JP5407078B2 - Semiconductor package - Google Patents

Description

  The present invention relates to a semiconductor package, and more particularly, a semiconductor package including a semiconductor element disposed inside a case and a feedthrough for electrically connecting the semiconductor element to an external device on a wall portion of the case. About.

  2. Description of the Related Art A semiconductor package in which a semiconductor device that generates heat and a semiconductor device having a cooling element for cooling the heat generating element are housed in a single package is known (see Patent Document 1). In the semiconductor package, the loss and reflection of high-frequency signals in the package are reduced, and power consumption in the cooling element is suppressed by blocking heat flowing into the cooling element from the outside, so that high efficiency and low power consumption are achieved. Planning is required.

  Here, FIG. 5 shows an example of a conventional semiconductor package 100 (see Patent Document 1). More specifically, the semiconductor package 100 includes a laser diode 105 for transmitting a laser mounted on the small substrate 106, a cooling element 103 for maintaining the laser diode 105 at a specified temperature, and a housing for storing them. The package 101 includes a feedthrough 102 that penetrates into the side wall of the package 101 and introduces a high-frequency signal input to the laser diode 105 from the outside to the inside of the package 101. The feedthrough 102 is configured by forming a conductor signal line and a ground line on a ceramic member. Further, the laser diode 105 placed on the small substrate 106 is disposed on the cooling element 103 via the heat dissipation substrate 104. A high-frequency signal introduced into the package through the feedthrough 102 is input to the laser diode 105 through the flexible substrate 111a formed of a low thermal conductivity member disposed between the feedthrough 102 and the small substrate 106. Is done. A laser emitted from the laser diode 105 based on the input of the high-frequency signal is arranged inside the package 101 and is made into a parallel beam by the first lens 121 for converting the laser emitted from the laser diode 105 into a parallel beam. Then, the light passes through the window 124 provided in the package 101 and is led out of the package 101. The window part 124 is usually formed of sapphire or a glass member. A second lens 122 for converging parallel laser beams is disposed outside the package. The converged laser beam is input to the optical fiber 123 and transmitted as an optical signal.

JP 2007-012717 A

As exemplified by the semiconductor package 100 described above, a ceramic feedthrough having a high degree of design freedom is often used. Ceramics are highly reliable, have relatively high thermal conductivity, and are extremely excellent in terms of releasing the heat generated by the chip to the outside, and are used in many packages. However, when the semiconductor element mounted on the package is a light emitting element such as a laser diode, the heat dissipation capability is not sufficient, and it is necessary to control the temperature such as forcibly cooling with a cooler such as a Peltier element. Come.
By the way, the ceramic feedthrough is arranged close to the element for the purpose of maintaining the electrical characteristics of the element. More specifically, when the signal transmission speed of the optical signal output from the light emitting element is high-speed transmission of, for example, 2.5 Gbps or more based on the signal input from the outside, the wiring portion that connects the feedthrough and the light emitting element It is known that the transmission loss increases and the high-frequency characteristics deteriorate, in order to suppress the deterioration, but it is necessary to bring the signal terminal of the feedthrough close to the conductor line of the substrate as much as possible.
However, as described above, when the ceramic feedthrough is close to the element, the high thermal conductivity of the ceramic may be disadvantageous. Ceramic feedthroughs often have a sheet-like or block-like structure depending on the manufacturing process, and heat from the outside of the package is also transferred to the inside. The problem that the heat dissipated by the ceramic cannot be ignored can arise.

  The present invention has been made in view of the above circumstances, can reduce the influence of heat propagating through the feedthrough to the inside of the case, prevent the malfunction of the semiconductor element, and suppress the power supplied to the cooling element. An object is to provide a possible semiconductor package.

  The present invention solves the above-described problems by the solving means described below.

The semiconductor package is a semiconductor package in which a semiconductor element is disposed inside a case that becomes a closed space, and a feed-through for electrically connecting the semiconductor element to an external device is provided on a wall portion of the case, The feedthrough has a cross-sectional area narrow portion whose cross-sectional area is smaller than other positions at any position in a direction orthogonal to the wall surface of the wall portion, and the cross-sectional area narrow portion is formed from the outside of the case. It becomes a heat insulating part that hinders heat conduction in the direction toward, and the narrow cross-sectional area part is formed by providing a gap part made up of a notch groove, a through hole, or a hole at a position inside the case in the feedthrough. The gap is required to be provided at a position where there is no wiring pattern in the feedthrough .

  According to the present invention, it is possible to suppress the heat conduction that enters the inside of the package through the feedthrough from the outside, it is possible to prevent thermal damage in the semiconductor element, and it is possible to suppress the power consumption of the cooling element. .

It is the schematic which shows the example of the semiconductor package which concerns on embodiment of this invention. It is the schematic which shows the example of the semiconductor package which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the structure of the space | gap part of the semiconductor package which concerns on embodiment of this invention. It is the schematic which shows the example of the semiconductor package which concerns on embodiment of this invention. It is the schematic which shows the example of the semiconductor package which concerns on the conventional embodiment.

1 and 2 show a configuration of a semiconductor package 1 according to an embodiment of the present invention. FIG. 1 is a plan view (schematic diagram) of the semiconductor package 1 with a lid portion removed, and FIG. 2 is a front sectional view (schematic diagram).
The semiconductor package 1 has a structure in which a semiconductor element 3 is accommodated in a case 2 and a feedthrough 10 for electrically connecting the semiconductor element 3 to an external device is disposed on a wall portion of the case 2. Have. As an example, the semiconductor element 3 is a light emitting element that emits light like a laser diode.

As shown in FIG. 2, the case 2 includes a substantially rectangular base body 2a and a frame body 2b joined to the peripheral edge of the base body 2a. (Not shown) are joined to form a closed space. Various electronic components such as the semiconductor element 3 and a temperature sensor (not shown) are bonded and fixed on the base 2 a via the cooling element 5 and the substrate 6.
Here, the base 2a is made of a Cu—W alloy or the like. The Cu—W alloy has a good heat dissipation and is suitable in that the thermal expansion coefficient is close to that of an Fe—Ni—Co alloy (Kovar) or ceramic used for other members. The frame 2b is made of an Fe—Ni—Co alloy or the like, and is formed in a predetermined frame shape using a known machining method such as a cutting method or a press method. The frame 2b may be an insulator such as ceramic. Further, the base body 2a and the frame body 2b may be integrally formed.

Here, reference numeral 4 denotes a thermally conductive metal block that places the semiconductor element 3 or the like on the upper surface and conducts heat from the element or the like. By cooling the heat conductive metal block 4 using the cooling element 5, the effect | action which the semiconductor element 3 grade | etc., Is cooled is acquired.
More specifically, the light emitting element such as a laser diode used as a semiconductor element 3 generates heat by light. Therefore, cooling using the cooling element 5 is required. Here, as the cooling element 5, for example, a Peltier element utilizing the Peltier effect is used, and a cooling action can be obtained by applying a voltage. The temperature control is performed by a control signal sent from an external device (drive circuit) through a feedthrough 10 (described later), and the cooling capacity is adjusted by changing the voltage applied to the cooling element (Peltier element) 5.

Further, the side wall portion of the case 2 is provided with a window portion for fixing the condenser lens 8 and an optical fiber (not shown). For example, the condenser lens 8 is made of a light-transmitting material such as sapphire or glass, and the light emitted from the semiconductor element (light emitting element) 3 is condensed by the condenser lens 8 and is sent to the outside of the package through the optical fiber. Is transmitted (in the direction of arrow L in FIGS. 1 and 2).
The oscillation control for emitting light is controlled by a control signal sent from an external device (drive circuit) to the semiconductor element (light emitting element) 3 through a feedthrough 10 (described later). More specifically, an external signal is introduced into the case 2 through a feedthrough 10 (described later), and transmitted to the semiconductor element (light emitting element) 3 by a bonding wire 7. Thereby, the semiconductor element (light emitting element) 3 performs an oscillation operation in response to an input signal from the outside, and emits an optical signal. This optical signal is collected by the condensing lens 8 in the window, and the collected light is output to the outside through an optical fiber of an interface (not shown).
Here, since the input signal has a high frequency of 2.5 Gbps or more (for example, 10 Gbps), it is required to suppress the inductance component by shortening the bonding wire 7 connecting the feedthrough 10 and the semiconductor element 3 as much as possible. The

On the other hand, the feedthrough 10 is fitted and joined to the other side wall of the case 2. The feedthrough 10 has a function of connecting the semiconductor element 3, the cooling element 5, and various electronic components disposed inside the case 2 to an external device (for example, a drive circuit), and has a lead terminal 11. And a metallized wiring layer 12 for connecting the lead terminal 11 and the semiconductor element 3 and the like.
In the present embodiment, the feedthrough 10 is supported by the side wall, that is, the frame 2b. However, the feedthrough 10 may be supported by, for example, the bottom (base 2a) other than the side wall.

The feedthrough 10 in the present embodiment is formed using a ceramic material. As an example, a resin binder, a solvent, or the like is added to and mixed with raw material powders such as alumina, silicon oxide (SiO ₂ ), calcium oxide (CaO), magnesium oxide (MgO), etc., and this is made into a mud-like shape. Thus, a plurality of ceramic sheets 10a to 10d are produced by forming into a sheet shape, and then the ceramic sheets are punched and laminated, and fired at a high temperature of about 1500 [° C.]. That is, the ceramic sheets 10a to 10d are combined by firing to form an integrated feedthrough 10.

  The lead terminal 11 is made of a metal material such as an Fe—Ni—Co alloy or an Fe—Ni alloy, and serves to electrically connect the optical semiconductor element 3 to an external device (such as a drive circuit) not shown. As an example, the lead terminal 11 is formed into a predetermined shape by punching, etching, or the like on a plate material made of an Fe—Ni—Co alloy.

Further, one end side of the metallized wiring layer 12 is connected to the electrode of the semiconductor element 3, the electrode of the cooling element 5, the electrode of various electronic components (not shown), the electrode of the substrate 6, etc. via the bonding wire 7. The other end side is connected to the lead terminal 11 via a metal brazing material such as silver brazing. By connecting the lead terminal 11 to an external device, the semiconductor element 3, the cooling element 5, various electronic components, the substrate 6, and the like are connected to the outside.
As an example, the metallized wiring layer 12 is formed by firing a metal paste containing a powder of a refractory metal such as W, Mo, or Mn. More specifically, for example, a metal paste obtained by adding and mixing an organic resin binder or a solvent to a metal powder such as W powder or Mn powder is applied to the ceramic sheet produced for the feedthrough 10 by a known screen printing method or the like. By baking after applying and applying a predetermined pattern, the feedthrough 10 is deposited at a predetermined position.

As described above, since it is necessary to make the bonding wire 7 connecting the feedthrough 10 and the semiconductor element 3 as short as possible, the feedthrough 10 is required to have a structure as close to the semiconductor element 3 as possible. Is done. However, in the feedthrough 10 formed using a material having a high thermal conductivity such as ceramic, an action of transferring heat outside the semiconductor package 1 to the inside of the package (inside the case 2) occurs, and the inside of the package ( There arises a problem that the temperature inside the case 2 is increased. As a result, in the part where the feedthrough 10 and the semiconductor element 3 are close to each other, there is a possibility that the semiconductor element 3 may be thermally damaged by the heat dissipated by the feedthrough 10. Of course, the problem of an increase in power consumption in the cooling element 5 also arises due to a temperature rise inside the package (inside the case 2).
Therefore, the feedthrough 10 according to the present embodiment has a heat insulating portion that inhibits heat conduction in the direction from the outside to the inside of the case 2 as a characteristic configuration, and can solve the above problems. The heat insulating portion is provided in the feedthrough 10 by forming a narrow cross-sectional area portion with a small cross-sectional area. That is, since heat conduction is suppressed as the cross-sectional area is small, a portion having a small cross-sectional area is provided to obtain an effect of inhibiting heat conduction. Therefore, for the purpose of suppressing heat transfer from the outside to the inside of the case 2, it is preferable to provide the heat insulating portion, that is, the narrow cross-sectional area portion, at a position inside the case 2 (inside the frame of the frame body 2 b).
In addition, although the heat insulation part in this embodiment aims at inhibition of the heat conduction in the direction which goes to the inside from the exterior of case 2, naturally, a heat insulation part is the reverse direction (direction which goes to the exterior from the inside of case 2). Needless to say, it also has an effect of inhibiting heat conduction.

A specific example of forming the narrow cross-sectional area will be described with reference to FIG. Note that FIG. 3 is an explanatory view showing the narrow cross-sectional area when the feedthrough 10 is viewed from above, and is a view for explaining the structure. Therefore, the arrangement position of the narrow cross-sectional area is completely the same as FIG. It doesn't match.
In the feedthrough 10, the narrow cross-sectional area as the heat insulating portion is a direction from the outside to the inside of the case 2, that is, a direction orthogonal to the wall surface of the side wall portion (here, the frame body 2 a) of the case 2 (arrow in FIG. 3). It is formed at any position in the (T direction) so that the cross-sectional area becomes smaller than other positions.
In this embodiment, the narrow cross-sectional area is formed by providing the feedthrough 10 with a gap formed by a cutout groove, a through hole, or a hole. Note that both are formed at a position inside the case 2.

As a first embodiment, as shown at the position AA in FIG. 3, a through hole (through hole) 13 is provided in the feedthrough 10 to form a narrow cross-sectional area. Thereby, the cross-sectional area of the AA line position in the arrow T direction can be made smaller than the cross-sectional area of the front-rear position.
As a method for forming the through-hole 13, in the above-described method for forming the feedthrough 10, that is, a solvent or the like is added to and mixed with alumina to form a mud, and this is formed into a sheet to form a plurality of ceramic sheets 10a to 10d. After the production, punching is performed at the same position in the surface of each sheet, and these are laminated and fired to form a through hole penetrating the entire feedthrough 10.

As a second embodiment, a narrow cross-sectional area is formed by providing a long through hole (slit) 14 in the feedthrough 10 as shown in the position of line BB in FIG. Thereby, the cross-sectional area of the BB line position in the arrow T direction can be made smaller than the cross-sectional area of the front-rear position.
The method of forming the through hole 14 is basically the same as the method of forming the through hole 13, but differs in that it is punched into a long hole instead of a round hole.

As a third embodiment, as shown in the CC line position in FIG. 3, a hole 15 is provided in the feedthrough 10 to form a narrow cross-sectional area. That is, unlike the through hole 13 and the through hole 14, the air hole 15 does not penetrate through the entire feedthrough 10 in the vertical direction of the feedthrough 10 (direction perpendicular to the substrate 6 mounting surface in the base 2 a). The purpose is the formed void (see FIG. 2). Thereby, the cross-sectional area of the CC line position in the arrow T direction can be made smaller than the cross-sectional area of the front-rear position.
As the method for forming the holes 15, in the above-described feedthrough 10 forming method, that is, by adding a solvent or the like to alumina to form a slurry, and forming this into a sheet, a plurality of ceramic sheets 10a to 10d are formed. After producing, punching is performed only on a predetermined sheet, that is, punching is performed by changing the in-plane punching position for each sheet, and by laminating and firing, each sheet is subjected to the punching process. It can be formed as a through hole penetrating the sheet, and can be formed as a hole when viewed as the entire feedthrough 10. Therefore, in the ceramic sheet in which the hole 15 is formed, it can be regarded as a through hole (through hole). Of course, it may be formed by pressing into a groove without punching into a through hole.

As a fourth embodiment, as shown in the DD line position in FIG. 3, the cut-through groove 16 is provided in the feedthrough 10 to form a narrow cross-sectional area. Thereby, the cross-sectional area of the DD line position in the arrow T direction can be made smaller than the cross-sectional area of the front-rear position.
As a method of forming the notch groove 16, in the above-described feedthrough 10 forming method, that is, by adding a solvent or the like to alumina and mixing it into a slurry shape, and forming this into a sheet shape, a plurality of ceramic sheets 10a to 10d are formed. After the production, for example, on the lower surface of the lowermost sheet 10d, a process (for example, press working) is performed to form grooves in a direction orthogonal to the arrow B direction, and these are stacked and fired. A notch groove can be formed.

As a fifth embodiment, as shown in the position of the line E-E in FIG. 3, the notch groove 17 is provided in the feedthrough 10 to form a narrow cross-sectional area. Thereby, the cross-sectional area of the EE line position in the arrow T direction can be made smaller than the cross-sectional area of the front-rear position.
The method of forming the notch groove 17 is basically the same as the method of forming the notch groove 16, but the notch groove 16 is provided on the lower surface or the upper surface of the ceramic sheet, whereas the notch groove 17 is formed of the ceramic sheet. The difference is that a groove is provided on the side surface.

  In any of the above-described embodiments, the void portion (illustrated as the through hole 13, the through hole 14, the hole 15, the notch groove 16, and the notch groove 17) is located at a position where there is no wiring pattern in the feedthrough 10, that is, the wiring. Formed to avoid patterns. In all the drawings, illustration of wiring patterns inside the feedthrough 10 is omitted for simplification of the drawings.

Next, a sixth embodiment will be described with reference to FIG. The sixth embodiment has a structure in which a coating made of a conductive metal material is provided on the inner surface (inner wall surface) of the gap portion formed in the above embodiment, and each ceramic sheet stacked vertically as a so-called VIA hole is provided. There exists an effect | action used as a conductor (wiring) for electrically conducting between the wiring patterns provided. For example, as shown in FIG. 4, the metallized wiring layer 12 of the ceramic sheet 10 b and the metallized wiring layer 12 of the ceramic sheet 10 d are electrically connected by a gap 18 having a coating 18 a made of a conductive metal material on the inner surface. Can do. Of course, since the inside of the space 18 is hollow, it goes without saying that the same effect as in the above-described embodiment can be obtained.
In addition, a well-known VIA hole formation method is employable as a formation method of the space | gap part 18 which has the film 18a on an inner surface.

In any of the above embodiments, the inside of the gap portion (hollow portion) is filled with air. Since air has a low thermal conductivity, it is suitable for forming a heat insulating part.
Furthermore, as a modified example, the heat insulating portion is filled by filling a heat insulating material (for example, resin or the like) inside the void portion (illustrated as the through hole 13, the through hole 14, the hole 15, the notch groove 16, and the notch groove 17). It may be formed.

  In addition, each said Example is only a typical illustration to the last, and is not limited to this. Any of the embodiments can be applied to one or a plurality or all of the laminated ceramic sheets 10a to 10d. Furthermore, it goes without saying that the present invention can be applied to the feed-through 10 formed integrally instead of the above-described laminated formation.

  As described above, according to the semiconductor package of the present invention, it is possible to suppress heat conduction from entering the inside of the package (that is, inside the case) from the outside via the feedthrough. As a result, the temperature rise inside the package (that is, inside the case) can be suppressed, so that the power consumed in the cooling element when the cooling action of the semiconductor element is obtained can be suppressed. In addition, it is possible to prevent thermal damage in the semiconductor element due to the temperature rise inside the package (that is, inside the case).

  Needless to say, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the present invention. In particular, a light emitting element (laser diode) has been described as an example of a semiconductor element. However, the present invention is not limited to this, and the same applies even when other semiconductor elements such as a light receiving element are mounted. Is possible.

DESCRIPTION OF SYMBOLS 1 Semiconductor package 2 Case 3 Semiconductor element 4 Thermal conductive metal block 5 Cooling element 6 Substrate 7 Bonding wire 8 Condensing lens 10 Feed through 11 Lead terminal 12 Metallized wiring layers 13 and 14 Through holes 15 Holes 16 and 17 Notch groove 18 Through Hole (with conductive metal coating on the inner surface)

Claims (4)

A semiconductor package is provided with a semiconductor element disposed inside a case that becomes a closed space, and includes a feedthrough for electrically connecting the semiconductor element to an external device on the wall of the case,
The feedthrough has a cross-sectional area narrow portion whose cross-sectional area is smaller than other positions at any position in a direction orthogonal to the wall surface of the wall portion, and the cross-sectional area narrow portion is formed from the outside of the case. It becomes a heat insulating part that inhibits heat conduction in the direction toward
The narrow cross-sectional area is formed by providing a gap formed by a notch groove, a through hole, or a hole at a position inside the case in the feedthrough ,
The semiconductor package according to claim 1, wherein the gap is provided at a position where there is no wiring pattern in the feedthrough . The gap portion, the semiconductor package according to claim 1, wherein the thermally insulating material is filled in. 3. The semiconductor package according to claim 1, wherein the gap portion is provided with a coating made of a conductive metal material on an inner surface, and also serves as a wiring in the feedthrough. The feedthrough has a shape in which a plurality of layers are laminated made of ceramic material, part or any one of claims 1-3, wherein the void portion to all of the layers are provided Semiconductor package.

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