JP2000261123A - Mounting structure of chip resistor and mounting method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure of a chip resistor which can reduce shearing distortion by increasing solder thickness, and a mounting method of the chip resistor. SOLUTION: In a chip resistor 10, component electrodes 12, 13 are formed on the upper, lower and side surfaces in the right and the left end portions of an alumina substrate 11. On the upper surface of the alumina substrate 11, a resistor 14 is formed between the component electrodes 12, 13. On the upper surface of the alumina substrate 11, a glass thick film 15 is formed on the upper surface and the periphery of the resistor 14. A glass thick film 17 is formed also on the lower surface (back) of the alumina substrate 11 and is arranged in contact with a printed wiring board 1. The component electrodes 12, 13 are bonded to soldering pads 2, 3 of the printed wiring board 1 by using solder 18, 19. The glass thick film 17 acts as a spacer between the chip resistor 10 and the printed wiring board 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip resistor mounting technique, and more particularly, to a technique for extending a thermal cycle fatigue life of a soldered portion of a chip resistor.

[0002]

2. Description of the Related Art Generally, as a method of extending the thermal cycle fatigue life of a surface mount component, a spacer is interposed between a printed wiring board and a surface mount component (leadless component), or the body is processed into a projection shape. Thus, the thickness of the solder is increased and the shear strain is reduced (Japanese Patent Application Laid-Open Nos. 5-110221 and 8-1).
No. 81419).

[0003]

However, under conditions where heat cycles are extremely high, it is necessary to secure a solder thickness of 60 μm or more. In order to form spacers in the existing printed wiring board manufacturing process, silk printing is required. It is necessary to perform multiple printing or thick printing of a solder resist or the like, and there is a problem that the cost is greatly increased due to an increase in the number of steps. Processing the body itself into a protruding shape also causes a problem that the cost of an inexpensive surface mount component (for example, a chip resistor) is significantly increased.

It is an object of the present invention to provide a mounting structure of a chip resistor and a mounting method of the chip resistor which can increase the thickness of the solder and reduce the shear strain with a novel structure.

[0005]

The invention according to claim 1 is characterized in that a chip resistor having a glass thick film formed on both upper and lower surfaces of an insulating substrate is used. According to the mounting structure of the chip resistor, when soldering the electrodes of the chip resistor to the pads of the printed wiring board, one of the glass thick films formed on the upper and lower surfaces of the insulating substrate is used. And a printed wiring board function as a spacer, thereby increasing the thickness of the solder and reducing the shear strain.

According to the chip resistor mounting method of the present invention, the front and back electrodes and the resistor are formed on the insulating substrate which is a constituent material of the chip resistor. Then, the resistor on the surface of the insulating substrate is covered with the thick glass film, and the thick glass film is formed on the back surface of the insulating substrate to form a chip resistor. Further, the chip resistor is arranged on the printed wiring board on which the pads are formed, and the electrodes of the chip resistor and the pads of the printed wiring board are soldered.

When the electrodes of the chip resistor are soldered to the pads of the printed wiring board, the glass thick film provided on the back or the surface functions as a spacer between the chip resistor and the printed wiring board, thereby reducing the solder thickness. Can be increased and shear strain can be reduced.

According to the method for mounting a chip resistor according to the third aspect, the front and back electrodes and the resistor are formed in the chip forming region of the insulating substrate which is a constituent material of the plurality of chip resistors. Then, the resistor on the surface of the insulating substrate is covered with the thick glass film, and the thick glass film is formed in the chip formation region on the back surface of the insulating substrate. Further, the insulating substrate is firstly divided into strips having a plurality of chip formation regions. After that, a side electrode is formed on the strip-shaped insulating substrate. Subsequently, the insulating substrate is secondarily divided into chip resistors divided into respective chips.
Then, the chip resistor is arranged on the printed wiring board on which the pads are formed, and the electrodes of the chip resistor and the pads of the printed wiring board are soldered.

When the electrodes of the chip resistor are soldered to the pads of the printed wiring board, the glass thick film provided on the back or the surface functions as a spacer between the chip resistor and the printed wiring board, thereby reducing the solder thickness. Can be increased and shear strain can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1, 2, and 3 show a mounting structure of the chip resistor of the present embodiment. FIG. 1 is a plan view of the chip resistor 10 and the printed wiring board 1, and FIG. 3 is a longitudinal sectional view taken along line AA of FIG.

As shown in FIG. 3, the resistor 14 disposed on the upper surface of the insulating substrate 11 in the chip resistor 10 is covered with a thick glass film (protective film) 15. Is formed with a display film 16 showing a resistance value. FIG. 2 is a plan view in a state where the glass thick film 15 and the display film 16 are removed.

The details will be described below. As shown in FIG. 3, soldering pads 2 and 3 are formed on the upper surface of the printed wiring board 1, and the soldering pads 2 and 3 form a part of a conductor pattern formed on the upper surface of the printed wiring board 1. The thickness of the solder pads (conductor patterns) 2 and 3 is about 40 μm.

The chip resistor 10, which is a surface mount component,
It has a square shape. Specifically, the alumina substrate 11 as an insulating substrate is composed of high-purity alumina, and has excellent thermal stability and mechanical strength. Component electrodes 12 and 13 are formed on the upper, lower, and side surfaces at the left and right ends of the alumina substrate 11. The component electrodes 12 and 13 are,
13a, lower electrodes 12b and 13b, and side electrodes 12
c, 13c. A resistor 14 is formed between the component electrodes 12 and 13 on the upper surface of the alumina substrate 11. The resistor 14 is made of a carbon film or a metal film.
As an example of the resistor 14, a highly reliable and stable ruthenium oxide-based metal glaze thick film can be given. The resistor 14 has a band shape as shown in FIG. 2, and a groove 14a is formed in a part thereof. The resistance value is adjusted to a predetermined value by the groove 14a.

[0014] As shown in FIGS.
A thick glass film 15 is formed on the upper surface of the resistor 14 and on the periphery thereof. This glass thick film 15
Is a thick film of special glass for protecting the resistor 14, and the thickness of the glass thick film 15 is about 100 μm. On the upper surface of the glass thick film 15, a display film 16 showing a resistance value is provided.
Are formed. That is, as shown in FIG. 1, the resistance value is displayed by a three-digit number.

Further, in this embodiment, as shown in FIG. 3, the lower surface (back surface) of the alumina
7 are formed. The glass thick film 17 is arranged so as to be in contact with the printed wiring board 1. In this state, the component electrodes 12 and 13 and the soldering pads 2 and 3 of the printed wiring board 1 are joined by the solders 18 and 19.

Here, the thickness of the glass thick film 17 is about 100 μm, which is the same as that of the glass thick film 15. Therefore, since the thickness of the soldering pads 2 and 3 is about 40 μm, a solder thickness of 60 μm between the soldering pads 2 and 3 and the component electrodes 12 and 13 can be ensured.

Next, a method of mounting the chip resistor 10 will be described. 4 to 11 show a manufacturing process of the chip resistor 10. First, as shown in FIG. 4A, an alumina substrate (insulating substrate) 30 as a constituent material of a plurality of chip resistors is used.
Prepare Slits (V-grooves) 31 and 32 are vertically and horizontally formed on the surface of the alumina substrate 30 so that division can be easily performed. FIG.
(B) shows the alumina substrate 1 in each chip formation region 30a.
1 shows a cross section of FIG.

As shown in FIGS. 5A and 5B, the electrodes 12a and 13a are provided on the upper surface (front surface) and the electrodes 12b and 13b are provided on the lower surface (back surface) of each chip forming region 30a of the alumina substrate 30. 13b is formed. This electrode 1
2a, 13a, 12b, and 13b are alumina substrates 30
A silver-based thick film having excellent adhesion to (11) and excellent connection to a resistance film is used. Further, as shown in FIG. 5C, the resistor 14 is formed on the upper surface of the chip formation region 30a of the alumina substrate 30.

Subsequently, as shown in FIG. 6A, a groove 14a by a laser is formed in a part of the resistor 14, and the resistance is adjusted (trimmed) to a target value. And FIG.
As shown in (a) and (b), a protective glass thick film 15 is formed on the resistor 14 on the upper surface (front surface) of the alumina substrate 30, and the resistor 14 is covered with the glass thick film 15.
Further, a display film 16 is formed on the upper surface of the protective film 15.

Subsequently, as shown in FIGS. 8A and 8B, a thick glass film 17 is formed in the chip forming region 30a on the lower surface (back surface) of the alumina substrate 30. And 1
As a next dividing step, the alumina substrate 30 is laterally divided along the slits 32 of FIG. 8A. As a result, as shown in FIG. 9A, the alumina substrate 30 is firstly divided into a strip shape having a plurality of chip forming regions 30a.

Further, as shown in FIGS. 9A and 9B, side electrodes (silver-based thick films) 12c and 13c are formed on the side surfaces of the divided strip-shaped alumina substrate 30. Then 2
In the next dividing step, the strip-shaped substrate 30 is divided along the slits 31 as shown in FIGS. 10A and 10B to obtain a resistor alone (chip-shaped chip resistor 10).
That is, as shown in FIGS. 11A and 11B, the alumina substrate 30 is secondarily divided into chip resistors 10 divided into respective chips.

Further, electroplating is performed on the electrode surface to form a nickel layer (middle) and a lead-containing tin layer (outside).
Then, the chip resistor (chip fixed resistor) 10 thus obtained is arranged on the printed wiring board 1 on which the pads 2 and 3 are formed as shown in FIGS. The electrodes 12, 13 of the container 10 and the pads 2, 3 of the printed wiring board 1 are soldered.

The chip resistor 10 is connected to the printed wiring board 1
When soldering, the glass thick film 17 provided on the back surface functions as a spacer between the chip resistor 10 and the printed wiring board 1, thereby increasing the solder thickness and reducing the shear distortion. it can.

When forming the glass thick film 17, as shown in FIG. 7, in the protective film forming step at the time of manufacturing the chip, the glass thick film 15 is formed on the surface (upper surface), and as shown in FIG. The glass thick film 17 is also formed on the back surface. Therefore, the formation of the glass thick film 17 at this time can be easily performed. In the step shown in FIG.
The same thick glass film as that for protecting the resistor is applied to the back surface of the alumina substrate 30, so that the space between the printed wiring board 1 and the printed wiring board 1 can be secured by a simple process of backing the alumina substrate 30 without resetting the positioning or the like. (17) can be formed.

That is, in order to secure the solder thickness of 60 μm or more, in the conventional method of interposing a spacer between the printed wiring board and the chip component or processing the component body into a projection shape, the number of steps is greatly increased. The processing of the projection shape causes a significant increase in cost. However, in the present embodiment, when applying the glass thick film for forming the protective film, it is only necessary to add the glass thick film coating step once. The solder thickness is 60 μm or more, which is simple and convenient and does not significantly increase the cost.

As described above, by forming the glass thick film 17 of the chip resistor 10 also on the back surface of the chip, a solder thickness of 60 μm can be secured at a low cost and the thermal cycle fatigue life can be extended.

As described above, this embodiment has the following features. (A) As shown in FIG. 3, a glass thick film 17 is formed on the back surface of the alumina substrate 11 in addition to the glass thick film 15 for protecting the resistor 14, and the chip resistor 10 for mounting is made of alumina. Glass thick films 15 on the upper and lower surfaces of the substrate 11,
17 was formed. Therefore, the chip resistor 10
When soldering to the printed wiring board 1, the glass thick film 17 provided on the back surface of the alumina substrate 11
It functions as a spacer between the printed wiring board 0 and the printed wiring board 1, whereby the thickness of the solder can be increased and the shear strain can be reduced. (B) As a mounting method, as shown in FIG. 5, front and back electrodes 12a, 13a, 12b, 13b and a resistor 14 are formed on an alumina substrate 11, which is a component of a chip resistor, as shown in FIG. Next, the resistor 14 on the surface of the alumina substrate 11 is covered with a glass thick film 15 and, as shown in FIG. 8, a glass thick film 17 is formed on the back surface of the alumina substrate 11 to form a chip resistor 10. As shown in the figure, on the printed wiring board 1 on which the pads 2 and 3 are formed,
The chip resistor 10 is arranged, and the electrode 1 of the chip resistor 10 is
2 and 13 and the pads 2 and 3 of the printed wiring board 1 were soldered. When the chip resistor 10 is soldered to the printed wiring board 1, the glass thick film 17 provided on the back surface functions as a spacer between the chip resistor 10 and the printed wiring board 1, thereby increasing the solder thickness. The shear strain can be reduced.

In addition to those described above, FIG.
2 may be used. In FIG. 12, a chip resistor 10 with a resistor 14 and a glass thick film 15 facing down is arranged on a printed wiring board 1, and pads 2, 3 and electrodes 12, 13 are soldered. Also in this case, the glass thick film 15 functions as a spacer, so that the solder thickness can be secured. In addition, printed wiring board 1
When mounting the chip resistor 10 on the surface of the chip resistor 10 without considering the front and back of the chip resistor 10, the same thickness of the glass thick films 15 and 17 of the same material is applied to both the front and back. Therefore, there is no variation between the chip resistor 10 mounted face down (FIG. 12) and the chip resistor 10 mounted face up (FIG. 3).

[Brief description of the drawings]

FIG. 1 is a plan view of a chip resistor and a printed wiring board.

FIG. 2 is a plan view of a chip resistor and a printed wiring board.

FIG. 3 is a longitudinal sectional view taken along line AA of FIG. 1;

FIG. 4 is an explanatory diagram for explaining a manufacturing process.

FIG. 5 is an explanatory diagram for explaining a manufacturing process.

FIG. 6 is an explanatory diagram for explaining a manufacturing process.

FIG. 7 is an explanatory diagram for explaining a manufacturing process.

FIG. 8 is an explanatory diagram for explaining a manufacturing process.

FIG. 9 is an explanatory diagram for explaining a manufacturing process.

FIG. 10 is an explanatory diagram for explaining a manufacturing process.

FIG. 11 is an explanatory diagram for explaining a manufacturing process.

FIG. 12 is a cross-sectional view of another example of a chip resistor and a printed wiring board.

[Explanation of symbols]

1: printed wiring board, 2, 3: soldering pad, 10
... chip resistor, 11 ... alumina substrate, 12, 13 ... electrode, 14 ... resistor, 15 ... glass thick film, 17 ... glass thick film, 30 ... alumina electrode.

Claims (3)

[Claims] In a mounting structure of a chip resistor in which electrodes of a chip resistor are soldered on pads of a printed wiring board, a glass thick film is formed on both upper and lower surfaces of an insulating substrate as the chip resistor. A mounting structure of a chip resistor, characterized by using a formed one. 2. A step of forming front and back electrodes and a resistor on an insulating substrate which is a constituent material of a chip resistor; and covering the resistor on a surface of the insulating substrate with a thick glass film. A step of forming a glass thick film on the back surface to form a chip resistor, and disposing the chip resistor on a printed wiring board on which pads are formed, and soldering the electrodes of the chip resistor and the pads of the printed wiring board. A method of mounting a chip resistor, comprising: 3. A step of forming front and rear electrodes and a resistor in a chip forming region of an insulating substrate, which is a constituent material of a plurality of chip resistors, and covering the resistor on a surface of the insulating substrate with a thick glass film. Forming a thick glass film in a chip forming region on the back surface of the insulating substrate; firstly dividing the insulating substrate into a strip having a plurality of chip forming regions; A step of forming side electrodes on the substrate; a step of dividing the insulating substrate into two parts to form chip resistors divided into chips; and a step of disposing the chip resistors on a printed wiring board on which pads are formed. And soldering the electrodes of the chip resistor and the pads of the printed wiring board.