Surface-mounted polymer PCT overcurrent protection element having small package size

Abstract

A surface-mounted polymer PTC overcurrent protection element having a small package size, comprising a PTC chip, an insulating layer (30), end electrodes (41, 42), and at least one conductive member (60). A dividing gap is designed on a first conductive electrode (21) to form first and second conductive areas (211, 212); the conductive member (60) is arranged at the edge or at least a corner of the first conductive area (211) side of the PTC chip, is used for conducting the first conductive area (211) and a second conductive electrode (22) on the PTC chip, and is not in contact with the end electrodes (41, 42); the main portion comprised in the dividing gap (70) of the first conductive electrode (21) is parallel to the longitudinal direction of the first end electrode (41) and the second end electrode (42).

Claims

1. A surface-mounted polymer PTC overcurrent protection element having a small package size, comprising: a first conductive electrode, a second conductive electrode, a PTC chip located between the first and second conductive electrodes, an insulating layer having a first layer side in contact with the first conductive electrode, a second layer side in contact with a first end electrode and a second end electrode, a dividing gap on the first conductive electrode to form first and second conductive areas, at least one conductive member arranged at an edge or at least a corner of the first conductive area for conducting the first conductive area and the second conductive electrode, wherein at least one portion in the dividing gap is parallel to the longitudinal direction of the first end electrode and the second end electrode, and wherein the dividing gap is filled with a resin material.

2. The surface-mounted polymer PTC overcurrent protection element of claim 1, wherein 1) The PTC chip is composed of a PTC core material having a first surface covering the first conductive electrode and a second surface covering the second conductive electrode; 2) the insulating layer is arranged between the first conductive electrode and the first and second end electrodes for electrical isolation, a first conductive connecting member arranged through one hole on the insulating layer and for electrical connection between the first end electrode and the first conductive area of the first conductive electrode, a second conductive connecting member arranged through another hole on the insulating layer for electrical connection between the second end electrode and the second conductive area of the first conductive electrode; 3) the first end electrode is located at one end of the second layer side of the insulating layer, the second end electrode is located at the other end of the second layer side of the insulating layer.

3. A method of for preparing the surface-mounted polymer PTC overcurrent protection element of claim 2, comprising the following steps: step 1, preparation of the PTC chip: mixing a conductive polymer and conductive filler in a mixer to form a mixture, mixing the mixture at 100-200 C., and then using extrusion or compression molding to make a composite material base layer with an area of 1005000 cm.sup.2 and a thickness of 0.13.0 mm from the mixture, pressing the first and second conductive electrodes on first and second surfaces of the composite material base layer respectively by hot pressing to make a composite material sheet, processing the composite material sheet by -ray (Co60) or electron beam irradiation crosslinking with 2100 Mrad dose, and then cutting the composite material sheet to obtain the PTC chip; step 2, etching or cutting the first conductive electrode to form the dividing gap and filling the dividing gap with an insulating material between the first conductive area and the second conductive area, wherein the first conductive area is larger than the area of the second conductive area; step 3, etching a groove and plating a metal to form the at least one conductive member at the edge or the corner of the first conductive area; step 4, covering the insulating layer on the first conductive electrode; step 5: setting the first and second end electrodes on the insulating layer in longitudinal parallel and making the main portion of the dividing gap to be parallel to the first and second end electrodes, drilling openings on the first and second end electrodes, arranging the first and second conductive connecting members through the openings and the insulating layer for making electrical connection between the first end electrode and the first conductive area between the second end electrode and the second conductive area of the first conductive electrode.

4. The method for preparing the surface-mounted polymer PTC overcurrent protection element having a small package size of claim 3, wherein in step 2, the dividing gap is a straight groove which is parallel to the end electrode, or an arc groove whose main portion is parallel to the end electrode.

5. The method for preparing the surface-mounted polymer PTC overcurrent protection element having a small package size of claim 3, wherein in step 3, the at least one conductive member is arranged at one end edge, one corner or two corners of the PTC chip.

6. The surface-mounted polymer PTC overcurrent protection element of claim 1, wherein the dividing gap is rectangular, triangular, arcuate, elliptical or polygonal.

7. The surface-mounted polymer PTC overcurrent protection element of claim 1, wherein insulating reinforcements are arranged at four corners, one end edge, two end edges or four end edges of the PTC chip.

8. The surface-mounted polymer PTC overcurrent protection element of claim 1, wherein the PTC overcurrent protection element is a single-side-soldering surface-mounted element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates the structure diagram of the surface-mounted polymer PTC overcurrent protection element having a small package size in Embodiment 1;

(2) FIG. 2 illustrates the exploded structure diagram of the surface-mounted polymer PTC overcurrent protection element having a small package size in Embodiment 1.

(3) FIG. 3 illustrates the structure diagram of the surface-mounted polymer PTC overcurrent protection element having a small package size in Embodiment 2.

(4) FIG. 4 illustrates the structure diagram of the surface-mounted polymer PTC overcurrent protection element having a small package size in Embodiment 3.

(5) FIG. 5 illustrates the bottom view of the second conductive electrode of the surface-mounted polymer PTC overcurrent protection element having a small package size in Embodiment 3.

(6) FIG. 6 illustrates the bottom view of the second conductive electrode of the surface-mounted polymer PTC overcurrent protection element having a small package size in Embodiment 4.

(7) FIG. 7 illustrates the structure diagram of the first conductive electrode of the surface-mounted polymer PTC overcurrent protection element having a small package size in Embodiment 5.

REFERENCE NUMBERS OF THE DRAWINGS

(8) 10the PTC core material; 21, 22the first and second conductive electrode; 211, 212the first and second conductive areas of the first conductive electrode; 30the insulating layer; 41, 42the first and second end electrodes; 51, 52the first and second conductive holes; 60, 60the conductive members; 61, 62the first and second conductive members; 70the dividing gap; 80the insulating reinforcement; 90reinforced layer; In FIG. 7: 21the first conductive electrode; 211, 212the first and second conductive areas of the first conductive electrode; 70the dividing gap.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(9) The Preparation of Material:

(10) Mixing the high polymer that is the component of conductive polymer composite base layers and conductive filler in a high-speed mixer, then mixing the mixture at 100-200 C., and then using extrusion or compression molding to make a PTC core material 10 with an area of 1005000 cm.sup.2 and a thickness of 0.13.0 mm; pressing the first and second conductive electrodes 21,22 on the first and second surfaces of the PTC core material 10 respectively by hot pressing to make a composite material sheet, processing the composite material sheet by -ray (Co60) or electron beam irradiation crosslinking with 2100 Mrad dose, and then cutting the composite material sheet to get a rectangular PTC chip.

Embodiment 1

(11) A surface mount polymer PTC overcurrent protection element having a small package size is illustrated in FIG. 1, and FIG. 2 illustrates the exploded structure diagram of the overcurrent protection element in FIG. 1, comprising:

(12) The first and second surfaces of the PTC core material 10 are covered with first and second conductive electrodes 21,22 to compose a PTC chip. A rectangular dividing gap 70 which is parallel to the longitudinal direction of the first and second end electrode 41,42 is etched or cut on the first conductive electrode 21 to form first and second conductive areas 211,212 that are not in electrical connect with each other.

(13) A conductive member 60 is arranged at the end edge of the PTC chip. The conductive member 60 conducts the first conductive area 211 which covers the first surface of the PTC chip and the second conductive electrode 22 which covers the second surface of the PTC chip.

(14) The surface of the first conductive electrode 21 is covered with an insulating layer 30 which electrically isolates the first end electrode 41 with the first conductive area 211 and the second end electrode 42 with the second conductive area 212 on the first conductive electrode 21 respectively.

(15) The first conductive holes 51 passes through the first end electrodes 41 and the insulating layer 30 to be in electrical connect with the first conductive area 211. The second conductive holes 52 passes through the second end electrodes 42 and the insulating layer 30 to be in electrical connect with the second conductive area 212.

(16) In Embodiment 1, using the first and second end electrodes 41,42 which cover the the upper surface of the insulating layer 30 as pads instead of directly using the first and second conductive area 211,212 as pads is to avoid the bonding strength between the first conductive electrode 21 and the PTC core material 10 from being weakened or even separation of the first conductive electrode and PTC core material while using the first and second conductive area 211,212 as pads during reflow soldering process.

(17) In Embodiment 1, preparation is according to the following steps:

(18) Step 1, the preparation of PTC chip: mixing the high polymer that is the component of conductive polymer composite base layers and conductive filler in a high-speed mixer, then mixing the mixture at 100-200 C., and then using extrusion or compression molding to make a PTC core material 10 with an area of 1005000 cm.sup.2 and a thickness of 0.13.0 mm; pressing the first and second conductive electrodes 21,22 on the first and second surfaces of the PTC core material 10 respectively by hot pressing to make a composite material sheet, processing the composite material sheet by -ray (Co60) or electron beam irradiation crosslinking with 2100 Mrad dose, and then cutting the composite material sheet to get a rectangular PTC chip.

(19) Step 2, etching or cutting a straight-groove dividing gap 70 on the first conductive electrode 21 to form first and second conductive areas 211,212; the area of the first conductive area 211 is larger than the area of the second conductive area 212 and determined according to the resistance value requirement of the PTC chip;

(20) Step 3, etching an outwards-opening groove and plating a metal conductive member 60 at one end edge of the first conductive area 211 of the PTC chip to conduct the first conductive area 211 and the second conductive electrode 22;

(21) Step 4, covering a insulating layer 30 on the first conductive electrode 21 and filling the dividing gap 70 with insulating material;

(22) Step 5: Setting first and second end electrodes 41,42 in longitudinal parallel and making the dividing gap to be parallel to the first and second end electrodes 41,42 and not to be in contact with the conductive member 60, drilling and electroplating first and second conductive holes 51,52 on the first and second end electrodes 41,42, conducting the first end electrode 41 and the first conductive area 211 through the first conductive hole 51 and using the first end electrode 41 as a pad; conducting the second end electrode 42 and the second conductive area 212 through the second conductive hole 52 and using the second end electrode 41 as a pad.

Embodiment 2

(23) As illustrated in FIG. 3, the surface-mounted polymer PTC overcurrent protection element having a small package size of Embodiment 2 is similar to Embodiment 1. In addition to Embodiment 1, a reinforced layer 90 is covered on the surface of the second conductive electrode 22 of the PTC chip in order to reinforce structural strength of the surface-mounted element, and a insulating reinforcement 80 is put into the conductive member 60 which conduct the first conductive electrode 21 and the second conductive electrode 22 in order to reinforce structural rigidity and strength of the overcurrent protection element, the specific structure is as follows:

(24) The first and second surfaces of the PTC core material 10 are covered with first and second conductive electrodes 21,22 to compose a PTC chip. A rectangular dividing gap 70 which is parallel to the longitudinal direction of the first and second end electrode 41,42 is etched or cut on the first conductive electrode 21 to form first and second conductive areas 211,212 that are not in electrical connect with each other.

(25) A conductive member 60 is arranged at the end edge of the PTC chip. The conductive member 60 conducts the first conductive area 211 which covers the first surface of the PTC chip and the second conductive electrode 22 which covers the second surface of the PTC chip. An insulating reinforcement 80 is put into the conductive member 60.

(26) The surface of the first conductive electrode 21 is covered with an insulating layer 30 which electrically isolates the first end electrode 41 with the first conductive area 211 and the second end electrode 42 with the second conductive area 212 on the first conductive electrode 21 respectively.

(27) The first conductive holes 51 passes through the first end electrodes 41 and the insulating layer 30 to be in electrical connection with the first conductive area 211 to use the first end electrodes 41 as pad. The second conductive holes 52 passes through the second end electrodes 42 and the insulating layer 30 to be in electrical connection with the second conductive area 212 to use the second end electrodes 42 as pad.

(28) The outer surface of the non-soldering side of the second conductive electrode 22 is covered by reinforced layers which may be an insulating layer, metal foil layers or any combination of insulating layers and metal foil layers in order to reinforce structural strength of the element.

(29) In addition to the advantages of the Embodiment 1, the structure of Embodiment 2 is reinforced.

Embodiment 3

(30) As illustrated in FIG. 4, the surface-mounted polymer PTC overcurrent protection element having a small package size of Embodiment 3 is similar to Embodiment 1, and FIG. 5 illustrates the bottom view of the second conductive electrode of the structure diagram in FIG. 4. In addition to Embodiment 1, the conductive member 60 is transferred from the middle of one end edge of the PTC chip to one corner of the end edge of the PTC chip. In addition to Embodiment 2, four corner holes are prepared in four corners of the PTC chip, and four insulating reinforcements are put into the four corner holes.

Embodiment 4

(31) As illustrated in FIG. 6, the bottom view of the second conductive electrode 22 surface-mounted polymer PTC overcurrent protection element having a small package size of Embodiment 4 is is similar to the bottom view of the second conductive electrode 22 of Embodiment 3 in FIG. 5. In addition to Embodiment 3, first and second conductive members 61,62 are arranged at the two corners of the first conductive area of the PTC chip.

(32) The design of double conductive members can improve the stability of the conductive members. When one of the conductive member is defective, the other conductive member can still conduct the first conductive area 211 of the first conductive electrode 21 and the second conductive electrode 22.

Embodiment 5

(33) As illustrated in FIG. 7, the first conductive electrode 21 of the surface-mounted polymer PTC overcurrent protection element having a small package size of Embodiment 5 is another preferred scheme. In addition to Embodiment 1 to 4, there are graphic designs in use for the dividing gap 70 on the first conductive electrode 21. Different from the graphic design of the straight-groove dividing gap in Embodiment 1, the graphic design of the dividing gap 70 is combined with arc and rectangular main portion which is still parallel to the longitudinal direction of the end electrodes. In Embodiment 5, the relative position and graphic of the dividing gap 70 determines the effective area of the first and second conductive area 211,212, and the the effective area of the second conductive area 212 determines the effective function part of the PTC overcurrent protection element. It can greatly improve design space of the product performance without relying on the formulation adjustment of PTC materials.

(34) The summary and features of the present invention have been disclosed as previously mentioned. However, the present invention as mentioned above is only brief or only related to a specific part of the present invention. Inventive Alternatives and Modifications. The scope of protection of the invention should not be limited by what is disclosed in the embodiments, but should also include various substitutions and modifications that do not deviate from the invention.