JPH04303909A - Resin molded electronic component - Google Patents

Abstract

PURPOSE:To prevent a fine crack from being produced in an element by a heat shock at a soldering operation by a method wherein a conductive paste composed of a thermoset resin containing a metal powder which is composed of silver or of an alloy of silver and palladium is applied and formed as an external electrode and a lead terminal is connected and hardened simultaneously. CONSTITUTION:A laminated ceramic capactor element 10 which has been formed by cutting and baking a laminated sheet in which a dielectric 1 and an internal electrode 2 have been laminated and thermocompression-bonded has dimensions of 2.5X5.6X1.2mm. The element 10 is coated with a conductive paste using a thermoset resin in such a way that lead terminals 4 sandwich the lengthwise direction of the element 10 and that the lead terminals 4 and revealed end parts of the internal electrode for the element 10 are wrapped. The paste is hardened by using a drier; external electrodes 3 are formed. The conductive paste using said thermoset resin is manufactured in the following manner: a silver powder having a particle size of 1 to 3mum and a scale-shaped silver powder having a long diameter of 10 to 25mum are mixed in the weight ratio of 1:1 to form a silver powder; the silver powder, is mixed with an epoxy resin in the weight ratio of 7:3; and this mixture is kneaded by using a three-roll mill.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to resin-clad electronic components, and more particularly to the formation of external electrodes of internal elements and the connection of lead terminals.

0002

2. Description of the Related Art A conventional resin-clad electronic component will be explained with reference to the drawings. FIG. 2 is a plan cross-sectional view of a conventional resin-clad electronic component and a perspective view of an element used therein. These conventional examples are exemplified by multilayer ceramic capacitors.

As shown in FIG. 2(b), a multilayer ceramic capacitor element 20 (hereinafter abbreviated as element 20) is formed by laminating a dielectric 1 and an internal electrode 2, bonding them by thermocompression, cutting and firing. Next, as shown in FIG. 2(a), a conductive paste is applied to the two exposed end surfaces of the internal electrodes facing each other.
The external electrode 23 is formed by firing at a temperature of 0° C. to 800° C. This conductive paste is produced by mixing silver or silver and palladium metal powder, glass frit, an organic solvent, and a resin, and kneading the mixture in a three-roll mill.

Next, the opposing external electrodes 23 of the element 20 are sandwiched between the lead terminals 24 and soldered with solder 26, and the element 20
and lead terminals 24 are connected and fixed, and the whole is covered with an exterior resin 25 to form a resin-clad electronic component.

[0005]

[Problems to be Solved by the Invention] In the conventional resin-clad electronic components described above, the lead terminals and the chip are connected by soldering, so that, like multilayer ceramic capacitors, thermal shock during soldering causes minute cracks in the element. sometimes occurred. Many of the products with minute cracks cannot be removed by ordinary electrical inspection, and there are also problems in that some products deteriorate in reliability during use on the market, leading to defects such as short circuits.

An object of the present invention is to prevent the occurrence of minute cracks in an element due to thermal shock during soldering, to prevent a decrease in reliability due to minute cracks in the element, and to be able to cope with the problem using inexpensive production equipment. Our objective is to provide resin-clad electronic components.

[0007]

[Means for Solving the Problems] In the resin-clad electronic component of the present invention, external electrodes are adhered to two end surfaces of which the internal electrode end surfaces are exposed, and lead terminals are firmly connected to the external electrodes. In a resin-clad electronic component formed by coating with an insulating resin, a conductive paste made of a thermosetting resin containing metal powder made of silver or an alloy of silver and palladium is deposited as the external electrode, and at the same time. It is constructed by connecting lead terminals and curing them.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a plan cross-sectional view of a resin-clad electronic component according to an embodiment of the present invention, and a perspective view of an element used therein.

In FIG. 1, 1 is a dielectric, 2 is an internal electrode, 10 is a multilayer ceramic capacitor element, 3 is an external electrode coated with a conductive paste made of a thermosetting resin containing metal powder, and 4 is a lead terminal. , 5 is an exterior resin.

As shown in FIG. 1(b), a multilayer ceramic capacitor element 10 (hereinafter referred to as element 1) is formed by laminating a dielectric 1 and an internal electrode 2, and cutting and firing a laminate plate which is bonded by thermocompression.
0) is approximately 2.5 mm x 5 in this example.
．． It has a size of 6 mm x 1.2 mm. This element 10
Apply a conductive paste using a thermosetting resin so as to sandwich the lead terminals 4 in the longitudinal direction of the element 10 and wrap the exposed ends of the lead terminals 4 and the internal electrodes of the element 10, and dry in a dryer at 150°C for 30 minutes. After curing, external electrodes 3 were formed.

[0011] The conductive paste using thermosetting resin is
Silver powder with a particle size of 1 to 3 μm and scaly silver powder with a major diameter of 10 to 25 μm were mixed at a weight ratio of 1:1, and an epoxy resin was mixed at a weight ratio of 7:3, and then mixed in a three-roll mill. Manufactured by kneading.

Next, the whole was insulated and covered with a hardening resin 5 such as epoxy to obtain a resin-covered electronic component of the present invention.

Next, the electrical characteristics (capacitance, dielectric loss) and tensile strength of the lead terminals were evaluated for the resin-clad electronic component according to the embodiment of the present invention and the conventional resin-clad electronic component shown in FIG. 2(a). A comparison was made, and as shown in Table 1, it was confirmed that the resin-clad electronic component of the present invention had performance equivalent to that of the conventional example. All values are shown as the average value of the number of tests.

[0014]

Next, as a second example, silver-palladium alloy powder (silver: palladium = 90:10) with a particle size of 3 to 6 μm was used.
A conductive paste manufactured by mixing and epoxy resin at a weight ratio of 7:3 and kneading in a three-roll mill is used to wrap the exposed end of the internal electrode of the element 10 and the lead terminal 4 sandwiched in the longitudinal direction of the element 10. Apply and dry in a dryer at 150℃
After curing for 30 minutes, the whole was insulated and covered with epoxy resin to obtain a resin-covered electronic component.

As a result of measuring the electrical characteristics (capacitance, dielectric loss) and tensile strength of the lead terminals of the resin-clad electronic component made in the second example, it was confirmed that it had the same performance as the conventional example. It was done.

When silver-palladium alloy powder is used as the metal powder used in the conductive paste, moisture resistance due to migration can be improved compared to silver powder.

However, from the viewpoint of property improvement and cost, the content of palladium in the alloy is preferably 5 to 30%.

As mentioned above, in the present invention, electrode formation and lead terminal attachment are performed by heat treatment at 150°C for about 30 minutes using a conductive paste using a thermosetting resin without soldering. Cracks caused by shock do not occur at all. Therefore, there is no decrease in reliability due to cracks in the market.

[0020]

As explained above, according to the present invention, external electrodes can be formed and lead terminals can be connected without soldering to connect lead terminals. This has the effect of preventing the occurrence of minute cracks in the element due to shock, and preventing a decrease in reliability due to minute cracks in the element. Moreover, it has the effect that production can be carried out using inexpensive drying equipment instead of the expensive firing furnace that is conventionally required for firing the external electrodes.

[Brief explanation of drawings]

FIG. 1 is a plan cross-sectional view of a resin-clad electronic component according to an embodiment of the present invention, and a perspective view of an element used therein.

[Fig. 2] A cross-sectional plan view of an example of a conventional resin-clad electronic component.
and a perspective view of an element used therein.

[Explanation of symbols]

1 Dielectric 2 Internal electrode 3 External electrode 4 made of conductive paste using thermosetting resin Lead terminal 5 Exterior resin 10 Multilayer ceramic capacitor element 20
Multilayer ceramic capacitor element 23 External electrode 24 Lead terminal 25 Exterior resin 26 Solder

Claims (1)

[Claims] 1. A resin-clad electronic component, in which external electrodes are formed on two exposed end faces of internal electrodes, lead terminals are firmly connected to the external electrodes, and the entire body is coated with an insulating resin. In the above, the external electrode is silver or
A resin-clad electronic component characterized in that a conductive paste made of a thermosetting resin containing metal powder made of an alloy of silver and palladium is deposited, and at the same time lead terminals are connected and hardened.