JP6971921B2 - Differential transmission lines, wiring boards and semiconductor packages - Google Patents

Description

The present invention relates to a differential transmission line including a pair of parallel signal lines, a semiconductor package having pin terminals for external connection, and a semiconductor device.

As a transmission line for transmitting a high frequency signal, a differential line including a pair of signal lines in which signals having opposite phases are transmitted is known. Usually, a ground conductor layer is arranged on both sides of the differential line in the width direction so as to sandwich both of the pair of signal lines of the differential line together to form a differential transmission line. In order to prevent short circuits between conductors having different potentials, the pair of signal lines are located at a distance from each other, and the differential line and the ground conductor layer are also located at a distance from each other.

The differential transmission line is arranged on an insulating substrate such as a ceramic plate to form a wiring board. The wiring board is mounted on a semiconductor package for mounting a semiconductor element such as an optical semiconductor element or a semiconductor integrated circuit element, and constitutes a part of a conductive path for electrically connecting the semiconductor element and an external electric circuit.

Japanese Unexamined Patent Publication No. 2008-10673 Japanese Unexamined Patent Publication No. 2004-304233

In a differential transmission line or the like including the above differential line, a part of a pair of signal lines in the length direction is bent in one direction in order to facilitate electrical connection between a semiconductor element and an external electric circuit, for example. In some cases. That is, the differential line is curved in a part of its length direction. In such a case, the length of the signal line on the one-way side where the differential line is bent, that is, the inner signal line and the outer signal line on the opposite side are different from each other. Due to this difference in length, transmission loss of high frequency signals can occur.

The differential transmission lines of one embodiment of the present invention have a first end and a second end, respectively, and are parallel to each other with a curved portion curved in the first direction between the first end and the second end. Of the differential line including the pair of signal lines, the ground conductor layer located at a distance from the pair of signal lines across the differential line, and the pair of signal lines in the curved portion. It includes an inner signal line located on the first direction side and a dielectric located between the ground conductor layer adjacent to the inner signal line.

The wiring substrate of one aspect of the present invention is located on an insulating substrate having an upper surface and the upper surface of the insulating substrate, and has a first end and a second end, respectively, and the first end and the second end, respectively. A differential line including a pair of parallel signal lines having a curved portion curved in the first direction between the ends and the pair of signal lines sandwiching the differential line is located at a distance from each other. Located between the grounded conductor layer and the grounded conductor layer adjacent to the inner signal line located on the first direction side of the pair of signal lines in the curved portion. It is provided with a differential transmission line including a dielectric layer.

The semiconductor device according to one aspect of the present invention is located in a wiring board having the above configuration, a housing having a housing portion for semiconductor elements, and the housing portion of the housing, and the differential line of the wiring board. And an electrically connected transmission line.

According to the transmission line of one aspect of the present invention, the presence of the dielectric slows the transmission speed of the signal in the inner signal line and increases the electrical length. Therefore, it is possible to cancel the difference in physical length between the inner signal line and the outer signal line in the curved portion of the pair of signal lines. Therefore, it is possible to provide a differential transmission line that is effective in reducing transmission loss.

According to the wiring board of one aspect of the present invention, the presence of the dielectric layer reduces the signal transmission rate in the inner signal line and increases the electrical length. Therefore, it is possible to cancel the difference in physical length between the inner signal line and the outer signal line in the curved portion of the pair of signal lines. Therefore, it is possible to provide a wiring board having a differential transmission line effective for reducing transmission loss.

According to the semiconductor device according to one aspect of the present invention, since the wiring board having the above configuration is included, it is possible to provide a semiconductor package effective for reducing the transmission loss of a high frequency signal.

(A) is a plan view showing a differential transmission line and a wiring board according to an embodiment of the present invention, and (b) is a plan view showing a state in which a dielectric (layer) is removed from (a). It is a perspective view which looked at the wiring board shown in FIG. 1 from the upper side. (A) is a perspective view showing a modified example of the wiring board shown in FIG. 2, and (b) is an enlarged perspective view showing a main part of (a). (A) and (b) are plan views which show the modification of the wiring board shown in FIG. 1, respectively. It is a perspective view which shows the modification of the wiring board shown in FIG. (A) is a plan view showing a wiring board of another embodiment of the present invention, and (b) is a perspective view of the wiring board shown in (a) seen from the upper side. It is a perspective view which looked at the semiconductor package of embodiment of this invention from the upper side.

The differential transmission line, wiring board, and semiconductor package of the embodiment of the present invention will be described with reference to the accompanying drawings. It should be noted that the distinction between the upper and lower parts in the following description is for convenience of explanation, and does not limit the upper and lower parts when the differential transmission line, the wiring board, or the semiconductor package is actually used. Further, the impedance in the following description means a characteristic impedance.

1 (a) is a plan view showing a differential transmission line and a wiring board according to an embodiment of the present invention, and FIG. 1 (b) shows a state in which a dielectric or a dielectric layer is removed from FIG. 1 (a). It is a plan view. FIG. 2 is a perspective view of the wiring board shown in FIG. 1 as viewed from above. 3A is a perspective view showing a modified example of the wiring board shown in FIG. 2, and FIG. 3B is an enlarged perspective view showing a main part of FIG. 3A. 4 (a) and 4 (b) are plan views showing a modified example of the wiring board shown in FIG. 1, respectively. FIG. 5 is a perspective view showing a modified example of the wiring board shown in FIG. 6 (a) is a plan view showing a wiring board of another embodiment of the present invention, and FIG. 6 (b) is a perspective view of the wiring board shown in FIG. 6 (a) as viewed from above. FIG. 7 is a perspective view of the semiconductor package according to the embodiment of the present invention as viewed from above.

The differential transmission line 10 of the embodiment is used, for example, as a conductive path for electrically connecting a semiconductor element and another electric circuit such as an external electric circuit. Differential transmission line 10 of the embodiment described below
Is arranged on the insulating substrate 11 to form the wiring board 20. The wiring board 20 is used as a connecting member for electrically connecting the semiconductor element and an external electric circuit or the like in the semiconductor package 30 on which the semiconductor element is mounted.

However, the above is a convenient form for explanation. The differential transmission line 10 is not limited to the one located on the insulating substrate 11, and may be used for signal transmission of a high frequency signal (several tens of GHz or more, etc.) in various forms. The wiring board 20 is not limited to the above-mentioned applications, and may be used alone as a board for mounting electronic components, for example.

The differential transmission line 10 of the embodiment has a differential line 1A including a pair of signal lines 1 parallel to each other, a ground conductor layer 2, and a dielectric 3. The pair of signal lines 1 have a first end a and a second end 1b, respectively. Further, each signal line 1 has a curved portion 1c bent in the first direction X between the first end 1a and the second end 1b. The pair of signal lines 1 are linear and parallel to each other except for the curved portion 1c. Even in the curved portion 1c, the distance between the pair of signal lines 1 is constant as in the linear portion, and the positional relationship is parallel to each other.

The ground conductor layer 2 is located with the differential line 1A interposed therebetween so as to be spaced apart from the pair of signal lines 1 (so as not to be electrically short-circuited). In the example shown in FIG. 1 and the like, the ground conductor layer 2 is composed of two ground lines (no sign as a ground line). Each of these two grounded lines is located on both sides of the differential line 1A in the width direction orthogonal to the length direction of the signal line 1.

The dielectric 3 is located in the curved portion 1c between the inner signal line 1 located on the X side in the first direction of the pair of signal lines 1 and the ground conductor layer 2 adjacent to the inner signal line. doing. In the following description, of the pair of signal lines 1, the one located on the X side in the first direction (inside the so-called curve) may be simply referred to as the inner signal line 1. Further, the other signal line 1 may be simply referred to as an outer signal line 1.

In this embodiment, the dielectric 3 is realized as a dielectric layer 3A made of a dielectric material. As described above, the differential transmission line 10 is located on the insulating substrate 11 to form the wiring board 20 of the embodiment. The dielectric 3 included in the differential transmission line 10 corresponds to the dielectric layer 3A located on the insulating substrate 11. In the following, for the sake of simplicity, the dielectric 3 may be referred to as a dielectric layer 3A without being particularly distinguished from the dielectric layer 3A.

The differential transmission line 10 is used, for example, as a conductive path for electrically connecting a semiconductor element and an external electric circuit as described above. The differential line 1A is a conductive path that transmits this signal. The pair of signal lines 1 included in the differential line 1A carry out differential transmission in which currents having opposite phases flow to each other and signals are transmitted by the potential difference.

The first end 1a and the second end 1b of the signal line 1 are, for example, a connection end portion electrically connected to a semiconductor element and a connection end portion electrically connected to an external electric circuit, respectively. Further, the signal line 1 has a curved portion 1c between the first end 1a and the second end 1b (near the center in the length direction in the example shown in FIG. 1 and the like). In other words, the signal line 1 is bent in the direction of 90 degrees or the like in the middle of the length direction. Since the signal line 1 has the curved portion 1c, for example, even when the direction in which the semiconductor element is connected and the direction in which the external electric circuit is connected are different from each other, they are electrically connected. be able to.

The ground conductor layer 2 sandwiching the differential line 1A has functions such as adjusting the characteristic impedance of each signal line 1 and reducing electromagnetic noise. In consideration of such a function, the ground conductor layer 2 is located along each of the signal lines 1 over the entire length in the length direction of the differential lines 1A (individual signal lines 1).

The dielectric 3 has a function of adjusting the electric length for each signal transmitted between the pair of signal lines 1 to the same value. That is, in the curved portion 1c, the physical length of the inner signal line 1 is shorter than the physical length of the outer signal line 1. If there is no dielectric 3, the electric length of the inner signal line 1 is also shorter than the electric length of the outer signal line 1. Due to this difference in electrical length, the phase may shift between the inner signal line 1 and the outer signal line 1, causing a transmission loss as the differential transmission line 10. On the other hand, the presence of the dielectric 3 makes it possible to slow down the signal transmission speed and lengthen the electrical length in the inner signal line 1. Therefore, the difference in physical length between the inner signal line 1 and the outer signal line 1 in the curved portion 1c of the pair of signal lines 1 can be canceled out so that the electric lengths can be made equal to each other. Therefore, it is possible to provide a differential transmission line 10 that is effective in reducing transmission loss.

Since the dielectric 3 is located on the insulating substrate 11 to form the wiring board 20 in this embodiment, it is the dielectric layer 3A as described above. However, the dielectric 3 is not limited to such a dielectric layer 3A, and may be any other form that can be located between the signal line 1 and the ground conductor layer 2. Other forms of the dielectric 3 include, for example, a coating material such as glass containing dielectric particles, a coating material such as epoxy for coating a conductor-shaped signal line (not shown), and the like.

As the dielectric material forming the dielectric 3, if there is no dielectric 3, a material having a relative permittivity exceeding that of air or the like located between the inner signal line 1 and the ground conductor layer 2 is used. be able to. Specifically, the dielectric 3 is an inorganic material such as alumina (relative permittivity of about 8 to 10) and glass (relative permittivity of about 4 to 10), and an epoxy resin (relative permittivity of about 3 to 5). Etc., resin materials and the like can be used. Further, the dielectric 3 may be made of barium titanate (relative permittivity of about 1200 to 1500), a so-called dielectric ceramic.

The range in which the dielectric 3 is located in the curved portion 1c can be appropriately set according to conditions such as the relative permittivity of the dielectric 3, the frequency of the signal transmitted through the signal line 1, and the curvature of the curved portion. That is, the existence range of the dielectric 3 is such that the difference in physical length between the pair of signal lines 1 in the curved portion 1c and the extension of the electrical length of the inner signal line due to the delay in signal transmission are about the same. Should be set.

The wiring board 20 is basically composed of, for example, a differential transmission line 10 having the above configuration and an insulating board 11 having an upper surface on which the differential transmission line 10 is located. In this case, the differential transmission line 10 has a dielectric layer 3A located on the upper surface of the insulating substrate 11. The insulating substrate 11 has, for example, a rectangular shape in a plan view and a flat plate shape.

That is, the wiring board 20 of the embodiment is located on the insulating substrate 11 having an upper surface, the differential line 1A including a pair of signal lines 1 parallel to each other, which are located on the upper surface of the insulating substrate 11, and the upper surface thereof. It has a ground conductor layer 2 and a dielectric layer 3A located on the upper surface of the insulating substrate 11 between the signal line 1 and the ground conductor layer 2. Each of the signal lines 1 has a first end 1a and a second end 1b, and has a curved portion 1c bent in the first direction X between the first end 1a and the second end 1b. The first direction X is, for example, a direction orthogonal to one outer side of the rectangular insulating plate 11. That is, the differential line 1A is bent by about 90 degrees. This bending is not limited to 90 degrees, and can be appropriately set according to conditions such as a connection position with an external electric circuit or the like.

Further, the ground conductor layer 2 is located on both sides of the signal line 1 in the width direction with the differential line 1A interposed therebetween. The ground conductor layer 2 is located at a distance from the pair of signal lines 1 in order to suppress an electrical short circuit.

Further, the dielectric layer 3A is a grounded conductor layer 2 adjacent to the inner signal line 1 located on the first direction X side of the pair of signal lines 1 and the inner signal line 1 in the curved portion 1c. It is located between and. In the following description of the wiring board 20, as in the above description of the differential transmission line 10, the signal line 1 on the first direction X side may be simply referred to as the inner signal line 1, and the other signal line 1 may be referred to. It may be simply referred to as the outer signal line 1.

The insulating substrate 11 has a function as a substrate for fixing the differential line 1A and the ground conductor layer 2 in a state of being electrically insulated from each other in a fixed positional relationship. The insulating substrate 11 has, for example, a rectangular flat plate as described above, and has an aluminum oxide-like sintered body, an aluminum nitride-based sintered body, a silicon nitride-based sintered body, a silicon-carbonized sintered body, and a mulite-based sintered body. It is made of an electrically insulating material appropriately selected from a glass-ceramic sintered body and the like. The insulating substrate 11 is not limited to those made of these ceramic materials. For example, the insulating substrate 11 may include a resin material such as an epoxy resin, a polyimide resin, and a polyamide resin, or may include a composite material in which a glass cloth or an inorganic filler is added to these resin materials.

When the insulating substrate 11 is made of an aluminum oxide sintered body, it can be manufactured by a manufacturing method including the following steps. First, raw material powders such as aluminum oxide, silicon oxide and calcium oxide are kneaded together with an organic solvent and a binder to prepare a slurry. Next, this slurry is molded into a strip-shaped ceramic green sheet by a molding method such as a doctor blade method or a lip coater method. Then, the ceramic green sheet is cut into a predetermined shape and size to prepare a plurality of sheets, and if necessary, a plurality of sheets are prepared and then fired at a temperature of about 1300 to 1600 ° C. The insulating substrate 11 can be manufactured by the above steps.

When the insulating substrate 11 is made of an epoxy resin, the insulating substrate 11 is heated and cured by filling a molding mold having an internal space similar to that of the insulating substrate 11 with an uncured epoxy resin material. Can be manufactured.

The signal line 1 is formed of a metal material appropriately selected from metal materials such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, chromium, titanium and cobalt. Further, the signal line 1 may be formed of an alloy material containing these metal materials. The signal line 1 can be formed in various forms such as a metallized layer, a plating layer, and a thin-film deposition layer. In the case of a tungsten metallized layer, for example, the signal line 1 can be formed by each of the following steps.

First, the tungsten powder is kneaded with an organic solvent and a binder to prepare a metal paste. Next, this metal paste is printed on the surface of the sheet to be the insulating substrate 11 by a method such as screen printing. Then, this metal paste is co-fired together with the sheet. The signal line 1 can be formed by the above method. The exposed surface of the metallized layer of tungsten may be coated with a plating layer such as nickel and gold. By adhering the plating layer, it is possible to improve characteristics such as suppression of oxidative corrosion of the signal line 1, wettability of the solder to the signal line 1, and bonding property of the bonding wire. The solder and the bonding wire are, for example, conductive connecting materials that electrically connect the signal line 1 and the external electric circuit.

The dielectric layer 3A has a function of making the electric lengths of the inner signal line 1 and the outer signal line 1 the same in the curved portion 1c. This function is the same as that of the dielectric 3 of the differential transmission line 10 described above. That is, in the curved portion 1c, the transmission speed of the signal on the inner signal line becomes slow due to the presence of the dielectric layer 3A. Therefore, the electric length of the inner signal line 1 becomes longer, and the electric length of the inner signal line 1 having a shorter physical length than the outer signal line 1 becomes longer. As a result, the difference in physical length between the pair of signal lines 1 in the curved portion 1c is canceled out, and the electric lengths are made the same. Therefore, the phase shift between the pair of signal lines 1 is reduced, and the transmission loss is reduced.

The dielectric layer 3A is formed of, for example, the same dielectric material as the dielectric 3 of the differential transmission line 10 of the above-described embodiment. The dielectric layer 3A may be integrally formed with the insulating substrate 11, or may be a layer formed separately from the insulating substrate 11 bonded to the upper surface of the insulating substrate 11. In this case, if the dielectric layer 3A has a relative permittivity equal to or higher than that of the insulating substrate 11, the signal transmission on the inner signal line 1 can be effectively delayed. That is, in this case, the air and the surface portion of the insulating substrate 11 are located between the inner signal line 1 and the ground conductor layer 2. Since this air portion is replaced by the dielectric layer 3A, the transmission speed of the inner signal line 1 can be slowed down.

The dielectric layer 3A can be formed by the following method, for example, as long as it contains alumina similar to that contained in the insulating substrate 11 made of an aluminum oxide sintered body. First, a raw material powder such as aluminum oxide and silicon oxide similar to that of the insulating substrate 11 is kneaded with an organic solvent and a binder to prepare a ceramic paste. Next, this ceramic paste is printed in a predetermined pattern on the surface of the sheet to be the insulating substrate 11 on which the metal paste to be the signal wiring 1 is printed. Then, this ceramic paste is co-fired with the metal paste and the sheet to obtain a sintered body containing alumina. By the above steps, the dielectric layer 3A containing alumina can be formed at a predetermined position on the upper surface of the insulating substrate 11.

As long as the dielectric layer 3A contains the same material as the material forming the insulating substrate 11, it can be easily integrally formed with the insulating substrate 11 as described above. It is also effective in improving the bonding strength between the dielectric layer 3A and the insulating substrate 11. Therefore, considering the productivity and reliability of the wiring board 20, the dielectric layer 3A preferably contains the same material as the material forming the insulating substrate 11.

When the dielectric layer 3A is made of a material different from that of the insulating substrate 11, for example, a layered dielectric material prepared separately from the insulating substrate 11 is used in the insulating substrate 11 via a bonding material such as glass, ceramic, brazing material, or resin material. It may be joined to the upper surface. In this case, it is easy to make the relative permittivity of the dielectric layer 3A larger than the relative permittivity of the insulating substrate 11. Therefore, it is easy to effectively reduce the signal transmission speed of the inner signal line 1 and extend the electric length. The layered dielectric material produced separately from the insulating substrate 11 is, for example, a thin layer of barium titanate, and is produced by, for example, a manufacturing method in which a sheet obtained by molding barium titanate powder together with a binder or the like is fired. Can be done.

In the wiring board 20, the range in which the dielectric layer 3A is located in the curved portion 1c (the length of the dielectric layer 3A along the signal line 1) is the same as that of the dielectric 3 in the differential transmission line 10 described above. It can be set in the same way. That is, the length of the dielectric layer 3A along the signal line 1 is set according to conditions such as the relative permittivity of the material forming the dielectric layer 3A, the frequency of the signal transmitted through the signal line 1, and the curvature of the curved portion. Set.

In the wiring board 20, the insulating substrate 11 may contain a first dielectric material, and the dielectric layer 3A may contain a second dielectric material having a higher dielectric constant than the first dielectric material. For example, when the insulating substrate 11 is made of an aluminum oxide sintered body, the insulating substrate 11 contains alumina as the first dielectric material. Further, at this time, for example, as shown in FIG. 3, the upper surface of the insulating substrate 11 may have a recess 4 in a portion where the dielectric layer 3A is located. Further, at least a part of the dielectric layer 3A (not shown in FIG. 3) in the thickness direction may be located in the recess 4. The portion in the thickness direction is, for example, a portion below the central portion in the thickness direction of the dielectric layer 3A.

In this case, the range of the dielectric layer 3A existing between the inner signal line 1 and the ground conductor layer 2 can be made larger in the vertical direction. Therefore, the effect of delaying signal transmission by the dielectric layer 3A on the signal line 1 can be enhanced. Therefore, the electric length of the inner signal line can be adjusted more easily and in the direction of lengthening, and the wiring board 20 can be advantageous for reducing the transmission loss.

Further, in this case, since a part of the dielectric layer 3A in the thickness direction is embedded in the recess 4, the strength of the bonding of the dielectric layer 3A to the insulating substrate 11 can be increased by the anchor effect. The effect of improving the bonding strength between the dielectric layer 3A and the insulating substrate 11 by the anchor effect can be obtained even when the dielectric layer 3A is made of the same material as the insulating substrate 11. Therefore, the insulating substrate 11 may have the recess 4 simply in order to increase the bonding strength between the dielectric layer 3A and the insulating substrate 11.

In each of the above examples, the wiring board 20 is positioned so that the dielectric layer 3A covers from the upper surface of the insulating substrate 11 to the inner signal line 1 in the curved portion 1c, for example, as shown in FIG. 4A. It may be a thing. In this case, the dielectric layer 3A exists at a position closer to the inner signal line 1 in a wider range. Therefore, the effect of delaying signal transmission by the dielectric layer 3A on the signal line 1 can be enhanced. Therefore, the electric length of the inner signal line 1 can be adjusted more easily and in the direction of lengthening, and the wiring board 20 can be obtained which is advantageous for reducing the transmission loss.

Further, in this case, the structure is such that the dielectric layer 3A is integrally covered from the signal line 1 to the upper surface of the insulating substrate 11. Therefore, the dielectric layer 3A can also obtain the effect of improving the bonding strength of the signal line 1 with respect to the upper surface of the insulating substrate 11. Therefore, it is advantageous for improving the reliability of the wiring board 20. Such an effect can be more easily obtained when the dielectric layer 3A contains the same dielectric material as the insulating substrate 11 and the dielectric layer 3A and the insulating substrate 11 are integrally formed by a method such as co-fired. Be done.

In each of the above examples, the wiring board 20 has the dielectric layer 3A on the ground conductor layer 2 adjacent to the inner signal line 1 in the curved portion 1c from the upper surface of the insulating substrate 11, as shown in FIG. 4B, for example. It may be located so as to cover the railroad track.

In this case, it is easy to increase the range of the dielectric layer 3A existing between the inner signal line 1 and the ground conductor layer 2 in a plan view. Therefore, the effect of delaying signal transmission by the dielectric layer 3A on the signal line 1 can be enhanced. As a result, the electric length of the inner signal line 1 can be adjusted more easily and in the direction of lengthening, and the wiring board 20 can be obtained which is advantageous for reducing the transmission loss.

Further, in this case, the structure is integrally covered with the dielectric layer 3A from the upper surface of the insulating substrate 11 to the upper surface of the ground conductor layer 2. Therefore, the dielectric layer 3A can also obtain the effect of improving the bonding strength of the grounding conductor layer 2 with respect to the upper surface of the insulating substrate 11. Therefore, it is advantageous for improving the reliability of the wiring board 20.

As in the example shown in FIG. 6, for example, the dielectric layer 3A covers at least a part of the curved portion 1c from the upper surface of the insulating substrate 11 to both the inner signal line 1 and the ground conductor layer 2. It may be a thing. Also in this case, each of the above-mentioned effects (improvement of ease of adjustment of electric length and improvement of reliability) can be effectively obtained. Further, it is easy to enhance the effect of improving the transmission characteristics and the reliability by adjusting the electric lengths thereof.

The range in which the dielectric layer 3A exists can be easily set to each of the above forms by, for example, adjusting the coating range of the ceramic paste to be the dielectric layer 3A. In this case, if the dielectric layer 3A extends beyond the inner signal line 1 in the direction of the outer signal line 1, the signal transmission is delayed even in the outer signal line 1. That is, since the action of lengthening the electric length also occurs in the outer signal line 1, the effect of aligning the electric lengths of the pair of signal lines may be reduced. Therefore, for example, the dielectric layer 3A may be set so as to cover a part of the inner signal line 1 in the width direction in consideration of the position accuracy at the time of applying the ceramic paste to be the dielectric layer 3A.

In each of the above examples, in the wiring board 20, for example, as shown in FIG. 1A, the dielectric layer 3A extends from both ends of the curved portion 1c of the pair of signal lines 1 to linear portions in both directions continuing to the curved portion. It may be postponed. The linear portion is a portion where the signal line 1 is connected to an external electric circuit or the like, and is hereinafter referred to as a connection portion 1d. In this case, since the ratio of the signal transmission delay can be finely adjusted in the connection portion 1d, it becomes easy to improve the adjustment accuracy of the electric length of the inner dielectric layer 3A. Further, at this time, the dielectric layers 3A may extend so as to have the same length as each other in both directions from both ends of the curved portion 1c toward the connecting portion 1d.

The phase shift between the internal and external signal lines occurs in the curved portion 1c where the difference in physical length occurs. Therefore, by correcting the electric length centering on the portion where the phase shift occurs, the electric length can be adjusted with higher accuracy, and at the same time, the transmission loss can be further improved. That is, the effect of reducing the transmission loss can be enhanced by correcting the electrical length at the location where the phase shift occurs and at a location close to the phase shift, rather than correcting the electric length before or after the phase shift occurs.

The effect of the wiring board 20 of the above embodiment will be specifically described by giving an example. The effect was confirmed by a simulation using S parameters. In this simulation example, the insulating substrate 11 is made of an aluminum oxide sintered body and has a square plate shape having a side length of 6 mm in a plan view. Each of the pair of signal lines 1 has a line width of 75 μm, a distance of 75 μm from the adjacent ground conductor layer, a distance of 105 μm between the inner and outer signal lines, and a line width of the ground conductor layer 2 of 200 μm. I set it to the one.

In the curved portion 1c, the signal line 1 is assumed to be curved at an angle of 90 °, the radius of curvature of the inner signal line 1 is 371 μm, and the radius of curvature of the outer signal line 1 is 958 μm.

The dielectric layer 3A is located between the inner signal line 1 and the ground conductor layer 2 adjacent to the inner signal line, and the first end 1a and the second end 1a and the second end 1a and the second end 1a are located at the same distance from the curved portion 1c. The length of the end 1b2 was 4240 μm (linear pattern), and the material was alumina.

Further, as a comparative example, a wiring board (not shown) set under the same conditions as each of the above conditions was set except that the dielectric layer 3A was not provided. Under the above conditions, the transmission loss was obtained by simulation with the frequency of the signal transmitted on the signal line 1 being 70 GHz.

The transmission loss was confirmed on S21. As a result, in the wiring board 20 of the embodiment, the transmission loss was about 0.1 dB, whereas in the wiring board of the comparative example, the transmission loss was about 1 dB. From the above results, it was possible to confirm the effect of reducing the transmission loss in the wiring board 20 of the embodiment and the differential transmission line 10 contained therein.

The radius of curvature described above is the length at the central portion of the line width of each of the inner and outer signal lines 1. Further, the length of the dielectric layer 3A also indicates the length in the central portion of the line width.

6 (a) is a plan view showing a wiring board of another embodiment of the present invention, and FIG. 6 (b) is a perspective view of the wiring board shown in FIG. 6 (a) as viewed from above. In the example shown in FIG. 6, two differential transmission lines 10 are located adjacent to each other on the upper surface of one insulating substrate 11. Each differential transmission line 10 has the same form as the differential transmission line 10 included in the wiring board 20 of any of the above embodiments.

As in the example shown in FIG. 6, two differential transmission lines 10 may be located parallel to each other on the upper surface of the insulating substrate 11. In the two differential transmission lines 10, the connection portions 1d of the respective signal lines 1 are parallel to each other, and the distance between the outer sides adjacent to each other in the curved portion 1c is constant. That is, in the curved portion 1c, the positional relationship is parallel to each other at the same adjacent interval as the connecting portion 1d.

In this case, since the two differential transmission lines 10 are arranged on one insulating substrate 11, the density of the arrangement of the differential line 1A and the differential transmission line 10 can be increased. This is effective for, for example, high integration of semiconductor elements electrically connected to the wiring board 20. In the example shown in FIG. 6, the ground conductor layer 2 located between the two differential transmission lines 10 is shared as the ground conductor layer 2 of each differential transmission line 10. As a result, the space for arranging the ground conductor layer 2 is reduced, so that the density of arrangement of the differential transmission line 10 can be improved.

In this embodiment, the dielectric layer 3A of the inner differential transmission line 10 located on the X side of the first direction of the two differential transmission lines 10 is the first direction of the two differential transmission lines 10. The dielectric constant is higher than that of the dielectric layer 3A of the outer differential transmission line 10 located on the opposite side to the X side. This difference in permittivity can be regarded as a difference in relative permittivity in practice.

As a result, in the inner differential transmission line 10 in which the physical length of the inner signal line 1 becomes shorter, the electric length of the inner signal line 1 can be lengthened more effectively. Therefore, in both of the two differential transmission lines, it is easy to make the electric lengths of the pair of signal lines 1 uniform, and the transmission loss can be effectively reduced. Therefore, in this case, the wiring board 20 can be effective for both the density of the arrangement of the differential transmission line 10 and the improvement of the transmission characteristics.

The difference in the dielectric constant of the dielectric layer 3A in the two differential transmission lines 10 is the frequency of the signal transmitted through each differential line 1A and the curvature of each signal line 1 in the curved portion 1c (in the curved portion 1c). It can be set as appropriate according to conditions such as line length). For example, when the dielectric layer 3A of the inner differential transmission line 10 is alumina, the dielectric layer 3A of the outer differential transmission line 10 is used by mulite (relative permittivity of about 6 to 7), glass, or the like. The difference in the relative permittivity is set to about 3 to 5 as the difference in the relative permittivity.

As described above, FIG. 7 is a perspective view of the semiconductor package 30 according to the embodiment of the present invention as viewed from above. The semiconductor package 30 has a wiring board 20 having any of the above configurations and a housing 21 having a semiconductor element accommodating portion 21a. The wiring board 20 is located so as to close the opening 22 provided in the wall portion of the housing 21. The wiring board 20 in this example functions as an input / output terminal that conducts inside and outside of the accommodating portion 21a. Further, the semiconductor package 30 has a transmission line 23 located in the accommodating portion 21a of the housing 21. The transmission line 23 is electrically connected to the differential line 1A of the wiring board 20. The semiconductor element 24 accommodated in the accommodating portion 21a is electrically connected to a portion of the transmission line 23 other than the portion to which the differential line 1A is connected. The semiconductor element 24 is housed in the semiconductor package 30, and the housed portion 21a is sealed with a sealing material (not shown) such as a lid to form the semiconductor device 40.

In the semiconductor package 30 and the semiconductor device 40, the wiring board 20 has a function of electrically connecting the inside and outside of the accommodating portion (the function of the input / output terminal). A portion of the differential transmission line 10 of the wiring board 20 located in the accommodating portion 21a is electrically connected to the semiconductor element 24 via the transmission line 23. Further, a portion of the differential transmission line 10 located outside the accommodating portion 21 is electrically connected to an external electric circuit. These electrical connections can be made via conductive connecting materials such as bonding wires, solders, conductive adhesives and flexible substrates.

The housing 21 has, for example, a rectangular shape (an elongated rectangular shape in the example shown in FIG. 7) in a plan view, and has a rectangular parallelepiped shape. An opening of the concave accommodating portion 21a is located on the upper surface of the rectangular parallelepiped housing 21. The portion of the housing 21 that surrounds the accommodating portion 21a is the wall portion. The semiconductor element 24 is mounted on, for example, the bottom surface of the accommodating portion 21a. Further, the semiconductor element 24 may be mounted on the bottom surface of the accommodating portion 21a via a mounting base (so-called submount).

For example, when the semiconductor element 24 is an optical semiconductor element having a photoelectric conversion function, an optical fiber is inserted and fixed in the through hole 25. This enables connection between the semiconductor element 24 and the outside by an optical signal. The semiconductor element 24 is connected to the outside via the wiring board 20.

The housing 21 in this example has a through hole 25 opened inside and outside the accommodating portion 21a in the wall portion on the short side side. The through hole 25 has a function of inserting and fixing a connecting material such as an optical fiber. An optical fiber is inserted into the through hole 25, and the end portion of the optical fiber is connected to a light receiving portion or a light emitting portion of the semiconductor element 24. This makes it possible to send and receive optical signals between the semiconductor element 24 (optical semiconductor element) and the outside.

The housing 21 is made of stainless steel such as iron-nickel-chromium alloy (JIS standard SUS304, SUS310, etc.), iron-nickel-chromium-molybdenum alloy (JIS standard SUS303, SUS316, etc.), iron-nickel-cobalt, for example. It is formed of a material appropriately selected from metal materials such as alloys and copper-zinc alloys.

The through hole 25 of the housing 21 is formed, for example, by drilling a hole. One end of a cylindrical fixing member including a ferrule or the like may be joined around the outer opening of the housing 21 of the through hole 25, or the fixing member may be fitted and joined to the through hole 25. The optical fiber is inserted into the through hole in the length direction of the tubular fixing member, and the optical fiber is positioned and fixed to the housing 21 via the fixing member.

The housing 21 can be manufactured by subjecting the raw material of the metal material forming the housing 21 to a process appropriately selected from metal processing methods such as rolling, punching, electric discharge, cutting and polishing. In this case, the housing 21 separately has a plate-shaped portion including the bottom surface of the accommodating portion 21a and a frame-shaped portion (wall portion) located on the outer periphery of the upper surface of the plate-shaped portion, and then these are formed. It may be manufactured by a method of joining them together. The plate-shaped portion and the frame-shaped portion can be joined by a joining method such as joining via a brazing material, for example.

Further, the housing 21 may be coated with a plating layer such as nickel and gold on the exposed surface thereof. With the gold-plated layer or the like, it is possible to obtain effects such as suppressing oxidation of the housing 21 and improving the wettability of the brazing material. As an example, a nickel layer having a thickness of 0.5 to 9 μm and a gold layer having a thickness of 0.5 to 9 μm are sequentially adhered to the surface of the housing 21 by a plating method such as an electroplating method. As a result, it is possible to prevent the housing 21 from being oxidatively corroded.

The housing 21 may be integrally molded as a whole. As a method of this integral molding, a method of applying the above-mentioned metal processing to the raw material of the material can be mentioned. When the housing 21 is integrally molded as a whole, it is advantageous in terms of improving the mechanical strength at the boundary portion between the plate-shaped portion and the frame-shaped portion and improving the position accuracy thereof. Is.

1 ・ ・ Signal line 1a ・ ・ 1st end 1b ・ ・ 2nd end 1A ・ ・ Differential line 1c ・ ・ Curved part 1d ・ ・ Connection part 2 ・ ・ Ground conductor layer 3 ・ ・ Dielectric 3A ・ ・ Dielectric layer 4 ... concave
10 ... Differential transmission line
11 ... Insulation board
20 ... Wiring board
21 ... Housing
21a ... Containment section
22 ... Opening
23 ... Transmission line
24 ... Semiconductor element
25 ... Through hole
30 ... Semiconductor package
40 ... Semiconductor device X ... First direction

Claims (8)

A differential line containing a pair of parallel signal lines having a first end and a second end, respectively, and having a curved portion curved in the first direction between the first end and the second end.
A grounded conductor layer located at a distance from the pair of signal lines across the differential line,
A dielectric located between the inner signal line located on the first direction side of the pair of signal lines and the ground conductor layer adjacent to the inner signal line in the curved portion. A differential transmission line. Insulated substrate with top surface and
It is located on the upper surface of the insulating substrate, has a first end and a second end, respectively, and is parallel to each other with a curved portion curved in the first direction between the first end and the second end. A differential line containing a pair of signal lines and
A grounded conductor layer located at a distance from the pair of signal lines across the differential line,
A dielectric layer located between the inner signal line located on the first direction side of the pair of signal lines and the ground conductor layer adjacent to the inner signal line in the curved portion. Wiring board with differential transmission lines including. The insulating substrate contains a first dielectric material, and the dielectric layer contains a second dielectric material having a higher dielectric constant than the first dielectric material.
The second aspect of claim 2, wherein the upper surface of the insulating substrate has a recess in a portion where the dielectric layer is located, and at least a part of the dielectric layer in the thickness direction is located in the recess. Wiring board. The wiring board according to claim 2 or 3, wherein the dielectric layer is located so as to cover from the upper surface of the insulating substrate to the signal line inside the curved portion. The invention according to any one of claims 2 to 4, wherein the dielectric layer is located so as to cover from the upper surface of the insulating substrate to the ground conductor layer adjacent to the signal line inside the curved portion. Wiring board. Claims 2 to claim that the dielectric layer extends from both ends of a curved portion of the pair of signal lines to a connecting portion in both directions following the curved portion so as to have the same length as each other in both directions. 5. The wiring board according to any one of 5. The two differential transmission lines are located parallel to each other on the upper surface of the insulating substrate.
The dielectric layer of the inner differential transmission line located on the first direction side of the two differential transmission lines is on the side opposite to the first direction side of the two differential transmission lines. The wiring board according to any one of claims 2 to 6, which has a higher dielectric constant than the dielectric layer of the outer differential transmission line located. The wiring board according to any one of claims 2 to 7.
A housing with a semiconductor element housing and
A semiconductor device located in the housing portion of the housing and including a transmission line electrically connected to the differential line of the wiring board.

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