25 is joined, the cladding material is pressed to form a through hole for inserting and sealing the lead 15 Then, after forming the inclined recess for mounting the light receiving element, the outer shape of the clad material 30 is extracted in accordance with the outer shape of the eyelet body 21. The eyelet main body 21 is separated from the band-shaped body of the clad material 30 by the outer diameter reduction processing, and becomes a piece.

  FIG. 4 shows a state in which the clad material 30 is roughly removed and subjected to pressing and shaving to expose the copper layer 23. In the present embodiment, the exposed surface 23 a of the copper layer 23 is exposed in a circular shape having a diameter of about 3.0 mm on the surface of the clad material 30. Also, the outline removal position of the eyelet body 21 is indicated by a two-dot chain line A. The radiator 25 is joined in the region of the exposed surface 23 a of the copper layer 23. The range in which the copper layer 23 is exposed is not limited to the circular shape as shown in FIG. 4, but at least the welding region (eyelet) of the cap 18 attached to the eyelet body 21 so that the cap 18 can be reliably welded. The outer peripheral edge of the main body is set so as to be covered with the second iron layer 24.

After the outer shape of the clad material 30 is extracted and formed into individual pieces, plating such as nickel plating for preventing corrosion of the eyelet body 21 is performed as necessary.
Next, after the lead 15 is glass-sealed to the eyelet body 21, the heat radiator 25 is brazed to the eyelet body 21. The radiator 25 is formed in a predetermined piece in advance in a process different from the process of forming the eyelet body 21 using the clad material 30.
FIG. 3 (d) shows a state where the radiator 25 is brazed to the exposed surface 23 a of the copper layer formed on the eyelet body 21. An eyelet body 21, a heat radiator 25 made of copper, and a brazing material are arranged in a brazing jig, and the brazing material is melted and brazed in a heating furnace. In this embodiment, the heat radiator 25 is joined to the eyelet body 21 by silver brazing. Reference numeral 25a denotes a bonding layer.

By disposing the eyelet body 21 and the radiator 25 on the brazing jig, the mutual positions of the eyelet body 21 and the radiator 25 are positioned. After the radiator 25 is brazed, the radiator 25 The laser element mounting surface (side surface of the heat radiating body) may be pressed flat so that the laser element mounting surface is accurately positioned.
In the semiconductor package stem of this embodiment, after the radiator 25 is brazed to the eyelet body 21, the outer surfaces of the eyelet body 21, the radiator 25, and the leads 15 and 15a are subjected to finish plating by nickel plating and gold plating. .

  In the optical semiconductor device, a laser element is bonded to the side surface of the radiator 25 of the semiconductor package stem, the laser element and the lead 15 are wire-bonded, and a monitoring element for monitoring the light emission of the laser element is provided in the inclined recess 26. After mounting, the cap 18 is assembled by welding to the outer peripheral edge of the eyelet body 21.

  In the above embodiment, the eyelet body 21 is formed using the clad material 30 having a three-layer structure of iron-copper-iron, but a material having a two-layer structure of copper-iron is used as the clad material. It is also possible to form a semiconductor package stem. Even in the case of using the clad material having the copper-iron two-layer structure, the iron layer in the region where the radiator is joined by pressing from the iron layer side covering the upper surface of the copper layer in the same manner as described above. A semiconductor with excellent heat dissipation and cap welding by exposing the copper layer by projecting the part from the surface of the clad material, exposing the copper layer part, and joining the radiator to the exposed surface of the copper layer It can be provided as a package stem.

It is sectional drawing which shows the structure of embodiment of the stem for semiconductor packages. It is explanatory drawing which shows the manufacturing process of the stem for semiconductor packages. It is explanatory drawing which shows the manufacturing process of the stem for semiconductor packages. It is a top view of the clad material in the state where the copper layer is exposed. It is sectional drawing which shows the structure of the conventional stem for semiconductor packages. It is sectional drawing which shows the other structure of the conventional stem for semiconductor packages.

Explanation of symbols

10, 11, 20 Stem for semiconductor package 12, 21 Eyelet body 12a Iron part 12b Copper part 16 Laser element 18 Cap 22 First iron layer 23 Copper layer 23a Exposed surface 24 Second iron layer 24a Iron layer part 25 Heat dissipation Body 26 Inclined recess 30 Cladding material 40 Press die 42 Recess 50 Cutting blade

Claims (3)

A method for manufacturing a stem for a semiconductor package, comprising an eyelet body, a heat dissipator provided in the eyelet body, and a lead sealed to the eyelet body,
For a clad material having a three-layer structure in which a copper layer is sandwiched between a pair of iron layers, a step of roughing to a larger diameter than the outer shape of the eyelet body,
Pressing the roughly blanked clad material from the surface side where the iron layer portion forms a stepped portion using a press mold in which a recess is formed in accordance with the region where the copper layer is exposed. And a step of pressing the region portion to which the iron layer radiator formed on one side of the clad material is joined so that the iron layer portion of the region portion protrudes in a step shape from the surface of the clad material,
Removing the iron layer portion protruding stepwise from the surface of the clad material to form a surface of the clad material on a flat surface, and performing a flattening process to expose the copper layer under the iron layer portion;
A step of performing a drilling process for forming a through hole for inserting and sealing a lead into the clad material subjected to the flattening process;
Separating the eyelet body into individual pieces from the clad material subjected to the perforating process, and a process of removing the outer shape to match the outer shape of the eyelet body;
Sealing the lead to the individual eyelet body with glass;
Brazing a heat radiator formed in a separate process from the individual eyelet main body to the exposed surface of the copper layer of the individual eyelet main body having the lead sealed with glass. Manufacturing method of semiconductor package stem. By the press work, the iron layer portion is protruded in a step shape from the surface of the clad material to a thickness equal to or more than the thickness of the iron layer including a part of the lower copper layer,
As the flattening process, the iron layer portion protruding stepwise from the surface of the clad material is removed by cutting from the copper layer by shaving, and the surface of the copper layer is flush with the surface of the iron layer. 2. The method of manufacturing a stem for a semiconductor package according to claim 1, wherein the stem is exposed to the surface.   The heat radiation body is brazed to an exposed surface of the copper layer of the individual eyelet body, and then a side surface that becomes a laser element mounting surface of the heat radiation body is pressed flat and positioned. A method for manufacturing a stem for a semiconductor package according to 1 or 2.

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