WO2015022784A1

WO2015022784A1 - Electronic component and method of manufacturing same

Info

Publication number: WO2015022784A1
Application number: PCT/JP2014/054540
Authority: WO
Inventors: 悟史今村
Original assignee: 株式会社村田製作所
Priority date: 2013-08-13
Filing date: 2014-02-25
Publication date: 2015-02-19
Also published as: TW201506960A

Abstract

An electronic component (1) is provided with: a ceramic base (2) including a first surface and a second surface, such that said second surface, in plan view from a predetermined first direction (T), is enveloped in the first surface and projects from the first surface; and a wire-bonding-use first electrode (3), which is formed upon the second surface and includes at least one metal layer. The first surface of the ceramic base (2) is visible in plan view from the first direction (T). As a result, it is possible for a bonding device to more accurately perform matching.

Description

Electronic component and manufacturing method thereof

The present invention relates to an electronic component including a ceramic substrate and a bonding electrode formed on the ceramic substrate, and a manufacturing method thereof.

Conventionally, as this type of electronic component, for example, there is a thermistor described in Patent Document 1. This thermistor includes a ceramic base having a positive temperature coefficient and an electrode deposited outside the entire upper surface of the ceramic base. After the dicing, the electronic component is bonded to a substrate on which the electronic component is to be mounted using a bonding apparatus. Hereinafter, the operation of the bonding apparatus will be described in more detail.

First, in the bonding apparatus, an image when an electronic component at a predetermined position is viewed from above is registered in advance. After the bottom surface of the electronic component is fixed on the mounting substrate, the bonding apparatus takes an image of the electronic component on the mounting substrate from above, and the mounting position of the electronic component is determined based on whether the captured image matches the registered image. Check if it is off. If there is no misalignment, the bonding apparatus secures one end of the bonding wire to the electrode on the upper surface of the electronic component and the other end to the electrode on the mounting substrate.

JP 2002-305102 A

In the above-described electronic component, electrodes made of a plurality of metal layers are formed over the entire upper surface of the ceramic substrate. Here, gold is used for the uppermost layer of the electrode from the viewpoint of stability and the like. However, due to the spreadability of the metal, the electrode may not have the shape as designed during dicing. Specifically, the top surface shape of the electronic component may change due to the occurrence of burrs (metal residue). Due to such deformation, the bonding apparatus may not perform matching correctly.

Therefore, an object of the present invention is to provide an electronic component that can be more accurately matched by a bonding apparatus and a method for manufacturing the same.

In order to achieve the above object, a first aspect of the present invention is an electronic component that is included in the first surface in a plan view from a first surface and a predetermined first direction, and the first surface. A ceramic substrate including a second surface protruding from the electrode, and a wire bonding electrode formed on the second surface and including at least one metal layer, wherein the first surface of the ceramic substrate includes the first surface, It is visible in a plan view from the first direction.

A second aspect of the present invention is a method for manufacturing an electronic component, comprising: a first step of creating a mother substrate made of ceramic; and a method of forming at least one metal layer on at least one surface of the mother substrate. Two steps and a grid-shaped cut having a predetermined depth with respect to the mother substrate on which the metal layer is formed with a first blade having a predetermined width from a first direction substantially perpendicular to the surface of the mother substrate. A third step of forming, and a second blade having a width narrower than that of the first blade is inserted from the first direction with respect to the grid-like cut formed in the third step, and the mother substrate is all cut. And four steps.

According to each of the above aspects, since the outline when the electronic component is viewed from the first direction is made of ceramic having a smaller extensibility than metal, the deformation of the outline is reduced. As a result, the bonding apparatus can perform pattern matching more accurately.

1 is a perspective view of a finished product of an electronic component 1. FIG. 2 is a top view and a longitudinal sectional view of the electronic component 1. FIG. It is the top view and front view of a ceramic base | substrate shown in FIG. FIG. 1 is a diagram showing a detailed structure of a first electrode and a second electrode.

<Embodiment>
Hereinafter, with reference to each figure, the electronic component which concerns on one Embodiment of this invention, and its manufacturing method are demonstrated in detail.

First, the L axis, W axis, and T axis of several drawings will be described. The T-axis direction indicates the direction from the bottom to the top of the electronic component 1, the L-axis direction indicates the direction from the left to the right of the electronic component 1, and the W-axis direction indicates the direction from the front to the back of the electronic component 1. Further, the T-axis direction, the L-axis direction, and the W-axis direction are examples of the first direction, the second direction, and the third direction, and T, L, and W are given as reference numerals for convenience of the following description.

<Embodiment>
FIG. 1 is a perspective view of a finished product of the electronic component 1. FIG. 2 is a plan view of the electronic component 1 from the first direction T (that is, a top view) and a vertical cross section along the one-dot chain line AA ′ in FIG. FIG. 5 is a longitudinal sectional view seen from the third direction W). 1 and 2, an electronic component 1 is, for example, a PTC thermistor having a positive temperature coefficient, and includes at least a ceramic substrate 2, a first electrode 3 for wire bonding, and a second electrode which is a bottom electrode. 4 is provided.

The base 2 includes a first surface S1, a second surface S2, and a third surface S3 that are substantially orthogonal to the first direction T, as shown in FIG. The surfaces S1 to S3 form a rectangular outline in a plan view from the first direction T (that is, a top view). The surface S3 is the bottom surface of the base 2. The surface S2 is the uppermost surface of the base 2 and protrudes from the surface S1 that is in the middle of both surfaces S2 and S3. In other words, the surface S2 is in the first direction T with respect to the surface S3, and the surface S1 is between both surfaces S2 and S3 with respect to the position in the first direction T.

Further, the surface S2 is included in the surface S1 in a plan view from the first direction T. Here, when the gravity centers of the surfaces S1 and S2 are G1 and G2, it is preferable that the surface S2 is included in the surface S1 in a top view so that the gravity centers G1 and G2 are at the same position on the LW plane. Further, the outlines of the surfaces S1 and S3 overlap each other when viewed from above.

The above surface S2 is connected to the surface S1 by four side surfaces, and the surface S1 is connected to the surface S3 by another four side surfaces.

Referring now to FIG. 2 again. Regarding the surfaces S1 and S3, the dimension along the second direction L (hereinafter referred to as L1) is 290 ± 25 [μm], and the dimension along the third direction W (hereinafter referred to as W1) is also 290 ± 25 [μm]. It is. The L dimension and W dimension (hereinafter referred to as L2 and W2) of the surface S2 are 230 ± 25 [μm]. In addition, the dimension (henceforth T1) along the 1st direction T of the electronic component 1 is 125 +/- 15 [micrometers]. In each of the above dimensions, the design target value is described before ±, and tolerance (allowable error range) is described after ±. The dimensions of the substrate 2 are not limited to the above, and other sizes may be used.

Next, the material of the base 2 will be described. In the present embodiment, the ceramic substrate 2 has a positive temperature characteristic, and is made of, for example, a ceramic material in which a predetermined additive is added to BaTiO ₃ (barium titanate). Here, the additive is a rare earth, typically Sm (samarium). In addition to this, Nd (neodymium), La (lanthanum), or the like can be used as an additive.

The base 2 as described above may have a single-layer structure or a laminate composed of a plurality of ceramic sheets.

The electrode 3 is used for wire bonding as described above, and is joined to the surface S2 so as to cover the entire surface S2. In the present embodiment, as a preferred example, the electrode 3 includes a first metal layer 31, a second metal layer 32, and a third metal layer 33 as shown in FIG. These

metal layers

31, 32, and 33 are laminated from the surface S <b> 2 toward the first direction T in this order of description. Since the metal layer 31 is in direct contact with the base 2, the metal layer 31 contains a metal (for example, zinc (Zn)) that can make ohmic contact with the base 2. The metal layer 32 contains a metal (for example, silver (Ag)) that is cheaper and more easily oxidized than the metal layer 33 as a main component, and the metal layer 33 is a metal that is stable even in a low temperature / high temperature environment (for example, , Gold (Au)).

Here, in order to reduce the height of the electronic component 1, it is necessary to suppress the T dimension of the electrode 3 as much as possible. In addition, the electronic component 1 is generally desired to be low cost. In order to satisfy these two requirements, Ag and Au excellent in spreadability are used for the metal layers 32 and 33 in this embodiment. Moreover, the deterioration of the electrode 3 is suppressed by covering Ag which is easily oxidized with Au.

Here, the thickness of the metal layer 31 is t1, the thickness of the metal layer 32 is t2, and the thickness of the metal layer 33 is t3. The electrode 3 satisfies 0.02 ≦ t1 / t2 ≦ 0.75 and 0.2 ≦ t3 / t2 ≦ 1.0 in order to satisfy the requirements such as the above-described reduction in height, cost, and quality. T2 is preferably 1.0 [μm] or less.

The electrode 4 is a bottom electrode joined to the surface S3 so as to cover the entire surface S3. In the present embodiment, an electrode 4 having a stacked structure similar to that of the electrode 3 is illustrated. The electrode 4 is not limited to this, and may have a structure different from that of the electrode 3.

<< Example of Manufacturing Method of Embodiment >>
The manufacturing method of the electronic component 1 generally includes the following steps (A) to (D).

(A) First, a BaTiO ₃ ceramic powder capable of obtaining desired characteristics is press-molded to a size of, for example, 35 [mm] × 25 [mm], thereby obtaining a molded body. Thereafter, degreasing and firing are performed on the molded body. Thereby, a mother substrate to be the base 2 after completion is obtained. The thickness of the mother substrate is adjusted by lapping or the like so that the T dimension of the finished electronic component 1 becomes 125 ± 15 [μm].

(B) Next, a layer mainly composed of Zn (hereinafter referred to as a Zn layer) is formed on, for example, vapor deposition on both surfaces of the mother substrate so as to obtain an ohmic junction with the ceramic mother substrate. The As a result, a Zn layer to be the first metal layer 31 after completion of the electronic component 1 and a Zn layer to be the lowermost layer of the electrode 4 are formed on the mother substrate.

Next, on both Zn layers, a layer containing Ag as a main component (hereinafter referred to as Ag layer) is formed by vapor deposition, for example. Thereby, an Ag layer to be the second metal layer 32 after completion and an Ag layer to be the second layer of the electrode 4 are formed on the mother substrate.

Next, an Au layer is formed by vapor deposition, for example, on both Zn layers. As a result, an Au layer to be the third metal layer 33 after completion and an Au layer to be the third layer of the electrode 4 are formed on the mother substrate.

(C) Next, the mother substrate obtained in the step (B) is half-cut by a dicer. Specifically, a blade (or a dicing saw) having a relatively wide blade width (for example, about 120 [μm]) is attached to the dicer. The dicer is half-cut using this blade to form a grid-like cut on the side of the mother substrate on which the metal layer to be the electrode 3 is formed. The cut amount (that is, the depth in the direction opposite to the first direction T) is not particularly limited, but is, for example, about 20 [μm]. The cutting pitch is about 230 ± 25 [μm], similar to the L dimension and W dimension of the surface S2.

(D) The mother substrate obtained in step (C) is fully cut by a dicer. Specifically, a blade having a relatively narrow blade width (for example, about 60 [μm]) is attached to the dicer. The dicer uses this blade to cut the mother substrate along the center in the width direction of the grid-like cut formed in the step (C).

The electronic component 1 is completed through the above steps (A) to (D).

《Action ・ Effect》
As described above, according to the electronic component 1, the outline of the second surface S2 is included in the outline of the first surface S1 and protrudes from the first surface S1 when viewed from above. Since the electrode 3 is formed only on the second surface S2 as described above, when viewed from above, the four sides of the electrode 3 are surrounded by a ceramic portion that is less malleable than metal and can be visually recognized. ing. Therefore, when the bonding apparatus photographs the electronic component 1 from above, the deformation amount of the outline of the electronic component 1 in the photographed image is extremely small, and as a result, the bonding apparatus can perform pattern matching more accurately. It becomes.

In addition, as shown in Table 1 below, the present inventor produced three types of electronic components (hereinafter referred to as samples No. 1 to No. 3) having different structures of the electrodes 3. The inventor of the present invention has made these sample nos. 1-No. For comparison with FIG. 3, an electronic component (hereinafter referred to as a conventional product) on which the electrode of Patent Document 1 was formed was produced. As shown in Table 1, sample no. 1, the thickness of the metal layer 31 in the first direction T is 0.15 [μm], the thickness of the metal layer 32 is 0.2 [μm], and the thickness of the metal layer 33 is 0.2 mm. 2 [μm]. Sample No. 2, no. See Table 1 for details of the three electrodes 3.

In addition, the inventor of the present invention has a sample no. 1-No. 3 and the conventional product were evaluated for wire bondability, quality (resistance to deterioration over time), and cost.

There are various bonding strength evaluation methods for the evaluation of wire bonding properties. The present inventor uses a wire bond pull tester manufactured by ROYCE Instruments, Inc. 1-No. 3 and the conventional product were subjected to a wire bond pull test. As a result, sample no. 1-No. There was no problem in either of 3 and the conventional product. In addition, the resistance to deterioration with time was good because the uppermost layer of the electrode was Au. Sample No. 1-No. As for No. 3, since the amount of Au used was small, the cost could be reduced. However, the conventional product was expensive because of the large amount of Au used.

<< Appendix 1 >>
Moreover, in the said embodiment, the electronic component 1 demonstrated as a PTC thermistor. However, not limited to this, the electronic component 1 may be an NTC thermistor having a negative temperature coefficient.

The electronic component and the manufacturing method thereof according to the present invention are suitable for NTC thermistors and PTC thermistors because the bonding apparatus can perform pattern matching more accurately.

DESCRIPTION OF SYMBOLS 1 Electronic component 2 Ceramic base | substrate 3 1st electrode 31 1st metal layer 32 2nd metal layer 33 3rd metal layer 4 2nd electrode T 1st direction L 2nd direction W 3rd direction S1, S2, S3 1st surface, Second side, third side

Claims

A ceramic base including a first surface and a second surface that is included in the first surface and projects from the first surface in a plan view from a predetermined first direction;
An electrode for wire bonding formed on the second surface and including at least one metal layer,
The electronic component, wherein the first surface of the ceramic base is visible in a plan view from the first direction.
The wire bonding electrode is at least one metal layer,
A first metal layer in ohmic contact with the ceramic substrate;
A second metal layer made of a metal that is relatively difficult to oxidize, the second metal layer being the outermost layer;
A third metal layer made of a metal that is relatively easily oxidized, and a third metal layer formed immediately below the second metal layer,
When the thickness of the first metal layer is t1, the thickness of the second metal layer is t2, and the thickness of the third metal layer is t3, t1 / t2 is 0.02 ≦ t1 / t2 ≦ 0. The electronic component according to claim 1, wherein t3 / t2 is 0.2 ≦ t3 / t2 ≦ 1.0, and t2 is 1.0 μm or less.
A first step of creating a mother board made of ceramic;
A second step of forming at least one metal layer on at least one surface of the mother substrate;
A grid-shaped cut having a predetermined depth is formed on the mother substrate on which the metal layer is formed with a first blade having a predetermined width from a first direction substantially perpendicular to the surface of the mother substrate. Process,
A fourth step of cutting all the mother substrate by inserting a second blade having a width smaller than that of the first blade from the first direction with respect to the grid-like cut formed in the third step, Manufacturing method of electronic components.