JPH09148708A - Mounting structure of electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a stress exerted on an electronic component generated by a difference between a mounting board and the electronic component in their thermal expansion coefficient. SOLUTION: An electronic component 1 is made up of a body 2 and lead terminals 6. The lead terminals 6 are joined in cascade to external electrodes 3 formed on one end of the body 2 through high-temperature solders 5 or the like. The electronic component 1 having the body 2 and lead terminals 6 joined thereto in cascade is mounted on a mounting board 10 to be electrically connected to electrically conductive patterns 11 and 12 formed on the mounting board 10 via solders 15 and 16. In this connection, the thermal expansion coefficient of the electronic component 12 is set to be equal to that of the mounting board 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic parts, especially
The present invention relates to a mounting structure of surface mount electronic components.

[0002]

2. Description of the Related Art As shown in FIG.
In, there is known one having external electrodes 52 and 53 at both ends. The external electrodes 52 and 53 are electrically connected to the conductor patterns 55 and 56 formed on the mounting substrate 54 via solders 57 and 58, respectively, so that the electronic component 51 is fixed to the mounting substrate 54. There is.

[0003]

However, since the thermal expansion coefficient of the electronic component 51 and the thermal expansion coefficient of the mounting substrate 54 are generally different, when the electronic component 51 is soldered to the mounting substrate 54, Thermal expansion and mounting substrate 54
A difference occurs in the amount of thermal expansion. Therefore, stress may be applied to the electronic component 51, and a defect such as a crack may occur.

Therefore, an object of the present invention is to provide a mounting structure for an electronic component, which can reduce the stress generated by the difference in the amount of thermal expansion from the mounting substrate.

[0005]

In order to achieve the above object, a mounting structure of an electronic component according to the present invention has a structure in which (a) external components are provided at both ends of the component main body and the external electrodes are connected in cascade. An electronic component having a lead terminal; and (b) a mounting substrate for surface-mounting the electronic component,
(C) The thermal expansion amount of the electronic component and the thermal expansion amount of the mounting substrate are substantially equal to each other.

[0006]

Since the amount of thermal expansion of the electronic component and the amount of thermal expansion of the mounting substrate are substantially equal, the stress generated in the component body is reduced.
This is because even if the difference in thermal expansion amount between the component body and the mounting substrate is large, the lead terminal absorbs the difference in thermal expansion amount.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a mounting structure for electronic parts according to the present invention will be described below with reference to the accompanying drawings. In each embodiment, the same components and the same portions are denoted by the same reference numerals. First Embodiment, FIGS. 1 and 2 As shown in FIGS. 1 and 2, the electronic component 1 is composed of a component body 2 and lead terminals 6. The electronic component 1 is a capacitor, an inductor, a resistor, a piezoelectric resonator, or the like. As a material for the component body 2, ceramic, resin or the like is used. External electrodes 3 and 4 are formed on both ends of the component body 2, respectively.
The external electrodes 3 and 4 are formed by applying and baking a conductive paste such as Ag or Ag-Pd by printing or dipping. The lead terminal 6 has an L shape, and the vertical portion 6
a is joined to one external electrode 3 of the component body 2.
The bonding between the lead terminal 6 and the external electrode 3 has conductivity,
A material that can maintain sufficient bonding strength even when heat is applied when mounting the electronic component 1 on the mounting substrate 10, such as high-temperature solder 5, is used. In this way, the electronic component 1 in which the component body 2 and the lead terminals 6 are connected in cascade is soldered to the conductor patterns 11 and 12 formed on the mounting substrate 10.
They are electrically connected via 5, 16 and are surface-mounted. As a material for the mounting substrate 10, metal, resin, or the like is used.

Here, the amount of thermal expansion of the electronic component 1 and the amount of thermal expansion of the mounting substrate 10 are set to be equal.
Looking at the thermal expansion coefficient, the thermal expansion coefficient of the component body 2 is α1,
Assuming that the thermal expansion coefficient of the mounting substrate 10 is α2 and the thermal expansion coefficient of the lead terminal 6 is α3, the relational expression α3>α2> α1,
Alternatively, one of the relational expressions α3 <α2 <α1 is satisfied. Therefore, the lead terminal 6 absorbs the difference in thermal expansion amount between the component body 2 and the mounting substrate 10, and the stress generated in the component body 2 is reduced.

A detailed description will be given using specific numerical values. Parts body 2
Has a length d1 of 5 mm, and its material is a thermal expansion coefficient α1.
Uses a ceramic of 5 × 10 ⁻⁶ / ° C. The lead terminal 6 has a length d2 of 7 mm, and its material is a thermal expansion coefficient α3.
Uses a copper plate material of 17 × 10 ⁻⁶ / ° C. Mounting board 1
0 means that the dimension d3 between the conductor patterns 11 and 12 is 12 m.
m, the material has a thermal expansion coefficient α2 of 12 × 10 ⁻⁶ / ° C.
The glass epoxy resin substrate of is used. In this case, when the temperature rises by 100 ° C., the respective thermal expansion amounts are 2.5 × 10 ⁻³ mm for the component body 2 and 11.9 for the lead terminal 6.
× 10 ^-3 mm, the distance between the conductor patterns 11 and 12 is 14.4 ×
It becomes 10 ^-3 mm. Therefore, the thermal expansion amount of the entire electronic component 1 is (2.5 + 11.9) × 10 ⁻³ = 14.4 × 10 ⁻³ m
m, and this thermal expansion amount is equal to the thermal expansion amount between the conductor patterns 11 and 12. As a result, the electronic component 1 is not subjected to stress due to the difference in coefficient of thermal expansion from the mounting substrate 10, and defects such as cracks do not occur.

[Second Embodiment, FIG. 3] As shown in FIG. 3, the electronic component 21 is composed of a component body 2 and lead terminals 26. The lead terminal 26 has a substantially C shape,
The vertical portion 26a is electrically joined to one of the external electrodes 3 of the component body 2 via the high temperature solder 5 or the like. The electronic component 21 in which the component main body 2 and the lead terminals 26 are connected in series is a conductor pattern 11, 1 formed on a mounting substrate (not shown).
It is electrically connected to 2 with solders 15 and 16 and is surface-mounted.

Here, the thermal expansion amount of the electronic component 21 and the thermal expansion amount of the mounting substrate are set to be equal, and the lead terminal 26 absorbs the difference in thermal expansion amount between the component body 2 and the mounting substrate. The stress generated in the component body 2 is reduced. Moreover,
Since the tip end portion 26b of the lead terminal 26 is bent inward and the portion facing the conductor pattern 11 is clearly partitioned, the wetting spread of the solder 15 is limited to this clear facing portion, and the spread of the solder varies. Can be suppressed. Therefore, variations in the amount of thermal expansion of the electronic component 21 and the amount of thermal expansion of the mounting substrate are reduced, and the amounts of thermal expansion can be made more uniform.

[Third Embodiment, FIG. 4] As shown in FIG. 4, the electronic component 31 includes a component body 2 and two lead terminals 3.
6, 37. In the lead terminals 36 and 37, the vertical portions 36a and 37a are the external electrodes 3 and 4 of the component body 2.
Are electrically connected to each other via high-temperature solder 5 or the like. The component body 2 and the two lead terminals 36 and 37 are vertically connected, and the electronic component 31 is electrically connected to the conductor patterns 11 and 12 formed on a mounting substrate (not shown) via solders 15 and 16 It is implemented. The two lead terminals 36 and 37 may be made of materials having the same thermal expansion coefficient, or may be made of materials having different thermal expansion coefficients.

Here, the thermal expansion amount of the electronic component 31 and the thermal expansion amount of the mounting substrate are set to be equal, and the difference between the thermal expansion amounts of the component body 2 and the mounting substrate is the lead terminals 36 and 37.
Is absorbed and the stress generated in the component body 2 is reduced.

[Other Embodiments] The mounting structure of the electronic component according to the present invention is not limited to the above-mentioned embodiment, but can be variously modified within the scope of the invention.
In particular, the length and the thermal expansion coefficient of the lead terminal shown in the above embodiment are not limited to this, and any combination of the thermal expansion coefficient and the length is selected. In addition to the above-described embodiment, the lead terminal may have various shapes such as a rod shape and a foil shape.

[0015]

As is apparent from the above description, according to the present invention, the electronic component is provided with the component body and the lead terminals that are connected in series to the external electrodes of the component body, and the amount of thermal expansion of the electronic component is increased. Since the thermal expansion amount of the mounting board was made approximately equal,
The difference in thermal expansion amount between the component body and the mounting board is absorbed by the lead terminals, and the stress generated in the component body can be reduced. As a result, it is possible to reduce defects in electronic components such as cracks caused by a difference in thermal expansion amount from the mounting substrate.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of an electronic component mounting structure according to the present invention.

FIG. 2 is a front view showing a mounting structure of the electronic component shown in FIG.

FIG. 3 is a perspective view showing a second embodiment of a mounting structure for an electronic component according to the present invention.

FIG. 4 is a perspective view showing a third embodiment of a mounting structure for an electronic component according to the present invention.

FIG. 5 is a front view showing a conventional electronic component mounting structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electronic component 2 ... Component main body 3, 4 ... External electrode 6 ... Lead terminal 10 ... Mounting board 21 ... Electronic component 26 ... Lead terminal 31 ... Electronic component 36, 37 ... Lead terminal

Claims (1)

[Claims] 1. An electronic component having a component body having external electrodes provided on both ends thereof and lead terminals connected in series to the external electrode, and a mounting substrate for surface-mounting the electronic component, A mounting structure for an electronic component, wherein the thermal expansion amount of the electronic component and the thermal expansion amount of the mounting substrate are substantially equal to each other.