JP2014190717A - Strip line resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strip line resonator capable of measuring a specific dielectric constant of a copper-plated laminate sheet of which the thickness is less than 0.6 mm, over a wide frequency range, without requiring any special jig, at low cost, according to a simple method and with high reproducibility.SOLUTION: A strip line resonator is formed by overlapping two printed circuit boards and used for measuring a specific dielectric constant of a dielectric substance in accordance with a strip line resonance method using a vector network analyzer. The strip line resonator has a strip line structure formed by overlapping a first substrate formed from a ground plane provided on one surface and a linear resonance pattern provided on an opposite surface, and a second substrate comprising a ground plane on one surface. On a side of the opposite surface of the first substrate, the second substrate is overlapped which is set to such a shape that both end portions of the resonance pattern on the first substrate are exposed.

Description

  The present invention relates to a stripline resonator used for measuring the relative dielectric constant of a thin copper clad laminate having a thickness of less than 0.6 mm, for example.

  The signal operating speed of LSIs mounted on printed wiring boards used in communication equipment is improving year by year, and LSIs with a signal transmission rate of 25 Gbps or more are beginning to appear. In such a printed wiring board that supports high-speed LSI operation, it is important to ensure the transmission characteristics of the base material in order to transmit high-speed signals, and the relative permittivity and dielectric loss tangent of the base material that affect the characteristics are also important. There is a demand for accurate measurement up to high frequencies. At the same time, these printed wiring boards are increasing in density and multi-layer, and the thickness of the copper-clad laminate used is 0.2 mm or less in the backplane of communication equipment.

  Examples of a method for measuring the relative dielectric constant of a general substrate for a printed wiring board include a capacitance method, a triplate stripline resonance method, and a cavity resonator method. Each will be described below.

  The first capacitance method is a method of filling a sample between two electrodes and measuring the capacitance between the electrodes. Since the frequency needs to be handled as a lumped constant, it is usually used in the kHz band to the MHz band because of the size of the sample. Even in the capacitance method using an impedance material analyzer, the measurement frequency is 1 MHz to 1.8 GHz (Non-Patent Document 1).

  The second triplate stripline resonance method is a measurement method for calculating a relative permittivity from the resonance frequency of a resonator having a stripline structure, and is a measurement method used from the MHz band to about 14 GHz. The measurement sample needs to be fixed by applying a certain pressure so that there is no gap using a dedicated jig in order to overlap and adhere the two substrates. The triplate stripline resonance method has a simple structure and can be measured under conditions close to the form of the transmission line of an actual printed wiring board (Non-patent Documents 2 and 3).

  The third cavity resonance method is a measurement technique for calculating the relative dielectric constant from the resonance frequency and Q value caused by inserting a sample into the resonator. With the cavity resonator method, a thin substrate can be measured, and the measurement frequency corresponds to a high frequency of 20 GHz or more, but it is not simple because a resonator is required for each frequency and costs are increased.

  Further, common problems in these relative dielectric constant measurement methods include, firstly, the thickness of the material is limited by the measurement method, and secondly, the measurement corresponding frequency varies depending on the measurement method.

  For example, Non-Patent Document 3 can be measured with a simple jig, and the relative permittivity can be easily calculated, so it can be said that it is suitable for measuring the relative permittivity of a printed wiring board. The thickness is 0.6 mm to 1.6 mm or more. When this measurement method is applied to a thin base material of less than 0.6 mm, the distance between the resonance pattern and the upper and lower ground planes is too short, so that there is a problem that signal energy cannot be supplied efficiently and resonance characteristics cannot be obtained.

Permittivity and Loss Tangent, Parallel Plate, 1MHz to 1.5GHz, IPC-TM-650 2.5.5.9 Stripline Test for Permittivity and Loss Tangent at X-Band, IPC-TM-650 2.5.5.5 Copper-clad laminate test method for printed wiring boards Non-dielectric constant and dielectric loss tangent JPCA-TM001, Japan Electronic Circuits Association

  The present invention solves the above-mentioned problems, and is not a sample thickness specified by a measurement method, but a copper-clad laminate of less than 0.6 mm, which is the same thickness as a copper-clad laminate used in an actual multilayer substrate To provide a stripline resonator with excellent practicality that can measure the relative dielectric constant of a plate over a wide frequency range, without requiring a special jig, at low cost and with a simple method with good reproducibility. It is an object.

  The gist of the present invention will be described.

  A stripline resonator which is configured by superposing two printed circuit boards and used for measuring the relative dielectric constant of a dielectric by a stripline resonance method using a vector network analyzer, which is a ground plane provided on one side and the opposite side A strip line structure formed by superimposing a first substrate having a linear resonance pattern provided on a surface and a second substrate having a ground plane on one side; and The second substrate set in a shape in which both ends of the resonance pattern of the first substrate are exposed is overlapped on the opposite surface side, and the resonance pattern of the first substrate is exposed during measurement. Both ends are set to feed electrodes that allow the vector network analyzer coaxial connector to input and output signals by electromagnetic coupling. Those of the stripline resonator according to claim.

  2. The stripline resonator according to claim 1, wherein the first substrate and the second substrate are integrated by a lamination press to form a three-layer substrate.

  The stripline resonator according to any one of claims 1 and 2, wherein the thicknesses of the first substrate and the second substrate are less than 0.6 mm. .

  The exposed length of both ends of the resonance pattern is set to 5 to 8 times the thickness of the first substrate and the second substrate. This relates to the described stripline resonator.

  Since the present invention is configured as described above, the relative permittivity of a copper-clad laminate having a thickness of less than 0.6 mm covers a wide frequency range, does not require a special jig, and is inexpensive and reproducible. The stripline resonator can be measured well and has excellent practicality.

It is a schematic explanatory perspective view of a present Example. It is a disassembled explanatory perspective view of a present Example. It is a schematic explanatory drawing of the principal part of a present Example. It is a schematic explanatory drawing explaining the use condition of a present Example. It is a graph which shows the resonant frequency measurement example measured with the vector network analyzer. It is a graph which shows the relative dielectric constant calculation example.

  An embodiment of the present invention which is considered to be suitable will be briefly described with reference to the drawings showing the operation of the present invention.

  When measuring the relative permittivity of the dielectric (insulating substrate) of the printed circuit board (copper-clad laminate) by the stripline resonance method using a vector network analyzer, both ends of the resonance pattern on the first substrate are intentionally The dielectric constants of the dielectrics of the first substrate and the second substrate are measured by inputting / outputting signals to / from the power supply electrodes formed by exposing them to each other by non-contact electromagnetic coupling via a coaxial connector. be able to.

  If the resonance pattern is not exposed with a normal method, that is, a thin substrate, the coaxial connector is more strongly coupled to the ground plane than the resonance pattern, and sufficient signal energy cannot be supplied to the resonance pattern.

  On the other hand, when the end portion of the resonance pattern is exposed and the power supply electrode is provided, the coupling between the coaxial connector and the resonance pattern can be freely controlled. For this reason, the present invention can efficiently supply signal energy for a thin copper clad laminate, and the relative dielectric constant can be easily measured even in a thin copper clad laminate having a thickness of less than 0.6 mm. Measurements can be made with good reproducibility. Further, such a power supply electrode shape has an advantage that the structure is simple and can be easily manufactured.

  Also, when measuring the relative permittivity using a stripline resonator, the relative permittivity is calculated from the resonant frequency measured with the vector network analyzer, so it is necessary to suppress unnecessary frequency fluctuations other than the resonance mode as much as possible. For example, it is possible to obtain a stable relative dielectric constant by setting the exposure length of the resonance pattern as short as about 5 to 8 times the thickness of the substrate.

  Specific embodiments of the present invention will be described with reference to the drawings.

  This embodiment is a stripline resonator that is configured by superposing two printed circuit boards and is used to measure the dielectric constant of a dielectric by a stripline resonance method using a vector network analyzer, and is provided on one side. A strip line structure formed by superimposing a first substrate having a microstrip line structure including a ground plane and a resonance pattern provided on the opposite surface, and a second substrate having a ground plane on one side. Then, the second substrate set to a shape in which both end portions of the resonance pattern of the first substrate are exposed is overlapped on the opposite surface side of the first substrate. The coaxial connectors of the vector network analyzer are connected by electromagnetic coupling between the exposed ends of the resonance pattern of one substrate. Is obtained by setting the signal to the input and output can be powered electrode.

  Specifically, the present embodiment (stripline resonator 10) is configured by superposing the macrostripline substrate 20 (first substrate) and the single-sided ground substrate 30 (second substrate) shown in FIG. Yes.

  The microstrip line substrate 20 includes a ground plane 21, a dielectric 22 (insulating substrate), and a resonance pattern 23 (signal wiring). The single-sided ground substrate 30 includes a ground plane 31 and a dielectric 32 (insulating substrate). Is done. The microstrip line substrate 20 and the single-sided ground substrate 30 can be formed only by etching, and no plating or laminating process is required and can be easily manufactured. The ground planes 21 and 31 are provided on the entire surface of one side of the dielectrics 22 and 32. The dielectrics 22 and 32 of the two substrates 20 and 30 are made of the same material, and the thicknesses of the dielectrics 22 and 32 are set to the same thickness. In this embodiment, the resonance pattern 23 is formed up to the substrate end, but it may be configured not to extend to the substrate end. Further, the resonance pattern 23 is not limited to a linear shape, and can be freely set to a shape that bends in the middle.

  The dimension of the single-sided ground substrate 30 is set to be shorter than that of the microstrip line substrate 20, and a part of the resonance pattern 23 at both ends exposed when they are overlapped becomes the feeding electrodes 11 and 12. If the exposed length of both ends of the resonance pattern 23 is too long, the resonance characteristics are affected. If the exposure length is too short, the signal cannot be fed. For example, the exposed length of both ends of the resonance pattern 23 is set to 5 to 8 times the thickness of the substrates 20 and 30. It should be noted that the remaining portions other than the portions to be the feeding electrodes 11 and 12 of the resonance pattern 23 are configured to be covered with the single-sided ground substrate 30.

  The wiring width and wiring length of the resonance pattern 23 formed as a resonator are set so as to resonate at a desired frequency depending on the relative permittivity and thickness of the dielectrics 22 and 32. Plural types of signal wiring lengths are prepared according to the frequency to be measured.

  FIG. 3 shows an example of the detailed structure of the feeding electrode portion. The central conductor of the coaxial connector 41 is brought close to the power supply electrode 11 to input / output signals by non-contact electromagnetic coupling.

  FIG. 4 shows an example of relative permittivity measurement. The vector network analyzer 100 is provided with coaxial cables 101 and 102 and coaxial connectors 41 and 42. The stripline resonator 10 is measured while being sandwiched from above and below by the aluminum plates 51 and 52 and in close contact with the fixing screw 53. When both substrates are integrated by a lamination press to form a three-layer substrate, the aluminum plates 51 and 52 need not be sandwiched.

  For example, the thicknesses of the dielectrics 22 and 32 are 0.2 mm, the wiring width is 1.0 mm, the wiring length is 85 mm, and 162 mm, respectively, and the feeding electrode length (each exposed length at both ends of the resonance pattern 23) is 1. By setting it to 0 mm, it is possible to obtain stable resonance characteristics up to 20 GHz.

FIG. 5 shows a measurement example of the resonance frequency measured by the network analyzer under the above conditions. An example of the relative permittivity derived from the resonance frequency of FIG. 5 is shown in FIG.
The relative dielectric constant is calculated by the following equation (1).

  Note that the present invention is not limited to this embodiment, and the specific configuration of each component can be designed as appropriate.

Claims (4)

  A stripline resonator which is configured by superposing two printed circuit boards and used for measuring the relative dielectric constant of a dielectric by a stripline resonance method using a vector network analyzer, which is a ground plane provided on one side and the opposite side A strip line structure formed by superimposing a first substrate having a linear resonance pattern provided on a surface and a second substrate having a ground plane on one side; and The second substrate set in a shape in which both ends of the resonance pattern of the first substrate are exposed is overlapped on the opposite surface side, and the resonance pattern of the first substrate is exposed during measurement. Both ends are set to feed electrodes that allow the vector network analyzer coaxial connector to input and output signals by electromagnetic coupling. Strip line resonator, characterized.   The stripline resonator according to claim 1, wherein the first substrate and the second substrate are integrated by a lamination press to form a three-layer substrate.   The stripline resonator according to any one of claims 1 and 2, wherein the thicknesses of the first substrate and the second substrate are less than 0.6 mm.   The exposed length of both ends of the resonance pattern is set to 5 to 8 times the thickness of the first substrate and the second substrate. Stripline resonator.

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