JP2700978B2 - Electronic component and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component, and more particularly to a chip-shaped electronic component such as a chip inductor, a chip capacitor, and an LC composite chip component, and a method of manufacturing the same. 2. Description of the Related Art Small electronic components (referred to as chip inductors, chip capacitors, etc.) have a large number of film-like electrodes arranged in a dielectric or are made of an electrically insulating magnetic material (eg, ferrite). It has a structure in which coil-shaped conductors are arranged inside. Generally, these electronic components are manufactured as a laminate by a lamination method such as a printing method, and then are sintered as a single body by high-temperature sintering. A conductive paste as an external terminal is applied to the end of the lead conductor exposed on the surface of the substrate and baked to obtain a finished product. [0003] Such an electronic component is mounted on a printed wiring board, and external terminals are soldered to predetermined printed wiring portions. However, the external terminals that have been baked are eroded by soldering during soldering. Ag, Pd constituting the external terminal
Or the diffusion of the alloy into the contact solder bath to cause poor soldering due to the occurrence of electrode breakage or partial thin layer). Recently, there has been a demand for electronic components with external terminals electroplated. strong. However, when a chip component is subjected to electroplating, an electrolytic solution at the time of electroplating penetrates into minute pores existing on an exposed surface of a magnetic material or a dielectric material. , A small amount of residue remains even after washing with water.
Etc.). External terminals are formed in at least two places, and these are joined to the conductor of the printed wiring board by soldering. The solder shrinks upon cooling to apply stress to the electronic component, and the constants L, In particular, in the case of a laminated-sintered type inductor or transformer, distortion due to this stress causes a magnetostriction phenomenon, and its inductance may fluctuate by 3% from the original value. Further, when such soldering is performed, a method of pasting an adhesive to a small portion at the bottom of the electronic component in advance and temporarily attaching the electronic component to a printed wiring board is used. In some cases, a phenomenon in which the adhesive penetrates into pores of the sintered body that constitutes most of the periphery of the electronic component and causes poor adhesion, and the phenomenon that the electronic component falls off is often seen.
This hindered the efficiency and automation of the process. The above two points are problems that exist regardless of the presence or absence of electroplating. Therefore, the present invention can prevent the deterioration of the electrical characteristics and the adhesiveness by preventing the intrusion of the electrolytic solution, the solder and the adhesive, and eliminate the change in the electrical characteristics even when the solder is used. And a method for manufacturing the same. According to a first aspect of the present invention, there is provided a structure having a ceramic surface portion such as a sintered magnetic material or a dielectric material, and connected to a lead end of an internal conductor, an electrode or the like. In an electronic component provided with a thin film-shaped external conductive terminal, all pores present on the ceramic surface portion are covered with a silicone resin.
And a synthetic resin selected from phenolic resins . According to a second aspect of the present invention, there is provided a sintered ceramic material such as a sintered magnetic material or a dielectric material, and a leading end of an internal conductor, an electrode or the like is led out to a side surface of the sintered ceramic. Including a step of impregnating the pores of the ceramic surface portion with a synthetic resin selected from a silicone resin and a phenol resin in a vacuum, vacuum-cleaning and removing the synthetic resin on the surface, and then drying and curing the resin. It is characterized by the following. In a third aspect of the present invention, the electronic component is a multilayer chip inductor. The electronic component according to the present invention is formed by impregnating a synthetic resin into pores forming a ceramic surface portion such as a sintered magnetic material and a dielectric material. The pores are closed with a synthetic resin such as silicone, while the surface portion excluding the pores remains exposed. As a result, even when the external conductive terminal connected to the lead-out end of the electronic component is electroplated to form an electrode or when the external terminal is soldered, the electrolytic solution or the solder is removed from the ceramic surface portion. There is no danger of infiltrating into the interior through the pores and deteriorating the electrical characteristics.In addition, even when the adhesive is used by using a surface other than the surface on which the electrodes are formed, the adhesive is not allowed to pass through the pores from the ceramic surface portion. This can avoid the situation of penetrating into the interior through the process and impairing the adhesiveness. In addition, since the fine pores on the ceramic surface are closed with a synthetic resin such as silicone, the stress in the electronic component caused by cooling of the solder can be reduced, and the characteristic change can be eliminated. . Further, according to the manufacturing method of the present invention, fine pores on the surface of the chip component are impregnated with a synthetic resin such as silicone to close the pores, while the surface portion excluding the pores is exposed. be able to. Therefore, when electroplating is performed on the base of the external terminal that is in contact with the lead end of the electronic component, there is no possibility that the electrolytic solution permeates from the surface of the sintered body to the inside to deteriorate the electric characteristics, and is generated by soldering. The stress in the electronic component was reduced, and the adhesive effect of the temporarily worn adhesive could be kept high. Embodiments of the present invention will be described below in detail. The electronic component shown in FIG. 1 has a sintered body 4 having a ceramic surface portion such as a sintered magnetic material or a dielectric, and a pore formed in the ceramic surface portion of the sintered body 4 selected from a silicone resin and a phenol resin. The electrodes 13 are formed on both sides of the sintered body 4. Next, a method of manufacturing the electronic component shown in FIG. 1 will be described with reference to FIGS. First, as shown in FIG.
Prepare This small chip 1 is a capacitor obtained by sintering an alternate laminate of electrodes and a dielectric paste layer in the case of a capacitor,
If it is an inductor, it is a laminate of a coil forming conductor and an alternating laminate of magnetic ferrite powder paste layers,
Another example is a sintered resistor. In any case, as shown in FIG. 2, the small chip 1 typically draws a conductor forming an internal conductor, an electrode, and the like from at least two places on the side of the rectangular parallelepiped, and also has a small outer peripheral surface. Most of the surface is the ceramic surface portion of the sintered body 4. That is, as shown in FIG. 3, a mixed solution having a ratio of silicone resin 2: solvent (gasoline) 8 is put in a beaker 5, and a large number of small chips 1 (with or without a base) are immersed therein. Then, this is sealed in a desiccator 6 and sucked by a vacuum pump 8 through a trap 7. After about 30 minutes, the vacuum impregnation is completed, and the small chip 1 is removed from the beaker 5,
Clean the surface thoroughly with gasoline. After drying at a high temperature of about 100 ° C. for about 30 minutes, a small chip 1 in which all pores are impregnated with a silicone resin is obtained. Instead of silicone resin,
Phenolic resins can also be used. In the small chip 1, the silicone resin penetrates all pores on the surface of the sintered body 4 to block them, but the other surfaces are exposed. Further, if necessary, an Ag paste or the like is brush-coated to form the electrode base 9 shown in FIG. Next, predetermined electroplating is performed on the electrode base 9 of the small chip 1. That is, as shown in FIG. 5, a rotary barrel 11 having a peripheral surface formed of a wire mesh is immersed in an electrolytic tank 10 containing a predetermined electrolytic solution, a large number of small chips 1 are accommodated therein, and the barrel 11 is rotated. Electricity is applied between the wire mesh and the center conductor while the electric current is being applied. Further, a gas is blown from the gas source 12 into the electrolyte for floating the small chip 1. In this way, a plating layer as a predetermined external terminal 13 is formed on the electrode base 9. For example, to form copper, nickel, and tin in this order on a silver base, plating may be performed in this order using three electrolytic cells. As described above, the electronic component shown in FIG. 1 can be obtained. Although the electronic components shown in FIG. 1 are exaggerated for easy viewing, they are actually thinner. In this electronic component, since all pores on the ceramic surface portion of the sintered body 4 are closed with silicone, there is no danger that the electrolytic solution enters the inside of the component, and the electrolytic solution is removed by washing with water. be able to. When the above-described technique of this embodiment was applied to a sintered body of an alternate laminate of a magnetic ferrite layer and a printed conductor for a coil, no deterioration of Q with time was observed.
In the present embodiment, the decrease in inductance was several percent of the conventional maximum, but was not observed at all in this embodiment. Although the reason for this is not clear, it is presumed that the impregnation of the pores on the ceramic surface with the silicone resin has made it difficult for distortion to occur.
It is also presumed that the chemical action is reduced. In any case, according to the present embodiment, the electrical characteristics of the electronic component were significantly improved. When the above-mentioned electronic component was temporarily attached to a printed wiring board with an adhesive, no decrease in adhesiveness was observed. In one experimental example, when the silicone resin was not impregnated, the electronic component fell off the substrate with a force of 0.2 to 2 kg, whereas the electronic component impregnated with the silicone resin and having the same configuration and the same dimensions had a size of 5 to 5 kg. Dropping occurred only with a force of 7 kg. Further, in the example of measuring the inductance before and after soldering, the inductor without the impregnation of the silicone resin had an inductance change of about 3%, while the inductor of the same dimensions and the same configuration impregnated with the silicone technique. In this case, only an inductance change of about 1% occurred. The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the invention. The electronic component to which the present invention is applied may be any electronic component as long as the surface of the ceramic to which the electrolyte is more or less easily adhered is at least partially exposed. For example. Even if the dielectric or magnetic material is not porous in the usual sense, if the electrolyte attached to the surface is difficult to remove by washing with water, the present invention can provide a remarkable effect. The same applies to the case where the electroplating is not performed and the adhesion is improved and the stress is reduced. still,
The relaxation of the stress is because the force applied to the small chip when the solder at both ends of the small chip contracts is partially supported by the filled resin, and the force applied to the sintered body decreases. According to the present invention described above, since the above-described structure is employed, all the pores on the ceramic surface are impregnated with the synthetic resin, so that the electrolyte, the solder and the adhesive can enter. Thus, it is possible to provide an electronic component and a method for manufacturing the same, which can prevent deterioration of electrical characteristics and adhesiveness by preventing the occurrence of electrical characteristics, and can eliminate changes in electrical characteristics even when solder is used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing an embodiment of an electronic component according to the present invention. FIG. 2 is a cross-sectional view of a semi-finished electronic component in the present embodiment. FIG. 4 Front view of small chip after completion of impregnation with silicone resin [FIG. 5] Cross-sectional view showing electroplating process [Description of symbols] 1 Small chip 2 Conductor leading end 3 Conductor leading end 4 Sintered body 13 External terminal

Claims (1)

(57) [Claims] In an electronic component having a ceramic surface portion such as a sintered magnetic material and a dielectric, and having a thin film-shaped external conductive terminal connected to a lead end of an internal conductor, an electrode, etc. Silicone resin and pores
An electronic component characterized by being impregnated with a synthetic resin selected from phenolic resins and phenolic resins . 2. An electronic component having a sintered ceramic surface such as a sintered magnetic material or a dielectric, and having leading ends of internal conductors, electrodes, etc. led out to the side surface of the sintered ceramic, has pores formed on the ceramic surface in a vacuum. A method of manufacturing an electronic component, comprising: impregnating a synthetic resin selected from a silicone resin and a phenol resin, washing and removing the synthetic resin on the surface, and drying and curing the resin. 3. 3. The method according to claim 2, wherein the electronic component is a multilayer chip inductor.