JPH0695558B2 - Electronic parts - Google Patents

Description

The present invention relates to a terminal of a resin-sealed electronic component, and is particularly useful as a small-sized surface mount type electronic component.

[Prior art]

A composite electronic component that arranges a high-frequency coil and a chip-shaped capacitor on a synthetic resin or ceramic substrate and connects those circuit elements on the substrate or by an internal conductor pattern to form a filter or delay line circuit, It is widely used along with the miniaturization of the entire electronic circuit.

Such an electronic component generally has a structure in which a terminal for leading a circuit to the outside is connected to a substrate and the entire circuit including the substrate is sealed with a resin except the terminal. The terminals are usually connected to the conductor pattern on the board by soldering.

After that, it is mounted on a circuit board together with other electronic components to form an electronic circuit as a finished product such as a television or a radio. The mounting on the circuit board is performed by directly soldering the terminals of the electronic component to the conductor pattern, and the terminals are surface-connected to the conductor pattern.

By the way, the manufacture of electronic components and the mounting of the electronic components on the circuit board are usually performed by different manufacturers such as so-called parts makers and set makers. Therefore, the surface of the terminal of the electronic component is plated with solder in order to prevent oxidation during an indefinite period until it is mounted on the circuit board and to improve solderability during mounting.

Since the composition of the solder plating is apt to oxidize itself when the amount of lead is large, the amount of tin is usually larger than that of lead. Exceptionally, there is also a tin-only plating.

FIG. 5 is an enlarged cross-sectional view of a terminal portion of a conventional composite electronic component, in which one end of the terminal 1 is soldered to the conductor pattern 3 of the substrate 2 with solder 4.
Shows the state of being connected.

The terminal 1 has a material 5 such as 42 alloy plated with solder, and 6 is a plating film thereof. Since the plating film 6 contains a large amount of tin, it easily melts when connecting an electronic component to a circuit board in the soldering process of a set maker, but the solder 4 is a high-temperature solder having a composition containing a large amount of lead. Then, the connection between the terminal 1 and the substrate 2 is maintained so as not to melt.
Reference numeral 8 is a resin that covers the entire substrate 2 with the terminal 1 exposed.

Now, the terminal 1 is mainly soldered to a circuit board whose horizontal portion 7 is not shown. The method is a flow soldering method in which the entire electronic component on the board is immersed in molten solder, or a heat is applied from the outside. A reflow method or the like in which the cream solder in the connection portion is melted by adding is added. Solder at this time is 230-240
It is heated to about ℃ and is in a molten state. The plating film 6 on the horizontal portion 7 of the terminal 1 is almost melted by the heat of the melted solder. Further, the plating film 6 in the other portion is melted or heated to a temperature at which it is easily melted by the heat of the molten solder and the heat conduction from the horizontal portion 7.

When the plating film 6 inside the resin 8 melts, the plating film 6 generates pressure inside the resin 8 mainly in the extending direction of the terminal 1, that is, in the horizontal direction. Then, it melts out as beaded solder 9 at the boundary between the resin 8 and the outside. Further, inside, the composition of the solder 4, which is high-temperature solder, changes in the direction of increasing the amount of tin due to the diffusion of tin from the plating film 6. Then, the melting temperature of the solder 4 becomes low, and the solder 4 may be melted by the heat when the electronic component is soldered to the circuit board.

The ball-shaped solder 9 drops onto the circuit board after mounting the electronic component and causes a short circuit accident, and the melting of the solder 4 causes a short circuit accident between the conductor patterns 3 of the substrate 2.

In order to prevent such an accident due to the plating film 6 melting inside the resin 8, solder plating may be applied only to the portion of the terminal 1 exposed from the resin 8 to the outside. Since it is necessary to separately perform only the plating process after the resin is sealed with the resin and completed, it is not desirable because it lacks the consistency of the production process.

〔Task〕

In addition to such composite electronic components, there are electronic components such as a resistor array and a capacitor array formed on a ceramic substrate, and a main body made of resin such as a ceramic filter. This is to prevent such an accident due to melting of the plating film inside the resin of the terminal of the component.

[Means for Solving the Problems]

The present invention relates to an electronic component which is entirely resin-sealed in a state in which a terminal soldered to an electronic component body is exposed, and the terminal has a tip portion including a connection portion with the body, which is higher than other portions. Is characterized in that the thickness of the solder plating is thin, and the amount of tin and the plating film of the terminal inside the resin is reduced.

〔Example〕

Hereinafter, an embodiment of an electronic component of the present invention will be described by taking a composite electronic component as an example with reference to FIGS. 1, 2, and 3.
1 is a plan view, FIG. 2 is a front view, and FIG. 3 is an enlarged sectional view of a terminal portion. The same parts as those in FIG. 5 are designated by the same reference numerals.

A high frequency coil 10 and a chip-shaped capacitor on the substrate 2.
11 are arranged and are surface-connected to a conductor pattern (not shown). Then, as an example, an LC filter circuit is configured. The inner tip of the terminal 12 is connected to the conductor pattern 3 provided on the side portion of the substrate 2 by the solder 4. The substrate 2 to which the circuit elements and the terminals 12 are connected is entirely resin-sealed in a state where only the terminals 12 are exposed from the side surface 13 to the outside. A portion surrounded by a dotted line in FIGS. 1 and 2 indicates a portion sealed with resin.

The circuit elements and terminals of the high-frequency coil 10 and capacitor 11
12 is soldered to the substrate 2 with high temperature solder.

The terminals 12 are formed by solder plating the material 5. However, unlike the case of FIG. 5, the film thickness of the plating film 6 is different between the inside and outside of the resin 8. The plating film 14 at the tip portion located inside the resin 8 has a small film thickness, and the plating film 15 on the outside is
Is thickened. The thin plating film 14 has a thickness of 2 μm, and the thick plating film 15 has a thickness of 10 μm.

When the distance L between the substrate 2 and the side surface 13 of the resin 8 where the terminal 12 is exposed becomes short, the plating film at the tip connecting the terminal 12 and the conductor pattern 3, that is, the plating film substantially below the solder 4 is formed.
Sometimes only 14 is thinned.

Thus, by thinning the film thickness of the plating film 14 of the terminal 12 substantially inside the resin, the pressure of the solder generated inside the resin becomes small even if the plating film 14 melts, and the ball-shaped solder 9 is formed outside the resin 8. Will not melt out or the composition of the solder 4 connecting the terminal 12 and the conductor pattern 3 will change and the melting temperature will not drop. The fact that the composition of the solder 4 does not change is related to the decrease in the amount of tin due to the thin film thickness in addition to the pressure.

FIG. 4 is an enlarged cross-sectional view of a terminal portion in another embodiment of the electronic component of the present invention. In this way, only the thickness of the plating film 16 of the substantially horizontal portion 7 connected to the circuit board of the terminal 12 is shown. Alternatively, the thickness of the plating film 17 at the tip portion extending from the inside to the outside of the resin 8 may be reduced. In short, resin 8
It is necessary to reduce the amount of plating film inside.

Except for the tip of the terminal 12, the intermetallic compound that grows at the boundary between the material 5 and the plated film is the plated film 15 and the plated film 16.
It is necessary to have a film thickness that reaches the surface of the substrate and does not have an adverse effect during soldering. In particular, the part connected to the circuit board, such as the horizontal part 7, is necessary. Considering the time and environment until the composite electronic component is mounted on the circuit board, this film thickness is preferably 3 to 15 μm.

In addition, the thin plated film 14 and the plated film 17 on the tip of the terminal 12
It was found from the experimental results that the film thickness of 1 may be in the range of 0.5 to 3 μm.

Note that the electronic component of the present invention does not need to be limited to one in which a circuit is configured by arranging passive circuit elements as in the embodiment, and an active circuit element or an integrated circuit such as a transistor is arranged. It is also possible to widely use a composite electronic component in which a circuit formed on a substrate is resin-sealed and the circuit is led to the outside by a terminal. Further, as described above, the present invention can be widely applied to other electronic components in which the terminals are internally soldered to the main body and resin-sealed. The surface connecting terminal can be exposed to the outside from the bottom surface or side surface of the resin and can be extended along the surface, and various modifications can be made.

The method of solder plating may be electroplating or dipping, and the composition thereof includes an exceptional case of only tin.

[Effects] As described above, in the electronic component of the present invention, the thickness of the plating film of the solder of the terminal embedded almost inside the resin is reduced, and the amount of the plating film in the resin that seals the main body is reduced. It is reduced. This also means reducing the amount of tin in the plating film in the resin.

Therefore, the plating film inside the resin does not melt out, the melting temperature of the high temperature solder that solders the main body such as the terminal and the substrate does not decrease, and it is possible to prevent short circuit accidents inside and outside the resin. it can. Of course, the reliability of the connection between the terminal and the main unit is also improved.

Also, the solder plating film is a composition that is used in normal solder plating with a tin to lead ratio of about 60:40 or 90:10, and does not require a special plating solution as when using a large amount of lead. No
It is convenient because the commercially available product can be used as it is.

The terminals are plated with solder in the state of a metal plate, punched out of the metal plate to be in the state of a lead frame, and connected to the board.
After that, a general method of resin-sealing and then cutting and separating to form a terminal can be used. The composition of the solder can be made different in the portions having different solder thicknesses. That is, it is also possible to partially apply thick plating having a different composition after applying thin solder plating. There is also no need for solder plating after resin-sealing of the main body in which the circuit is configured, and there is also an advantage that the consistency of the production process can be maintained.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an electronic component of the present invention, and FIG.
The drawing is a front view, FIG. 3 is an enlarged sectional view of a terminal portion, FIG. 4 is an enlarged sectional view of a terminal portion of another embodiment, and FIG. 5 is an enlarged sectional view of a conventional electronic component. 1, 12: terminal, 2: substrate, 6, 14, 15, 16, 17: plated film,
8: Resin

Claims (4)

[Claims] 1. An electronic component which is entirely resin-sealed in a state in which a terminal soldered to an electronic component main body is exposed, and the terminal has a tip portion including a connecting portion with the main body which is another portion. An electronic component characterized in that the thickness of the solder plating is thinner than that of the electronic component. 2. The electronic component according to claim 1, wherein the tip portion of the terminal is a portion substantially inside the resin with the connecting portion with the substrate. 3. The electronic component according to claim 1, wherein the tip portion of the terminal is a portion inside the resin and a portion extending outward in the vicinity of the resin. 4. The thickness of the solder plating on the tip of the terminal is 0.
The electronic component according to any one of claims 1, 2 and 3, wherein the thickness is 5 to 3 µm and the other portions are 3 to 15 µm.