JPH05326316A - Electronic component - Google Patents

Abstract

PURPOSE:To provide electronic components which are capable of preventing the penetration of an electrolyte, solder and a bonding agent so as to avoid the degradation of electric and bonding properties, and what is more, eliminating changes in the electric properties. CONSTITUTION:In terms of an electric component which provides ceramic surface portions, such as a sintering magnetic substance and dielectrics, and what is more, a thin film-shaped external terminal 13 connected to pull-out ends 2 and 3 for an internal conductor and electrodes, synthetic resin is impregnated into pores existing on the ceramic surface portions. This construction makes it possible to prevent the penetration of an electrolyte, solder and a bonding agent in order to avoid the degradation of bonding properties, and what is more, eliminating changes in electric properties even when solder is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic parts, and more particularly to chip-shaped electronic parts such as chip inductors, chip capacitors and LC composite chip parts.

[0002]

2. Description of the Related Art Small electronic parts (also called chip inductors, chip capacitors, etc.) have a large number of film electrodes arranged in a dielectric or a coil inside an electrically insulating magnetic material (ferrite etc.). In general, these electronic parts are manufactured as a laminated body by a lamination method such as a printing method and then made into an integral sintered body by high temperature sintering, and the surface of this sintered body is formed. A conductive paste as an external terminal is applied and baked on the exposed lead conductor end to obtain a finished product.

Such an electronic component is mounted on a printed wiring board and external terminals are soldered to predetermined printed wiring parts. However, the external terminals that have been baked are eroded during soldering ( Ag and Pd that compose the external terminals
Or, its alloy diffuses and migrates into the solder solder bath, causing a phenomenon of electrode breakage and partial thin layer formation, resulting in poor soldering.) Recently, there has been a demand for electronic parts with electroplated external terminals. strong.

[0004]

However, when a chip component is electroplated, the electrolytic solution at the time of electroplating penetrates into minute pores existing on the exposed surface of a magnetic substance, a dielectric substance, etc., and after washing with water. Even a small amount remains and the electrical characteristics (Q
Etc.).

Further, the external terminals are formed at at least two places, and these are joined to the conductors of the printed wiring board by soldering, but the solder shrinks during cooling and applies stress to the electronic parts, and the constants L, C influences C and the like, and particularly in the case of a laminated-sintered type inductor or transformer, the strain due to this stress causes a magnetostriction phenomenon, and the inductance thereof may fluctuate by 3% from the original value.

Further, when such soldering is performed, a method is used in which an adhesive is previously attached to a small portion on the bottom of the electronic component and the electronic component is temporarily attached to the printed wiring board. In this case, the adhesive often enters the pores of the sintered body that constitutes the majority of the periphery of the electronic component to cause adhesion failure, and the phenomenon that the electronic component falls off is often seen.
It was an obstacle to streamlining the process and automation. The above two points are problems that exist regardless of the presence or absence of electroplating.

Therefore, the present invention can prevent the invasion of the electrolytic solution, the solder, and the adhesive to avoid the deterioration of the electric characteristics and the deterioration of the adhesiveness, and eliminate the change of the electric characteristics even when the solder is used. It is an object of the present invention to provide an electronic component that can be manufactured.

[0008]

The present invention provides a sintered magnetic material,
In an electronic component having a ceramic surface portion such as a dielectric and having a thin film external terminal connected to a lead-out end of an internal conductor, an electrode, etc., pores present in the ceramic surface portion are impregnated with a synthetic resin. It is a thing.

[0009]

In the electronic component of the present invention, synthetic resin is impregnated into pores forming a ceramic surface portion such as a sintered magnetic material and a dielectric material. Therefore, fine pores on the ceramic surface portion are made of silicone or the like. It is blocked with a synthetic resin, while the surface part except the pores remains exposed.

As a result, even when the external terminal connected to the lead-out end of the electronic component is electroplated or the external terminal is soldered, the electrolytic solution or the solder passes through the pores from the ceramic surface portion to the inside. There is no risk of permeation and deterioration of electrical characteristics, and even when an adhesive is used, it is possible to avoid a situation in which the adhesive permeates from the ceramic surface portion through the pores to the inside and impairs adhesiveness.

Further, since the fine pores on the surface of the ceramic are closed with a synthetic resin such as silicone, it is possible to reduce the stress in the electronic component caused by the cooling of the solder and eliminate the characteristic change. be able to.

[0012]

EXAMPLES Examples of the present invention will be described in detail below.

The electronic component shown in FIG. 1 comprises a sintered body 4 having a ceramic surface portion such as a sintered magnetic body and a dielectric body, and external terminals 13 formed on both sides of the sintered body 4. A synthetic resin selected from silicone resin and phenol resin is permeated into the pores of the ceramic surface portion 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. 2, a sintered compact small chip 1
To prepare. In the case of a capacitor, this small chip 1 is obtained by sintering an alternating laminated body of electrodes and dielectric paste layers,
If it is an inductor, it is a laminate of an alternating laminated body of a coil forming conductor and a magnetic ferrite powder paste layer,
Others include sintered resistors.

In any case, as shown in FIG. 2, the small chip 1 is typically a rectangular parallelepiped, and internal conductors, conductors forming electrodes, etc. are drawn out from the inside at least at two positions on the side, and at the same time the outer peripheral surface Most of it is the ceramic surface portion of the sintered body 4.

A base may be preliminarily formed on the sides of the conductor lead-out ends 2 and 3 drawn out at least at two places on the side by electroless plating or brush coating of a conductive paste (silver or the like). Alternatively, the silicone impregnation treatment may be performed as it is.

That is, as shown in FIG. 3, a mixture of silicone resin 2: solvent (gasoline) 8 is put in a beaker 5, and a large number of small chips 1 (regardless of the presence or absence of a base) are immersed therein. Then, this is sealed in the desiccator 6 and sucked by the vacuum pump 8 via the trap 7. After about 30 minutes, vacuum impregnation is completed and the small chip 1 is taken out from the beaker 5,
Thoroughly clean the surface with gasoline. When dried at a high temperature of about 100 ° C. for about 30 minutes, a small chip 1 impregnated with a silicone resin is obtained. A phenol resin or an epoxy resin may be used instead of the silicone resin.

In the small chip 1, the silicone resin penetrates into the pores on the surface of the sintered body 4 to block them, but the other surfaces are exposed. When the base plating is formed in advance, the silicone resin is hardly adhered to the base surface, and some adhesion is not a problem. When the undercoat is not formed, it is brushed with Ag paste or the like to form the electrode undercoat 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 made of a wire net is dipped in an electrolytic bath 10 containing a predetermined electrolytic solution, a large number of small chips 1 are housed therein, and the barrel 11 is rotated. While energizing, electric current is applied between the wire mesh and the central conductor. Further, gas is blown into the electrolytic solution from the gas source 12 to float 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, in order to form silver, copper, nickel and tin in this order on a silver base, three electrolytic baths may be used and plating may be performed in this order.

The electronic component shown in FIG. 1 can be obtained as described above. The electronic component shown in FIG. 1 is exaggerated for clarity, but is actually thinner.

In this electronic component, since the pores in the ceramic surface portion of the sintered body 4 are blocked with silicone, there is no risk that the electrolytic solution will enter the inside of the component, and the electrolytic solution can be removed cleanly by washing with water. it can.

When the above-described technique of this embodiment was carried out on a sintered body of an alternating laminated body of a magnetic ferrite layer and a printed conductor for a coil, deterioration of Q with time was not observed at all,
In addition, the maximum decrease in inductance of several percent was not found in this embodiment at all.

The reason for this is not clear, but it is presumed that the strain is less likely to occur by impregnating the pores of the ceramic surface portion with the silicone resin.
It is also presumed that the chemical action is reduced. In any case, according to this example, the electrical characteristics of the electronic component could be greatly improved.

Further, 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 from the substrate with a force of 0.2 to 2 kg, whereas the electronic component impregnated with the silicone resin and the electronic component of the same size had 5 to 5 kg. Only with a force of 7 kg did shedding occur.

Further, in the example of measuring the inductance before and after soldering, the inductance change of about 3% was observed in the case without silicone resin impregnation, whereas the inductor of the same size and the same constitution impregnated with silicone was used. Then, the inductance did not change by about 1%.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made within the scope of the gist thereof.

The electronic component to which the present invention is applied may be any electronic component as long as the surface of the ceramic is exposed to at least a part of the ceramic to which the electrolytic solution easily adheres. For example. Even if the dielectric material and the magnetic material are not porous in the usual sense, if the electrolytic solution adhering to the surface is difficult to remove by washing with water, the application of the present invention is very effective.

The same applies to the case where the adhesiveness is improved and the stress is relieved when electroplating is not applied. still,
The stress is relaxed because the force applied to the small chip when the solder on both ends of the small chip contracts is partially supported by the filled resin, and the force applied to the sintered body decreases.

[0030]

According to the present invention described above, since it has the above-mentioned structure, the pores of the ceramic surface are impregnated with the synthetic resin to prevent the electrolytic solution, the solder and the adhesive from invading. It is possible to avoid deterioration of characteristics and deterioration of adhesiveness,
Further, it is possible to provide an electronic component capable of eliminating a change in electrical characteristics even when solder is used.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an electronic component of the present invention.

FIG. 2 is a sectional view of a semi-finished electronic component product according to this embodiment.

FIG. 3 is an explanatory diagram of a silicone resin impregnation method.

FIG. 4 is a front view of a small chip after completion of impregnation with silicone resin.

FIG. 5 is a sectional view showing an electroplating process.

[Explanation of symbols]

 1 Small Chip 2 Conductor Lead End 3 Conductor Lead End 4 Sintered Body 13 External Terminal

Claims (1)

[Claims] 1. An electronic component having a ceramic surface portion such as a sintered magnetic material and a dielectric material, and further including a thin film external terminal connected to a lead-out end such as an internal conductor and an electrode, wherein the ceramic surface portion is provided. An electronic component characterized in that existing pores are impregnated with a synthetic resin.