JP2008263047A - Cap for optical semiconductor element, package for optical semiconductor element, and optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cap for an optical semiconductor element capable of taking an effective measure against stray light, a package for an optical semiconductor element, and an optical pickup device. <P>SOLUTION: The cap CP for the optical semiconductor element used to airtightly seal a stem 30 having the optical semiconductor element mounted includes an outer cap 10 having a light transmitting window 14 provided to allow light to transmit through the internal optical semiconductor element and the outside when the stem 30 is airtightly sealed and an inner cap 20 formed to be slightly smaller than the cap 10. The inner cap 20 has an opening 22a at a position corresponding to the window 14 when put in the outer cap 10 and has a black plated film P2 coated on its surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical pickup device used for an optical disk device, an optical communication device, and the like. More specifically, the stem for mounting an optical semiconductor element such as a laser diode or a light receiving element is hermetically sealed, and light is applied to the upper surface. An optical semiconductor element cap having a window (light transmission window) for transmitting light, and adapted to mount a hologram element on the light transmission window, an optical semiconductor element package including the cap, and the package The present invention relates to an optical pickup device used.

  FIG. 6 schematically shows a configuration example of a conventional optical pickup device in the form of a perspective view. This optical pickup device is described in Patent Document 1.

  As shown in the figure, the optical pickup device includes a semiconductor laser element 63 disposed on a silicon submount on a stem 61 and having a laser emission optical axis parallel to the upper surface of the stem 61 and incorporating a light receiving element 62 for monitoring. A reflection mirror 64 that reflects light emitted from the front surface of the semiconductor laser element 63 in a direction perpendicular to the upper surface of the stem 61, and light (return light) reflected by a recording medium (not shown) such as an external optical disk. The signal detecting light receiving element 65 for receiving light is covered with a protective cap 67 having a light transmitting portion 66 on the upper surface, and a hologram element 68 is further formed on the light transmitting portion 66 of the protective cap 67 by, for example, an ultraviolet curable adhesive 69. It is fixed by. The hologram element 68 has two diffraction gratings for dividing the laser beam 70 into two tracking sub-beams and a main beam for reading information from the recording medium, that is, a diffraction grating 71 for generating a tracking beam. A first-order diffraction grating 72 for guiding the reflected light from the recording medium to the signal detecting light receiving element 65 is formed on the upper surface. The protective cap 67 is welded onto the stem 61 for hermetic sealing for the purpose of protecting the reliability of each mounted element.

  As described above, in the hologram optical pickup apparatus, the light receiving elements 62 and 65 are mounted in the package together with the light emitting element 63, so that the laser light reflected by the optical disk or the like outside the apparatus is received for signal detection in the package. Although it is necessary to return to the element 65, at that time, depending on the assembly accuracy of the package, light that does not require a part of the return light to the part other than the part to receive light (the light receiving element 65) (hereinafter referred to as “stray light”). It will be hit. Such stray light is not only caused by the return light from the outside, but also the laser light emitted from the rear surface of the semiconductor laser element 63 is irregularly reflected in the protective cap 67, and the irregularly reflected laser light is inherently reflected. It is also caused by interfering with the return light. When such stray light increases, there arises a problem that offset correction must be performed on the detected signal amount (return light), and thus a countermeasure for reducing or substantially eliminating stray light has been indispensable.

  In order to prevent stray light, it is basically desirable that the reflectance of light on the inner surface of the cap body (metal portion of the cap) be low (that is, stray light can be absorbed). As one of the methods, conventionally, a countermeasure against stray light has been taken by applying black plating to the cap. This is a method in which a light transmission window (glass plate) is welded to a cap body (metal part) using a welding material and then black plating is applied. Conventionally, a low melting point containing lead (Pb) as the welding material. Glass was used.

  However, due to the trend of lead-free (lead-free) in consideration of environmental impact in recent years, lead used to weld the cap body (metal) and the light transmission window (glass) in the production of the cap so far (Pb) -based low-melting glass can no longer be used, and lead-free low-melting glass has been used as an alternative. We use bismuth-based low-melting glass containing bismuth (Bi) as the lead-free low-melting glass. Noble metal plating is required to adhere the bismuth (Bi) -based low-melting glass and the metal (cap body), and our company has performed palladium (Pd) plating. At that time, if the Pd plating is simply applied, the plating surface becomes a silver or white-like glossy surface and is reflected. Therefore, it is necessary to apply black plating as a countermeasure against stray light to the cap.

  In this case, a method of applying black plating before welding the light transmission window (glass) to the cap body (metal) and a method of applying black plating after welding can be considered. However, in the method of applying black plating before welding, there is a problem that the cap main body is heated at the time of welding, thereby causing abnormal color tone (discoloration) of the black plating, which is not a countermeasure against stray light. In addition, the film is formed in such a way that the black plating is superimposed on the palladium (Pd) plating that should have been applied to increase the adhesion between the bismuth (Bi) -based low melting point glass (welding material) and the metal (cap body). Therefore, there is also a problem that the degree of adhesion (strength at the welded portion) decreases.

  On the other hand, in the method of performing black plating after welding, black plating is performed on the cap on which the light transmission window (glass) is welded, so that a lot of dirt is generated on the glass surface, resulting in a defective product. was there. In addition, plating pretreatment (surface cleaning treatment using acid or alkali chemicals) is generally performed before plating treatment, but bismuth (Bi) low melting point glass has very high acid / alkali resistance. Therefore, if the plating pretreatment is performed before the black plating is performed, the original function of the Bi-based glass is impaired by the pretreatment liquid, so that the welding strength is lowered, and the glass may be removed in some cases ( In other words, there is a problem that the light transmission window falls off).

  In this way, when palladium (Pd) plating necessary to bring the metal (cap body) into close contact with the bismuth (Bi) -based low-melting glass used as a welding material is performed, countermeasures against stray light as has been conventionally performed It was difficult to perform black plating for.

  Therefore, in order to cope with such inconvenience, the inventor of the present application has studied a method of performing matte palladium plating on the cap. As will be described in detail later, the matte palladium plating refers to palladium plating in which the plating surface is finished with a matte finish, and is formed by forming “needle crystals” of palladium on the plating surface. When the normal palladium (Pd) plating as described above is performed, the plating surface becomes a glossy surface close to silver or white, whereas when this matte palladium (Pd) plating is applied. The plating surface becomes a matte surface close to dark gray or black. In other words, the blackening treatment equivalent to the conventional black plating is performed, which contributes to suppressing the reflection of light on the inner surface of the cap body (metal part) and is expected to be an effective countermeasure against stray light. Is done.

As a technique related to the above prior art, for example, as described in Patent Document 2, a light cap window is sealed with a low melting point glass not containing lead in a cap body made of metal as a semiconductor. When manufacturing caps for equipment, matte palladium plating is applied to the surface of the cap body, and a light transmission window is sealed on the cap body through a eutectic alloy layer formed at the interface between the low melting point glass and the cap body. There is something to do.
JP-A-8-161766 JP 2006-120864 A

  As described above, the package used in the conventional optical pickup device (the stem on which the optical semiconductor element is mounted and the cap for hermetically sealing the package) is matte palladium as a process corresponding to black plating for stray light countermeasures. A method of applying (Pd) plating to the cap has been studied.

  However, when matte Pd plating is performed before the light transmission window (glass) is welded to the cap body (metal), recrystallization (that is, the cap body is heated to heat the plating surface). There was a problem that “acicular crystals” disappeared and the surface became partially flat), resulting in uneven gloss on the plating surface. On the other hand, when matte Pd plating is performed after welding, the original of bismuth (Bi) -based low melting point glass by an acid or alkaline chemical solution during the plating pretreatment, as in the case of normal Pd plating described above. There is a problem in that the function of is impaired and the welding strength is reduced (in some cases, the glass is removed).

  As described above, in the conventional technology, a lead-free low melting point glass is used as a welding material for welding a light transmitting window (glass plate) to a cap body (metal) with respect to a cap constituting a package. Alternatively, it is difficult to perform an effective countermeasure against stray light by applying a blackening process corresponding to this.

  The present invention was created in view of the problems in the prior art, and an object of the present invention is to provide an optical semiconductor element cap, an optical semiconductor element package, and an optical pickup device that can effectively take measures against stray light. .

  In order to solve the above-described problems of the prior art, according to a basic form of the present invention, there is provided a cap for an optical semiconductor element used for hermetically sealing a stem on which an optical semiconductor element is mounted, wherein the stem is hermetically sealed. Corresponding to the position of the light transmission window when housed in the outer cap, and an outer cap having a light transmission window arranged so that light can be transmitted between the optical semiconductor element and the outside when stopped There is provided a cap for an optical semiconductor element, comprising an inner cap having an opening portion arranged so as to have a black plating film deposited on the surface thereof.

  According to the configuration of the cap for an optical semiconductor element according to the present invention, an inner cap that is slightly smaller than the outer cap apart from the original cap (outer cap) for hermetically sealing the stem on which the optical semiconductor element is mounted. And a black plating film is deposited on the surface of the inner cap. Accordingly, a part of the light reflected by a recording medium such as an optical disk outside the cap and returned to the cap through the light transmission window (outer cap) and the opening (inner cap) becomes “stray light”, and the light receiving element (optical semiconductor) Even if it hits a part other than the element (on the stem) and is reflected by that part and scattered within the inner cap, the black plating film is deposited on the surface, so the light is reflected on the inner cap surface. Is suppressed, and an effective stray light prevention function can be achieved.

  According to another aspect of the present invention, there is provided a stem for mounting at least each of the light-emitting and light-receiving optical semiconductor elements, and the above-mentioned optical semiconductor element cap adapted to hermetically seal the stem. A package for an optical semiconductor device is provided.

  According to still another aspect of the present invention, the optical semiconductor element package described above, a hologram element mounted on the light transmission window of the outer cap and having two diffraction gratings, and on the stem A semiconductor laser element mounted and disposed on the stem so that the emitted laser light is transmitted through the light transmission window and directed to one diffraction grating of the hologram element; Light reception arranged so that light reflected outside in response to laser light transmitted through the light transmission window and the hologram element can be detected through the other diffraction grating of the hologram element and the light transmission window. An optical pickup device comprising an element is provided.

  Other structural features, such as the cap for an optical semiconductor element according to the present invention, and advantageous advantages based thereon will be described in detail with reference to embodiments of the invention to be described later.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is an exploded perspective view of a package including an optical semiconductor element cap according to an embodiment of the present invention.

  The optical semiconductor element package 40 shown in the figure is a hologram type optical pickup device (a type in which a light emitting element and a light receiving element are arranged close to each other in a package) used in an optical disc apparatus such as a CD reproducing apparatus or a DVD recording / reproducing apparatus. As a basic configuration thereof, a stem 30 for mounting an optical semiconductor element such as a semiconductor laser element or a light receiving element, and a protective cap CP (hereinafter, referred to as airtight sealing covering the stem 30 and hermetically sealed) Simply referred to as “cap”). This cap CP has a double cap structure of an original cap (outer cap 10) for hermetically sealing the stem 30 and an inner cap 20 characterizing the present invention. The outer cap 10 is provided with a window (light transmission window 14) for transmitting laser light on the upper surface thereof. The inner cap 20 formed to be slightly smaller than the outer cap 10 is provided at the time of assembly. An opening 22a is provided so as to correspond to the position of the light transmission window 14 when accommodated in the outer cap 10. Then, at a later stage (at the customer), a required optical semiconductor element is mounted on the stem 30, the inner cap 20 is accommodated in the outer cap 10, and a protective cap CP is assembled. Is further hermetically sealed, and a hologram element is mounted on the light transmission window 14 of the outer cap 10, and other required optical elements are provided to produce an optical pickup device.

  In the optical semiconductor element cap CP according to the present embodiment, the outer cap 10 is formed by applying a glass plate (for example, alkali-containing borosilicate glass) as a light transmission window 14 to the cap eyelet (cap body) 12 with a low melting point. It is formed by welding glass 16 as a welding material. The cap body 12 is formed by pressing a thin plate-like metal material into a cap shape in which a light transmission hole (opening) 12a is formed in the upper portion, and the peripheral edge portion of the lower portion protrudes outward, and the flange 12b. It is molded to prescribe. As a material of the cap body 12, iron (Fe), an iron-nickel (Fe-Ni) alloy, an iron-nickel-cobalt (Fe-Ni-Co) alloy (Kovar), or the like is preferably used.

  In the present embodiment, bismuth (Bi) -based low melting point glass 16 not containing lead (Pb) is used as a welding material for welding glass (light transmission window 14) to metal (cap body 12). And since this Bi type | system | group low melting glass 16 is used, it is a eutectic at the temperature which welds the bismuth (Bi) and light transmission window 14 which are contained in Bi type | system | group low melting glass 16 on the outermost surface of the cap main body 12. A reactive metal is deposited, a eutectic alloy layer with Bi is formed, and the light transmission window 14 is welded.

  Examples of metals that cause a eutectic reaction with the Bi-based low-melting glass 16 at the temperature at which the light transmission window 14 is welded include gold (Au), silver (Ag), zinc (Zn), and palladium (Pd). . In the present embodiment, among these metals, Pd (palladium) is used as a metal formed by being deposited on the outermost surface of the cap body 12, and the Pd plating film P1 is deposited. In the present embodiment, nickel (Ni) plating is applied as a base plating of palladium (Pd) plating (P1) to protect the cap body 12 as well. As the base plating for Pd plating, plating other than Ni plating may be used, and the base plating may be formed in a plurality of layers of different metals. The base plating and the Pd plating (P1) can be performed by electrolytic plating using a barrel. By using barrel plating, Ni plating and Pd plating (P1) are performed on the entire outer surface of the cap body 12.

  In this embodiment, the reason for depositing the palladium (Pd) plating film P1 on the outermost surface of the cap body 12 is that palladium (Pd) and bismuth (Bi) contained in the Bi-based low-melting glass 16 are This is because a eutectic reaction can be easily formed at the welding temperature at which the light transmission window 14 is welded to easily form a eutectic alloy layer. Through this Pd—Bi eutectic alloy layer, the light transmission window 14 is reliably welded to the cap body 12 (the peripheral portion of the opening 12a).

  Further, in the present embodiment, a glass containing at least Bi2O3, SiO2, Al2O3, B2O3, MgO, ZnO is used as the bismuth (Bi) -based low melting point glass 16 used for welding the light transmission window 14. Here, Bi 2 O 3 is a main component constituting the Bi-based low-melting glass 16, and eutectic reacts with Pd of the palladium (Pd) plating film P 1 deposited on the surface of the cap body 12 to transmit the light transmission window 14. Since the Pd—Bi eutectic alloy layer is hermetically welded, the low melting point glass to be used must contain a considerable amount (about 30% by weight or more). In the present embodiment, the low melting point glass 16 containing 50% by weight of Bi2O3 is used. The Bi-based low-melting glass 16 is used by being powder-molded into a ring-shaped tablet in advance according to the size of the opening (light transmission hole) 12a of the cap body 12 or by being molded into a paste.

  The outer cap 10 is a carbon jig, a cap main body 12 having a surface subjected to Pd plating (P1) (with an opening (light transmission hole 12a) having a required size in the center), and a Bi-based cap. A carbon jig in which a tablet made of low-melting glass 16 and a light transmission window 14 (glass plate formed slightly larger than the opening 12a of the cap body 12) are aligned and set, and these parts are set. Is put in a heating furnace and heated to a temperature at which the low melting point glass 16 is melted. In the present embodiment, the light transmission window 14 is welded to the cap body 12 by heating in a heating furnace up to 500 ° C. in a nitrogen gas atmosphere.

  The inner cap 20 that characterizes the present invention has a shape equivalent to the cap body 12 of the outer cap 10 (however, a shape that is slightly smaller than the outer cap 10). Therefore, the inner cap 20 (cap body 22) is formed by pressing a thin plate-like metal material (Fe, Fe—Ni alloy, Fe—Ni—Co alloy, etc.), so that an opening 22a is formed in the upper portion. It is shaped like a cap, and its lower peripheral portion protrudes outward to define the flange 22b. The opening 22a of the inner cap 20 is provided at a location corresponding to the position of the light transmission window 14 when accommodated in the outer cap 10 as described above. A characteristic configuration of the inner cap 20 is that a black plating film P2 useful for preventing stray light is deposited on the surface thereof.

  On the other hand, the stem 30 includes an eyelet 32 processed and molded into a required shape (a shape similar to a track in the stadium in the example of FIG. 1), a heat radiating portion 34 standing on the eyelet 32, and an eyelet 32. A plurality of leads 36 and 36G are provided. The eyelet 32 is provided with a plurality of through holes 32a penetrating in the thickness direction. Leads 36 are inserted into the respective through holes 32a and sealed by the glass 38 in the respective through holes 32a. Is fixed. A part of the leads 36G is spot welded to the lower surface of the eyelet 32 and functions as a ground terminal. That is, some of the leads 36G are provided in a state of being electrically connected to the eyelet 32, and all the other leads 36 are electrically insulated from the eyelet 32 through the sealing glass 38. Is provided.

  For example, the eyelet 32 and the heat radiating portion 34 can be integrally obtained by forming a metal solid by a forging technique (press processing), and iron (Fe) is used as a material thereof. However, it is needless to say that other materials such as copper (Cu) and Cu alloy may be used. The heat radiating portion 34 may be integrally formed with the eyelet 32, but may be “brazed” on the eyelet 32 after being separately molded into a block having a required shape. In that case, it is preferable to use Cu having high thermal conductivity as the material of the heat radiating portion 34 in order to enhance its heat radiating function. At a later stage, a light emitting element such as a semiconductor laser element is mounted on the heat radiating portion 34 at an appropriate position on its side surface (the light emitting element 42 is mounted on the mounting surface 34a in FIG. 2), and the upper surface thereof is The light receiving elements are mounted at various locations (the light receiving elements 44 are mounted on the mounting surface 34b in FIG. 2).

  The leads 36 and 36G can be obtained by cutting the metal wires into predetermined lengths, respectively. The materials thereof are copper (Cu), iron (Fe), kovar (iron (Fe), nickel ( Ni) and cobalt (Co) alloys) are preferably used.

  In this embodiment, the entire surface of the stem 30 is covered and a gold (Au) plating film P3 is deposited on the outermost surface. This takes into account the function of the stem 30 (mounting an optical semiconductor element), and the attributes required for the outermost surface (bonding property for facilitating electrical connection with the mounted element, solder wetting) This is for maintaining the sex etc.). Similarly to the outer cap 10, nickel (Ni) plating is applied as a base plating for Au plating (P 3) to protect the stem 30 itself. The Au plating base plating may be plating other than Ni plating, and the base plating may be formed in a plurality of layers of different metals. Ni plating and Au plating (P3) as the base plating can be performed by electrolytic plating using a barrel. Ni plating and Au plating (P3) are performed on the entire outer surface of the stem 30 by using the barrel plating method.

  The stem 30 can be assembled, for example, by the following method. First, a metal material (Fe) is formed into a required shape by pressing, and an eyelet 32 provided with a plurality of through holes 32a penetrating in a thickness direction at predetermined locations, and the metal material (Cu) is formed into a required shape. A heat radiating portion 34 processed into a block, a required number of leads 36 and 36G each cut to a predetermined length, and a necessary amount of glass 38 for sealing are prepared. Next, the heat radiating portion 34 is brazed with the positional relationship shown in FIG. 1 on the eyelet 32, and further, a ground lead 36G is spot welded to the lower surface (outer surface) of the eyelet 32. Next, these parts are set on a carbon jig. In other words, on the carbon jig, the lead 36 is inserted into each of the plurality of through holes 32a provided in the eyelet 32, and alignment is performed with a required amount of glass 38 embedded in the gaps in the respective through holes 32a. Set. Then, a carbon jig in which these components are set is placed in a heating furnace and heated to a temperature at which the glass 38 is melted (around 800 ° C.), whereby each lead 36 is caused by the glass 38 in the corresponding through hole 32a. Sealed and fixed (stem 30 completed).

  As described above, according to the configuration (FIG. 1) of the optical semiconductor element cap CP according to the present embodiment, the stem 30 on which the optical semiconductor element such as the semiconductor laser element or the light receiving element is mounted is hermetically sealed. Apart from the original cap (outer cap 10), an inner cap 20 that is slightly smaller than the outer cap 10 is provided, and a black plating film P2 is deposited on the surface of the inner cap 20. As a result, a part of the light reflected by a recording medium (not shown) such as an optical disk outside the cap CP (outside the package) and returning to the inside of the package (inside the cap CP) becomes “stray light” as a light receiving element ( Even when it hits a portion (on the stem 30) other than the light receiving element 44) illustrated in FIG. 2 and is reflected by that portion and scattered in the inner cap 20, the black plating film P2 is deposited on the surface thereof. The reflection of light on the surface of the inner cap 20 is suppressed, and an effective stray light prevention function can be achieved.

  Further, while the inner cap 20 is subjected to black plating (P2) necessary for stray light countermeasures, the outer cap 10 is separately provided with palladium (Pd) necessary for welding the light transmission window 14 to the cap body 12. ) Since plating can be applied, the caps 10 and 20 are not restricted by each other's conditions.

  Further, since the inner cap 20 is not provided with the glass (light transmission window 14) as provided in the outer cap 10, there is no problem even if the surface is roughened (surface roughening). For example, in the case where slight uneven glossiness is generated on the surface, a more reliable countermeasure against stray light can be realized by performing such surface roughening.

  Further, since the inner cap 20 is finally sealed by the outer cap 10 when assembled as the package 40, no external pressure is applied to the inner cap 20 when used as the package 40. Therefore, the inner cap 20 is not required to have such a high strength, and even if a thin material is used, the role (stray light countermeasure) can be sufficiently achieved.

  The package 40 including the optical semiconductor element cap CP according to the present embodiment can be suitably used for the optical pickup device as described above. FIG. 2 is an exploded perspective view showing a configuration example in that case, with a part cut away.

  In the optical pickup device 50 shown in FIG. 2, a hologram element 46 is mounted on the light transmission window 14 of the outer cap 10 of the double-structured cap CP. This hologram element 46 is the same as the hologram element 68 illustrated in FIG. And has two diffraction gratings. Further, in the stem 30, a semiconductor laser element (chip) 42 is mounted at an appropriate location (mounting surface 34 a) on the side surface of the heat radiating portion 34, and a light receiving element (chip) at an appropriate location (mounting surface 34 b) on the upper surface of the heat radiating portion 34. ) 44 is mounted. At this time, the semiconductor laser element 42 is directed so that laser light emitted from the front surface thereof is directed to one diffraction grating of the hologram element 46 through the opening 22a (inner cap 20) and the light transmission window 14 (outer cap 10). On the other hand, the light receiving element 44 is reflected externally (recording medium such as an optical disk) in response to the laser light emitted from the semiconductor laser element 42 through the opening 22a, the light transmission window 14, and the hologram element 46. The arranged light can be detected through the other diffraction grating of the hologram element 46, the light transmission window 14 and the opening 22a. Further, although not shown in FIG. 2, the optical semiconductor elements 42 and 44 are connected to the corresponding leads 36 and 36G via wires, that is, the upper surfaces of the leads slightly protruding from the eyelet 32, respectively. And is electrically connected to the surface to which the Au plating film P3 is applied.

  Although not particularly shown in the configuration example shown in FIG. 2, an optical semiconductor element corresponding to the monitor light receiving element 62 illustrated in FIG. 6 is also mounted on the stem 30, and the hologram element 46 is also mounted. In addition, other optical elements necessary for the function of the optical pickup device 50 (such as an objective lens provided between the hologram element and a recording medium such as an optical disk outside the apparatus) are also included.

  According to this optical pickup device 50, the laser light emitted from the rear surface (the lower surface in the illustrated example) of the semiconductor laser element 42 strikes the stem 30, is reflected by that portion, and is scattered in the cap CP. Even in such a case, since it is absorbed by the black plating film P2 deposited on the surface of the inner cap 20, the irregular reflection of the laser beam in the protective cap as seen in the conventional type is suppressed. As a result, interference with the return light from the optical disk or the like is suppressed and the amount of stray light is reduced, whereby the optical pickup device 40 with a small offset component of the signal amount (return light) can be obtained.

  In the above-described embodiment (FIGS. 1 and 2), the inner cap 20 has the same shape as the cap body 12 of the outer cap 10 (the upper portion has the opening 22a, and the lower peripheral portion forms the flange 22b. However, as apparent from the gist of the present invention (effectively absorbing the stray light scattered in the package), the shape of the inner cap 20 is not limited to this. Of course, it is not limited. For example, various modifications as illustrated in FIGS.

  In the modification shown in FIG. 3, the inner cap 20 a is shaped like a cap in which an opening 24 a equivalent to the opening 22 a of the inner cap 20 according to the above-described embodiment is formed on the upper portion of the cap body 24. Has been. In this configuration example, the lower peripheral portion of the cap body 24 does not form a flange. Moreover, in the modification shown in FIG. 4, as the shape of the inner cap 20b, the entire upper part of the cap body 26 is formed into a cap shape having an opening (opening 26a). Also in this configuration example, the lower peripheral portion of the cap body 26 does not form a flange. In the modification shown in FIG. 5, the shape of the inner cap 20c is a cap shape in which the entire upper portion of the cap body 28 is opened (opening 28a), and the peripheral portion of the lower portion protrudes outward. It is molded so as to define the flange 28b. In this configuration example, as shown in more detail on the right side, the flange 12b of the inner cap 20c is combined with the V-shaped groove formed in the flange 28b so that a part of the flange 12b of the outer cap 10 is fitted. ing.

  In the above-described embodiment, the case where the black plating film P2 is deposited on the surface of the inner cap 20 has been described as an example. However, as is apparent from the gist of the present invention, the coating is performed on the surface of the inner cap 20. Of course, the plating film to be formed is not limited to this. For example, matte palladium (Pd) plating may be applied to the surface of the inner cap 20.

Matte palladium (Pd) plating refers to palladium plating in which the plating surface finishes matte. When this matte Pd plating is applied to the surface of the inner cap 20, the plating surface is dark gray or blackish. It becomes a glossy surface. Matte Pd plating uses a palladium plating solution that does not contain a brightener (see, for example, JP-A-2001-335986 as an example of a palladium plating solution), and matte plating is performed using a Hull cell copper plate. This is done by setting the current density condition. For example, the plating condition in the case of performing matte palladium (Pd) plating is a current density of 0.25 (A / dm ² ) and 5 minutes.

  When matte Pd plating was applied to the surface of the inner cap 20 and the surface state was observed with an electron microscope, palladium “needle crystals” were formed on the plating surface. The appearance of the inner cap 20 with the matte Pd plating is a dark gray or blackish matte surface. The surface of the Pd plating is formed on a very fine irregular surface by needle crystals, and the inner cap 20 It is thought that light is diffusely reflected and scattered on the surface. That is, matte palladium (Pd) plating can be formed by plating under plating conditions in which “needle crystals” are formed on the plating surface. Further, when the plating thickness of the matte Pd plating is thin, the matte Pd plating is not finished to a sufficiently matte surface, and the black color tone becomes thin. Therefore, when matte Pd plating is applied to the surface of the inner cap 20, it is necessary to form it with a sufficient thickness so as to be finished on a matte surface close to black. For example, it is desirable to form the matte Pd plating film P1 to a thickness of 0.3 μm or more.

  Moreover, in embodiment mentioned above, as the form of the inner side cap 20, black plating (P2) was given to the surface of what was shape | molded in cap shape one size smaller than the outer side cap 10 by pressing a thin plate-shaped metal material. Although the case has been described as an example, as is apparent from the gist of the present invention, the form of the inner cap 20 is of course not limited thereto. In short, even if a part of the return light from the outside of the package becomes stray light and scatters in the package, some processing (means) that can absorb the stray light is applied to at least the inner surface of the inner cap. It is enough. Therefore, the material to be used is not limited to metal, and the means for blackening is of course not limited to “plating”.

  For example, an appropriate resin (polycarbonate resin, acrylic resin, etc.) mixed with a material having an attribute to absorb light (black pigment, black dye ink, etc.) is molded into a required cap shape, or The inner cap intended by the present invention can also be produced by coating the surface (at least the inner surface) with the material after molding the resin into a required cap shape.

  In the above-described embodiment, the outer cap 10 has been described by taking as an example the case where the lead-free bismuth (Bi) -based low-melting glass 16 is used as the low-melting glass for welding the light transmission window 14 to the cap body 12. However, it goes without saying that the lead-free low-melting glass is not limited to bismuth (Bi) type. For example, other low melting glass such as vanadate low melting glass (low melting glass mainly composed of vanadium (V)) can be used. Even when a vanadate-based low-melting glass is used, the cap main body 12 is plated with palladium (Pd), so that when the light transmission window 14 is welded, the vanadine is bonded to the interface between the low-melting glass and the cap main body 12. A eutectic alloy layer of vanadium (V) and palladium (Pd) contained in the acid-based low-melting glass is formed, the low-melting glass is adhered to the cap body 12 and the light transmission window 14 is hermetically welded. Can do.

It is a disassembled perspective view which partially cuts and shows the structure of the package provided with the cap for optical semiconductor elements which concerns on one Embodiment of this invention. FIG. 2 is an exploded perspective view showing a schematic configuration of the optical pickup device using the package of FIG. It is a perspective view which notches some structures which show the structure concerning the modification of the cap for optical semiconductor elements shown in FIG. FIG. 7 is a perspective view showing a configuration according to another modification of the optical semiconductor element cap shown in FIG. 1 with a part cut away. FIG. 10 is a perspective view showing a configuration according to still another modification of the optical semiconductor element cap shown in FIG. 1 with a part cut away. It is a see-through | perspective perspective view which shows the structural example of the conventional optical pick-up apparatus roughly.

Explanation of symbols

10 ... outer cap,
12 ... cap eyelet (cap body),
12a: Light transmission hole (opening),
12b ... flange,
14 ... Glass plate (light transmission window),
16 ... Bismuth (Bi) low melting point glass (welding material),
20, 20a, 20b, 20c ... inner cap,
22, 24, 26, 28 ... the cap body,
22a, 24a, 26a, 28a ... opening,
22b, 28b ... flange,
30 ... stem,
32 ... Eyelets
34 ... heat dissipation part,
34a, 34b (mounting surface of optical semiconductor element),
36, 36G ... Lead,
38 ... Glass for sealing,
40. Package for optical semiconductor element,
42, 44 ... optical semiconductor element,
46. Hologram element,
50. Optical pickup device,
CP ... (for optical semiconductor element) cap,
P1 ... Palladium (Pd) plating film,
P2 ... Black plating film,
P3: Gold (Au) plating film.

Claims (7)

An optical semiconductor element cap used to hermetically seal a stem on which an optical semiconductor element is mounted,
An outer cap having a light transmission window arranged so that light can be transmitted between the optical semiconductor element and the outside when the stem is hermetically sealed;
And an inner cap having an opening disposed so as to correspond to the position of the light transmission window when housed in the outer cap, and having a black plating film deposited on the surface thereof. An optical semiconductor element cap.   2. The cap for an optical semiconductor element according to claim 1, wherein a matte palladium plating film is deposited on the surface of the inner cap instead of the black plating film.   In place of the inner cap, an inner cap obtained by molding a resin having a property of absorbing light into a resin into a required shape is provided, and the inner cap is accommodated in the outer cap. 2. The cap for an optical semiconductor element according to claim 1, wherein the cap for the optical semiconductor element is formed so as to have an opening at a portion corresponding to the position of the light transmission window when it is formed.   Instead of the inner cap, an inner cap obtained by coating the surface with a material having the property of absorbing light after molding a resin into a required shape, the inner cap is provided on the outer cap. 2. The cap for an optical semiconductor element according to claim 1, wherein the cap for an optical semiconductor element is formed so as to have an opening at a portion corresponding to the position of the light transmission window when accommodated.   The outer cap is made of a thin plate-like metal material formed into a cap shape having an opening smaller than the size of the light transmission window, and a palladium plating film is deposited on the surface of the cap body; A glass plate as the light transmitting window, and the glass plate is formed by welding a low melting point glass not containing lead to a peripheral portion of the opening of the cap body. The cap for optical semiconductor elements according to claim 1. A stem for mounting at least each of the light-emitting and light-receiving optical semiconductor elements;
An optical semiconductor element package comprising: the optical semiconductor element cap according to any one of claims 1 to 5 adapted to hermetically seal the stem. The package for optical semiconductor elements according to claim 6,
A hologram element mounted on the light transmission window of the outer cap and having two diffraction gratings;
A semiconductor laser element mounted on the stem and disposed so that the emitted laser light is transmitted through the light transmission window and directed to one diffraction grating of the hologram element;
Light that is mounted on the stem and reflected externally in response to laser light emitted from the semiconductor laser element through the light transmission window and the hologram element is reflected on the other diffraction grating of the hologram element and the light. An optical pickup device comprising: a light receiving element arranged to be detected through a transmission window.

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