JP2007281134A - Chip-type electronic component, its mounting board, and its mounting method - Google Patents

Abstract

An object of the present invention is to reduce the interfacial tension to reduce the tombstone generation moment and prevent solder defects regardless of the combination of manufacturing conditions and material composition.
The present invention provides an external electrode 30 formed on both sides of an electronic component body and conducting to an internal electrode of the electronic component body, and a part of which extends around the upper and lower surfaces of the electronic component body. In the chip-type electronic component 31 provided, the outer peripheral portion is covered with a resist layer 20 from the upper half of the external electrode 30 in the height direction to the periphery of the upper surface of the electronic component main body.
[Selection] Figure 1

Description

  The present invention provides a chip-type electronic device that includes external electrodes formed on both sides of an electronic component body and conducting to internal electrodes of the electronic component body, and a part of which extends around the upper and lower surfaces of the electronic component body. The present invention relates to a component, its mounting board, and its mounting method.

  Recently, chip-type electronic components having a smaller electronic component size have been used in response to demands for miniaturization of substrates associated with miniaturization of electronic devices and high density mounting on substrates. In this chip-type electronic component, external electrodes exposed on both sides of the component main body are extended to the periphery of the upper and lower surfaces of the electronic component main body.

  Then, the electronic component is placed on the substrate while the bottom surface side of the external electrode is in contact with the solder paste printed in advance on the substrate electrode (conductive part) formed on the substrate, and then heated. The solder is melted and electrically connected, and at the same time, the electronic component is fixed on the substrate.

For example, FIG. 4 shows an example of a chip-type capacitor. Inside the ceramic dielectric 1 constituting the main body, a plurality of left and right internal electrodes 2 with one end exposed at the side of the dielectric 1 are vertically arranged in a predetermined manner. The outer electrode inner layer 3, the outer electrode intermediate layer 4, and the outer electrode outer layer 5 that are connected to each of the inner electrodes 2 are formed on the outer surface of the outer electrode, and the outer electrode outer layer 5 is formed on the outer surface of the outer electrode. The lower portion extends around the top and bottom surfaces of the dielectric 1.
The actual size of this chip-type capacitor is extremely small, for example, a length of 1.0 mm, a width of 0.5 mm, and a thickness (height) of 0.5 mm, and its weight is extremely light.

By the way, when soldering such a minute component on a substrate, a rising phenomenon called a tombstone, which is based on one soldering position, tends to occur, causing a connection failure.
This is because the interfacial tension of the molten solder varies between the left and right connection positions, and a rotational moment is likely to occur at one solder connection portion due to the influence of these.

  FIG. 5 is a diagram for explaining the tombstone phenomenon. Reference numeral 10 denotes a substrate, and reference numeral 11 denotes a pair of substrate electrodes formed on the component installation position of the substrate 10. As shown in FIG. 5A, a solder paste 12 is applied to the substrate electrode 11 to a predetermined thickness by printing or the like, and then, as shown in FIG. 5B, on both sides of the chip capacitor. A chip-type electronic component 14 provided with the external electrode 13 is supplied onto the solder paste 12. In this state, the solder paste 12 at the installation position is pushed away, and the chip-type electronic component 14 is positioned on both the substrate electrodes 11 by the load W of the electronic component and the adhesive force F1 due to the flux component in the solder paste 12. Temporarily fixed.

  Next, the solder paste 12 is melted by heating. However, if a slight time difference occurs in the melting of the left and right solder pastes 12 at this time, one side is melted as shown in FIG. However, the other side may still be in a paste state. In this case, the melted solder crawls up along the side surface of the external electrode 13 due to the wetting, and is formed in a substantially right triangle cross section. Then, the resultant force of the longitudinal load Fy and the lateral load Fx caused by the scooped solder becomes an interfacial tension, and a rotational moment M1 is generated to tilt the chip-type electronic component 14 in the interfacial tension direction. This rotational moment M1 5 becomes larger than the rotation inhibition moment M2, which is the resultant force of the adhesive force F1 of the unmelted solder paste and the load W, as shown in FIG. 5D, the chip-type electronic component 14 is tilted, and the outside on the other side The electrode 13 is heated and melted with a predetermined time delay while being separated from the solder paste 12, and is solidified by cooling. The bottom surface of the external electrode 13 on the melt side acts as the rotation-suppressing interfacial tension F′1 but is not effective because it has a contact area slightly smaller than the contact area in the height direction.

  Even if the probability of occurrence of the above tombstone phenomenon is about 0.1%, for example, when 100 or more chip-type electronic components are bonded to one substrate by the solder, Since one of the 10 substrates is a defective product and the yield is lowered, this tombstone phenomenon has been a major obstacle to increasing the mounting density.

  As measures to prevent the occurrence of the tombstone phenomenon, conventionally, at the design stage, the left and right substrate electrodes on which components are installed are made uniform and the conductive pattern connected to them is made uniform. Strict management was performed focusing on how to match the right and left melting timings, such as optimization and prevention of dispersion, and setting of reflow conditions for melting the left and right solders as much as possible.

  Further, in parallel with the above process control, in Patent Document 1 described below, the tombstone can be suppressed by devising the composition of the external electrode and the solder. In this technique, the metal constituting the outer layer electrode is melted before the bonding material is melted, so that a liquid-liquid interface is formed, and the interfacial tension is reduced to reduce the tombstone generation moment.

JP-A-6-177525

  However, the former process management method completely eliminates the tombstone phenomenon because it changes to a state in which tombstones are likely to occur even if the solder paste printing conditions, heating conditions in the furnace, and temperature distribution change slightly. I couldn't do it.

  In the method of Patent Document 1, the combination of the material composition of the external electrode and the solder is limited to a combination of specific substances, and the others have no freedom of selection.

  The present invention solves the above-described problems, and reduces the interfacial tension to reduce the tombstone generation moment and prevent solder defects regardless of the combination of manufacturing conditions and material composition as described above. The chip-type electronic component, its mounting substrate, and mounting method are provided.

  In order to solve the above-mentioned problem, a first aspect of the present invention is formed on both sides of an electronic component main body and is conducted to internal electrodes of the electronic component main body, and a part thereof is around the upper and lower surfaces of the electronic component main body. A chip-type electronic component having an extended external electrode, wherein the outer electrode is covered with a resist layer from the upper half in the height direction to the periphery of the upper surface.

According to the first aspect of the present invention, due to the presence of the resist layer, when the solder is joined, the creeping height of the solder is less than half that of the prior art, and the moment causing the tombstone due to the difference in melting time on both sides is also halved. In addition, connection failures caused by tombstones can be prevented. Furthermore, since it can be manufactured simply by adding a simple post-processing of applying a resist to a ready-made chip-type electronic component provided by the manufacturer, the manufacturing is also simple.
In the present invention, the “upper half in the height direction” is not an upper half in a strict sense, and is appropriately set in consideration of tombstone prevention and solderability. Of course.

  According to a second aspect of the present invention, there is provided an external electrode formed on both sides of the electronic component main body and conducting to the internal electrode of the electronic component main body, and a part of which extends around the upper and lower surfaces of the electronic component main body. The external electronic electrode is formed in a multilayer structure, the outermost layer is formed of a resist layer from the upper half of the height direction to the periphery of the upper surface, and the remaining part of the outermost layer is an electrode layer It is characterized by being formed by.

  According to the second aspect of the present invention, the same effect as the first aspect can be obtained, and there is no step by making the outermost layer of the external electrode the same thickness as the resist layer and the electrode layer. A uniform appearance structure can be formed.

  According to a third aspect of the present invention, there is provided an external electrode formed on both sides of the electronic component main body and conducting to the internal electrode of the electronic component main body, and a part of which extends around the upper and lower surfaces of the electronic component main body. The external electrode is formed in a multilayer structure, the outermost layer is formed of a plating resist layer from the upper half in the height direction to the periphery of the upper surface, and the remaining part of the outermost layer is the chip-type electronic component It is characterized by being formed of an electrode plating layer plated in a state where a plating resist layer is formed.

  According to the third aspect of the present invention, the electrode plating layer forming the outermost layer of the external electrode is formed by plating the remaining portion of the outermost layer in a state where the plating resist layer is formed. Therefore, its manufacture is simple.

  According to a fourth aspect of the present invention, there is provided a chip-type electronic component mounting substrate in which the chip-type electronic component is mounted with its external electrodes soldered to the electrode portions of the substrate. A chip-type electronic component according to any one of the first to third aspects.

  According to the fourth aspect of the present invention, in addition to the effect of preventing tombstones, the amount of solder used can be reduced as compared with the case where a conventional chip-type electronic component is mounted on a substrate. Can be achieved well and economically.

According to a fifth aspect of the present invention, there is provided the external electrode of the chip-type electronic component according to any one of the first to third aspects, on a solder paste previously provided with a predetermined thickness on the substrate electrode. The step of temporarily fixing the bottom surface in a positioning state, the step of heating to the melting temperature of the solder paste in the temporarily fixed state, and solidifying the solder by cooling to electrically connect the external electrode and the substrate electrode of the chip-type electronic component And a step of fixing the chip-type electronic component on the substrate at the same time.
According to the fifth aspect of the present invention, the same effect as that of the fourth aspect can be obtained.

A sixth aspect of the present invention includes a transport unit that transports a recording medium, a recording execution unit that performs recording on the recording medium transported by the transport unit, and operations of the transport unit and the recording execution unit. A chip-type electronic component mounting board on which a control circuit to be controlled is formed, wherein the chip-type electronic component mounting board is a chip according to any one of the first to fourth aspects It is a mounting board of a mold type electronic component.
According to the present invention, it is possible to improve the stability and reliability of each control execution of the recording apparatus.

  A seventh aspect of the present invention is an electronic device on which a chip-type electronic component mounting board on which a control circuit is formed is mounted, the chip-type electronic component mounting board of the first to fourth aspects. It is a mounting substrate for a chip-type electronic component described in any one of the above. ADVANTAGE OF THE INVENTION According to this invention, stability and reliability in each control execution of an electronic device can be improved.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
[Chip-type electronic components]
FIG. 1 is a cross-sectional view showing a first embodiment in which the present invention is applied to a chip-type capacitor. In the following embodiments, the same reference numerals are used for the same parts as those in the prior art, and the description thereof is omitted, and only different parts or newly added parts are described using different reference numerals.

  In FIG. 1, a solder resist layer 20 is formed on the outer side from the upper half of the side surface of the outer electrode outer layer 5 in the chip capacitor to the upper surface to cover the outer electrode outer layer 5. The solder resist layer 20 can be made of a known resin material that is non-adhesive to solder.

  In this structure, the upper surface side of the solder resist layer 20 is shown as being formed up to the periphery of the upper surface of the dielectric 1, but it may not be provided on the upper surface from the viewpoint of preventing tombstones. The actual size of the chip capacitor is 1.0 mm in length, 0.5 mm in width, and 0.5 mm in thickness (height) as described above. Accordingly, the solder resist layer 20 is formed at a position above the position of 0.25 mm in height, which is the upper half of the side exposed portion of the outer electrode outer layer 5, but the tombstone prevention effect and the adhesion to the solder In view of this, it may be slightly above or below this position. Further, in this structure, the processing may be added to a ready-made product manufactured by a chip-type electronic component manufacturer, or the processing may be added in the final step of manufacturing the chip-type electronic component. Well, both are easy to make.

  Next, FIG. 2 is a cross-sectional view showing a second embodiment applied to a chip-type capacitor. In this embodiment, the outer side of the outer electrode outer layer 5 from the upper half to the upper surface is covered with a plating resist layer 22. The electrode plating layer 23 is formed by covering in advance and then from the lower half of the outer electrode outer layer 5 to the lower surface.

  The plating resist layer 22 may be made of the same material as the soloder resist layer 20 of the first embodiment. As a plating method, an electrolytic method, a molten metal dipping method, or the like can be selected according to the material, film thickness, and the like. As the metal material constituting the electrode plating layer 23, a known material can be used.

  In each of the above embodiments, the chip type capacitor is exemplified as an example of the chip type electronic component of the present invention. However, the present invention is applicable to electronic components that can be made into chips, such as various resistance elements and semiconductors.

[Chip-type electronic component mounting board]
Next, a procedure for mounting a chip type electronic component including the chip type capacitor provided with the above resist layer on a substrate will be described with reference to FIG. First, as shown in (a), a solder paste 12 is applied to a predetermined thickness on a substrate electrode 11 formed on the substrate 10 by printing or the like. Of course, the coating thickness is designed to be thinner than the conventional one because the connection area to the external electrode of the chip-type electronic component described later is reduced.

  Next, as shown in (b), the chip-type electronic component 31 having the external electrodes 30 described above on both sides and the upper half of which is covered with the resist layer 20 (22) is supplied onto the solder paste 12. In this state, the solder paste 12 at the installation position is pushed away, and the chip-type electronic component 31 is placed on both substrate electrodes 11 by the load W of the chip-type electronic component 31 and the adhesive force F1 due to the flux component in the solder paste 12. Temporarily fixed in the positioning state.

  After that, the solder paste 12 is melted by heating, but if a slight time difference occurs in the melting of the left and right solder pastes 12 at this time, as shown in FIG. The side may still be pasty. In this case, the solder on the melted side crawls up along the side surface of the external electrode 30 due to the wetting, and is formed into a substantially right triangle cross section. However, this scooping height is the height to the lower edge of the resist layer 20 (22), and the rest is blocked by the resist layer 20 (22).

  Then, the resultant force of the longitudinal load Fy and the lateral load Fx due to the scooped solder becomes an interfacial tension, and a rotational moment M1 is generated that tends to tilt the electronic component 31 in the interfacial tension direction. However, since this rotational moment M1 is halved compared to the conventional case (see FIG. 5), this rotational moment M1 is smaller than the rotational inhibition moment M2, which is the resultant force of the adhesive force F1 of the unmelted solder paste and the load W. In addition, since the area of the interfacial tension F1 ′ with respect to the bottom surface on the melting side is relatively increased, the rotational force is further reduced, and as a result, as shown in FIG. As it is, the other side solder paste 12 melts with a predetermined time delay, so that a complete balance is maintained.

  Thereafter, both outer electrodes 30 are electrically connected to the substrate electrode 11 by solidification of the solder by cooling, and at the same time, the fixing of the electronic component 31 to the substrate 10 is completed.

  In the above embodiment, the tombstone phenomenon can be suppressed from the structural aspect, and at the same time the amount of solder applied can be reduced, so that high-density mounting can be achieved with good yield and economically.

[Recording device (electronic equipment) on which a chip-type electronic component mounting board is mounted]
The mounting substrate on which the chip-type electronic component 31 described in FIGS. 1 and 2 is mounted is mounted on various electronic devices and used for various control executions. An ink jet recording apparatus that is an example of an electronic apparatus includes a transport unit that transports a recording medium, a recording execution unit that performs recording on the recording medium transported by the transport unit, the transport unit, and the recording execution And a chip-type electronic component mounting board on which a control circuit for controlling the operation of the unit is formed. As the chip-type electronic component mounting substrate, the chip-type electronic component mounting substrate according to the above embodiment is used. Accordingly, stability and reliability can be improved when executing control in various operations of the ink jet recording apparatus.

Sectional drawing which shows 1st Embodiment which applied this invention to the chip-type capacitor | condenser. Sectional drawing which shows the 2nd Embodiment. (A)-(d) is explanatory drawing which shows the mounting procedure to the board | substrate using the chip-type electronic component which concerns on this invention. A conventional chip is a cross-sectional view of another capacitor. (A)-(d) is explanatory drawing which shows the mounting procedure to the board | substrate using the conventional chip type electronic component.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Ceramic dielectric body (electronic component main body), 2 Internal electrode, 3 External electrode inner layer, 4 External electrode intermediate layer, 5 External electrode outer layer, 10 Board | substrate, 11 Board | substrate electrode, 12 Solder paste, 20, 22 Resist layer, 23 Metal Plating layer, 30 external electrode, 31 chip type electronic component

Claims (7)

A chip-type electronic component comprising external electrodes formed on both sides of the electronic component body and conducting to the internal electrodes of the electronic component body, and a part of which extends around the upper and lower surfaces of the electronic component body; ,
A chip-type electronic component, wherein an outer periphery of the external electrode is covered with a resist layer from the upper half of the height direction to the periphery of the upper surface. A chip-type electronic component comprising external electrodes formed on both sides of the electronic component body and conducting to the internal electrodes of the electronic component body, and a part of which extends around the upper and lower surfaces of the electronic component body; ,
The external electrode is formed in a multilayer structure, the outermost layer is formed of a resist layer from the upper half of the height direction to the upper surface, and the remaining part of the outermost layer is formed of an electrode layer. Chip-type electronic components. A chip-type electronic component comprising external electrodes formed on both sides of the electronic component body and conducting to the internal electrodes of the electronic component body, and a part of which extends around the upper and lower surfaces of the electronic component body; ,
The external electrode is formed in a multilayer structure, the outermost layer is formed of a plating resist layer from the upper half of the height direction to the periphery of the upper surface, and the remaining part of the outermost layer is plated with the plating resist layer formed. A chip-type electronic component, wherein the chip-type electronic component is formed of an electrode plating layer.   4. A chip-type electronic component mounting board in which a chip-type electronic component is mounted by soldering its external electrode to an electrode portion of the board, and the chip-type electronic component according to claim 1. A chip-type electronic component mounting board, wherein the chip-type electronic component is described.   A step of temporarily fixing the bottom surface of the external electrode of the chip-type electronic component according to any one of claims 1 to 3 to a positioning state on a solder paste previously provided with a predetermined thickness on the substrate electrode; The process of heating up to the melting temperature of the solder paste in a fixed state, and solidifying the solder by cooling to electrically connect the external electrode and the substrate electrode of the chip-type electronic component and simultaneously fix the chip-type electronic component on the substrate A chip-type electronic component mounting method comprising the steps of: A chip on which a transport unit that transports a recording medium, a recording execution unit that performs recording on a recording medium transported by the transport unit, and a control circuit that controls operations of the transport unit and the recording execution unit are formed A recording apparatus comprising a mold-type electronic component mounting board,
5. The recording apparatus according to claim 1, wherein the chip-type electronic component mounting substrate is a chip-type electronic component mounting substrate according to claim 1.   5. An electronic device on which a chip-type electronic component mounting board on which a control circuit is formed is mounted, wherein the chip-type electronic component mounting board is mounted on the chip-type electronic component according to claim 1. An electronic device characterized by being a substrate.

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