KR20140067107A - Positive temperature coefficient(ptc) device - Google Patents

Abstract

The present invention provides a PTC device in which the possibility of poor electrical connection of a solder connecting portion formed for connecting to a substrate is reduced as much as possible. A PTC device having a PTC unit having a layered PTC element and a PTC unit having a first layered electrode and a second layered electrode disposed on both surfaces of the layered PTC element and on both surfaces thereof and an insulating layer located outside of each layered electrode, The PTC element has a first end portion and a second end portion and has a first quadrangular cylinder concave portion at each corner portion at the first end portion and a second quadrant cylindrical concave portion at the second end portion at the first end portion , Each first quadrant cylindrical recess has a first castration electrode electrically connected to the first layered electrode, and each second quadrant cylindrical recess has a second castration electrode connected to the second layered electrode Respectively.

Description

PTC device {POSITIVE TEMPERATURE COEFFICIENT (PTC) DEVICE}

The present invention relates to a PTC device, particularly a surface mount type PTC device.

For example, a PTC device is used in various electric devices as a circuit protection device and constitutes a protection circuit of an electric device. Such a PTC device is disposed on a protection circuit board having a protection circuit. In that case, a surface mount type PTC device is often used in consideration of arrangement convenience.

The surface mount type PTC device is disposed in a protection circuit formed on a protection circuit board by being stacked such that the electrodes are placed on a tab or pad provided on a protection circuit board and electrically connected by brazing.

Such a PTC device is schematically shown in a perspective view in Fig. The illustrated PTC device 10 has a PTC element 11 constituting it. The PTC element 11 has layered electrodes disposed on the PTC element and both surfaces of the PTC element, and an insulating layer located outside the layered electrodes. In Fig. 1, these constituent elements are not shown, but are shown integrally as the PTC element 11. Fig.

The PTC element 11 has semi-cylindrical recessed portions 12 and 14 at side end faces at both side ends thereof and has side metal layer portions (for example, conductive metal plating layers) 16 and 18 on the surface of the semi-cylindrical recessed portion . On the other hand, the PTC element 11 also has end metal layer portions (for example, conductive metal plating layers) 20, 22 and 24, 26 on both upper and lower surfaces thereof. The side metal layer portions 16 and 18 are integrally connected to the end metal layer portions 20, 22 and 24 and 26 at the upper and lower ends thereof and are connected to the so-called castellation electrodes 20 + 16 + 22 and 24 + 18 +26).

In addition, in the illustrated embodiment, the castration electrode has metal layer portions on both the upper and lower surfaces of the PTC element 11. Generally, the castration electrode is provided on both ends of one of the upper and lower surfaces of the PTC element, (That is, it is not necessary to have the end metal layer portion at the end of the other surface). Thus, the castration electrode has an end metal layer portion at both ends of at least one of the upper surface and the lower surface of the PTC device.

Although not shown, in such a PTC device, one castration electrode is electrically connected to one electrode of the PTC device located in the PTC device, and the other castration electrode is electrically connected to the other electrode of the PTC device electrically Respectively. Such a PTC device is disclosed in, for example, Patent Document 1 below.

Such a PTC device is mounted on a substrate by printing a solder cream on a pad provided on the substrate, and applying a solder cream on the pad through the solder cream portion to the pad of the castration electrode A PTC device is disposed so that the end metal layer portion (for example, 22) is located, and the substrate on which the PTC device is disposed is placed in a reflow furnace to melt and solidify the solder. FIG. 2 is a cross-sectional view schematically showing a state in which the PTC device is mounted on a substrate by soldering.

2 is a cross-sectional view of the PTC device 10 of FIG. 1 mounted on a substrate 28, taken along a vertical plane including line X-X thereof. In Fig. 2, only the right end of the PTC device shown in Fig. 1 is shown, and the castration electrode is shown exaggerating its thickness for easy understanding. A solder connecting portion 32 is formed by brazing between the pad 30 on the substrate and the end metal layer portion 22 of the castellation electrode, and the solder connecting portion 32 is integrally joined and electrically connected. The solder melted in the reflow furnace is also wetted on the semi-cylindrical recessed portion and solidified as it is, and the solder portion 34 exists as a fillet portion also on the side metal layer portion 16 of the castellation electrode, 32, respectively.

U.S. Patent No. 6377467

As described above, it has been found that when the substrate on which the PTC device is soldered is used, the electrical connection between the PTC device and the substrate becomes poor. More specifically, it has been found that a part of the solder connecting portion 32 is peeled off between the end metal layer portion 22 and the pad 30, and as a result, the electrical connection therebetween becomes insufficient. Therefore, a problem to be solved by the present invention is to reduce the possibility that such an electrical connection becomes poor as much as possible.

The solder connecting portion 32 may be broken or the solder connecting portion may be formed on the end metal layer portion 22 and / or the side metal layer portion 16, The occurrence of peeling of a part of the solder connecting portion 32 can be seen.

Further investigation of this phenomenon shows that when the PTC device is operated, the temperature rises and the PTC element expands, and then the temperature of the PTC element lowers and contracts to return to its original shape. In the process of expansion and contraction . Further, even when the environment of the electric apparatus having the substrate (for example, an automobile room) repeats a rise in temperature and a drop in temperature, the PTC element repeats the process of expansion and contraction.

When the PTC element repeatedly expands and shrinks, stress is generated due to the volume change thereof, and it is highly likely that cracks, peeling, and the like will occur due to such stress. Particularly, in the case where the semi-cylindrical concave portion is provided on the side of the PTC device as described above, the stress generated by the expansion and contraction tends to concentrate the stress on the portion, and as a result, the phenomenon such as cracking and peeling tends to occur Came to the judgment. Therefore, by restraining the concentration of stress as described above, more specifically, by increasing the number of places where stress is likely to be concentrated, by reducing the total amount of stress concentrated at each of such locations, And the possibility of occurrence of defective electrical connection can be reduced.

Based on the above-described idea, the inventors have made intensive investigations on the suppression of the concentration of stress. As a result, it has been found that the points where stress is likely to be concentrated are not formed at two locations on both sides of the PTC device, It is thought that the possibility of the failure of the electrical connection is reduced by forming the portion at four positions.

Thus, in a first aspect, the present invention provides a PTC device,

In this PTC device,

A PTC unit having a layered PTC element and a first layered electrode and a second layered electrode disposed on both surfaces of the layered PTC element, and an insulating layer disposed outside (that is, outside the PTC unit) of each layered electrode Layered) PTC element,

The PTC element has a first end portion and a second end portion and has a first quadrangular cylinder concave portion at each corner portion at the first end portion and a second quadrant cylindrical concave portion at the second end portion at the first end portion ,

Each of the first quadrant cylindrical recesses has a first castration electrode electrically connected to the first layered electrode and each second quadrant cylindrical recess has a second castration electrode connected to the second layered electrode Have

.

In one embodiment, in addition to the first quadrant cylindrical recess and the second quadrant cylindrical recess, the PTC device may further include the above-described semi-cylindrical recess at the first end and the second end.

In a PTC device of the first aspect described above, in one preferred embodiment, a plurality of PTC units each having a PTC element and layered electrodes disposed on both surfaces thereof may be laminated via an insulating layer.

That is, in a second aspect, the present invention provides another PTC device,

In this PTC device,

A plurality of layered PTC elements and a plurality of PTC units each having a first layered electrode and a second layered electrode disposed on both side surfaces of the respective PTC elements and a plurality of PTC units disposed between the PTC units to sandwich the PTC units therebetween And a PTC element as a laminate in which an insulating layer is laminated,

The PTC element has a first end and a second end,

The PTC element has a first quadrangular cylinder concave portion at each corner portion at a first end portion and a second quadrangular cylinder concave portion at a corner portion at a second end portion,

Each of the first quadrant cylindrical recesses has a first castration electrode electrically connected to the first layered electrode of each PTC element and each second quadrant cylindrical recess has a second casting electrode connected to the second layered electrode, Having a tullation electrode

.

In one embodiment, the PTC device may further include the above-described semi-cylindrical recessed portion at the first end and the second end of the PTC element laminate, in addition to the first quadrant cylindrical recess and the second quadrant cylindrical recess.

In the PTC device of the present invention, since the quadrilateral recessed portion is provided at the corner portion of the PTC element or the PTC element laminate and the castration electrode is disposed at the portion, the stress generated by the expansion and contraction of the PTC element is concentrated As a result, the total amount of stress acting on one castellation electrode can be reduced, so that the possibility of a poor electrical connection of the solder connecting portion functioning in electrical connection with the PTC device can be reduced As much as possible.

1 schematically shows a perspective view of a conventional PTC device.
2 schematically shows a state in which a conventional PTC device is mounted on a substrate.
3 schematically shows a plan view of the PTC device of the present invention.
4 schematically shows another plan view of the PTC device of the present invention.
Fig. 5 schematically shows a cross-section (along the line YY in Fig. 4) of the inventive PTC device with a single PTC unit.
Fig. 6 schematically shows a cross section (along the line YY in Fig. 4) of the PTC device of the present invention having a plurality of PTC units.
Fig. 7 schematically shows a perspective view of the PTC device of the present invention shown in Fig. 3;
8 schematically shows a plan view of a compact to explain the manufacturing method of the PTC device of the present invention.

3 is a plan view of a PTC device (corresponding to the case of viewing in the direction of arrow A in Fig. 1) when mounting the PTC device of the present invention on a substrate such that the surface facing the substrate faces upward, A perspective view is schematically shown in Fig. Therefore, the lower surface 38 of the PTC device shown in Figs. 1 and 2 becomes the upper surface 38 in Figs. 3 and 7. In the illustrated embodiment, the PTC device 10 has the PTC device 11, and the PTC device has the first end 42 and the second end 44.

The PTC element includes a first quadrant cylindrical recess (see FIG. 3) 36 or a first quadrant cylindrical recess (see FIG. 7) 36 and a second quadrant cylindrical recess (see FIG. 3) (In the case where there is no cutout portion), or a rectangular parallelepiped shape in the perspective view of Fig. 7, which is cut out from the first quadrant cylindrical recess (see Fig. . These quadrant circular portions (or quadrangular cylinder concave portions) 36 and 37 are derived from the PTC element 10 constituting the PTC device having quadrant cylindrical recesses as cut-out portions at four corner portions.

More specifically, the PTC device 11 has two first quadrangular cylindrical portions 36 at a first end 42 and two first quadrangular cylindrical portions 36 at a second end 44 37). In another form, between the two first or second quadrangular cylindrical portions 36 and / or 37, there may be a semi-cylindrical recess 12 as shown in Fig.

It is particularly preferable that the quadrant cylindrical recess 36 has a shape of a quarter of the diameter of the cylinder (and thus, a shape of a quadrant in FIG. 3). However, as long as the four corners of the PTC element 11 are notched, the PTC element 11 may have another notch shape instead of the quadrature shape. In the plan view, the notch shape may be a right triangle shape or a ¼ ellipse shape.

The illustrated PTC device 10 has a side metal layer portion 16 on a side surface 40 defining each first quadrangular concave portion 36 of the PTC device 11 and has one end (Upper end portion 46 in the form shown in Fig. 4A), and the metal layer portions are integrally connected to constitute the first castration electrode 50. [ The PTC device 10 has the side metal layer portion 17 on the side surface 41 defining the second quadrant cylindrical recessed portion 37 of the PTC element 11 and has one end portion Has an end metal layer portion 23 at an upper end 47 and these metal layer portions are integrally connected to constitute a second castration electrode 52. [

The lateral metal layer of the castration electrode extends over the entire surface of the side surface defining the recess. The end metal layer portion 22 and / or 23 may be annular as shown in Fig. 3, Or may have a rectangular shape (however, it may have a notch corresponding to a quadrant) as shown in Fig.

7) of the side surface metal layer portion 20 (in Fig. 7, for example, the front side surface of the side surface metal layer portion 20 (That is, the end metal layer portion 22 or 23 on one end portion 46, the side metal layer portion 16 or 17 on the side surface, and the other end portion 48 on the other end portion 48) The end metal layer portion 20) may constitute the first and / or the second castration electrode. Although not shown, the first castration electrode 50 is electrically connected to the first layered electrode disposed on the main surface of one or a plurality of PTC elements constituting the PTC element, and the second castration electrode The electrode 52 is electrically connected to the second layered electrode disposed on the main surface of one or a plurality of PTC elements constituting the PTC element.

The entire castellation electrode may be formed by a plating process using a conductive metal. In this case, after plating a portion of the conductive metal (for example, copper, nickel, tin or the like) after masking the portion other than the portion forming the castration electrode, and then removing the masking, the castration electrode is formed . In this case, the side metal layer portion and the end metal layer portion are all constituted by a plating layer.

In another embodiment, the end metal layer portion may be a metal foil and a plating layer formed thereon. In this case, as will be described later, a pressed body obtained by laminating a metal foil on the insulating resin sheet forming the insulating layer as the outermost layer of the PTC element is formed. After the metal foil is left at predetermined positions by etching, A metal layer portion can be formed. Also in this embodiment, the side metal layer portion is constituted by the plating layer.

Further, in another embodiment, a metal layer having excellent corrosion resistance is formed on the outermost layer of the castellation electrode formed by the plating layer or the metal layer and the plating layer formed thereon by the plating process . For example, in the case where the outermost layer is made of copper, it is preferable to superpose nickel, then a plated layer of tin, or nickel, and then a gold plated layer thereon.

Fig. 5 schematically shows a cross section of the PTC device according to the present invention taken along line Y-Y in Fig. 4. The illustrated PTC element 10 includes a layered PTC element 54 and a PTC unit 60 having a first layered electrode 56 and a second layered electrode 58 disposed on both sides of the layered PTC element 54, Layered PTC element 66 having a first insulating layer 62 and a second insulating layer 64 located outside the electrode (that is, outside the PTC unit). The PTC element 66 has a first end 42 and a second end and at a first end thereof a first quadrant cylindrical recess 36 at each corner portion and at a second end, And has a second quadrant cylindrical recess 37 in its portion.

Further, the PTC unit including the layered PTC element, the layered electrode (usually, metal foil) located on both sides thereof, and the insulating layer is a well-known member, and is described in, for example, the above patent document, and therefore detailed description thereof is omitted.

As shown, a first castration electrode 50 electrically connected at its end 68 to the first layered electrode 56 is formed on the side 40 defining the first quadrant cylindrical recess, A second castration electrode 52 electrically connected to the second layered electrode 58 at the end portion 70 is formed on the side surface 41 defining the second quadrant cylindrical recessed portion 37 .

In order to facilitate understanding, in the illustrated embodiment, each castration electrode includes a lateral metal layer portion 72 (corresponding to reference numeral 16 or 18 in FIG. 1) and an upper surface of the PTC element 66 (Corresponding to reference numeral 20 or 24 in Fig. 1) and 76 (corresponding to 22 or 26 in Fig. 1) located at both ends of the lower metal layer 74 . The metal layer portion is preferably a metal plating layer from the viewpoint of efficient production as described later.

Fig. 6 schematically shows a cross-sectional view of a PTC device according to another embodiment of the present invention, which is cut in the same manner as in Fig. 3. In the illustrated form, a plurality of layered PTC elements 78 and 80 as a plurality of examples, and first layered electrodes 82 and 84 and second layered electrodes 86 and 88, respectively, disposed on opposite sides of each PTC element, And two PTC units 90 and 92 each having a plurality of PTC units. These PTC units are sandwiched by the insulating layers 94, 96, and 98 so as to locate the insulating layers on both sides thereof, and are disposed therebetween. These insulating layers and PTC units disposed therebetween are laminated to form a PTC element as a laminate.

5, the PTC element has a first end portion 42 and a second end portion 44, and at these ends, a first quadrant cylindrical portion 36 and a second quadrant cylindrical portion 37 , And a first castration electrode (50) and a second castration electrode (52) are formed on the side defining them. The first layered electrodes 82 and 84 are electrically connected to the first castration electrode 50 at the ends thereof and the second layered electrodes 86 and 88 are electrically connected to the second castration electrode 50. [ And is electrically connected to the electrode 52.

In the embodiment shown in Fig. 6, two PTC units are stacked, but more PTC units may be stacked so that the PTC unit is sandwiched by the insulating layer. In this case, one layer electrode of each PTC unit is connected to the first castration electrode and the other one of the layer electrodes is connected to the second castration electrode, so that the device in which the PTC unit is connected in parallel have.

For example, the PTC device of the present invention can be manufactured as follows. (For example, a metal foil) constituting the layered electrode, or by simultaneously extruding the polymer PTC composition and the metal layer onto the both main surfaces of the polymer PTC sheet obtained by extrusion molding the polymer PTC composition, A metal layer is sandwiched between the metal layers. Subsequently, the obtained laminate is etched to remove a portion of the metal layer (a portion corresponding to the portion 100 in Fig. 5 or 6), and thereafter, an insulating resin sheet (for example, And a conductive metal foil (for example, a copper foil) is superimposed on the outer side as required, and these are integrally pressed to obtain a pressed body.

Thereafter, as shown in Fig. 8, a cylindrical hole is formed at a predetermined portion of the pressed body. Then, the whole of the perforated squeeze body is subjected to copper plating treatment at one time, and then only the portion corresponding to the end metal layer portion of the upper and lower surfaces and the cylindrical concave portion formed by perforation are masked, Is etched. Thereafter, the masking is removed, and one portion (22) or (23) corresponding to the end metal layer portion of the upper surface and the lower surface (a rectangle obtained by cutting out the fan-shaped portion 104 at 90 degrees) A plated layer 106 on the side of the cylindrical recess formed by perforation and a larger rectangular plating layer 106 is formed. 8 is a schematic plan view of the compact 102 thus formed. The portion corresponding to the end metal layer portion 22 or 23 on the upper surface and the lower surface formed as described above is constituted by a copper foil and a copper plating layer formed thereon. For example, as shown in Figs. 5, 6, and 7 They are represented as an integral. Thereafter, the pressed body 102 may be subjected to a metal plating treatment (for example, a plating treatment of nickel or tin), if necessary.

Further, by drilling, the thickness portion of the layered metal disposed on the PTC element is exposed to the side surface portion of the cylindrical concave portion, and such side surface portion is plated to form a side metal plating layer of the castration electrode on the side surface, Is electrically connected to the side metal plating layer.

The PTC device 10 of the present invention can be obtained by cutting the plated compact 102 along the dividing line 110 in the longitudinal direction and the dividing line 112 in the transverse direction in this manner. Thus, the PTC device can be efficiently manufactured by forming the pressed body in a state in which the PTC devices are adjacent to each other laterally and vertically, and then dividing the pressed body.

5 and 6, the layered electrode of the PTC device is formed by the formation of the compacted body, the perforation and the plating treatment as described above, except that the quadrangular cylindrical concave portion is formed at a predetermined portion of the PTC element. A method of manufacturing a PTC device having a structure electrically connected to a castration electrode is basically known and can be referred to, for example, Patent Document 1 described above.

Further, the PTC device of the present invention is particularly effective when the PTC element is rigid. That is, when the conductive polymer composition constituting the PTC element comprises a relatively hard polymer, for example, when a polyvinylidene fluoride resin (PVDF) is contained, compared with a resin (e.g., polyethylene) , It is difficult to relieve the stress caused by the expansion and contraction of the PTC element. Therefore, it is effective to form a quadrant cylindrical recess in the PTC device and form a castration electrode thereon.

10: PTC device
11: PTC element
12, 14: semicylindrical concave portion
16, 18: side metal layer portion
20, 22, 24, 26: end metal layer portion
28: substrate
30: Pad
32: solder connecting portion
34: solder portion
36: first quadrant cylindrical recess
37: second quadrant cylindrical recess
40, 41: side
42: First end
44: second end
46: one end
48: the other end
50: First castration electrode
52: second castration electrode
54: Layered PTC element
56: first layer electrode
58: second layer electrode
60: PTC unit
62: first insulating layer
64: second insulating layer
66: PTC element
68: end of the first layer electrode
70: end of the second layered electrode
72: side metal layer portion
74, 76: end metal layer portion
78, 80: Layered PTC element
82, 84: first layer electrode
86, 88: second layer electrode
90, 92: PTC unit
94, 96, 98: insulation layer
100: a part of the metal layer
102:
104:
106: Larger rectangular plating layer

Claims (6)

There is provided a PTC device comprising a PTC element having a layered PTC element and a PTC unit having a first layered electrode and a second layered electrode respectively disposed on both surfaces thereof and an insulating layer positioned outside of each layered electrode,
The PTC element has a first end portion and a second end portion and has a first quadrangular cylinder concave portion at each corner portion at the first end portion and a second quadrant cylindrical concave portion at the second end portion at the first end portion ,
Each of the first quadrant cylindrical recesses has a first castration electrode electrically connected to the first layered electrode and each second quadrant cylindrical recess has a second castration electrode connected to the second layered electrode And the PTC device. A plurality of layered PTC elements and a plurality of PTC units each having a first layered electrode and a second layered electrode disposed on both side surfaces of the respective PTC elements and a plurality of PTC units disposed between the PTC units to sandwich the PTC units therebetween And a PTC element as a laminate in which an insulating layer is laminated,
The PTC device has a first end and a second end,
The PTC element has a first quadrangular cylinder concave portion at each corner portion at a first end portion and a second quadrangular cylinder concave portion at a corner portion at a second end portion,
Each of the first quadrant cylindrical recesses has a first castration electrode electrically connected to the first layered electrode of each PTC element and each second quadrant cylindrical recess has a second casting electrode connected to the second layered electrode, Wherein the PTC device has a tilting electrode. 3. The method according to claim 1 or 2,
Each of the castration electrodes has a side metal layer portion formed on a side defining the quadrant cylindrical recess and an end metal layer portion extending on an end of one main surface of the PTC element. The method of claim 3,
Wherein the end metal layer portion comprises a metal foil portion and a metal plating layer portion formed thereon. The method according to claim 3 or 4,
Wherein the side metal layer portion is formed by a metal plating layer. 6. The method according to any one of claims 1 to 5,
Wherein the layered PTC element is formed of a conductive polymer composition comprising polyvinylidene fluoride.

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