JP2002198543A - Package for optical semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a package for an optical semiconductor element which can enhance the optical-to-electrical signal transducing speed and which can make the optical-to-electrical transducing speed high and smooth. SOLUTION: The housing package is provided with a bottom plate 2 having a mounting part 2a in which the optical semiconductor element 3 is mounted on the surface; a frame body 7 which is attached to, and mounted on, the bottom plate 2 so as to surround the mounting part 2a; a fixing member 11 which is attached to, and mounted on, a through hole 7b arranged and installed in the sidewall of the frame body 7, and which has a through hole 11a at the inside into which the transmission line 10 of a light signal is inserted; a first dielectric 16 which is formed so as to pass the frame body 7 and in which a signal wiring layer 18 is formed on the surface; an input/output terminal 24 for a second dielectric 17 which is bonded to the first dielectric 16 by sandwiching the wring layer 18, in such a way that both ends of the wiring layer 18 are exposed and which is arranged between the first dielectric 16 and the frame body 7 so as to pass the frame body 7 and a lid body 9 which is attached to, and mounted on, the surface of the frame body 7 and which airtightly seals the elements 3. A gap 26 is formed just under the exposed part 18a of the wiring layer 18 at the first dielectric 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device housing package for housing an optical semiconductor device, and more particularly to an improvement of an input / output terminal for inputting / outputting a signal from inside the package.

[0002]

2. Description of the Related Art In recent years, an optical semiconductor housing package (hereinafter, referred to as an optical semiconductor device) housing various optical semiconductor elements used in the field of optical communication and the like.
Optical package) is attracting attention. The general structure of such an optical package is, as shown in a schematic sectional view of FIG. 3, an optical semiconductor element (hereinafter abbreviated as an optical element) 32 mounted on an upper surface of a metal substrate 30 and a surface of an insulating base 31. A metal frame 35 is joined and fixed to the surface of the substrate 30 so as to surround the mounting portion 30 a on which the mounting substrate 33 to be mounted is mounted. Further, a lid 36 for hermetically sealing the optical element 32 is provided on the upper surface of the frame 35, and the substrate 30, the frame 35
The optical element 32 is hermetically sealed by the lid 36.

Further, a through hole 35a is provided in a side wall of the frame 35, and a transmission line (hereinafter referred to as an optical line) of an optical signal such as an optical fiber is provided inside an outer wall surrounding the through hole 35a of the frame 35. A fixing member 38 having a through hole 38a for inserting the 37 is adhered and fixed.
The optical element 32 is arranged to receive the optical signal output from the tip of the optical path 37 inserted into the through hole 38 a of the optical element 8. The optical path 37 is bonded to the fixing member 38 by an adhesive 39 such as solder filled in the through hole 38a of the fixing member 38.

On the other hand, a signal received by the optical element 32 is formed so as to penetrate the side wall of the frame 35 via a wiring circuit (not shown) formed on the mounting substrate 33 or a wire bonding 40. The input / output terminal 44 having the signal wiring layer 43 formed between the two dielectrics 41 and 42 is connected to the exposed portion of the signal wiring layer 43, and the other end of the signal wiring layer 43 is connected to the frame 35. Is connected to a lead terminal 45 formed outside the package, and an external circuit (not shown) is connected to the package by the lead terminal 45.

[0005] The structure of the input / output terminal 44 is the same as that of the dielectric 4.
The signal wiring layer 43 is formed in the center of the upper surface of the first substrate 1, and the ground layer (ground conductor layer) 47 is formed on the lower surface of the dielectric 41. A microstrip line is formed by the signal wiring layer 43 and the ground layer 47. And the dielectric 42
Are bonded to the dielectric 41 with the signal wiring layer 43 interposed therebetween, and the dielectric 4 is connected so that both ends of the signal wiring layer 43 are exposed.
2 has a so-called feed-through structure formed shorter than the dielectric 41.

[0006]

In the above-mentioned optical semiconductor element housing package, the optical semiconductor element is generated in the package in order to increase the efficiency of photoelectric conversion performed by the optical semiconductor element and the connection circuit connected thereto. Although it is necessary to reduce the capacitance (C) component, the above-described conventional package for housing an optical semiconductor element has a large capacitance component generated in the package, and is particularly formed so as to penetrate the side wall of the frame described above. Since a large capacitance is generated in the signal wiring layer portion of the feedthrough portion having a long line length, there is a problem that the signal-processing capability is reduced due to a decrease in the optical-electric conversion speed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to improve the conversion speed of an optical-electrical signal and to transmit and receive optical-electrical signals at high speed and smoothly. It is an object of the present invention to provide a package for storing an optical semiconductor element.

[0008]

The present inventors have studied the structure of the input / output terminals with respect to the above-mentioned problems.
By forming a void in the dielectric positioned immediately below the portion where the signal wiring layer of the input / output terminal is exposed, the capacitance component generated in the signal wiring layer can be reduced, and the capacitance component of the entire package is reduced. As a result, they have found that the conversion speed of the optical-electrical signal can be improved, and the optical-electrical signal can be transmitted and received at high speed and smoothly.

That is, the optical semiconductor element housing package of the present invention is attached to the bottom plate surface so as to surround the optical semiconductor element mounting part, the bottom plate having a mounting part on which the optical semiconductor element is mounted on the upper surface. A frame, and a through hole formed through the side wall of the frame or attached to a through hole provided in the side wall of the frame and for inserting an optical signal transmission line therein. A first dielectric having a cylindrical fixing member having a hole, a first dielectric formed through the frame, and having on its surface a signal wiring layer electrically connected to the optical semiconductor element; The first signal line is bonded to the first dielectric with the signal line layer interposed therebetween such that both ends of the signal line layer of the dielectric are exposed, and the second line is disposed between the first dielectric and the frame. An input / output terminal comprising: a second dielectric; and an optical semiconductor element attached to an upper surface of the frame. The be one which includes a lid for sealing hermetically, and is characterized in that the formation of the void portion just below the exposed portion of the signal wiring layer of the first dielectric.

[0010] Here, the space just above the space is formed.
The signal wiring layer has an effective dielectric constant of 8 or less;
Thickness of the entire dielectric (t₁Thickness of the void portion with respect to)
(T_Two) Ratio (t_Two/ T₁) Is 0.1 or more, before
The thickness of the entire first dielectric (t) ₁) Is 0.25 to 1 mm
And the width of the signal wiring layer (w_TwoAbove)
The width of the gap (w₁) Ratio (w₁/ W_Two) Is 2.5 or more
Is desirable.

[0011]

FIG. 1 is a schematic sectional view of an example of an optical semiconductor element housing package (hereinafter, abbreviated as an optical package) according to the present invention, and FIG. 2 is a schematic perspective view of an input / output terminal. I will explain based on.

According to the optical package 1 of FIG. 1, an insulating substrate 4 on which an optical semiconductor element 3 is mounted is provided on the upper surface of the bottom plate 2.
A metal frame 7 is attached to and fixed to the surface of the bottom plate 2 via a connection member such as welding or solder so as to surround the mounting portion 2a for mounting the mounting substrate 5 made of. . A lid 9 for hermetically sealing an optical semiconductor element (hereinafter, abbreviated as an optical element) 3 is provided on an upper surface of the frame 7, and the bottom plate 2, the frame 7, and the lid 9 provide light. The element 3 is hermetically sealed.

Further, a through hole 7a is provided in a side wall of the frame 7, and a transmission line (hereinafter referred to as an optical line) of an optical signal such as an optical fiber is provided inside an outer wall surface of the frame 7 surrounding the through hole 7a. A fixing member 11 having a through-hole 11a for inserting the 10 is adhered and fixed, and the through-hole 7a of the frame 7 and the through-hole 11a of the fixing member 11 are connected to each other.

The optical element 3 is arranged to receive an optical signal output from the tip of the optical line 10 inserted into the through hole 11 a of the fixing member 11. The optical line 10 is bonded to the fixing member 11 by an adhesive 13 such as solder filled in the through hole 11a of the fixing member 11.

On the other hand, the optical element 3 is formed through a side wall of the frame 7 via a wiring circuit (not shown) formed on the mounting substrate 5 and a wire bonding 15, and both ends are formed of a first dielectric. The exposed portion 18a of the signal wiring layer 18 exposed from the upper surface of the body 16 and sandwiched between the two dielectrics 16 and 17 of the first dielectric 16 and the second dielectric 17 on the side wall of the frame 7 Is connected to

The signal wiring layer 18 is formed of the first dielectric 1
The lead terminal 20 formed outside the frame 7 on the frame 6 is connected by joining with a brazing material such as silver brazing, and an external circuit (not shown) and the optical package 1 are connected by the lead terminal 20. ing.

Further, the signal wiring layer 18 formed on the upper surface of the first dielectric 16 is arranged on the same line as the optical line 10 particularly for the purpose of reducing the inductance and the like. Signal wiring layer 1 caused by thermal expansion difference
In order to suppress the generation of stress on the transmission line 8 and prevent the transmission characteristics of the signal transmitted through the signal wiring layer 18 from deteriorating, the first
A ground conductor layer (ground layer) 22 is formed on the lower surface of the first dielectric 16 (the bottom opposite to the surface on which the signal wiring layer 18 is formed). Thus, a microstrip line is formed by the signal wiring layer 18 and the ground layer 22, and the optical package is formed by the first dielectric 16, the second dielectric 17, the signal wiring layer 18 and the ground layer 22. 1 form an input / output terminal 24 for connecting the inside and the outside.

(Void) According to the present invention, in the input / output terminal 24, the first dielectric 16 located immediately below the exposed portion 18a in the portion where the signal wiring layer 18 of the first dielectric 16 is formed. The main feature is that the air gap 26 is formed in the first dielectric 16, whereby the effective dielectric constant of the first dielectric 16 relating to signal transmission characteristics can be reduced, and the capacitance component generated in the signal wiring layer 18 can be reduced. Therefore, the capacitance component of the entire package 1 can be reduced. As a result, T = 2.19CR (where, T: a rise value indicating light receiving sensitivity (an efficiency value for converting an optical signal into an electric signal), C: the capacity of the package (entire wiring + optical element), and R: (entire wiring) The conversion speed of the optical-electrical signal represented by the resistance value of the + optical element) can be improved, and the optical-electrical signal can be transmitted and received at high speed and smoothly.

Here, the shape of the gap portion 26 may be any shape such as a rectangular shape and a bowl shape, but is desirably a rectangular shape from the viewpoint of ease of production and increasing the volume of the gap portion. Further, an R portion or a taper may be provided at the corner. The void 26 may be provided inside the first dielectric 16, but is preferably formed as a cutout on the bottom surface of the first dielectric 16 in terms of ease of manufacture.

The thickness (height) of the gap 26 is determined by the thickness (height) of the entire first dielectric 16 from the viewpoint of reducing the capacitance component and maintaining the mechanical strength of the first dielectric 16. t ratio of the thickness of the gap portion 26 with respect to _{1) (t 2) (t} 2 / t 1) of 0.1 or more, particularly 0.3 or more, it is desirable that more than 0.5. In addition, the thickness (t ₁ ) of the first dielectric 16 is 0.25 to 2 mm, particularly 0.36 to 1 mm in terms of reducing the capacitance component and maintaining the mechanical strength.
It is desirable that

On the other hand, the width (w ₁ ) of the gap 26 is
In terms of reducing the capacitance component, the ratio (w ₁ / w ₂ ) to the width (w ₂ ) of the signal wiring layer 18 is 2.5 or more, especially the first dielectric 1
In order to maintain the strength of No. 6, it is desirable that it is 2.5 to 3.

Further, the width (w ₁ ) of the gap 26 may be the same as the width (w ₃ ) of the first dielectric 16, that is, both ends of the gap 26 may be open. However, in order to improve the strength and the transmission characteristics of the signal transmitted through the signal wiring layer 18, the cross section of the first dielectric 16 in the width direction forms a concave portion, and the inside of the concave portion becomes the void portion 18. In other words, the width (w ₁ ) of the gap 26 is the first
It is preferable that the width of the dielectric 16 is smaller than the width (w ₃ ).

Further, the length (d) of the gap 26 depends on the length of the exposed portion 18a on the surface of the first dielectric 16 on which the signal wiring layer 18 is formed. Part 26
Is preferably the same as the length (d) of the first dielectric 16 and the length of the exposed portion 18a on the surface of the first dielectric 16 on which the signal wiring layer 18 is formed.
The exposed portion 18a has a length of, for example, 0.5 to 2 mm, particularly 0.8 to 1 in terms of connection reliability with the lead terminal 20 and the wire bonding 15 connected to the signal wiring layer 18. The gap 26 is formed to have a length (d) of 0.2 to 2 mm, preferably 0.5 to 1.5 mm. Note that the lengths of the two exposed portions 18a do not necessarily have to be the same, and may vary depending on the connection state with the lead terminals 20 connected to the signal wiring layer 18 and the wire bonding 15.

Further, by forming the gap 26, the effective dielectric constant of the signal wiring layer 18 located immediately above the gap 26 becomes 8 or less, particularly 6 or less, and the rise time (T) of the gap 26 is reduced. The ratio (Tr ratio) is 100 or less, especially 30 or less, when the time when the film is not formed is 100.

On the other hand, the bottom plate 2 functions as a support member for supporting the mounting substrate 4 on which the optical element 3 is mounted.
It is made of a metal material such as iron (Fe) -nickel (Ni) -cobalt (Co) alloy, copper (Cu) -tungsten (W) alloy, aluminum, Cu-Mo, Cu, or ceramics. The frame 7 and the lid 9 are made of a metal having a thermal expansion coefficient close to that of the bottom plate 2, for example, a metal material such as an iron (Fe) -nickel (Ni) -cobalt (Co) alloy or a ceramic. 3 is hermetically sealed, and radiates heat generated in the optical element 3 and the like to the outside.

The bottom plate 2, the frame 7, the lid 9 and the lead terminals 20 can be formed by applying a conventionally known metal working method such as a rolling method or a punching method to a metal ingot. . In order to enhance the corrosion resistance and improve the wettability with respect to the brazing material, a metal plating film, particularly a nickel plating film having a thickness of 2 to 6 μm and a gold plating film having a thickness of 0.5 to 5 μm are provided on these outer surfaces. It is desirable to form them sequentially.

The space between the bottom plate 2 and the frame 7 and the space between the frame 7 and the lid 9 are Pb-based, Pb-Sn-based, gold (A
u) -tin (Sn) alloy, Ag-Cu-based, Au-Ge-based solder or other low melting point brazing material, or welding by seam welding or the like. When the bottom plate 2, the frame 7 and the lid 9 are made of ceramics, they are joined by forming a metallized surface on the ceramics.

The fixing member 11 has a thermal expansion coefficient close to that of the frame 7, for example, iron (Fe) -nickel (Ni)-
An optical line 10 such as an optical fiber is inserted into a through hole 11a inside the metal member such as a cobalt (Co) alloy, and the fixing member 11 and the optical line 10 are bonded by an adhesive such as a resin or a solder material. Fixed. When the fixing member 11 and the optical line 10 are connected by soldering, in order to enhance the solder wettability of the optical line 10, a thin film forming method such as a vapor deposition method is previously applied to the outer peripheral surface near the tip of the optical line 10. By Ta, Ti,
It is preferable to insert the optical line 10 into the fixing member 11 after performing at least one metallization selected from the group consisting of W, Mo, Cr, Ni, Pb, Sn, Au, and Pd.

Further, the first dielectric 16 and the second dielectric 17 constituting the input / output terminal 24 are made of alumina (Al
Ceramics such as ₂ O ₃ ), aluminum nitride (AlN), cordierite, mullite, quartz, glass ceramics, and resins such as Teflon are applicable.
It is desirable to be made of ceramics from the viewpoint of bondability and strength with the metal frame 7, and the difference in thermal expansion coefficient between the frame 7 and the frame 7 at 40 to 400 ° C. is 10 in terms of thermal expansion characteristics.
× 10 ^-6 / ° C. or less, it is preferably made in particular 5 × 10 ^-6 / ℃ following ceramics.

Further, the first dielectric 16 and the second dielectric 1
7 may be used to join the fired ceramics,
It is desirable that they are formed at the same time by firing from the viewpoint of improvement in dimensional accuracy and ease of manufacture.

Further, the signal wiring layer 18 and the ground layer 22 formed on the surface of the first dielectric 16 are made of molybdenum (Mo) -manganese (Mn), tungsten (W),
It is formed of a conductor layer containing at least one metal selected from the group consisting of copper (Cu), silver (Ag), palladium (Pd), platinum (Pt), and gold (Au). Or formed of a high-purity metal such as a metal foil.

The signal wiring layer 18 and the ground layer 2
2 is a plated film (not shown) of Ni, Cu, Au or the like for improving moisture resistance and oxidation resistance and electrically connecting with the lead terminals 20, the wire bonding 15 or the frame 7. Is preferably formed. Further, the signal wiring layer 18 is connected to the lead terminal 20 and the wire bonding 15 via a brazing material such as silver brazing or solder, and the ground layer 22 is joined to the frame 7 by brazing material or the like.

Further, the insulating base 4 is made of alumina (Al ₂
O ₃ ), aluminum nitride (AlN), cordierite, mullite, quartz, ceramics such as glass ceramics, and resins such as Teflon are applicable.
It is desirable to be made of ceramics from the viewpoint of bondability and strength with the metal bottom plate 2 and the frame 7, and the difference in thermal expansion coefficient between the frame 7 and the frame 7 at 40 to 400 ° C. from the viewpoint of thermal expansion characteristics. It is desirable to use ceramics of 10 × 10 ⁻⁶ / ° C. or less.

The optical element 3 mounted on the surface (the side according to FIG. 1) of the insulating base 4 is arranged at a position where the optical signal emitted from the optical line 10 is efficiently received. Also,
The mounting substrate 5 is joined to the mounting portion 2a of the bottom plate 2 by solder and / or organic resin via a metallized metal layer formed on the lower surface thereof.

(Other Embodiments) According to FIG. 1, the bottom plate 2, the frame 7 and the lid 9 are formed separately, but the present invention is not limited to this. Alternatively, the frame and the lid may be formed as one body.

FIG. 1 shows a structure in which a fixing member 11 for fixing the optical line 10 is bonded to the side surface of the frame 7, but the fixing member itself is formed so as to penetrate the side wall of the frame 7. May be.

Further, in FIG. 1, only the optical element 3 which is a light receiving element for receiving the optical signal emitted from the optical line 10 is mounted, but a plurality of optical elements may be mounted. Conversely, a light emitting element that emits a signal may be mounted on the optical line. According to the present invention, since it is particularly effective when converting an optical signal into an electric signal, it is desirable to provide a light receiving element for receiving a signal emitted from the optical line as the optical element.

[0038]

First, a bottom plate, a frame, a lid, and a fixing member made of an iron-nickel-cobalt alloy and having a nickel plating film and a gold plating film formed on the outer surface were prepared.

On the other hand, a sintering aid is added to the alumina raw material powder, and an appropriate organic binder, a solvent and the like are added and mixed to form a slurry, and a green sheet is formed using this slurry by a doctor blade method. Molybdenum (Mo) -manganese (Mn) and tungsten (W) are formed at predetermined positions on the green sheet by screen printing.
A predetermined wiring layer was applied using a metallizing paste containing as a main component, a plurality of the layers were laminated, and then fired at 1600 ° C. to produce an insulating substrate on which an optical element was mounted.

On the other hand, a conductor layer constituting a signal wiring layer having a width of 0.5 mm after firing is formed on the green sheet by a screen printing method to produce a first green sheet.
After forming a conductor layer forming a ground layer on the surface of another green sheet, a notch was formed in this green sheet to produce a U-shaped second green sheet. Further, the green sheet was cut into a predetermined shape to prepare a third green sheet forming a second dielectric. Then, the second green sheet, the first green sheet, and the third green sheet are laminated in this order, and are stacked at 1600 ° C.
Then, the input / output terminal of FIG. 2 was produced.

The shape of the cutout (hollow portion) after firing is the shape shown in FIG. 2, and the specific dimensions are the width (w ₃ ) of the first dielectric ₃ mm and the length 3. 5mm, 2nd
Assuming that the length of the dielectric is 1.5 mm and the width of the second dielectric is the same as the width (w ₃ ) of the first dielectric, the exposed length of both ends of the signal wiring layer of the first dielectric 1.0m each
m. The shape of the gap is 1.5 m in width (w ₁ ).
The input / output terminal was manufactured by changing the thickness (t ₁ ) of the entire first dielectric and the thickness (t ₂ ) of the void portion as shown in Table 1 while keeping m and the length 1.0 mm constant. The dielectric constant of the alumina ceramic after firing was 10.

Next, a frame was joined to the surface of the bottom plate by silver brazing, and a through hole of 2 mmφ was formed at a predetermined position on the side wall of the frame by a drill or punching metal.
The fixing member was joined to the side surface of the through-hole forming portion by silver brazing, and the input / output terminals were arranged in through-holes formed in the other side wall of the frame, and joined by silver brazing. Further, the insulating substrate was joined to a predetermined position of the bottom plate by soldering.

The insulating base and the signal wiring layer of the input / output terminal are connected by wire bonding made of gold, and the signal wiring layer is made of an iron-nickel-cobalt alloy via Ag-Cu solder. Then, a lead terminal having a nickel plating film and a gold plating film formed on the outer surface thereof was joined.

Further, after mounting an optical semiconductor device for light reception at a predetermined position on the side surface of the insulating base, a lid was bonded to the upper surface of the frame by seam bonding. Further, a TaN film-N is formed on the outer peripheral surface near the tip by a vapor deposition method in the through hole of the fixing member.
An optical fiber on which an i-plated film and an Au-plated film were sequentially formed was inserted, and the optical fiber and a fixing member were joined and fixed by soldering, thereby producing an optical semiconductor element housing package.

For the obtained optical package, a signal was input from an optical fiber, and the rise time was measured by a photoelectric conversion pulse pattern measuring instrument. With the rising value of 1 being 100, the ratio (Tr ratio) of the rising value (Tr value) in each shape was calculated.
The dielectric constant of the dielectric (ε = 10), the thickness of the first dielectric (t ₁ ), the thickness of the gap (t ₂ ), the width of the signal wiring layer (0.5 mm), and the width of the gap ( From the shape of w ₁ = 1.5 mm), the effective dielectric constant of the signal wiring layer located immediately above the gap was calculated by simulation. The results are shown in Table 1.

[0046]

[Table 1]

As is clear from the results in Table 1, Sample No. having no voids was formed. Sample No. 1 in which a gap was formed as compared with Sample Nos. 1 and 7 In any of 2 to 6, the effective permittivity decreases,
It was confirmed that the Tr ratio was smaller than 100, that is, the rise time could be shortened.

[0048]

According to the package for storing an optical semiconductor of the present invention, a void is formed in a dielectric located immediately below a portion where the signal wiring layer of the input / output terminal is exposed, so that the signal wiring layer can be formed. The generated capacitance component can be reduced, and as a result of reducing the capacitance component of the entire package, the conversion speed of the optical-electric signal can be improved, and the optical-electric signal can be transmitted and received at high speed and smoothly.

[0049]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an optical semiconductor element housing package of the present invention.

FIG. 2 is a perspective view illustrating a structure of an input / output terminal of the package for housing an optical semiconductor element of FIG. 1;

FIG. 3 is a schematic sectional view of a conventional package for housing an optical semiconductor element.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical semiconductor element accommodation package (optical package) 2 ... Bottom plate 2a ... Mounting board mounting part 3 ... Optical semiconductor element (optical element) 4 ... Insulating base 5 ... Mounting board 7 ··· Frame 7a, 7b ··· Through hole 9 ··· Lid 10 ··· Transmission line (optical line) for optical signal 11 ··· Fixing member 11a ··· Through hole 13 ··· Joining member 15 ··· Wire bonding 16 first dielectric 17 second dielectric 18 signal wiring layer 18a exposed portion 20 lead terminal 22 ground layer 24 input / output terminal 26 gap

Claims (5)

[Claims] 1. A bottom plate having a mounting portion on which an optical semiconductor element is mounted on an upper surface, a frame attached to the surface of the bottom plate so as to surround the optical semiconductor device mounting portion, and penetrating a side wall of the frame. Or a cylindrical fixing member having a through hole for inserting a transmission line of an optical signal therein, and being attached to a through hole provided in a side wall of the frame body, A first dielectric formed through the frame and having on its surface a signal wiring layer electrically connected to the optical semiconductor element, and both ends of the first dielectric signal wiring layer being exposed; And a second dielectric disposed between the first dielectric and the frame body, the second dielectric being connected to the first dielectric with the signal wiring layer interposed therebetween. An optical semiconductor device comprising: a terminal; and a lid attached to an upper surface of the frame body and hermetically sealing the optical semiconductor device. An optical semiconductor element housing package, wherein a cavity is formed immediately below an exposed portion of the signal wiring layer of the first dielectric. 2. The optical semiconductor element housing package according to claim 1, wherein an effective dielectric constant of said signal wiring layer immediately above said void portion is 8 or less. 3. The ratio (t ₂ / t ₁ ) of the thickness (t ₂ ) of the void portion to the thickness (t ₁ ) of the entire first dielectric is 0.
3. The package for housing an optical semiconductor element according to claim 1, wherein the number is one or more. 4. The package according to claim 1, wherein the thickness (t ₁ ) of the entire first dielectric is 0.25 to ₁ mm. 5. The ratio (w ₁ / w ₂ ) of the width (w ₁ ) of the gap to the width (w ₂ ) of the signal wiring layer is 2.5 or more. 5. The package for housing an optical semiconductor element according to any one of 4.