JPH10335777A - Component mounting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit bonding materials from being one-sided quantitatively on one end side of each component electrode and to prevent the generation of a tombstone phenomenon, by a method wherein steps forming a constriction in the middle of the package are provided on the boundaries between the electrodes of a chip component to expose the surfaces of the electrodes expose, and at the same time of the connection of the component with a substrate, the bonding materials are made to spread on the steps to adhere to the exposed surfaces of the steps. SOLUTION: There are such steps G as a packaging 1b constricts in the middle between electrodes 1a on the boundaries between the electrodes 1a of a chip component 1 and the packaging 1b, and the surfaces of the steps are covered with one part of each electrode 1a. Electrode lands 2a to correspond to the electrodes 1a are provided on the upper surface of a substrate 2. When the chip component 1 is mounted to the substrate 2, creamy solders 3 are prepared on the substrate electrodes 2a, the component electrodes 1a are aligned with the substrate electrodes 2a, and thereafter, the solders 3 are molten by heating and are cured to connect electrically the electrodes 1a with the electrodes 2a. The solders 3 molten by heating spread also on the steps 9 to adhere to the exposed surfaces of the steps of the electrodes 1a. Moreover, the molten solders 3 spread on both of the end surface side of each electrode 1a and the side of the packaging 1b and are never one-sided only on the end surface side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a component mounting structure in which electrodes of a chip component are connected to electrodes of a substrate via a bonding material such as solder.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional component mounting structure of this type, in which 101 is a chip component, 101a is an electrode of the chip component 101, 101a is an exterior of the chip component 101, 102 is a substrate, and 102a is a substrate. The electrodes (lands) 103 on the substrate 102 are solder (Sn-Pb based alloy).

As shown in FIG. 8, a chip component 101 has a substantially prismatic shape as a whole, and both ends in the longitudinal direction are electrodes 10.
1a, and a portion between the electrodes is covered with an exterior 101b made of resin, glass, or the like. By the way, chip component 10
Reference numeral 1 denotes a chip resistor, a chip inductor, a chip capacitor, a chip jumper, a composite circuit component, and the like, and an exterior 101b covers a circuit conductor inside the exterior.

When mounting the chip component 101 on the substrate 102, the cream solder 10 is placed on the substrate electrode 102a.
3 is prepared, and the component electrode 10 is prepared.
The chip component 101 is mounted on the substrate 102 by aligning the substrate electrode 1a with the substrate electrode 102a. After the components are mounted, the cream solder 103 is heated and melted, and the molten solder 103 is hardened to electrically connect the component electrodes 101a and the board electrodes 102a. As can be seen from FIG. 7, the solder 103 that has been heated and melted goes around and adheres to the end face of each component electrode 101a and two side faces adjacent to the end face before curing.

[0005]

In the above-described conventional component mounting structure, since the amount of the solder 103 is biased toward the end face of each component electrode 101a, the balance between the solder curing speed and the amount of solder between the component electrodes 101a is reduced. Even if it is slightly collapsed, a force for raising the chip component 101 in the process of connecting the components is exerted, and a so-called chip standing phenomenon may occur to cause a connection failure.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a component mounting structure capable of preventing a chip standing phenomenon and making a good connection.

[0007]

In order to achieve the above object, according to the present invention, an electrode of a chip component whose exterior is exposed adjacent to an electrode is made of a bonding material such as solder. In the component mounting structure connected to the electrode of the substrate via
A step is provided at the boundary between the electrode of the chip component and the outer package so that the outer package falls inside to expose the electrode surface to the step, and when connecting the component, the joining material is wrapped around the step to connect the joining material to the step of the component electrode. Its main feature is that it is attached to the exposed surface.

According to the present invention, a step is provided at the boundary between the electrode of the chip component and the package so that the package falls down inside, the electrode surface is exposed to the step, and the joining material is wrapped around the step when the component is connected. Since the bonding material is adhered to the step-exposed surface of the component electrode, it is possible to prevent the bonding material from being quantitatively biased toward one end of the component electrode, thereby preventing a chip standing phenomenon caused by the bias. Can be.

[0009]

1 and 2 show a component mounting structure according to the present invention, in which 1 is a chip component, 2 is a substrate, and 3 is a solder (Sn-Pb alloy).

As shown in FIGS. 3 (a) and 3 (b), the chip part 1 has an external shape having a smaller square pillar portion between a pair of square pillar portions. The rectangular prism portions on both sides in the longitudinal direction are covered with the electrode 1a, the rectangular prism portion at the center in the longitudinal direction is covered with the exterior 1b, and the pair of electrodes 1a and the exterior 1b are exposed adjacently. In addition, both electrodes 1a
And a conductor film 1c for a circuit exists inside the exterior 1b,
The conductor film 1c is formed on the surface of the insulating element 1d having a shape similar to the external shape.

Incidentally, in the structure of the chip component 1,
A chip resistor can be formed by forming the conductor film 1c from a resistive material and trimming the central portion as necessary, and forming the conductive film 1c from a low-resistance material and forming a spiral groove in the central portion. Is formed, a chip inductor having a coil of a predetermined number of turns can be formed, and a chip jumper can be formed by forming the conductor film 1c from a low-resistance material.

Further, each electrode 1a of the chip component 1 and the exterior 1
a step G at the boundary with the outer surface 1b such that the exterior 1b falls inside.
The step surface is covered by a part of each electrode 1a. Further, the corners and ridges of each electrode 1a are provided with roundness, and the radius R1 of the corners and ridges adjacent to the step G has a radius of curvature of 10 to 70 μm, preferably 10 to 30 μm. It is in. Similarly, the corner portion and the ridge line portion adjacent to the end face are also provided with a radius of curvature R2 having a radius of curvature, preferably a radius of curvature larger than the above.

On the other hand, a rectangular or circular electrode (land) corresponding to the electrode 1a of the chip component 1 is provided on the upper surface of the substrate 2.
2a is provided. Length L of the substrate electrode 2a
1 is larger than the length L2 of the component electrode 1a, and in the mounted state, the component electrode 1a is located at or near the center in the longitudinal direction of the substrate electrode 2a. Further, the length L3 of the portion of the substrate electrode 2a closer to the exterior than the boundary between the component electrode 1a and the exterior 1b matches or approximates the height t1 of the step-exposed surface of the component electrode 1a.

When mounting the chip component 1 on the substrate 2, a substrate 2 in which cream solder 3 is pre-coated on the substrate electrode 2a is prepared, and the component electrode 1a and the substrate electrode 2a are aligned and the chip component 1 is mounted. 2 mounted on. After the components are mounted, the cream solder 3 is heated and melted, and the molten solder 3 is hardened to electrically connect the component electrodes 1a and the board electrodes 2a.

Since a step G is provided at the boundary between the electrode 1a and the package 1b of the chip component 1 so that the package 1b falls inside and the electrode surface is exposed to the step G, the solder 3 melted by heating is Before curing, the adhesive wraps around and adheres to the end face of each component electrode 1a and the two side surfaces adjacent thereto, and also wraps around the step G and attaches to the step exposed surface of the component electrode 1a.

In other words, by circulating the molten solder 3 on both the end face side and the exterior side of each component electrode 101a, it is possible to suppress the quantity of the solder 3 from being unevenly distributed only on the end face side,
Even if the balance between the solder hardening speed and the amount of solder between the component electrodes 1a is slightly distorted, it is possible to prevent the chip component 101 in the middle of component connection from exerting a force for starting up the component, thereby making it difficult for the chip standing phenomenon to occur. it can.

Further, the roundness R1 is provided at the corners and ridges of each component electrode 1a adjacent to the step G, so that the molten solder 3 can smoothly flow into the step exposed surface of the component electrode 1a to expose the step. It is possible to increase the solder attachment area to the surface.

Further, the length L1 of the substrate electrode 2a is made larger than the length L2 of the component electrode 1a.
a is located at or near the center in the longitudinal direction of the substrate electrode 2a, so that the molten solder 3 wraps around the end face side and the exterior side of each component electrode 101a effectively to reduce the chip standing phenomenon. It can be reliably prevented.

Further, the height t1 of the step-exposed surface of the component electrode 1a is equal to or approximated to the length L3 of the portion of the substrate electrode 2a closer to the exterior than the boundary between the component electrode 1a and the exterior 1b. The connection strength can be increased by optimizing the shape of the solder 3 attached to the step exposed surface of the component electrode 1a.

FIG. 4 shows an example of a procedure for manufacturing the insulating element 1d used in the chip component 1, that is, the insulating element 1d having a smaller square pillar portion between a pair of square pillar portions. . In the drawings, a single-piece example is shown for convenience, but the same processing is actually performed on a multi-piece material substrate.

In preparing the insulating element, first, FIG.
A material plate Z having a predetermined thickness made of alumina or the like as shown in FIG. Next, as shown in FIG. 1B, two rectangular through-holes Za having a predetermined width and length are formed in parallel at predetermined positions of the material plate Z. Next, as shown in FIG.
To form a groove Zb having the same width as. Next, as shown in FIG. 3D, the material plate Z after the through holes Za and the grooves Zb are formed.
Is cut along a line CL passing through the center in the width direction of each substrate through-hole Za. As described above, the unit element Z1 as shown in FIG. 9E is completed. If the unit element Z1 is barrel-polished and rounded at corners and ridges, the insulating element 1d used in the chip component 1 is obtained.

FIGS. 5A and 5B show a chip component 11 capable of constructing a mounting structure similar to that of the above-mentioned chip component 1. FIG.

The chip component 11 has an external shape having a smaller cylindrical portion between a pair of square pillar portions. The quadrangular prism portions on both sides in the longitudinal direction are covered with the electrode 11a, the cylindrical portion at the center in the longitudinal direction is covered with the exterior 11b, and the pair of electrodes 11a and the exterior 11b are exposed adjacent to each other. Further, a conductor film 11c for a circuit exists inside the two electrodes 11a and the exterior 11b.
Is formed on the surface of the insulating element 11d having a shape similar to the external shape.

Incidentally, in the structure of the chip component 11, similarly to the above-described chip component 1, a chip resistor can be formed by forming the conductor film 11c from a resistance material and trimming the central portion as necessary. Can,
Further, by forming the conductor film 11c from a low-resistance material and forming a spiral groove in the center thereof, a chip inductor having a coil having a predetermined number of turns can be formed. Further, the conductor film 11c is formed from a low-resistance material. By doing so, a chip jumper can be configured.

There is a step G at the boundary between each electrode 11a of the chip component 1 and the exterior 11b such that the exterior 11b falls inside, and the step surface is covered by a part of each electrode 11a. Furthermore, the corners and ridges of each electrode 1a are provided with roundness, and the corners and ridges adjacent to the step G have a radius of curvature of 10 to 70 μm,
Preferably it is in the range of 10 to 30 μm. Similarly, the corner portion and the ridge line portion adjacent to the end face are similarly provided with a radius of curvature, preferably a roundness having a larger radius of curvature than the above.

In the chip components 1 and 11 described above, the exteriors 1b and 11b have a prismatic or columnar outer shape. However, as shown in FIG. A similar step G can be provided at the boundary between the exterior 1b 'and the component electrode 1. Further, in the above-described embodiment, an example in which solder is used as a bonding material is exemplified. However, components may be connected using a bonding material other than solder, for example, a thermosetting conductive resin or the like.

[0027]

As described in detail above, according to the present invention,
It is possible to prevent the bonding material from being quantitatively biased only on one end side of the component electrode, prevent a chip standing phenomenon caused by the bias, and perform component connection satisfactorily.

[Brief description of the drawings]

FIG. 1 is a diagram showing a component mounting structure according to the present invention.

FIG. 2 is an enlarged view of a main part of the component mounting structure shown in FIG. 1;

FIG. 3 is a perspective view of the chip component shown in FIG. 1 and its bb line;
Line cross section

FIG. 4 is a diagram showing a procedure for producing an insulating element used in the chip component shown in FIG. 1;

FIG. 5 is a perspective view of a chip component showing another example and its bb line.
Line cross section

FIG. 6 is a side view of a chip component showing another example.

FIG. 7 is a diagram showing a conventional component mounting structure.

FIG. 8 is a perspective view of the chip component shown in FIG. 7;

[Explanation of symbols]

1: chip parts, 1a: electrodes, 1b, 1b '... exterior, G
... steps, 2 ... substrates, 2a ... electrodes, 3 ... solder, 11 ... chip components, 11a ... electrodes, 11b ... exterior.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Tomio Higashi, 1197 Shimada, Inami-cho, Hidaka-gun, Wakayama Prefecture Inside Chuki Seiki Co., Ltd. (72) Inventor Ikuo Kakiuchi 1197-1, Shimada, Inami-cho, Hidaka-gun, Wakayama Prefecture Chuki Seiki Inside (72) Inventor Manabu Teraoka 1197 Shimada, Inami-cho, Hidaka-gun, Wakayama Prefecture Chuki Seiki Co., Ltd.

Claims (4)

[Claims] In a component mounting structure in which an electrode of a chip component whose electrode and exterior are exposed adjacent to each other is connected to an electrode of a substrate via a bonding material such as solder, the exterior is provided at a boundary between the electrode of the chip component and the exterior. Is provided so that the electrode surface is exposed at the step, and a joining material is wrapped around the step to attach the joining material to the step-exposed surface of the component electrode at the time of component connection. Component mounting structure. 2. The component mounting structure according to claim 1, wherein at least corners and ridges of the component electrode adjacent to the step are rounded. 3. The device according to claim 1, wherein the length of the substrate electrode is greater than the length of the component electrode, and the component electrode is located at or near the center in the length direction of the substrate electrode. 3. The component mounting structure according to 1 or 2. 4. The height dimension of the step-exposed surface of the component electrode is equal to or approximated to the length dimension of the exterior side portion of the board electrode relative to the boundary between the component electrode and the exterior. The described component mounting structure.