JP2012227434A - High-frequency package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-frequency package which reduces leakage of a high-frequency signal from a vent hole.SOLUTION: There is provided a high-frequency package comprising: a multilayer substrate 1 formed by stacking a plurality of dielectric substrates; a semiconductor device mounted on the multilayer substrate 1; a metal lid 3 bonded to the multilayer substrate 1 so as to surround a mount region of the semiconductor device in an approximately circular pattern, to form a cavity between the metal lid 3 and the multilayer substrate 1; solder 4 which bonds the multilayer substrate 1 and the metal lid 3; a vent hole 5 formed between the multilayer substrate 1 and the metal lid 3 by the solder 4 which is broken and configured to let an inside and an outside of the cavity be communicated with each other; and a suppression waveguide tube having a length equal to a natural-number multiple of approximately 1/2 of an in-substrate effective wavelength of a signal wave output from the semiconductor device, formed in the multilayer substrate 1, including an opening exposed over the vent hole 5 in a bonding portion to the metal lid 3, and including a short-circuited tip.

Description

  The present invention relates to a high frequency package.

  Conventionally, by forming an annular pattern so as to surround the high-frequency oscillation unit on the substrate on which the high-frequency oscillation unit for transmitting radio waves is mounted, by joining the lid to the substrate with solder stacked on the annular pattern, A high-frequency package having a structure in which a high-frequency oscillation unit is sealed with a lid is known (for example, see Patent Document 1).

  In the high-frequency package having the above-described structure, the internal space in which the high-frequency oscillation unit is housed may be a non-airtight space without being airtight. When making a high-frequency package non-hermetic, it is necessary to provide minute ventilation holes that do not leak radio waves for the purpose of preventing condensation. Conventionally, a method has been proposed in which the vent hole is formed in solder for joining the substrate and the lid. According to this method, for example, one portion of the annular pattern is divided to form a void portion without a pattern locally. As a result, no solder is placed in the gap, so that a small ventilation hole can be easily formed in a part of the solder that joins and seals the substrate and the lid.

  In-vehicle millimeter wave radars, etc. are applied to safety measures such as cruise control and mitigation of damage to drivers when collisions are unavoidable by detecting distance to the vehicle ahead and relative speed using millimeter wave electromagnetic waves. Yes. In such an in-vehicle millimeter wave radar, there are many methods of multiplying from a low frequency in order to obtain a transmission signal. In this case, since many frequency components exist in the module, the overseas EMI standards (FCC, etc.) It has become very difficult to be satisfied.

  In an in-vehicle millimeter-wave radar, a radar module usually includes a high-frequency package on which a high-frequency device for a radar apparatus is mounted, a control / interface board that supplies a bias signal and a control signal to the high-frequency package, a waveguide plate, and the like. However, in order to satisfy the above EMI standard, conventionally, the entire radar module is often covered with a metal cover.

JP 2010-278152 A

  However, in the method of forming a vent hole in the solder for joining the substrate and the lid, the solder fillet cannot be formed into an appropriate shape due to variations in the amount of solder applied, resulting in an increase in the size of the vent hole. there were. For this reason, conventionally, the amount of solder applied is strictly controlled so that the vent hole does not become large. However, due to manufacturing variations, there are cases where the width of the vent hole inevitably increases. If the size of the vent hole is larger than a predetermined value, a high-frequency signal inside the high-frequency package leaks to the outside, and there is a problem that EMI characteristics deteriorate and system noise increases.

  The present invention has been made in view of the above, and an object thereof is to obtain a high-frequency package in which leakage of a high-frequency signal from a vent hole is reduced.

  In order to solve the above-described problems and achieve the object, the present invention surrounds a multilayer substrate in which a plurality of dielectric substrates are stacked, a semiconductor device mounted on the multilayer substrate, and a mounting region of the semiconductor device in a substantially annular shape. A metal lid that is bonded to the multilayer substrate and forms a cavity between the multilayer substrate, a solder layer that joins the multilayer substrate and the metal lid, and the multilayer substrate and the metal lid due to the disconnection of the solder layer. Is formed in the multilayer substrate with a vent hole communicating between the inside and outside of the cavity and a length that is a natural number times approximately half of the effective wavelength in the substrate of the signal wave output from the semiconductor device. And a suppression waveguide having an opening exposed across the ventilation hole at the joint with the metal lid and having a short-circuited tip.

  According to the present invention, even when the width of the vent hole is widened, there is an effect that leakage of high-frequency signals from the vent hole can be suppressed.

FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a high-frequency package according to the present invention. FIG. 2 is a top view of the conductor pattern of the vent hole portion. 3 is a cross-sectional view taken along the line III-III in FIG.

  Embodiments of a high-frequency package according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a high-frequency package according to the present invention, and shows a vent hole portion. FIG. 2 is a top view of the conductor pattern of the vent hole portion. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1 and shows the vent hole portion from a lateral viewpoint.

  A multi-layer substrate 1 configured by laminating a plurality of dielectric substrates and having a semiconductor device mounted thereon is provided with a grounded conductor pattern 2, and the conductor pattern 2 and the metal lid 3 are joined via a solder 4. Has been. The metal lid 3 is fixed to the multilayer substrate 1 with the solder 4 via the conductor pattern 2, so that a cavity for housing a semiconductor device is formed between the metal lid 3 and the multilayer substrate 1. The conductor pattern 2 surrounds the mounting area of the semiconductor device in a substantially annular shape, and has one portion without a conductor, thereby forming a vent hole 5. The width of the vent hole 5 is sufficiently narrower than λ / 2, and leakage of high frequency signals through the vent hole 5 is prevented. Note that “λ” represents the wavelength at the center frequency f0 of a high-frequency signal (such as a signal output from a semiconductor device mounted on the multilayer substrate 1) to be leaked.

  The multilayer substrate 1 includes a suppression waveguide constituted by ground vias 7a and 7b, an inner layer ground conductor 1a inside the multilayer substrate 1, and a dielectric filled therein. The suppression waveguide opening 6 is provided so as to straddle the vent hole 5 in the conductor pattern 2, which is a joint region between the multilayer substrate 1 and the metal lid 3. That is, the conductor pattern 2 is provided with a portion where no conductor exists because of the waveguide opening 6 of the suppression waveguide. The width of the suppression waveguide opening 6 is λ / 2 or more, and is a waveguide for a high-frequency signal to be prevented from leaking.

  In the suppression waveguide, the distance from the waveguide opening 6 to the ground via 7b at the back end of the waveguide is λ / 2, and the suppression waveguide opening 6 is short-circuited to vent. The leakage amount of the high frequency signal passing through the hole 5 is reduced. That is, the suppression waveguide becomes a short stub by branching inside the vent hole 5, and the length of the suppression waveguide is λ / 2, so that the suppression at the waveguide opening 6 is suppressed. The input impedance of the waveguide for use is “0”. Therefore, a part of the high-frequency signal that passes through the vent hole 5 and leaks to the outside is reflected by the portion of the waveguide opening 6 that is a branch point and returns to the package. In this way, the suppression waveguide functions as a BEF (Band Elimination Filter) and prevents electromagnetic waves in a band including the frequency f0 from passing through the vent hole 5.

  As described above, the conductor pattern 2 on which the metal lid 3 is mounted is provided with the waveguide opening 6 for suppressing leakage to the outside, and the λ / 2 length is suppressed from the waveguide opening to the inside of the circuit board 1. A waveguide is formed. By providing this configuration, a high-frequency signal leaking through the vent hole 5 becomes a short circuit point in the waveguide opening 6 and the amount of leakage to the outside is reduced. Therefore, even when the amount of the solder 4 is reduced due to manufacturing variations and the width of the vent hole 5 is widened, the high-frequency signal hardly leaks out of the cavity. Thereby, the product yield of a high frequency package can be improved.

  In the manufacturing process of the multilayer substrate 1, since the ground vias 7a and 7b and the inner layer ground conductor 1a can be formed, secondary assembly work is unnecessary, and the manufacturing process can be simplified and the cost of the apparatus can be reduced.

  The suppression waveguide is composed of a suppression waveguide opening 6, an inner layer ground conductor 1 a inside the multilayer substrate 1, and ground vias 7 a and 7 b, and is bent in the plane direction of the multilayer substrate 1 in the middle. Therefore, even the multilayer substrate 1 having a thickness less than λ / 2 can be formed. That is, the multilayer substrate 1 can be thinned.

  Although the case where the distance from the waveguide opening 6 to the ground via 7b is λ / 2 is taken as an example here, the same effect can be obtained even when the distance is an integral multiple of λ / 2. Further, here, the configuration in which the suppression waveguide is bent in the layer direction of the multilayer substrate 1 has been described as an example, but when the multilayer substrate 1 is thick, the suppression waveguide is not bent and the stacking direction is It may be extended to In this case, the end portion of the suppression waveguide may be a short-circuit end by the inner layer ground conductor.

DESCRIPTION OF SYMBOLS 1 Multilayer substrate 1a Inner-layer grounding conductor 2 Conductor pattern 3 Metal lid 4 Solder 5 Vent hole 6 Waveguide opening 7a, 7b Ground via

Claims (2)

A multilayer substrate in which a plurality of dielectric substrates are laminated;
A semiconductor device mounted on the multilayer substrate;
A metal lid that is bonded to the multilayer substrate so as to surround the mounting region of the semiconductor device in a substantially annular shape and forms a cavity between the multilayer substrate;
A solder layer for joining the multilayer substrate and the metal lid;
A vent hole formed between the multilayer substrate and the metal lid by disconnecting the solder layer, and communicating between the inside and outside of the cavity;
A signal wave output from the semiconductor device is formed in the multilayer substrate having a length that is a natural number multiple of approximately ½ of the effective wavelength in the substrate, and an opening is formed at the junction with the metal lid. A suppression waveguide that is exposed across the hole and whose tip is short-circuited;
A high-frequency package comprising:   2. The suppression waveguide includes an inner layer ground conductor, a plurality of ground vias, and a dielectric filled in the inner layer ground conductor and the plurality of ground vias. High frequency package.

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