JPS6134961A - Electronic part and manufacture thereof - Google Patents

Abstract

PURPOSE:To ensure excellent adhesion between a coating chiefly composed of Ni, Ag, or Au covering a lead and an epoxy resin for sealing said lead by a method wherein a Cu oxide layer is formed on at least a side of said coating in contact with said resin. CONSTITUTION:A Cu-base alloy lead 4, covered by a coating layer 7 formed of Ni, Ag, or Au with the mean diameter of the crystals therein not more than 2mum, is connected to an electronic part main body. Annealing is performed at temperatures 150-450 deg.C for the formation of a resin layer covering the entirety of the electronic part main body and a part of the wiring. By this, a type of chemical bondage is established between a Cu oxide layer 8 formed on the surface of the coating layer 7 covering the lead 4 and the sealing epoxy resin, which results in a strong adherence between the Cu oxide layer 8 and the sealing epoxy resin. Accordingly, moisture is efficiently prevented from penetrating the junction between the lead 4 and the epoxy resin when the electronic device is used in service.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an electronic component and a method for manufacturing the same, and more specifically,
The present invention relates to a resin-sealed electronic component that has good adhesion between a conductive wire connected to an electronic component body and a resin layer, and a method for manufacturing the same.

[Technical background of the invention and its problems]

In resin-sealed electronic components, as shown in FIG. The entire body 1 and a portion of the leads 1s4.5 are sealed with a resin layer 6.

As the material for forming the lead wire, a Cu-based alloy having high conductivity is usually used, and as the sealing resin, an epoxy resin is generally used.

By the way, in the case of a 3i semiconductor element having a junction between the main body of the electronic component and the lead wire being connected, Cu from the lead wire melts out during the cleaning process and adheres to the Si surface, especially near the PN junction, causing damage to the element. 2゜This causes problems such as deterioration of reverse voltage resistance characteristics.For this reason, conventionally, Cu-based alloys
The surface of the lead wire is coated in a layered manner with a material mainly composed of Ni, Ag, or Au to prevent Cu from leaching out from the lead wire. At this time, the coating layer is formed as an aggregate of crystal grains made of Ni, Ag, Au, or the like.

However, such a coating layer has poor bonding properties with the sealing epoxy resin, and micro-gaps occur at the interface between the coating layer and the resin layer, and especially when electronic components are used in a humid environment, water can leak through these micro-gaps. A problem has arisen in which particles flow into electronic components and deteriorate the electrical characteristics of the devices.

[Purpose of the invention]

The present invention solves such conventional problems and improves the Cu-based alloy).
Also, the adhesion between the lead wire, on which a coating layer mainly composed of Ni, Ag, or Au is formed, and the epoxy resin for the electronic component body is good, and moisture does not flow in from the interface between the two. Our goal is to provide highly reliable electronic components and their manufacturing methods.

[Summary of the invention]

In order to eliminate the poor adhesion between the lead wire having a coating layer and the epoxy resin as described above, (1) replace the material constituting the coating layer of the lead wire with one that has good adhesion with the epoxy resin, or (2) Although it is possible to further coat the lead wire coating layer with a substance that has good adhesion to the epoxy resin, conventional materials for the coating layer, i.e.
Materials whose main components are Ni, Ag, or Au have the advantage that they can be easily coated on lead wires such as Cu-based alloys by plating, etc., and can also be easily joined to other components by soldering. Therefore, it is hard to say that method (1) above is a good idea. ~ Therefore, the inventors of the present invention focused on method (2) above and conducted extensive research. As a result, the material of the lead wire was made of Cu.
Focusing on the fact that it is a metal alloy, if a coating layer having an average crystal grain size as described below is formed on the lead wire and then heat-treated under the specified conditions described below, the amount of each metal element constituting the coating layer can be reduced. Cu, which is the main constituent material of the lead wire, diffuses through the grain boundaries and bleeds onto the surface of the coating layer.
The present invention has been completed based on the discovery that the oxides are immediately concentrated on the surface because they are diffused into the surface, and are immediately transformed into oxides that have good adhesion to the resin.

That is, the present invention provides an electronic component body; a Cu-based alloy connected to the electronic component body and having on its surface a coating layer containing at least one selected from the group consisting of Nf, Ag, and Au as a main component; In an electronic component comprising a conductive wire; and a resin layer formed to cover the entire electronic component body and a part of the conductive wire, a layer made of an oxide of Cu is provided on at least the surface of the coating layer that is bonded to the resin layer. It is characterized by the formation of

In such a configuration, the thickness of the Cu oxide layer is 1000
It is preferable that it is A or less. If the layer thickness exceeds 1000×, Cu in the oxide layer may be eluted during the electronic component cleaning step after the lead wire forming step, which is not desirable.

Furthermore, the method for manufacturing electronic components of the present invention includes Ni, Ag, and A
A lead wire made of a Cu-based alloy whose main component is at least one selected from the group consisting of u and on whose surface a coating layer having an average crystal grain size of 2 gm or less is formed is connected to the electronic component body. After that, annealing is performed at a temperature of 150 to 450°C, and then a resin layer is formed covering the entire electronic component body and a part of the conductive wire.

In the above manufacturing process, the thickness of the lead wire coating layer is 3
It is less than μm. If the layer thickness is extremely large, it is not preferable because the subsequent process of grain boundary diffusion of Cu requires a long time. However, by appropriately selecting conditions for Cu grain boundary diffusion, such as temperature, it is possible to form a Cu oxide layer by grain boundary diffusion up to a thickness of about 6 μm. Since this coating layer mainly contains Nl, Ag, or Au, it can be easily formed by plating. Furthermore, the average crystal grain size of the material constituting this coating layer is 2P'm or less. If the average grain size exceeds 2 μm, the grain boundaries will decrease and it will be difficult to uniformly diffuse Cu at the grain boundaries.
In order to form such a coating layer having an average crystal grain size of 2 μm or less, for example, when using a plating method, various conditions such as the temperature of the plating bath, the current density, and the degree of stirring of the plating bath must be appropriately selected. is desirable.

The lead wire on which such a coating layer is formed is bonded to an electronic component body, for example, a rectifying element made of 81 semiconductor, via solder or the like, and then sintered. This process is carried out at 150-450℃.
It is preferably carried out at 200 to 400°C. The sintering temperature is 1
If the temperature is less than 50°C, grain boundary diffusion of Cu will not proceed sufficiently, and if the sintering temperature exceeds 450°C, Cu will not be diffused in the coating layer.
This is undesirable because intragranular diffusion or grain size growth occurs.

The sintering time to form an oxide layer of 1000X or less on a coating layer with a thickness of 3 μm or less is within 1 hour, but if the coating layer is thick, for example, about 6 μm, the sintering time is 4 to 4 μm. It is preferable to set it as 5 hours. Furthermore, when the coating layer is Ag or Au, this annealing step may be performed in a vacuum or in the air, but when the coating layer is Ni, it may be performed in a vacuum or in an inert environment to prevent grain boundary oxidation. It is preferable to perform this in gas.

In this sintering process, as shown in Figure 1, the lead wire 4
Then, Cu diffuses through the grain boundaries 7a of the coating layer 7 to the surface of the target 17 as shown by arrows in the figure, and the diffused Cu is immediately oxidized to form a Cu oxide layer 8.

Finally, the entire electronic component body and a portion of the lead wires are sealed with epoxy resin to complete the electronic component.

In the electronic component thus obtained, a certain chemical bond is formed between the Cu oxide layer formed on the surface of the coating layer of the lead wire and the sealing epoxy resin, and the oxide layer and Strongly adheres to epoxy resin. Therefore, when the electronic component is used, moisture is effectively prevented from entering through the joint surface between the lead wire and the epoxy resin. Furthermore, because the average crystal grain size of the coating layer has been reduced to make it fine, even if moisture does enter, it will take a long path to reach the component body.
This has the additional effect of making it difficult for moisture to reach the electronic component body.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to provide an electronic component with extremely good adhesion between a sealing epoxy resin and a lead wire by a simple method. Even when used continuously in a humid environment, the electrical characteristics do not deteriorate, and its industrial value is extremely high.

[Embodiments of the invention]

Example 1 A Cu lead wire on which a Ni plated layer with an average crystal grain size adjusted to ll1rr1 was formed to a thickness of 1.5 μm was connected to a rectifying element made of a Si semiconductor using eutectic solder. After protecting the vessel bonding area of the rectifying element with a polyimide resin, the rectifying element was heat-treated at 200° C. for 1 hour in a vacuum as a sintering process. As a result of analyzing the surface of the coating layer using an Auger electron spectrometer, it was confirmed that Cu was concentrated. The rectifier was then sealed with epoxy resin to complete a sealed rectifier.

A pressure cooker test (PCT) was conducted on this sealed rectifier element, and then a current conduction characteristic test was conducted. PCT is a test in which the device is left in a humid atmosphere of 80% H2O at 121°C for 8 hours. ■ Current carrying characteristic test is a test in which current is applied to I in the forward direction and the leakage current value is checked over the elapsed time. be. FIG. 2 shows the results, where the vertical axis shows the leakage current value when a voltage of 400 V is applied, and the horizontal axis shows time.

Comparative Example A sealed rectifier was manufactured in the same manner as in the above example except that the average crystal grain size of the coating layer was 5 μm and no sintering was performed, and PCT and DC energization were performed in the same manner as above. Characteristic tests were conducted. The results are shown in Figure 2.

As is clear from FIG. 2, it was confirmed that the electronic component of the present invention had significantly superior DC current conduction characteristics after PCT compared to the conventional electronic component. □Example 2 A resin-sealed rectifier was manufactured in the same manner as in Example 1, except that the coating layer was an Ag plating layer. The surface condition of the coating layer after annealing and the DC current conduction characteristics after PCT were the same as in Example 1.

In this embodiment, a rectifying element is used as the main body of the electronic component, but it goes without saying that the present invention is not limited to this and can be applied to transistors, thyristors, integrated circuits, etc.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the formation process of the CU oxide layer in the method for manufacturing electronic components of the present invention, and Figure 2 compares the DC current conduction characteristics of the electronic component of the present invention after PCT with those of conventional ones. FIG. 3 is a conceptual cross-sectional view showing the general structure of a resin-sealed electronic component. 1... Electronic component body, 4.5... Lead wire, 6...
- Epoxy resin layer, 7... coating layer, 7a... grain boundary,
8...Cu oxide layer.

Claims (1)

[Claims] 1. Electronic component body; connected to the electronic component body, Ni,
A conductive wire made of a Cu-based alloy having a coating layer mainly composed of at least one selected from the group consisting of Ag and Au; and a conductive wire formed to cover the entire electronic component body and a part of the conductive wire. In electronic components with resin layers,
An electronic component characterized in that a layer made of Cu oxide is formed on at least the surface of the coating layer that is bonded to the resin layer. 2. The electronic component according to claim 1, wherein the layer made of the oxide has a thickness of 1000 Å or less. 3. The electronic component according to claim 1, wherein the resin layer is a layer made of epoxy resin. 4. A conductive wire made of a Cu-based alloy whose main component is at least one selected from the group consisting of Ni, Ag, and Au, and a coating layer having an average crystal grain size of 2 μm or less is formed on its surface. After connecting to the electronic component body, 150
A method for manufacturing an electronic component, comprising annealing at a temperature of ~450°C, and then forming a resin layer covering the entire electronic component body and a portion of the conductive wire.