JPH0682860U - Surface mount electronic components - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a surface-mounting electronic component in which the bonding surfaces of lead terminals can be aligned on the same plane, and furthermore, soldering for surface-mounting can be performed easily and reliably. The present invention is a surface mount type electronic component having a plurality of lead terminals 5a, 5b extending from the electronic component body 10 so as to be joined to a mounting surface.
The lead terminals 5a, 5 are provided on at least the joint surfaces of a and 5b.
The solder layer 7 was formed so that the joint surface of b was in the same plane.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to treatment of a bonding surface of a lead terminal of a surface mount electronic component with a printed wiring board.

[0002]

[Prior art]

 At present, there are many electronic components that can be surface-mounted on a printed wiring board by reflow processing, along with other electronic components. Moreover, even in an electronic component having a lead terminal extending from an electronic component body that has not been conventionally surface-mounted, the lead terminal is bent so that it can be surface-contacted with the printed wiring board.

For example, in a ladder type filter and a piezoelectric resonator, a piezoelectric element or a terminal plate having lead terminals is housed in a case whose one surface is initially open, and the opening of the case is sealed with resin or the like. However, in order to enable surface mounting, the lead terminals extending from the sealing surface of the case are bent so that they are the same as the side surfaces of the case, and are compatible with surface mounting. Was there.

FIG. 3 is a sectional view of an ordinary piezoelectric resonator. In the figure, 1 is a case, 2 is a frame, 3 is a piezoelectric element, 4a and 4b are terminal plates having lead terminals, 5a and 5b are lead terminals extending from the case 1, and 6 is a sealing member.

That is, in the conventional piezoelectric resonator, the lead terminals 5a and 5b extend from the substantially central portion of the thickness of the case 1, and the lead terminals 5a and 5b are formed in a lead hole formed in a printed wiring board (not shown). It was mounted on the board by solder dip.

In order to enable the surface mounting treatment of such a piezoelectric resonator, as shown in FIG. 4, the lead terminals 5a and 5b are directed downward, for example, at a portion having a predetermined length (surface side to be surface mounted). Then, the first bending treatment was performed, and then the second bending treatment was performed so as to be flush with the joint surface. As a result, the lead terminals 5a and 5b are subjected to the second bending treatment so that the joint surface to be surface-mounted (hereinafter simply referred to as the joint surface) becomes the same plane and reflowed onto the printed wiring board like other electronic components. Surface mounting by soldering becomes possible.

[0007]

[Problems to be solved by the device]

 However, in the above-described bending-processed electronic component, when mounted on a printed wiring board, it is necessary that the joint surfaces of the two lead terminals 5a and 5b simultaneously and surely contact the printed wiring board. If there is a difference in height between the joint surfaces of the two lead terminals 5a and 5b, some lead terminals will not reach the cream solder during reflow soldering, and accurate joining cannot be performed, which makes inspection and correction troublesome. become.

Here, the bending treatment of the lead terminals 5a and 5b is carried out even if the lead terminals 5a and 5b and the bending die are formed with great care, and the dimensional tolerances of the component parts and the deformation during handling are changed. Therefore, the amount of elastic deformation when the lead terminals 5a and 5b are incorporated in the case 1 is not uniform, and the heights thereof are not uniform.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to align the joint surfaces of lead terminals on the same plane regardless of the material of the lead terminals and the dimensional variations of the components. It is another object of the present invention to provide a surface mount type electronic component which can be easily and reliably soldered for surface mount.

[0010]

[Means for solving problems]

 According to the present invention, in a surface mount type electronic component formed by bending a plurality of lead terminals extending from an electronic component element body so as to come into surface contact with a printed wiring board, a printed wiring board for each lead terminal is provided. The surface-mounting electronic component is characterized in that the area of surface contact is on the same plane as the solder layer coated on each of the lead terminals.

[0011]

[Action]

 According to the present invention, since the solder layer for aligning the lead terminals on the same plane is formed on the joint surface of the surface-mounted lead terminals extending from the electronic component body, as a result, each lead is Since the joint surfaces of the terminals are aligned on the same plane by the solder layer, even if the lead terminals are processed or the lead terminals are deformed due to the structure, surface mounting can be easily performed.

Further, since the solder layer is formed on the joint surface of each lead terminal, the wettability of the solder is improved when the cream solder is applied on the printed wiring board and the reflow treatment is performed, and the solder joint is easily performed. In addition to being able to do so, the joining can be performed reliably.

Further, depending on the thickness of the solder layer, it is not necessary to excessively apply the cream solder to a predetermined pattern on the printed wiring board at the time of surface mounting, and the solder bridge due to the supply of the cream solder is eliminated. Therefore, it can contribute to the high density of the predetermined pattern on the printed wiring board.

[0014]

【Example】

 Hereinafter, a surface mount electronic component of the present invention will be described with reference to the drawings.

FIG. 1 is an external perspective view of a surface mount type electronic component, for example, a piezoelectric resonator according to the present invention, and FIG. 2 is a sectional structural view thereof. The same parts as those in FIG. 4 will be described using the same reference numerals.

In the figure, reference numeral 10 is an electronic component base body including a case 1, a piezoelectric element 3, and terminal plates 4 a and 4 b, and 5 a and 5 b are lead terminals extending from the electronic component base body 10.

The case 1 has a housing shape with one side surface opened, and is made of a resin having excellent heat resistance, such as PPS.

Inside the case 1, one piezoelectric element 3, terminal plates 4 a and 4 b holding the piezoelectric element 3 and a frame body 2 for positioning and sealing are housed. A vibration electrode is formed on the piezoelectric element 3, and a projection is formed at the center of each of the terminal plates 4a and 4b, so that the vibration electrode of the piezoelectric element 3 is formed on both the terminal plates 4a and 4b. It is sandwiched by the protrusions to provide electrical continuity.

Further, the terminal plates 4a, 4b are made of an elastic metal material such as phosphor bronze so as not to affect the vibration mode of the piezoelectric element 3 described above, and the lead terminals 5a, 5b are connected from one end thereof. It is extended integrally.

The lead terminals 5 a and 5 b are extended from the opening of the case 1 to the outside, and each of them is extended by a predetermined length to enable surface mounting. Bending is performed, and then second bending is performed so that the joint surfaces of the lead terminals 5a and 5b are flush with each other.

The lead terminals 5a and 5b are extended from the opening of the case 1 and hermetically sealed by a sealing member 6 made of resin or the like.

The characteristic structure of the present invention is that the solder layer 7 is formed on at least the joint surface of the lead terminals 5a, 5b, in the figure, the surface of the lead terminals 5a, 5b on the tip side of the second bending position. ing.

The solder layer 7 is formed to completely align the joint surfaces of the lead terminals 5a and 5b on the same plane. That is, since the lead terminals 5a and 5b are made of an elastic phosphor bronze or the like in terms of material, and are structurally bent twice, the lead terminals 5a and 5b are singly joined together, Even if they are aligned on the same plane, they may not be perfectly aligned on the same plane as a result of the repulsion and deformation of the bent portion. Therefore, the solder layer 7 compensates for a slight difference in height of the joint surface between the lead terminals 5a and 5b, and when the bottom surface of the case 1 projects beyond the joint surface of the lead terminals 5a and 5b, It serves to align the joint surfaces of the lead terminals 5a and 5b with the bottom surface of the case 1. Therefore, the thickness of the solder layer 7 is sufficient to correct the height difference, but in various experiments by the present inventor, the deformation amount (within 250 μm) of the lead terminals 5a and 5b was determined. Considering this, the solder layer 7 may be attached to have a thickness of at least 250 μm 2, preferably 300 μm or more.

The solder layer 7 is obtained by subjecting the lead terminals 5a and 5b to a second bending treatment, and then immersing the portion including the joint surface of the lead terminals 5a and 5b in a molten solder bath (not shown), Before pulling out from the solder bath and cooling and solidifying the solder, use a flat plate jig such as alumina having poor solder wettability so that the bottom surface of the case 1 and the joint surfaces of the lead terminals 5a and 5b are flush with each other. It is formed by placing it or pressing it lightly, and then cooling and solidifying the solder layer 7. In addition, in order to improve the workability, it is possible to collectively process the upper surface side of the case 1 using a jig for vacuum suction.

In the surface-mounted electronic component having the above structure, there is no difference in height at the joint surface of the lead terminals 5a and 5b, and the difference in displacement is -50 μm or less, and cream solder is applied to the printed wiring board. It is possible to perform reliable bonding by applying and supplying the solution and then performing a normal reflow soldering process.

In addition, since the solder layer 7 is formed on the lead terminals 5a and 5b, the solder wettability is improved during the reflow soldering process by the cream solder, and the bonding can be easily performed, and further, the bonding is surely performed. Becomes

Depending on the supply amount of the solder layer 7, it is possible to perform surface mounting on the printed wiring board only by soldering the solder layer 7 without applying cream solder on the printed wiring board. It is possible to increase the density of the predetermined wiring pattern.

In the above-described embodiment, the lead terminals 5a and 5b have been described as the piezoelectric resonators having the elastic lead terminals bent. However, in the electronic component in which the lead terminals are made of a metal material having a small elasticity, Is also effective for improving the reliability of surface mounting for electronic parts that have lead terminals for surface mounting formed on the case, and is extremely effective for piezoelectric resonators and ladder filters. Not limited to this, it can be applied to all surface mount electronic components.

[0029]

[Effect of device]

 As described above, according to the present invention, the bonding surface of the lead terminal can be aligned on the same plane by the solder layer, and further, the surface mounting type electronic component in which the surface mounting solder bonding can be easily and surely performed. Becomes

[Brief description of drawings]

FIG. 1 is an external perspective view of a surface mount electronic component of the present invention.

FIG. 2 is a cross-sectional view of a surface mount electronic component of the present invention.

FIG. 3 is a sectional view of a conventional electronic component.

FIG. 4 is a cross-sectional view of a conventional surface mount electronic component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Case 2 ... Frame body 3 ... Piezoelectric element 4a, 4b ... Terminal plate 5a, 5b ... Lead terminal 6 ... Sealing member 7 ... Solder layer

Claims (1)

[Scope of utility model registration request] 1. A surface mount type electronic component formed by bending a plurality of lead terminals extending from an electronic component element body so as to come into surface contact with a printed wiring board. A surface mounting type electronic component, wherein the contact area is on the same plane by the solder layer coated on each of the lead terminals.