JP2008227105A - Transmission line mounting board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission line mounting board having a transmission characteristic of low loss in a frequency band from DC (Direct Current) to GHz and having a prescribed delay characteristic. <P>SOLUTION: High dielectric ratio resin layers 10 and 11 are formed so that they cover metallic conductors of the transmission lines (signal layers 3 and 4) formed on confronted faces of confronted dielectric substrates 7. Unnecessary electromagnetic coupling between signal wirings is suppressed. Solder balls 9 connect the signal layer 3 and the signal layer 4 while they function as spacers so that the signal layer 3 and the signal layer 4 are separated by a prescribed interval. Since the transmission line mounting board has a laminated structure of signal layer 3/high dielectric ratio resin layer 10/air layer/high dielectric radio resin layer 11/signal layer 4, a low dielectric ratio layer (air layer) exists between the high dielectric ratio resin layers 10 and 11 even if they are arranged. Consequently, addition of capacity due to the high dielectric ratio resin layers 10 and 11 is prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission line mounting board on which a signal transmission line formed on a semiconductor chip, a semiconductor package, an interposer board, and a printed board is mounted. The present invention relates to a transmission line mounting substrate that is also effective for circuits in the following frequency bands.

  Conventionally, in a mounting structure in which signal wirings of a plurality of dielectric substrates are connected via solder balls, in order to suppress unnecessary electromagnetic coupling between the signal wirings and maintain good high frequency characteristics, In general, a layer configuration in which no signal wiring is formed on the facing surface layers of the connected substrates, or a layout design that keeps the distance between the facing wirings as large as possible has been used.

  On the other hand, Patent Document 1 discloses a configuration in which a dielectric layer having a high dielectric constant is provided on a plurality of wirings formed on the same substrate surface in this type of transmission line. In this prior art, a signal line and a ground line are formed on a base dielectric layer, and an upper dielectric layer is overlaid thereon. A ground conductor layer or a lower shield ground line and a shield ground layer are provided on the lower surface of the base dielectric layer and the upper surface of the upper dielectric layer, respectively.

  Patent Document 2 discloses a layer structure including a dielectric layer and a conductive layer sandwiching the dielectric layer. However, Patent Document 2 relates to an interconnection module having a reduced power distribution impedance unlike the present invention. A module incorporating a dielectric constant embedded capacitor structure is disclosed, and basically relates to a capacitor device.

  Patent Document 3 discloses a plastic BGA package in which a solder ball pad is provided with a notch so that the solder ball is firmly fused to the solder ball pad.

  Further, Patent Document 4 discloses a flip chip assembly in which a flip chip is mounted on a printed wiring board. In this prior art, the area other than the solder bump is filled with the underfill resin between the printed wiring board and the flip chip connected by the solder bump, thereby strengthening the connection by the solder bump.

JP-A-11-68414 JP 2005-501415 gazette JP 2004-22615 A JP 2006-521703 A

  However, in the case of the layer configuration shown in Patent Document 1, if signal lines are stacked in layers, it becomes wiring / high dielectric constant layer / wiring, and unnecessary capacitance is added between wiring layers, which is not preferable in terms of characteristics.

  Also, since Patent Document 2 has a layer configuration of wiring / high dielectric constant layer / wiring, as in Patent Document 1, an unnecessary capacitance is added between the wirings, which is not preferable in terms of characteristics. is there.

  Patent Documents 3 and 4 disclose electrical connection between substrates or between a substrate and a chip using solder balls, both of which are used to strengthen the connection between solder balls and pads. Although this technique is disclosed, there is no disclosure about improvement of high-frequency transmission characteristics.

  Therefore, in the prior art, in order to avoid unnecessary electromagnetic field coupling between the signal lines that degrade the high frequency characteristics, a layer configuration in which signal lines are not formed on the opposing surface layers of the substrates connected via solder balls is used. Alternatively, there is no other way than to design a layout that keeps the distance between opposing wirings as large as possible. However, when the design as described above is performed, there is a problem that the design specifications cannot be satisfied or the cost increases due to the increase in the number of substrate layers and the substrate dimensions.

  Recently, high-density mounting due to miniaturization of devices has been demanded, and the development of technology for avoiding the coupling of electromagnetic fields that degrade the above-described high-frequency characteristics has been demanded as the size of solder balls becomes smaller. ing.

  In addition, as described in Patent Document 4, in the solder ball portion, a mounting structure in which an underfill resin is filled in order to fix the connection portion mechanically and firmly is known. However, due to manufacturing restrictions, it is difficult to set the impedance of the connection part to a desired value, and there is a problem that the high frequency characteristic and the delay characteristic are deteriorated. It has been demanded.

  On the other hand, high-frequency band exceeding 1 GHz and high-speed transmission exceeding 1 Gbps have been used for various devices. As a result, a technique for manufacturing a device having a uniform characteristic in a large amount at a low cost has been demanded.

  The present invention has been made in view of such a problem, and it is possible to prevent deterioration of transmission characteristics even in signal transmission in a high-frequency band exceeding 1 GHz and high-speed transmission exceeding 1 Gbps, and good electrical signals can be obtained. An object of the present invention is to provide a transmission line mounting substrate that can retain high-frequency characteristics and delay characteristics, has low-loss transmission characteristics in a frequency band from DC (direct current) to GHz, and has predetermined delay characteristics. To do.

  A transmission line mounting substrate according to the present invention includes a plurality of opposing dielectric substrates, a signal transmission line formed of a metal conductor formed on at least an opposing surface of the substrate, and the opposing signal transmission line. A high dielectric constant resin layer provided on at least a part of the surface, and a solder ball that connects the opposing signal transmission lines with a part thereof with a gap between the opposing high dielectric constant resin layers. It is characterized by that.

  In the present invention, when a high frequency current flows through the signal wiring, an electromagnetic field in a quasi-TEM mode (Transverse Electromagnetic mode) that is a basic transmission mode is generated around the wiring. This electromagnetic field is electromagnetically coupled to nearby wiring, resulting in deterioration of high frequency characteristics. Basically, electromagnetic waves have the property of being confined in a region with a high dielectric constant. The present invention utilizes such properties of electromagnetic waves, and by adding a high dielectric constant resin layer on the opposing metal conductor, unnecessary electromagnetic coupling between signal wirings can be suppressed.

  The high dielectric constant resin layer can also be formed on a semiconductor chip, a semiconductor package, an interposer substrate, and a printed substrate by a printing technique or the like.

  Further, in the present invention, a part of the region including the solder balls in the gap between the opposing dielectric substrates is filled with a paraelectric resin material or a ferroelectric resin material having a predetermined dielectric constant. Can be configured.

  Further, a partial region including the solder balls in the gap between the opposing dielectric substrates is filled with a ferroelectric resin material, and a bias electric field is applied to the ferroelectric resin material. It can be constituted as follows. By applying this bias electric field, an impedance adjustment function can be provided.

  Furthermore, the high dielectric constant resin layer can be, for example, a composite material of a resin and a ceramic powder. For example, a barium titanate titanate powder is dispersed in an epoxy resin. The ferroelectric resin layer can also be a composite material of, for example, a resin and a ceramic powder. For example, a barium titanate powder is dispersed in an epoxy resin.

  The dielectric resin material can be filled relatively uniformly using the capillary phenomenon after being applied around the solder balls. In the case of a ferroelectric resin material, the impedance of the transmission line connection portion can be adjusted by utilizing the physical property that the dielectric constant of the material changes due to the bias electric field.

  In the present invention, a signal transmission line made of a metal conductor is provided on each opposing surface of the opposing dielectric substrate, each signal transmission line is electrically connected by a solder ball, and at least the surface of the signal transmission line A high dielectric constant resin layer is provided on a part, solder balls are used as spacers, and the high dielectric constant resin layer on each transmission line is held with a predetermined gap, thereby suppressing unnecessary electromagnetic coupling between signal wires. be able to. That is, since the high dielectric constant resin layer is provided so as to cover the signal transmission line, electromagnetic coupling between the signal transmission lines can be prevented. In the present invention, since an air layer is interposed between the high dielectric constant resin layers, wiring / high dielectric constant layer / low dielectric constant layer (air) / high in the thickness direction of the substrate. A dielectric constant layer / wiring is arranged. For this reason, in the structure of wiring / high dielectric constant layer / wiring as in the prior art, an unnecessary capacitance is added between the wirings, which is not preferable in terms of characteristics. However, in the present invention, the high dielectric constant layer is not provided. Even if it is provided, since a low dielectric constant layer (air) is interposed between them, unnecessary capacitance is prevented from being added.

  Also, the impedance of the transmission line connection portion is adjusted by filling the periphery of the solder ball with a paraelectric resin material or a ferroelectric resin material having a predetermined dielectric constant, and applying a bias electric field in the ferroelectric resin material. Is possible.

  According to the present invention, since the high dielectric constant resin layer is provided on the metal conductor constituting the signal transmission line, electromagnetic coupling between the signal transmission lines can be prevented, and loss of high frequency signals can be particularly prevented. In the present invention, since an air layer (low dielectric constant layer) exists between the high dielectric constant layers, an unnecessary capacitance is added between the signal transmission lines even if the high dielectric constant layer is provided. There is no end. Thus, according to the present invention, a transmission line structure having a low loss transmission characteristic and a predetermined delay characteristic can be obtained in a frequency band from DC (direct current) to GHz. In addition, according to the present invention, deterioration of transmission characteristics can be prevented even at high speed transmission exceeding 1 Gbps.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a transmission line mounting substrate according to the first embodiment of the present invention. The dielectric substrate 7 is a laminate of two dielectric substrates 7a and 7b. On one dielectric substrate (for example, the dielectric substrate 7a), the ground layers 2 and 5 are respectively connected to the insulating layer 2a, It is formed by being electrically separated by 5a. The dielectric substrates 7a and 7b are stacked with the ground layers 2 and 5 therebetween. The size of the dielectric substrate 7 is, for example, 50 mm × 50 mm, and the substrate material may be a glass base epoxy resin laminate having a heat resistance grade of FR4.

  Further, signal layers 1, 3, 4, and 6 as signal wirings are formed on the front and back surfaces of the dielectric substrate 7. The signal layer 1 and the signal layer 3, and the signal layer 4 and the signal layer 6 are connected by a through hole 8 that penetrates the dielectric substrate 7. A pair of dielectric substrates 7 are arranged so that the surface on the dielectric substrate 7 a side faces each other, and the signal layers 3, 4 formed on the surface of the dielectric substrate 7 a are formed by solder balls 9. Electrically connected. A high dielectric constant resin layer 10 and a high dielectric constant resin layer 11 are formed on the surface of the dielectric substrate 7 a and on the surfaces of the signal layers 3 and 4 excluding the area around the solder balls 9. As the high dielectric constant resin layers 10 and 11, a composite material in which barium titanate barium titanate powder is dispersed in an epoxy resin material can be used. A composite material in which barium strontium titanate powder is dispersed in an epoxy resin material has a relative dielectric constant of 20, for example.

  In the transmission line mounting substrate configured as described above, the high dielectric constant resin layer is formed so as to cover the metal conductors of the transmission lines (signal layers 3 and 4) formed on the opposing surfaces of the opposing dielectric substrate 7. Since 10 and 11 are formed, unnecessary electromagnetic coupling between the signal wirings (signal layers 3 and 4) can be suppressed. In addition, in the present embodiment, the signal layer 3 and the signal layer 4 are electrically connected by the solder balls 9, and the signal layer 3 and the signal layer 4 are separated at a constant interval. That is, the solder ball functions as a spacer so that a gap is formed between the signal layer 3 and the signal layer 4, and mechanically connects the signal layer 3 and the signal layer 4. For this reason, in this embodiment, since the signal layer 3 / the high dielectric constant resin layer 10 / the air layer / the high dielectric constant resin layer 11 / the signal layer 4 is formed, the high dielectric constant resin layers 10 and 11 are formed. However, since a low dielectric constant layer (air layer) is interposed therebetween, it is possible to prevent a capacitance from being added due to the high dielectric constant resin layers 10 and 11.

As a result, even in signal transmission in a high-frequency band exceeding 1 GHz and high-speed transmission exceeding 1 Gbps, deterioration of transmission characteristics can be prevented, and good high-frequency characteristics and delay characteristics of electric signals can be maintained. A transmission line mounting substrate according to a second embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the transmission line mounting substrate of the first embodiment shown in FIG. 1 in that a gap between the dielectric substrates 7 around the solder balls 9 is filled with a ferroelectric resin 12. . That is, a part of the region including the solder balls 9 in the gap between the dielectric substrates 7 arranged opposite to each other is filled with the ferroelectric resin 12. As the ferroelectric resin 12 filling the periphery of the solder ball 9, a composite material having a relative dielectric constant of 40 in which barium titanate powder is dispersed in an epoxy resin material can be used.

  In the present embodiment, in addition to the same effects as the first embodiment, the region between the substrates around the solder balls 9 is filled with the ferroelectric resin 12, so this ferroelectric resin By applying a bias electric field to 12, the relative dielectric constant of the material can be adjusted. As a result, the impedance of the transmission line connection portion can be adjusted. The bias electric field applied to the ferroelectric resin 12 can be generated by applying a DC voltage to the conductor portions constituting the signal layers 3 and 4 on which the solder balls 9 are mounted.

  It should be noted that a paraelectric resin can be used instead of the ferroelectric resin 12 as the resin filling the region between the substrates around the solder balls 9. This also makes it possible to adjust the impedance of the transmission line connection portion.

  FIG. 3 is a graph showing a comparison of transmission characteristics with respect to the transmission line structure. The conventional structure in the figure is a transmission line structure when the high dielectric constant resin layers 10 and 11 are not provided in the transmission line mounting substrate of the first embodiment shown in FIG. As shown in FIG. 3, compared with the transmission line of the conventional structure, the transmission lines of the first embodiment and the second embodiment of the present invention are both less deteriorated in transmission characteristics in the high frequency band exceeding GHz. The invention shows that a transmission line connection structure with smaller signal loss and superior transmission characteristics than the conventional structure can be realized.

  In Patent Documents 3 and 4, the periphery of the solder ball is filled with a resin, which is filled with an underfill resin in order to firmly fix the solder ball portion. In this way, the impedance of the transmission line is not adjusted by filling a paraelectric resin material or a ferroelectric resin material having a predetermined dielectric constant.

  In this way, in each of the above-described embodiments, a transmission line structure having a low-loss transmission characteristic and a predetermined delay characteristic is obtained in a frequency band from DC (direct current) to GHz. According to the present invention, deterioration of transmission characteristics can be prevented even at high speed transmission exceeding 1 Gbps.

  The transmission line mounting substrate of the present invention can be used for a high-speed / high-frequency circuit exceeding 1 GHz in a communication device, a radar device, a measurement device, and the like, and the present invention is not intended to limit the use frequency. In addition, it can be used for a circuit having a frequency band of 1 GHz or less.

It is sectional drawing which shows the transmission line mounting board | substrate of 1st Embodiment of this invention. It is sectional drawing which shows the transmission line mounting board | substrate of 2nd Embodiment of this invention. It is a graph which shows the relationship between a transmission line structure and a transmission characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3, 4, 6: Signal layer 2, 5: Ground layer 7: Dielectric substrate 8: Through hole 9: Solder ball 10, 11: High dielectric constant resin layer 12: Ferroelectric resin (paraelectric resin)

Claims (5)

Provided on at least a part of the surface of the plurality of dielectric substrates arranged opposite to each other, a signal transmission line formed of a metal conductor formed on at least the opposite surface on the substrate, and the opposite signal transmission line A transmission line mounting board comprising: a high dielectric constant resin layer; and a solder ball for connecting the opposing signal transmission lines with a part thereof with a gap between the opposing high dielectric constant resin layers. The partial region including the solder balls in the gap between the opposing dielectric substrates is filled with a paraelectric resin material having a predetermined dielectric constant. Transmission line mounting board. A part of the region including the solder balls in the gap between the opposing dielectric substrates is filled with a ferroelectric resin material, and a bias electric field is applied to the ferroelectric resin material. The transmission line mounting substrate according to claim 1. The transmission line mounting substrate according to any one of claims 1 to 3, wherein the high dielectric constant resin layer is a composite material of resin and ceramic powder. The transmission line mounting substrate according to claim 3, wherein the ferroelectric resin material is a composite material of a resin and a ceramic powder.

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