JP2002135027A - Manufacturing method of chip-type antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for inhibiting the resonance frequency of a chip-type antenna. SOLUTION: In the chip-type antenna where a plurality of electrodes such as radiating, grounding, and power-feeding electrodes are installed in an insulating base material, the outer enclosure of the electrodes is machined and finished by a mechanical or physical/chemical method. The separation distance between the electrodes or the position relationship is adjusted, thus drastically restraining the variation in a resonance frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an antenna element, and more particularly to an improvement in a method for finishing an electrode or the like provided on an insulating substrate.

[0002]

2. Description of the Related Art A chip type antenna is mainly used for a cellular phone or the like. Since this antenna is configured to be surface-mountable, it can be directly assembled with other components on a mounting circuit board, and the antenna device can be manufactured compactly. FIG. 9 is a perspective view of a chip antenna filed by the present inventors in Japanese Patent Application No. 2000-113686. This antenna has a configuration in which a substantially trapezoidal radiating electrode 13 is provided at the center of the main surface of an insulating base 11, and ground electrodes 15, 17 and a feeding electrode 12 are provided on both sides as shown in the figure. The radiation electrode 13 is connected to the ground electrodes 15, 1 on both sides.
7, but has no ground electrode on the opposite main surface facing the radiation electrode 13, so that the ground electrode 1
The shielding on the side surface by 5 and 17 is effective, and a stable antenna operation can be obtained.

[0003]

Generally, a radiation electrode and the like of an antenna element are formed on an insulating substrate by a screen printing method. As is well known, the screen printing method is a method in which an electrode pattern of a conductive paste is printed on a base using a screen, and an electrode is formed through a heating and firing process. Manufacturing method. According to this method, it is difficult to arrange and form the electrode pattern with high accuracy due to thermal expansion and contraction or mechanical expansion of the screen itself and instability of wettability between the conductive paste and the substrate. An error in the shape and size of the electrode pattern has been recognized as a cause of the variation in the resonance frequency, but in a conventional mobile phone, such an error is within the allowable range of the specification and has been used without any practical problem.

[0004] However, it has already been announced that in the field of portable radio equipment, the trend toward higher frequencies has progressed rapidly, and a shift from 800 MHz to a 5 GHz band to which no frequency is currently assigned has been performed. For example, in Bluetooth, 2.4-2.
A frequency band of 5 GHz is allocated. Also, the bandwidth for a Bluetooth antenna is 100 MHz.
It is said that z or more is required.

Prior art antennas have a bandwidth of 10
Although having a little over 0 MHz, the center frequency at resonance 2.45G
There is a large variation of ± 30 MHz with respect to Hz, and it is necessary to take measures against this. As the center frequency is closer to the lower limit or the upper limit, there is a case where the target frequency deviates from the target specification described above. In order to avoid this, an improvement of the screen printing method can be considered, but it has a serious problem in terms of time and cost, and is not a drastic measure. Therefore, adding a finishing step after forming the electrode pattern is one of the realistic options. Naturally, this finishing method must satisfy mass production.

As an electrode processing method of a chip type antenna,
Electrode trimming is known. FIG. 10 is a schematic diagram of a radiation electrode that has been subjected to a trimming process. In the figure, a trimming portion is a concave portion 29 between the radiation electrode 13 and the ground electrode 15.
It is. When the deuter 23 or the like is used, the insulating substrate 1
A part of 1 is removed together with the electrode, resulting in a recess 29 having an irregular appearance as shown. Meanwhile, trimming the head of the radiation electrode 13, the capacitance C _G between the radiation electrode and the ground electrode indicated by the equivalent circuit of FIG. 11, the effectively altering. When _CG is finely adjusted, the resonance frequency of the resonance circuit composed of Lr slightly changes. However, the productivity of the recess 29 is low because it is manually worked.
When the depth or outer shape of the antenna itself is not constant, the gain or the bandwidth characteristic is slightly changed, and there is a problem that the antenna characteristic is not constant.

[0007] An electrode trimming method other than that described above is shown in FIGS. First, FIG.
This is a method described in Japanese Patent Application Laid-Open No. 0-256825, in which impedance matching is performed simultaneously with adjustment of the resonance frequency. Notch 4 in ground electrode 15 and radiation electrode 13
9-1 and 49-2 are provided to adjust the resonance frequency. This is the same method as the method shown in FIG. However, the notch 49-3 is provided for impedance matching and can be said to be a versatile method. In the following drawings and the like, the same or equivalent parts are denoted by the same symbols,
I want to be consistent.

Further, the trimming of the electrodes shown in FIG. 13 is a method of expanding the frequency band, and two notches 53-1 and 5-5 are formed at the inner corners of the loop-shaped radiating conductor 51.
3-2 is a method of changing the current distribution in the loop-shaped radiation conductor 51. Japanese Patent Application Laid-Open No. 10-274839 discloses the detailed operation principle.

FIG. 14 shows a special case in which an electrode dedicated to trimming is provided. This is disclosed in JP-A-10-2478.
No. 08 is a method of forming a spiral conductor 61 in the dielectric substrate 11 and then separately disposing a trimming-dedicated electrode 63 electrically connected to the conductor 61 on the upper surface of the dielectric substrate 11. Trimming electrode 63 as necessary
It is disclosed that the resonance frequency is adjusted by removing a part of the area and changing its area. As described above, the conventional method mentioned above has another problem in that since the electrode is manually trimmed for each antenna element, mass productivity is poor and it cannot be manufactured at low cost.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides a manufacturing method capable of greatly reducing the variation of the resonance frequency of an antenna and having excellent mass productivity. Things. Hereinafter, the essence of the invention will be described in detail for each claim.

First, the first aspect of the present invention relates to finishing of an outer electrode portion such as a radiation electrode, a ground electrode, or a feed electrode of an antenna, and attempts to finish an electrode pattern to a desired shape and size. Things. Conventionally,
The only processing method performed on the outer electrode part was trimming. In the present invention, unlike the case of trimming, the outer shape of the electrode after processing does not have irregularities and maintains the electrode shape that should be originally possessed. Therefore, there is no significant change in the electrode shape before and after the processing, and only a change can be seen on the insulating substrate side. However, it is not necessary to process the entire electrode outer shell, and selection and processing are naturally performed according to the purpose.

In practicing the present invention, a process of arranging and forming an electrode pattern on an insulating substrate precedes, but it is necessary to manufacture the electrode pattern to an extent that takes into account the screen error. If there is no processing allowance in the formed electrode pattern, the effects of the invention cannot be sufficiently enjoyed.
However, as described above in the strict sense of the present invention, this constraint can be relaxed to a considerable extent when applying the present invention to control bandwidth. This will be mentioned in a later claim.

Another object of the present invention is to adjust a mutual positional relationship between a plurality of electrodes. In the first aspect, a processing method for each electrode itself is used, but the present invention adjusts a relative position between the electrodes. This is because the relative position of each electrode has a significant influence on the antenna characteristics, and is a key to be able to manufacture a higher-performance antenna overall. Further, it is considered that the relative positional error between the electrodes does not originally occur in the printing misalignment of the electrodes, but there is a case where the adjustment is necessary when viewed individually, which is included in the embodiment of the present invention.

According to a third aspect of the present invention, in the above-described electrode arrangement, a radiation electrode and a ground electrode having the greatest influence on the resonance frequency are defined. As apparent from the equivalent circuit diagram shown in FIG. 11, the capacitance C _G to form between the radiation electrode and the ground electrode is to determine the resonant frequency, less variation C
To obtain _G , it is most effective to precisely define the separation distance between the radiation electrode and the ground electrode. However, since both electrodes need to be considered as three-dimensional rather than two-dimensional arrangement, it goes without saying that the above can be extended not only to the separation distance but also to the arrangement relation. The configuration of the radiation electrode and the ground electrode is shown in FIG.
000-113686 can be targeted.

According to a fourth aspect of the present invention, there is provided a method of performing the above-described processing on a mother substrate at a time, and taking into account mass productivity. The method of simultaneously forming a large number of elements on a wide substrate, performing batch processing, and then dicing into chips is a normal manufacturing method for the production of electronic components such as LSIs. There are no references disclosing the technology. Unlike the conventional trimming that targets the local part of the electrode, the present invention is intended to process the entire electrode configuration, so that processing on the mother substrate is a necessary condition that must first be satisfied. is there. In the prior art, there is no idea of processing the outer shell after forming the radiation electrode, and a method of trimming a part of the electrode is sufficient. Another reason is that a high-frequency antenna of several GHz band is not required.

As a means for processing the electrodes of the chip antenna on the substrate, a method using a rotary cutter, sand blast, laser irradiation, or the like, or application of a lithography technique can be used. In the former method, the substrate material is also removed together with the electrode material. However, the latter method mainly uses a reaction to the electrode material, so that the surface of the processed substrate is different. However, in any of the methods, the elements are arranged on the mother substrate in consideration of workability and workability. For example, an arrangement in which one pass of the cutter is possible by a mechanical method is used. Also, with the method using a resist mask,
It is necessary to keep a sufficient distance between the elements.

A fifth aspect of the present invention is a method in which the machining of the electrodes also serves to adjust the resonance frequency at the same time. If the antenna element to be processed is aligned on the substrate and the wiring for measurement is provided, the characteristic inspection can be performed simultaneously with the processing. In the step of forming chips by dicing, the above-mentioned lead wires for measurement, terminals for measurement, and the like are not removed and remain. Next, embodiments of the invention will be described in detail.

[0018]

FIG. 1 is a perspective view of a chip antenna according to the present invention. This is an embodiment for the radiation electrode 13, the ground electrodes 15, 17 and the feed electrode 12 as shown. The appearance of the antenna surface is significantly different from that of the conventional antenna. That is, the processing method according to the present invention includes removing unnecessary electrode patterns together with the base material using mechanical or physicochemical processing means. As a result, unnecessary electrode surroundings are removed and lowered, Conversely, the required electrode pattern remains in an island shape. The processing means will be described in detail in the embodiments described later, but a method using a mechanical processing device such as a rotary cutter, a physicochemical method such as lithography, plasma etching, chemical etching, and sand blast is effective. However, it is not necessary to process all the electrodes as shown in the embodiment, and it goes without saying that selection can be made as needed.

The above means can sufficiently secure an accuracy of about μm from the processing principle, and can improve the accuracy by one digit or more compared to the case of screen printing. Further, the removal amount from the insulating base, that is, D1, D2, etc. shown in the figure is preferably about several μm to mm, but may be as close to zero as possible. On the other hand, since D1, D2, and the like affect the bandwidth characteristics, it is important to appropriately select the values in consideration of the target characteristics. In this embodiment, the radiation electrode 13 and the ground electrode 15
And the gap Gd is determined as designed, and the variation width of the resonance frequency can be reduced to half or less of the conventional value.

FIGS. 2 and 3 show the relationship between the removal amount of the dielectric substrate and the bandwidth. First, FIG. 2 shows a bandwidth BW characteristic with respect to a depth D of a concave portion such as a groove. A concave portion such as a groove is a portion facing the radiation electrode 13 and the ground electrode in FIG. 1 and has a depth D1 at a location indicated by Gd in the figure, but is denoted by D for generality. As shown in FIG.
W also spreads, BW is about 3 times 7% around D = 0.6mm
To expand. On the other hand, FIG. 3 shows the width Gd 'of the concave portion such as the groove versus the BW characteristic. BW is almost proportional to Gd ', and it can be seen that Gd' has a greater effect on BW than D in comparison with the case of FIG. From the above results, the bandwidth BW can be controlled by appropriately combining D or Gd '.

Further, it is conceivable that oxidative corrosion of the cut surface of the electrode progresses depending on the use environment. As a countermeasure, a coating can be applied to the electrode part after implementation of the present invention. 400 ~ 500 glass etc. as coating
Although it is possible to apply a material which is baked at a temperature of ° C. or a resin film is treated at a temperature of about 200 ° C., the material is not limited to the above-mentioned material as long as it is a material which delays the corrosion of the electrode.

FIG. 4 shows an implementation concept in the case where a large number of chip-type antennas are collectively processed. A large number of chip antennas 10 are arranged on a mother substrate 80. After completing the necessary processing, the sheet is cut in the horizontal direction to obtain a plate piece 82. Further, a chip-shaped antenna 10 is obtained by cutting a predetermined position after forming an electrode on the cut surface. In this embodiment, the radiation electrode 13
A method of inserting a groove 19 between the radiation electrode 13 and the ground electrode 15 in order to adjust the separation distance Gd between the radiation electrode 13 and the ground electrode 15 with high accuracy will be described. For example, as a method for providing the groove 19, a mechanical device having a rotary cutter 21 as shown in FIG. 5 is used. At the time of machining the groove 19, the cutter enters in the vertical direction shown in FIG. Since the width of the rotary cutter 21 is selected to be equal to Gd, it is easy to machine the groove 19 with a width accuracy of several μm. Naturally, the gap between the radiation electrode 13 and the ground electrode 15 before processing is formed narrower than Gd.

FIG. 6 shows a method using a mask pattern film. A necessary portion of the electrode 65 is covered with a mask film 67, and high-speed charged particles or an etchant is applied to remove a portion not covered with the mask. Generally, PV
D, CVD, etc. This is a lithography technique used in the manufacture of LSIs and the like, and can easily obtain a precision of the order of μm or less and can process a plurality of antennas simultaneously. Therefore, it is most suitable for processing small components such as chip-type antennas. FIG. 7 shows a method using the reverse action of electroplating, in which a portion not covered with the mask film 65 is electrochemically etched.

FIG. 8 shows the concept of a manufacturing method for pursuing mass productivity. In this method, lead lines 86 and 88 and a measuring terminal 84 are formed in a dicing line surrounded by a two-dot chain line, and required electric performance can be checked. By including the step of performing such a measurement after the groove processing, the number of processing steps can be reduced, and a line for automatic measurement can be realized, thereby contributing to significant cost reduction. Further, as compared with the manufacturing method shown in FIG. 4, fine adjustments such as deepening the groove after the measurement can be performed, and there is an advantage that there is no variation in quality and the yield is improved.

[0025]

As is apparent from the above description, the present invention makes it possible to greatly reduce the variation in the resonance frequency of the chip antenna, which has been a problem of the prior art. In addition, since the manufacturing method according to the present invention is excellent in mass productivity, its ripple effect is great.

[Brief description of the drawings]

FIG. 1 is a perspective view of a chip antenna according to an embodiment of the present invention.

FIG. 2 shows the relationship between the depth of a concave portion such as a groove and the bandwidth of the present invention.

FIG. 3 shows the relationship between the width of a concave portion such as a groove and the bandwidth of the present invention.

FIG. 4 is an application example when the present invention is applied to a mother board.

FIG. 5 is a conceptual diagram showing a machining example according to the present invention.

FIG. 6 is a conceptual diagram showing an etching method according to the present invention.

FIG. 7 is a conceptual diagram illustrating an electrical etching method according to the present invention.

FIG. 8 is a concept of an embodiment method showing a measuring and cutting method according to the present invention.

FIG. 9 is a perspective view of an example of an antenna element embodying the present invention.

FIG. 10 is a perspective view of an antenna element trimmed by a conventional method.

FIG. 11 is an equivalent circuit diagram of a chip antenna.

FIG. 12 shows a conventional method of adjusting the resonance frequency and impedance.

FIG. 13 shows a conventional method of adjusting the resonance frequency.

FIG. 14 shows a conventional method using an electrode dedicated to trimming.

[Explanation of symbols]

10: chip antenna, 11: insulating base, 12: feed electrode, 13: radiation electrode, 15, 17: ground electrode, 19:
Groove, 21: cutter, 23: duda, 29: concave, 4
9: Notch, 51: Loop radiation conductor, 53: Notch, 61: Spiral conductor, 63: Trimming dedicated electrode, 6
5: Electrode film, 67: Mask film, 75: Electrolyte, 77: Negative electrode, 80: Mother substrate, 82: Substrate arranged in row, 84: Measurement terminal, 86, 88: Lead wire

Claims (5)

[Claims] 1. A chip antenna comprising a plurality of electrodes, such as a radiation electrode, a ground electrode, and a feed electrode, disposed on an insulating substrate. A method of manufacturing a chip antenna, comprising a finishing step. 2. In a chip antenna in which a plurality of electrodes such as a radiation electrode, a ground electrode, and a power supply electrode are arranged on an insulating base, a required electrode separation distance or a relative positional relationship is obtained after the formation of the electrodes. As described above, the method for manufacturing a chip antenna includes a processing step of finishing the outer contour of the electrode. 3. The method according to claim 2, wherein the electrodes are at least a radiation electrode and a ground electrode. 4. The method of manufacturing a chip antenna according to claim 1, further comprising a step of processing a required electrode outer shell before dicing the chip antenna formed on the motherboard. Method. 5. The method for manufacturing a chip antenna according to claim 1, wherein a resonance frequency and / or a bandwidth is measured during or after processing required electrodes.