CN1210994C - Electrical device having PTC conductive polymer - Google Patents

Abstract

An electrical device having PTC conductive polymer is made by combining electrodes, in which electroless nickel plating is formed on an electrolytic copper foil, with PTC conductive polymer. The electrodes have electroless-plated nickel layers at both sides of an electrolytic copper foil and the PTC conductive polymer is welded between the electrodes in a sandwich type.Because the electroless-plated nickel of the electrical device has even thickness, the electrical device gives improved PTC characteristics and good chemical and mechanical binding capacity between the electrodes and the PTC conductive polymer.

Description

Electronic components with PTC conductive polymers

technical field

The present invention relates to an electronic component with a positive temperature coefficient (positive temperature coefficient, PTC for short) conductive polymer, in particular to an electrode that forms an electroless nickel plating layer (electroless nickel polymer) on an electrolytic copper foil and a PTC conductive Conductive polymer electronic components manufactured by polymer bonding method, using PTC conductive polymer, ensure to improve the properties of PTC and obtain good chemical and mechanical bonding ability between electrodes and PTC conductive polymer.

Background technique

There are many electronic components with PTC conductive polymers in the related prior art. The conductive polymer exhibits the PTC properties of a conductive filler dispersed on an organic polymer.

PTC means a property in which a resistance value rapidly increases due to a temperature increase within a relatively small temperature range. High-molecular substances having PTC properties are generally used in thermostatic wires, protection devices for preventing current overload, circuit protection units, heaters, and the like.

The conductive polymer is mechanochemically bonded to at least one electrode in an electronic component, and a metal plate, usually used as an electrode, is bonded to the conductive polymer. The purpose of this metal plate is to connect the conductive polymer to an external electrode without deteriorating the PTC properties of the conductive polymer. For these reasons, the conductive polymer should have good bonding ability to ensure the electrical and mechanical bonding ability of the metal plate.

The bonding ability between the metal plate and the conductive polymer generally has two properties: mechanical bonding ability and chemical bonding ability. In order to improve the mechanical bonding ability, a process of increasing the surface roughness of the metal plate is required to suppress the separation between the metal plate and the conductive polymer. However, despite having the same surface roughness, the metal plate exhibits a significantly different ability to bind to the polymer due to the difference in the chemical bonding ability between the metal and the polymer. For most polymers like natural rubber and polypropylene, the chemical binding capacity increases in the order of copper, iron, nickel, aluminum, zinc, etc. Metal sheets combined with polymers are therefore processed according to scaling properties, surface treatments with brass or zinc or adhesive applications with silanes.

Meanwhile, electroplating is a typical method for suppressing separation performance between a metal plate and a conductive polymer by increasing surface roughness of the metal plate. Today, a copper plated foil for printed circuit boards (here replaced by PCB) and a metal plate used in electronic components with PTC properties can be prepared using this method.

Copper plated foil for PCB can be made into a thickness of 10-150 μm. In this plated foil, a ring-shaped node is formed on a node in the form of a pyramid, which acts as a mechanical fixation for the conductive polymer.

To make a PCB, copper foil is laminated on a base board, then heated and pressed. Copper foil should have chemical corrosion resistance (for example, acid resistance), resistance to discoloration after etching when connected to the substrate, and rust resistance after etching. For these reasons, the surface of copper foil used in PCBs is covered with a coating containing zinc, indium, brass or the like (Japanese Patent Publication No. 51-35711), or a two-layer electroplated copper layer is used (Japanese Patent Laid-Open No. 53-39376). In these examples, the copper-zinc layer is produced by electroplating the surface of the copper foil in an electroplating bath containing copper ions, zinc ions, a strong acid, and an alkali on the cathode, and then subjecting it to chromate treatment (U.S. No. 5,304,428 patent).

Other technologies related to conductive polymer electronic devices with PTC properties are listed in US Patent No. 4,426,633, US Patent No. 4,689,475, US Patent No. 4,800,253, US Patent No. 5,874,885, and US Patent No. 5,234,573. are disclosed.

However, conventional electrodes fabricated by electrolytic plating or electrodeposition exhibit thickness non-uniformity, which causes phase separation of the electrode from the PTC polymer.

Therefore, the inventors of the present invention have produced an electrode having a uniform thickness by subjecting an electroplated copper foil for PCB to electroless plating in order to solve the above-mentioned problems.

Contents of the invention

The object of the present invention is to provide a kind of electronic component, this electronic component is made by the electrode that forms the electroless nickel plating layer of uniform thickness on an electrolytic copper foil and the PTC conducting polymer combined method, utilizes PTC conducting polymer, ensures The properties of the PTC are improved and a good chemical and mechanical bonding ability is obtained between the electrode and the PTC conductive polymer.

In order to achieve the above object, the present invention provides a kind of electronic device that has positive temperature coefficient (PTC) conductive polymer, and this device comprises the first and the second electrode that have electroless-electroplated nickel metal layer on both sides of electroplated copper foil and A single sheet of PTC conductive polymer welded between the first and second electrodes, wherein the electroless-electroplated nickel metal has a uniform thickness, and its thickness is between 0.01 and 10 μm, and the surface roughness of the electroplated copper foil is preferably between Between 1 and 20 μm. To ensure that the PTC conductive polymer has sufficient binding capacity.

Description of drawings

These and other features, aspects and advantages of the present invention will become more apparent in conjunction with the following description, claims and drawings, in which corresponding parts have been designated with the same numerals.

Fig. 1 is a surface photo of an electroplated copper foil used in the present invention;

Figure 2 is a photo of the surface of an electroless nickel metal-plated copper foil sample with a thickness of 1 μm;

Fig. 3 is an electronic device of the present invention; and

FIG. 4 is a resistance-temperature curve diagram of the electronic device obtained according to the first to third embodiments.

Detailed ways

The following are preferred embodiments of the present invention described in detail with reference to the accompanying drawings. The present invention provides an electronic device and an electroless-plated metal electrode comprising a conductive polymer having a PTC (Positive Temperature Coefficient) property. The PTC conductive polymer is welded between electrodes in a sandwich-like fashion.

Conductive polymers with PTC properties can be obtained by mixing conductive fillers, cross-connection media, antioxidants, etc., with organic polymers.

Here, the organic polymer may be one of polyethylene, ethylene-acrylic acid copolymer, ethylene-ethylacrylic acid copolymer, ethylene-vinyl acetate polymer, and acetic acid-butylacrylic acid polymer, wherein, Preferably polyethylene is used.

The conductive filler can be one of powdered nickel metal, gold powder, copper powder, silver powder copper, alloy powder, carbon black, carbon powder or carbon graphite, among which carbon black is preferably used.

Metal electrodes are made by electroless-plating a metal that has good chemical bonding to PTC conductive polymers and good mechanical bonding to electroplated copper foil. The surface roughness R _Z of the electroplated copper foil can be guaranteed to be between 1 and 20 μm through the electrolytic plating manufacturing process. The electroplated copper foil used in the present invention is available from LG Industry Co.

Electroplated copper foil is an electroless-nickel-plated metal. The electroless nickel metal-plating process includes a degreasing process, a pickling process, a driving process, a photosensitive treatment process, an electroless nickel metal-plating process, and a rinsing process. The surface photograph in Fig. 2 is an electroless-plated sample with a nickel metal layer thickness of 1 μm. From Figure 2, it is easy to know the surface roughness and surface morphology of the sample, which is not much different from the actual one.

From the above description, nickel metal is the electroless-electroplated metal on copper, and the electrodes 2 are welded on both sides of the PTC conductive polymer 1 to make the electronic device as shown in FIG. 3 .

Now, embodiments of the present invention are described in detail below. However, these embodiments are only some preferred solutions, and should not be regarded as limiting the present invention.

Example 1

The PTC conductive polymer is prepared by mixing polyethylene and carbon black. The surface roughness of an electroplated copper foil is controlled between 5 and 10 μm by electrolytic plating. Then, an electroless nickel metal-plating process with a thickness of 1 μm was formed on the electroplated copper foil through a degreasing process, a pickling process, a driving process, a photosensitive treatment process, an electroless nickel metal-plating process, and a rinsing process. layers to make electrodes. The electrodes are welded on both sides of the sandwich-like PTC conductive polymer to obtain an electronic device as shown in FIG. 3 .

Example 2

The PTC conductive polymer is prepared by mixing polyethylene and carbon black. The surface roughness of an electroplated copper foil is controlled between 5 and 10 μm by electrolytic plating. Then, an electroless nickel metal-plating process with a thickness of 10 μm was formed on the electroplated copper foil through a degreasing process, a pickling process, a driving process, a photosensitive treatment process, an electroless nickel metal-plating process, and a rinsing process. layers to make electrodes. The electrodes are welded on both sides of the sandwich-like PTC conductive polymer to obtain an electronic device as shown in FIG. 3 .

Example 3

An electronic device was produced in the same manner as in Example 1. However, the drive and photosensitive treatment processes are removed during the electroless-plating process, and the electroless nickel metal-plating process is carried out following the pickling process. Chromium metal is then overlaid on the electroless nickel metal-plated layer by displacement plating in a chromium bath.

comparative example

Using electroless nickel metal-plating on copper, which is different from that described in the above Examples 1-3, and adopting the method of welding the copper foil on the PTC conductive polymer to prepare the traditional electrode to form the electronic device of the form shown in Figure 3 .

test 1

Resistance-Temperature Properties

FIG. 4 shows the change curves of the resistance of Examples 1 to 3 with the temperature of the electronic component. As shown in FIG. 4, it can be easily understood that the electronic component of the present invention has no special difference in resistance-temperature properties compared with the electronic component using conventional electroplated copper foil.

This means that the electronic component of the present invention not only strengthens the binding ability between the PTC conductive polymer and the electrode, but also ensures its resistance-temperature properties like the traditional electronic device using electroplated copper foil.

test 2

humidity test

Before and after the humidity test, the electrical resistances of the electronic components obtained in Example 1 and Comparative Example were measured. The results are listed in Table 1 below.

Table 1 Before humidity test After humidity test Embodiment 1 (nickel metal) 200mΩ 190mΩ Comparative example (copper) 200mΩ   Less than 10mΩ

As shown in Table 1, the electronic components using copper electrodes in the comparative example had a large difference in resistance value before and after the humidity test. However, the resistance value of the electronic component obtained by the electroless nickel metal plating method of Example 1 has a decrease value of less than 10 mΩ after the humidity test.

Considering the results shown in Tests 1 and 2, it can be easily understood that compared with traditional electronic components using electrolytic plating and electroplating, the electronic components of the present invention obtain better PTC properties and more efficient between the PTC conductive polymer and the electrode. Good bonding ability.

The advantage of electroless plating employed in the present invention is that it can smooth uneven surfaces compared to electrolytic plating or electroplating.

Therefore, the advantage of the electronic component using the electrode of electroless-electroplated nickel metal on the electrolytic copper foil used in the present invention is that it obtains better mechanical and chemical bonding ability on the PTC conductive polymer, and has a greater impact on the PTC properties. change.

The electronic component with PTC conductive polymer of the present invention described above needs to be understood in conjunction with the embodiments. However, any changes based on the intent and scope of the present invention are within the protection scope of the present invention.

Claims (1)

1. electronic component with positive temperature coefficient (PTC) conductive polymer comprises:

Contain first and second electrodes that have or not electricity-electronickelling metal level on the both sides of electro copper foil; And

Be welded on the single PTC conductive polymer sheet between first and second electrodes,

It is even to it is characterized in that not having electricity-electronickelling metal layer thickness, is 0.01-10 μ m; The surface roughness of electro copper foil is between 1～20 μ m.

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