TWM635439U - Circuit protection device - Google Patents

Abstract

A circuit protection device includes a first temperature sensitive resistor, a second temperature sensitive resistor, an insulating multilayer, a first and second electrode layer, and at least one external electrode. The first temperature sensitive resistor and the second temperature sensitive resistor are electrically connected in parallel, and have a first upper conductive layer and a second lower conductive layer, respectively. The insulating multilayer includes an upper insulating layer, a middle insulating layer, and a lower insulating layer. The upper insulating layer is between the first upper conductive layer and the first electrode layer. The middle layer is laminated between the first temperature sensitive resistor and the second temperature sensitive resistor. The lower insulating layer is between the second lower conductive layer and the second electrode layer. The external electrode is disposed on the first electrode layer, and extends beyond a peripheral wall the along a horizontal direction.

Description

Circuit Protection Components

The present invention relates to a circuit protection element, and more specifically, to a heat-stable circuit protection element with a thermally sensitive element connected in parallel.

It is known that the resistance of conductive composite materials with positive temperature coefficient (Positive Temperature Coefficient, PTC) characteristics is very sensitive to the change of specific temperature, which can be used as the material of the current sensing element, and has been widely used in circuit protection elements. Specifically, the resistance of PTC conductive composite materials can maintain a very low value at normal temperature, so that the circuit or battery can operate normally. However, when an over-current or overtemperature occurs in a circuit or a battery, its resistance value will instantly increase to a high resistance state (at least 10 ⁴ Ω), which is called a trip. , and cut off the excessive current to achieve the purpose of protecting the battery or circuit components.

Taking polymer PTC materials as an example, carbon black is usually used as a conductive filler, and carbon black is dispersed between crystalline polymers. This crystal structure allows the carbon particles to be concentrated in the grain boundaries, and they are packed so tightly together that electricity can flow through the insulating plastic polymer via these "carbon chains". Under normal room temperature conditions, there are a considerable number of carbon chains in these high molecular polymers, thus forming a conductive channel. When the overcurrent causes the temperature of the component to rise until it exceeds the phase transition temperature (such as the melting point) of the polymer, the polymer will expand and the carbon particles that were originally tightly connected will be separated. In this way, the conductive carbon chain channel is destroyed and can no longer conduct current, so that the resistance also rises sharply, which is the so-called "trip" phenomenon.

When the temperature returns below its phase transition temperature, the polymer recrystallizes and the conductive carbon chains reform. However, in practice, the conductive carbon chain cannot maintain the original conductivity due to the incomplete recovery of the polymer expansion, so the resistance cannot return to the original low resistance value. In addition, there is a phenomenon that the resistance value increases significantly after repeated triggering, that is, there is a problem of poor resistance recovery or resistance reproducibility.

In more detail, when the PTC polymer material is triggered, it will produce a considerable volume change rate, and its coefficient of thermal expansion (Coefficient of Thermal Expansion, CTE) will suddenly increase (for example: to more than 5000 ppm/K). Therefore, after multiple triggers, the PTC polymer material undergoes multiple drastic changes in volume, which will make the structure unable to return to the initial state, and then lead to a situation where its resistance value rises sharply at room temperature. However, most of the conductive layers in contact with the surface of the PTC material layer are made of metal conductive materials such as nickel foil, copper foil or nickel-plated copper foil, where the thermal expansion coefficient of copper foil and nickel-plated copper foil is about 17 ppm/K, and that of nickel The coefficient of thermal expansion is 13 ppm/K, which is much smaller than that of PTC polymer materials. Therefore, traditionally, the structural design of the conductive layer is mainly improved to solve the aforementioned problem of resistance reproducibility. For example: increasing the thickness of the conductive layer to strengthen the structural strength.

Furthermore, the development of electronic products is advancing by leaps and bounds nowadays. In order to achieve fast charging and discharging effects, the products to be protected by circuits (such as batteries) require more and more current than before. For this reason, traditionally, the size of a single heat-sensitive element in a circuit protection element (that is, two conductive layers plus a positive temperature coefficient material layer stacked in the middle) is designed to be larger, thereby increasing the surface area of the conductive layer to reduce overall resistance. However, excessive size of circuit protection components will take up too much space, and the application will be limited under the trend of miniaturization of electronic products. In addition, even if the circuit protection element is successfully designed to be smaller and maintain a low resistance value, the circuit protection element will face the problem of thermal stability, that is, the heat generated by the circuit protection element is easy to accumulate and cannot be dissipated outward, resulting in the circuit protection element It is impossible to increase the holding current (Hold Current; I _hold ), and even when the circuit protection element is triggered, it will expand and cause excessive thermal stress, and cause the problem of poor resistance recovery or resistance reproducibility as mentioned above, so the circuit protection element is used in the application restricted.

Obviously, miniaturized circuit protection components are the future trend, but miniaturized circuit protection components face many of the above-mentioned problems. In view of this, the conventional circuit protection devices need to be improved to solve the above-mentioned problems of poor resistance recovery, low resistance value and thermal stability structure.

In this invention, at least two heat-sensitive elements are connected in parallel, so that the circuit protection element can have a lower resistance value under a certain size, so as to increase the current passing capacity. In other words, the aforementioned parallel structure means that the circuit protection element can be designed to be smaller in size while maintaining low resistance value characteristics. In addition, the electrical and structural characteristics of circuit protection components are highly susceptible to thermal energy as the size shrinks and/or the amount of current increases. Based on the possible design problems caused by the parallel connection of heat-sensitive elements, this creation has improved a number of different components to increase the thermal stability of the circuit protection element: First, the upper and lower inner electrodes (hereinafter referred to as the first electrode layer and the second electrode layer) The upper and lower insulating layers with a coefficient of thermal expansion much smaller than that of the positive temperature coefficient (PTC) material layer are added below and above the electrode layer, thereby increasing the structural strength of the circuit protection component and solving the problem caused by thermal expansion of the circuit protection component. The problem of poor resistance reproducibility; secondly, adding an external electrode, adjusting its surface area, position and extension length to increase its surface area exposed to the environment, thereby improving the heat dissipation rate of the circuit protection component, and thereby improving the maintenance of the circuit protection component Current (Hold Current, I _hold ); third, add a plurality of gaps on the same side of the circuit protection element to disperse the stress of thermal expansion; fourth, package the circuit protection element on the periphery, in addition to isolating the influence of environmental factors, Further stabilize the overall structure of the circuit protection element.

One embodiment of the invention is a circuit protection element, which has an upper surface, a lower surface opposite to the upper surface, and a peripheral wall connecting the upper surface and the lower surface. The circuit protection element includes a first heat-sensitive element, a second heat-sensitive element, an insulating material multilayer structure, a first electrode layer, a second electrode layer and a first external electrode. The first thermal element includes a first upper conductive layer, a first lower conductive layer, and a first positive temperature coefficient (Positive Temperature Coefficient, PTC) material layer stacked between the first upper conductive layer and the first lower conductive layer . The second thermal element includes a second upper conductive layer, a second lower conductive layer, and a second positive temperature coefficient material layer stacked between the second upper conductive layer and the second lower conductive layer. The insulating material multilayer structure has an upper insulating layer, a middle insulating layer and a lower insulating layer. The upper insulating layer extends beyond the first upper conductive layer, thereby completely covering the first upper conductive layer and covering part of the first positive temperature coefficient material layer. The intermediate insulating layer is stacked between the first lower conductive layer and the second upper conductive layer, and is connected to the first thermal element and the second thermal element. The lower insulating layer extends beyond the second lower conductive layer, thereby completely covering the second lower conductive layer and covering part of the second positive temperature coefficient material layer. The first electrode layer and the second electrode layer are attached to the upper insulating layer and the lower insulating layer respectively, and the first electrode layer is electrically connected to the first upper conductive layer and the second upper conductive layer, and the second electrode layer is connected to the first The lower conductive layer and the second lower conductive layer are electrically connected. The first external electrode is disposed on the first electrode layer and extends beyond the peripheral wall along a first horizontal direction parallel to the first electrode layer.

In one embodiment, the circuit protection element further includes a right notch and a left notch. The upper insulating layer is attached between the first electrode layer and the first upper conductive layer, so that the first electrode layer and the first upper conductive layer are separated by a distance, and the first electrode layer and the first upper conductive layer extend parallel to each other to the right. The notch is electrically connected through the right notch.

In one embodiment, the distance is 0.02 mm to 0.06 mm.

In one embodiment, an opening is formed directly above where the upper insulating layer covers part of the first positive temperature coefficient material layer without covering the first electrode layer, so that the first electrode layer will not extend to the left gap, so that the first electrode layer Not electrically connected to the left notch.

In one embodiment, the circuit protection element further includes an insulating material, and the insulating material is filled into the opening.

In one embodiment, the right notch has a right conduction member, so that the first electrode layer, the first upper conductive layer and the second upper conductive layer are electrically connected, and the left notch has a left conduction member, so that the second electrode layer, the first The lower conductive layer and the second lower conductive layer are electrically connected.

In one embodiment, the circuit protection device further includes a structure-strengthening metal film, and the structure-strengthening metal film covers the surface of the first electrode layer, the surface of the second electrode layer, the surface of the right conducting element, and the surface of the left conducting element, so that the first The electrode layer, the second electrode layer, the right conducting element and the left conducting element are isolated from ambient gas.

In one embodiment, the peripheral wall has a left side wall, a right side wall, a front side wall and a rear side wall, the left side wall is opposite to the right side wall, and the front side wall is opposite to the rear side wall, wherein the left notch is located on the left side wall, and the right notch is located on the right side wall.

In one embodiment, the first external electrode extends beyond the right side wall along the first horizontal direction.

In one embodiment, the circuit protection element has a first length parallel to the first horizontal direction, and the first external electrode is counted from the right side wall and has a second length beyond the right side wall, and the sum of the first length and the second length is On a 100% basis, the second length accounts for 31% to 53%.

In one embodiment, the second length is 4 mm to 8 mm.

In one embodiment, the upper surface of the circuit protection element has an upper surface area of the circuit protection element, and the first external electrode has an upper surface area of the first outer electrode, and the ratio of the upper surface area of the first outer electrode divided by the upper surface area of the circuit protection element is 1.37 to 1.64 .

In one embodiment, the circuit protection device further includes a second external electrode disposed on the second electrode layer covering the structural strengthening metal film, wherein the first external electrode extends beyond the front sidewall in a second horizontal direction parallel to the first electrode layer, And the second external electrode extends beyond the rear sidewall parallel to the first external electrode.

In one embodiment, the circuit protection device further includes a second external electrode, disposed on the second electrode layer covering the structural strengthening metal film, and extending beyond the left sidewall along a direction opposite to the first horizontal direction.

In one embodiment, the circuit protection device further includes a packaging tape. The packaging tape is wound around the upper surface, the front side wall, the lower surface and the rear side wall with the circuit protection component as the axis, so that the circuit protection component only exposes the right side wall, the left side wall, part of the first external electrode and part of the second electrode. external electrode.

In one embodiment, the circuit protection element further includes an insulating frame. The insulating frame covers the circuit protection element, so that the circuit protection element only exposes part of the first external electrode and part of the second external electrode.

In one embodiment, the circuit protection element further includes a plurality of right notches and a plurality of left notches opposite to the right notches, respectively disposed on the right side wall and the left side wall of the peripheral wall, wherein the first external electrode extends along the first horizontal direction beyond the right side wall.

In one embodiment, the circuit protection device further includes a second external electrode disposed on the second electrode layer and extending beyond the left sidewall parallel to the second electrode layer along a direction opposite to the first horizontal direction.

In one embodiment, the circuit protection component further includes a package tape, and the package tape is wound around the circuit protection component, so that the circuit protection component only exposes the right side wall, the left side wall, part of the first outer electrode and part of the second outer electrode. electrode.

In one embodiment, the circuit protection element further includes an insulating frame, and the insulating frame covers the circuit protection element, so that the circuit protection element only exposes part of the first external electrode and part of the second external electrode.

To make the above and other technical contents, features and advantages of this creation more obvious and easy to understand, the relevant embodiments are specifically listed below, together with the accompanying drawings, and are described in detail as follows.

Please refer to Fig. 1 to Fig. 5, which are perspective views, sectional views, partial enlarged views and top views of the first embodiment of the invention. In FIG. 1 , a circuit protection device 100 has a PTC chip structure as a core. The PTC chip structure has a left notch 62 and a right notch 61 , and a first external electrode 51 is disposed on the upper surface 101 and a second external electrode 52 is disposed on the lower surface 102 . For the convenience of understanding and illustration, in FIG. 2 , the first external electrode 51 and the second external electrode 52 are separated from the PTC chip structure. In addition, the x, y, and z axis systems in the drawings are used to present the orientation in space, which is convenient for explaining the creation from various perspectives. The circuit protection device 100 has an upper surface 101 , a lower surface 102 opposite to the upper surface, and a peripheral wall 103 connecting the upper surface 101 and the lower surface 102 . The peripheral wall 103 has a left side wall S2, a right side wall S1, a front side wall S4, and a rear side wall S3. The left side wall S2 is opposed to the right side wall S1, and the front side wall S4 is opposed to the rear side wall S3. The left notch 62 is located on the left side wall S2, and the right notch 61 is located on the right side wall S1. In order to increase the structural strength of the circuit protection element to avoid the problem of poor resistance recovery or resistance reproducibility caused by expansion when triggered, and to prevent the electrode layers used as electrical connections (such as the first electrode layer 41 and the second electrode layer 42) and the oxidation of the conductive member (such as the right conductive member 63 and the left conductive member 64), the upper surface 101, the lower surface 102, the left notch 62 and the right notch 61 are covered with a structural strengthening metal film 80 (for example: tin foil, nickel foil , Nickel-plated copper foil, which can be formed by spraying or electroplating).

Please refer to FIG. 3 , which is a sectional view cut down along line AA in FIG. 1 . The circuit protection element 100 includes a first thermal element 10, a second thermal element 20, an insulating material multilayer structure 30, a first electrode layer 41, a second electrode layer 42, a left notch 62, a right notch 61 and at least one external electrode ( For example: the first external electrode 51 and/or the second external electrode 52). The first electrode layer 41 is electrically connected to the first thermosensitive element 10 and the second thermosensitive element 20 through the right notch 61, and the second electrode layer 42 is electrically connected to the first thermosensitive element 10 and the second thermosensitive element through the left notch 62. 20 electrical connection. The first electrode layer 41 and the second electrode layer 42 can be regarded as internal electrodes of the circuit protection device 100 . In an embodiment, the circuit protection device 100 can also be made into a surface-mountable type without the external electrodes 51 and 52 , so as to be directly soldered on the circuit board to form a current path together with the external circuit. The first thermosensitive element 10 comprises a first upper conductive layer 12, a first lower conductive layer 13 and a first positive temperature coefficient (Positive Temperature Coefficient, PTC) material layer 11. The second thermal element 20 includes a second upper conductive layer 22 , a second lower conductive layer 23 and a second positive temperature coefficient material layer 21 stacked between the second upper conductive layer 22 and the second lower conductive layer 23 . In addition, the circuit protection element has a first length L1, and the external electrode (such as the first external electrode 51 ) extends outward from the peripheral wall 103 by a second length L2 and itself has a third length L3. It should be noted that the circuit protection element 100 includes at least two heat-sensitive elements (namely, the first heat-sensitive element 10 and the second heat-sensitive element 20) with a positive temperature coefficient material layer, and these two heat-sensitive elements adopt Parallel structure design. Compared with the traditional circuit protection element with the same size but only a single thermal element, the circuit protection element 100 has at least two parallel thermal elements, which can effectively increase the surface area of the electrode layer and reduce the resistance. In other words, the circuit protection device 100 can also have a lower resistance value to increase the current passing capacity when the size is reduced. In addition, in order to make the aforementioned parallel structure more stable under high temperature environment, the present invention further improves different components. Please continue to refer to the following for details.

Please continue to refer to Figure 3 with the partial enlarged view of Figure 4. The insulating material multilayer structure 30 has an upper insulating layer 31 , a middle insulating layer 32 and a lower insulating layer 33 . The upper insulating layer 31 extends beyond the first upper conductive layer 12 , thereby completely covering the first upper conductive layer 12 and partially covering the first positive temperature coefficient material layer 11 . The intermediate insulating layer 32 is stacked between the first lower conductive layer 13 and the second upper conductive layer 22 , and connects the first thermal element 10 and the second thermal element 20 . The lower insulating layer 33 extends beyond the second lower conductive layer 23 , thereby completely covering the second lower conductive layer 23 and covering part of the second positive temperature coefficient material layer 21 . In one embodiment, the insulating material multilayer structure 30 can be selected from epoxy resin glass fiber composite material, epoxy resin, polyester resin, polyamide resin, phenolic resin, polyamine resin, polycyanate resin, Malay In the group consisting of imide resin, polyolefin resin, diphenylene ether resin, photosensitive resin and combinations thereof, the coefficients of thermal expansion of these materials are much smaller than those of the positive temperature coefficient material layers 11 and 21 . In addition, in order to improve adhesive properties, structural strength or other physical properties, the intermediate insulating layer 32 may be selected from the aforementioned resins, and may further include inorganic functional micro- or nano-particles.

More specifically, the upper insulating layer 31 is attached between the first electrode layer 41 and the first upper conductive layer 12 and forms physical contact with the two, so that the first electrode layer 41 and the first upper conductive layer 12 are separated by one The distance D, and the first electrode layer 41 and the first upper conductive layer 12 are parallel to each other and extend rightward along the y-axis to the right notch 61 , and are electrically connected through the right notch 61 . In addition, the upper insulating layer 31 covers part of the first positive temperature coefficient material layer 11 directly above (ie along the z-axis direction) not covering the first electrode layer 41 to form an opening O, so that the first electrode layer 41 will not extend to The left gap 62 , so that the first electrode layer 41 is not electrically connected to the left gap 62 . In addition, on the plane where the first electrode layer 41 is located (ie, the xy plane), there is no metal layer extending from the left gap 62 to cover the upper insulating layer 31 . That is to say, there is no electrode layer at the other end on the plane where the first electrode layer 41 is located, so even if the welding position of the first external electrode 51 on the xy plane deviates too much, it is not easy to be connected with the electrode at the other end. layer connection resulting in a short circuit. In one embodiment, the circuit protection device 100 further includes an insulating material 70 , such as solder resist ink commonly known as green paint. The insulating material 70 is filled into the opening O, thereby further increasing the insulation between the first electrode layer 41 and the left notch 62 , and reducing the solderability to prevent the external electrodes from being welded thereon. The lower insulating layer 33 is attached between the second electrode layer 42 and the second lower conductive layer 23 and forms physical contact with the two. There is also an opening O directly below the portion where the lower insulating layer 33 covers part of the second positive temperature coefficient material layer 21 , and its structure is the same as that of the opening O above the upper insulating layer 31 .

In this embodiment, the thermal expansion coefficient difference between the upper insulating layer 31 and the positive temperature coefficient material layer 11 is large, that is, the thermal expansion coefficient of the upper insulating layer 31 is much smaller than that of the positive temperature coefficient material layer 11, so the upper insulating layer 31 is increased. The layer 31 can suppress the expansion of the first positive temperature coefficient material layer 11, increase the structural strength of the overcircuit protection element 100, and solve the problem of poor resistance reproducibility caused by expansion when the element is triggered. In addition, the present invention further divides the conductor layer into two (namely the first upper conductive layer 12 and the first electrode layer 41 ) and connects them to the right notch 61 on the same side, thereby further increasing the conductor surface area in a single thermal element. In detail, when the first electrode layer 41 is separated from the first upper conductive layer 12 through the upper insulating layer 31, the lower surface of the first electrode layer 41 will not be coplanar with the upper surface of the first upper conductive layer 12, This in turn increases the size of the conductor surface area. As for the lower insulating layer 33, the second lower conductive layer 23, and the second electrode layer 42, they have the same relative structural design as the aforementioned upper insulating layer 31, the first upper conductive layer 12, and the first electrode layer 41. praise. The upper insulating layer 31 and the lower insulating layer 33 sandwich the two thermosensitive elements (ie, the first thermosensitive element 10 and the second thermosensitive element 20 ) from above and below to limit the degree of thermal expansion of the circuit protection element 100 and avoid deformation. . It should be particularly mentioned that the thickness of the upper insulating layer 31 and the lower insulating layer 33 is not too thick, so they do not occupy too much space of the circuit protection device 100 , and the space occupancy rate is low. For example, the distance D is about 0.02 mm to 0.06 mm. In one embodiment, the distance D is 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm or 0.06 mm. In addition, along the y-axis direction, the first electrode layer 41 has a fourth length L4, and the first upper conductive layer 12 has a fifth length L5. Both the fourth length L4 and the fifth length L5 are greater than half of the length of the circuit protection element 100 (ie, the first length L1 ), so as to obtain a lower resistance value. Generally speaking, in order to avoid excessive metal surface exposure, the size of the first electrode layer 41 is smaller than that of the first upper conductive layer 12 . That is, the fourth length L4 is smaller than the fifth length L5. In one embodiment, the aforementioned first length L1 is about 7 mm to 9 mm, for example: 7 mm, 7.3 mm, 7.9 m, 8.2 mm, 8.7 mm or 9 mm. According to the present invention, L4 can also be larger than L5, but it should not be too close to the left gap 62, so as to avoid the possibility of electric arc and even short circuit. It can be seen from the above that, in the case of low space occupancy, the upper insulating layer 31 and the lower insulating layer 33 can increase the surface area of the electrode conductor and increase the structural strength of the overcircuit protection element 100 .

Continuing to refer to FIG. 3 , the first electrode layer 41 and the second electrode layer 42 are attached to the upper insulating layer 31 and the lower insulating layer 33 respectively, and the first electrode layer 41 is connected to the first upper conductive layer 12 and the second upper conductive layer 22 are electrically connected, and the second electrode layer 42 is electrically connected to the first lower conductive layer 13 and the second lower conductive layer 23 . In more detail, the right notch 61 has a right conducting member 63, so that the first electrode layer 41, the first upper conductive layer 12 and the second upper conducting layer 22 are electrically connected by the right conducting member 63, and the left notch 62 has a The left conducting member 64 makes the second electrode layer 42 , the first lower conductive layer 13 and the second lower conducting layer 23 form an electrical connection through the left conducting member 64 . Also as mentioned above, the circuit protection device 100 may be coated with the structural strengthening metal film 80 as required. The structural strengthening metal film 80 covers the surface of the first electrode layer 41, the surface of the second electrode layer 42, the surface of the right via 63 and the surface of the left via 64, so that the first electrode layer 41, the second electrode layer 42, the right The conduction element 63 and the left conduction element 64 are isolated from ambient air. The thermal expansion coefficient of the structural strengthening metal film 80 is much smaller than that of the positive temperature coefficient material layers 11 , 21 , so the structural strength of the overcircuit protection element 100 can be increased. In addition, when the surfaces of the metal electrodes (ie, the first electrode layer 41 and the second electrode layer 42 ) are easily oxidized, the exposed parts can be covered with a structure-strengthening metal film 80 that is not easily oxidized but has good conductivity. Referring again to FIG. 2 , the upper surface of the first electrode layer 41 is covered with the structural strengthening metal film 80 , so that part of the upper surface 101 of the circuit protection element 100 is covered with the structural strengthening metal film 80 , and the rest of the upper surface 101 is covered with the insulating material 70 . On the right side wall S1 , the surface of the right conducting member 63 on the right notch 61 is also completely covered with the structural strengthening metal film 80 . In addition, the material of the structural strengthening metal film 80 may have the same composition as the solder, so as to facilitate soldering of other components. For example, the structural strengthening metal film 80 can be a tin-containing metal film, which helps to increase the adhesion between it and the tin-containing alloy solder. As for the lower surface 102 and the left notch 62 having the same design as the above-mentioned upper surface 101 and the right notch 61, no further comments are made here.

Please refer to FIG. 5 and FIG. 2 , which are top views of the circuit protection device 100 . For ease of understanding, the description below is mainly based on the structural design of the first external electrode 51 , wherein the second external electrode 52 may have the same structural design as the first external electrode 51 . The first external electrode 51 is disposed on the first electrode layer 41 and extends beyond the peripheral wall 103 along a first horizontal direction parallel to the first electrode layer 41 . More specifically, the first external electrode 51 may extend beyond the right sidewall S1 along the y-axis in a first horizontal direction away from the left sidewall S2. Therefore, the right side wall S1 and the right notch 61 on it will be covered under the first external electrode 51 (shown by the dotted line in FIG. 5 ). The first horizontal direction is substantially parallel to the y-axis. The circuit protection element 100 has a first length L1 parallel to the first horizontal direction, and the first external electrode 51 has a second length L2 beyond the right side wall S1 counted from the right side wall S1 (see FIG. 2 and FIG. 3 ). In this creation, based on the sum of the first length L1 and the second length L2 as 100%, the second length L2 accounts for 31% to 53%. The proportion of the aforementioned second length L2 can also be referred to as the elongation of the external electrodes. In one embodiment, the elongation of the external electrodes may be 31%, 33%, 36%, 38%, 42%, 46%, 47%, 49% or 53%. For example, when the first length L1 is 8.2 mm and the second length L2 is 5 mm, it can be calculated that the elongation rate of the external electrode is about 38%. Through the extra extension of the external electrode, the surface area of the first external electrode 51 exposed to the environment is increased, which can effectively increase the heat dissipation rate, and further increase the holding current (Hold Current, I _hold ) of the circuit protection device 100 . The aforementioned improvement of the elongation of the external electrodes can be applied to circuit protection elements of different sizes, but it should be noted that the extension of the second length L2 is not unlimited. When the elongation of the external electrodes is lower than 31%, the first external electrodes 51 will be too short to be spot-welded to external components. When the elongation of the external electrodes is greater than 53%, the first external electrodes 51 will be too long and easily bent and deformed. Furthermore, if the extension ratio of the external electrodes is greater than 53%, the overall size of the circuit protection device 100 will be too long and occupy too much space. In a preferred embodiment, in order to further improve the spot welding yield and speed up the heat dissipation rate, the elongation of the external electrodes is adjusted to be greater than 47%, that is, between 47% and 53%. Regarding the selection of the material of the external electrodes, the first external electrode 51 and the second external electrode 52 can be copper sheets, nickel sheets or steel sheets. Nickel sheet is suitable for spot welding because of its soft material, but not suitable for reflow soldering (reflow) joining method. The structural strength of copper sheet is better than that of nickel sheet, so it is suitable for the process of reflow soldering.

In FIG. 5 , the circuit protection device 100 further has a first width W1 , and each of the first external electrode 51 and the second external electrode 52 has a second width W2 . In one embodiment, the first width W1 is 4 mm to 6 mm, for example: 4 mm, 4.3 mm, 4.5 mm, 5.3 mm, 5.7 mm or 6 mm. The second width W2 is preferably equal to or smaller than the first width W1 to facilitate the assembly process. As mentioned above, the extended length (the second length L2 ) of the first external electrode 51 is beneficial to heat dissipation. In addition, the upper surface area of the first external electrode 51 can also be adjusted accordingly. Specifically, the upper surface area of the circuit protection element 100 can be obtained by multiplying the first length L1 by the first width W1, and the first external electrode 51 can be obtained by multiplying the third length L3 (refer to FIG. 3 ) by the second width W2. The upper surface area of the first external electrode. In one embodiment, the third length L3 is about 9.25 mm to 12.25 mm, such as 9.25 mm, 10.25 mm, 11.25 mm or 12.25 mm. In order to achieve a good heat dissipation effect, the invention adjusts the upper surface area of the first external electrode 51 , so the ratio of the upper surface area of the first outer electrode divided by the upper surface area of the circuit protection element is preferably 1.37 to 1.64. Taking one model size of the circuit protection device 100 as an example, the circuit protection device 100 has a first length L1 of 8.2 mm and a first width W1 of 5.3 mm. In order to effectively improve the heat dissipation, the third length L3 of the first external electrode 51 can be set to 12.25 mm, and the second width W2 thereof can be selected to be 5.3 mm which is the same as the first width W1. From the foregoing, it can be calculated that the upper surface area of the first external electrode is about 64.93 mm ² , and the upper surface area of the circuit protection element is about 43.46 mm ² , the ratio of the two is about 1.49. That is to say, when the upper surface area of the first external electrode 51 is larger than the upper surface area of the circuit protection element 100 and falls within the ratio range of 1.37 to 1.64, the first external electrode 51 can effectively increase the heat dissipation rate, and further improve the circuit protection element 100. The maintenance current (Hold Current, I _hold ). In addition, in an embodiment, the aforementioned first external electrode 51 with an upper surface area of ^64.93 mm can also be arranged in a direction away from the right side wall S1, so that the second length L2 is 8 mm, thereby having an optimal external electrode Elongation. In other words, the invention not only adjusts the surface area of the first external electrode 51 , but also sets it away from the peripheral wall 103 . In this way, if a part of the first external electrode 51 is covered by the encapsulation process later, the first external electrode 51 still has a considerable upper surface area of the first external electrode exposed to the environment, thereby effectively improving the heat dissipation rate and thereby improving circuit protection. The sustaining current of element 100. In one embodiment, the present invention selects circuit protection elements 100 of different sizes, and makes the ratio of the upper surface area of the first outer electrode divided by the upper surface area of the circuit protection element be 1.37, 1.43, 1.49, 1.55, 1.58, 1.61 or 1.64. In a preferred embodiment, the ratio of the upper surface area of the first external electrode divided by the upper surface area of the circuit protection element is 1.49 to 1.64, and the circuit protection element 100 has a larger holding current at this time.

Please refer to FIG. 6 , which is a circuit protection device 200 of the second embodiment of the present invention. The difference between FIG. 6 and FIG. 5 lies in that the extension directions of the first external electrodes 51 and the second external electrodes 52 are different. In FIG. 5 , the first external electrode 51 of the circuit protection element 100 extends beyond the right sidewall S1 along the first horizontal direction, and is disposed on the first electrode layer 41 covering the structural strengthening metal film 80 . The second external electrode 52 extends beyond the left sidewall S2 along the direction opposite to the first horizontal direction, and is disposed on the second electrode layer 42 covering the structural strengthening metal film 80 . In FIG. 6 , the first external electrode 51 of the circuit protection element 200 extends beyond the front sidewall S4 parallel to the first electrode layer 41 along the second horizontal direction, and the second external electrode 52 extends beyond the rear side parallel to the first external electrode 51 . Side wall S3. That is to say, the first external electrode 51 and the second external electrode 52 extend outward perpendicular to the long side of the circuit protection device 200 . The aforementioned first horizontal direction is substantially parallel to the y-axis, and the second horizontal direction is substantially parallel to the x-axis; that is, on the xy plane, the first horizontal direction and the second horizontal direction are substantially perpendicular to each other. Accordingly, the first external electrode 51 and the second external electrode 52 may have different designs according to requirements.

Please continue to refer to FIG. 7 , which is a circuit protection device 300 according to the third embodiment of the present invention. The parts in FIG. 7 that are the same as those in the first embodiment will continue to use the same reference numerals, and no more praise is given here. The difference between FIG. 7 and FIG. 2 lies in the number of notches, and the notches are set at specific positions. Specifically, the circuit protection element 300 further includes a plurality of right notches (such as the first right notch 65 and the second right notch 66) and a plurality of left notches (such as the first left notch 67 and the second notch) opposite to these right notches. The left notches 68 ) are respectively disposed on the right side wall S1 and the left side wall S2 of the peripheral wall 103 . Increasing the number of notches on the same sidewall can disperse the stress caused by thermal expansion, making the circuit protection element 300 less likely to break. In the case where the left and right sides (the right side wall S1 and the left side wall S2 ) are symmetrical, the stress dispersion will be more significant. In one embodiment, the first right notch 65 and the second right notch 66 are semi-cylindrical recessed spaces with the same notch radius. In another embodiment, in order to make the structure more symmetrical, the first right notch 65 and the second right notch 66 can be symmetrically arranged on the right side wall S1, which means that the right side wall S1 is divided into three rectangles with roughly equal surface areas. side wall. The aforementioned situation also can do the same design on the left side wall S2. In addition, the first external electrode 51 may extend beyond the right side wall S1 along the first horizontal direction, and be disposed on the first electrode layer 41 covering the structural strengthening metal film 80, while the second external electrode 52 may extend along the first horizontal direction opposite to the first horizontal direction. It extends beyond the left sidewall S2 and is disposed on the second electrode layer 42 covering the structural strengthening metal film 80 . In another embodiment, the first external electrode 51 may extend beyond the front sidewall S4 along the second horizontal direction, and the second external electrode 52 may extend beyond the rear sidewall S3 parallel to the first external electrode 51 . In other words, the arrangement direction of the first external electrode 51 and the second external electrode 52 in FIG. 7 may be the same as that in FIG. 5 or FIG. 6 .

In order to make the present invention easier to understand, please continue to refer to FIG. 8 which shows the manufacturing process of the circuit protection element 100 (see FIG. 1 ) according to the first embodiment of the present invention. The process can be roughly divided into steps 1 to 7, see below for details.

Step 1: Provide the first upper conductive layer sheet 120, the first lower conductive layer sheet 130, and the first positive temperature coefficient material layer sheet 110, and heat-compress the first positive temperature coefficient material layer sheet 110 on the first upper conductive layer between the plate 120 and the first lower conductive layer plate 130 . then. Then the first upper conductive layer plate 120 and the first lower conductive layer plate 130 are etched, so that the first upper conductive layer plate 120 and the first lower conductive layer plate 130 expose the first positive temperature coefficient material layer plate 110 and form a plurality of The first upper conductive layer 12 and a plurality of first lower conductive layers 13 .

Step 2: Repeat the operation of step 1 to obtain the second positive temperature coefficient material layer plate 210 , a plurality of second upper conductive layers 22 and a plurality of second lower conductive layers 23 . Sequentially provide the first electrode layer sheet 410 and the upper insulating layer sheet 310 above the first upper conductive layers 12; provide the middle insulating layer sheet 320 between the first lower conductive layers 13 and the second upper conductive layers. between the layers 22 ; and providing the lower insulating layer sheet 330 and the second electrode layer sheet 420 located below the second lower conductive layers 23 .

Step 3: Carrying out thermocompression according to the stacking method in step 2 to obtain a laminated structure with double-layer positive temperature coefficient material layer plates.

Step 4: Drilling the stacked structure in Step 3 and forming a plurality of via holes H. Drilling methods can be mechanical drilling, laser drilling or other drilling techniques. After drilling, electroplating is performed to form via holes H. Referring to FIG. The via hole H is not limited to a Plating Through Hole (PTH), as long as it has a conductive connection feature, such as a conductive pillar or other similar structures. Accordingly, a plurality of right conducting elements 63 and a plurality of left conducting elements 64 are formed in the conducting holes H. Meanwhile, a plurality of upper insulating layers 31, a plurality of first positive temperature coefficient material layers 11, a plurality of intermediate insulating layers 32, a plurality of second positive temperature coefficient material layers 21 and a plurality of The lower insulating layer 33 .

Step 5: Etching the first electrode layer plate 410 and the second electrode layer plate 420 drilled in step 4, thereby forming a plurality of openings O to expose the upper insulating layers 31 and the lower insulating layers 33, and at the same time A plurality of first electrode layers 41 and a plurality of second electrode layers 42 are also respectively formed thereon.

Step 6: Covering the structure strengthening metal film 80 on the surfaces of the first electrode layers 41, the second electrode layers 42, the right vias 63 and the left vias 64, thereby increasing the protection of the circuit protection element 100 Structural strength and avoid surface oxidation of conductor electrodes. In one embodiment, the structural strengthening metal film 80 can be a thin film containing tin, and the structural strengthening metal film 80 can be coated on the first electrode layers 41, the second electrode layers 42, the The surfaces of the right conducting elements 63 and the left conducting elements 64.

Step 7: Carry out cutting along the cutting line d1-d1, cutting line d2-d2, cutting line d3-d3 and cutting line d4-d4, at least three circuit protection components can be cut out as shown in the figure.

In addition, in order to further improve the insulation and structural stability of the circuit protection component, the present invention can also perform a packaging step according to requirements, so that the circuit protection component has a package structure, as shown in FIGS. 9 to 11 .

9 and 10 show a circuit protection device 400 according to the fourth embodiment of the present invention. In FIG. 9 , the circuit protection device 400 further includes a packaging tape 90 . The packaging tape 90 can be a film tape formed of high molecular polymer. For example, the packaging tape 90 is composed of a polymer substrate and an adhesive. The aforementioned polymer substrate can be polyester film, and the adhesive can be silicone. In FIG. 10 , the packaging tape 90 is wound around the upper surface 101, the front side wall S4, the lower surface 102, and the rear side wall S3 with the circuit protection element 400 as the axis, so that the circuit protection element 400 only exposes the right side wall S1 and the left side wall. Wall S2 , part of the first external electrode 51 and part of the second external electrode 52 . It should be noted that the upper part of FIG. 10 is a disassembled view of the circuit protection device 400 , and only the first external electrode 51 and the second external electrode 52 are independently extracted. It can be seen from this that the packaging tape 90 does not cover the right side wall S1 and the left side wall S2 . In addition, the packaging strip 90 can slightly protrude from the right sidewall S1 and the left sidewall S2 along the y-axis direction, or can be flush with the right sidewall S1 and the left sidewall S2. In the case that the packaging strip 90 exceeds the peripheral wall 103 along the y-axis, the second length L2 is calculated from the packaging strip 90 along the y-axis (as shown in FIG. 9 ). Through the arrangement of the packaging tape 90 , the circuit protection device 400 can have better insulation and structural stability. Besides, the packaging tape 90 can be made of transparent or opaque material. The packaging tape 90 made of transparent material is beneficial to defect detection, and the circuit protection device 400 in the packaging tape 90 can be inspected with the naked eye or a photosensitive element for defects, thereby facilitating quality control and improving product yield. The components other than the packaging tape 90 can be the same as those of the aforementioned first embodiment, second embodiment, and third embodiment, and no more praises are given here.

FIG. 11 shows a circuit protection device 500 of the fifth embodiment of the present invention. The difference from FIG. 10 is that the circuit protection element 500 in FIG. 11 does not use the encapsulation tape 90 , but the insulating frame 91 . The insulating frame 91 may be composed of cured thermosetting polymer. Through injection molding or other coating processes, the circuit protection element 500 can be wrapped with a fluid thermosetting polymer, and then cured. Accordingly, the insulating frame 91 covers the circuit protection device 500 , so that the circuit protection device 500 only exposes part of the first external electrode 51 and part of the second external electrode 52 . The components other than the insulating frame 91 can be the same as those of the aforementioned first embodiment, second embodiment, third embodiment and fourth embodiment, and no more praises are given here.

In short, in this creation, by coating the structure strengthening metal film 80 on the surface of the circuit protection element 100, and setting the upper insulating layer 31 and the lower insulating layer 33 in the circuit protection element 100, the strength of the circuit protection element is increased. Structural strength, so as to avoid the problem of poor resistance recovery or resistance reproducibility caused by the expansion of the circuit protection element 100 when triggered. In addition, the invention adjusts the surface area and position or extension length of the external electrodes 51, 52 to increase their surface area exposed to the environment, thereby increasing the heat dissipation rate of the circuit protection element, and further increasing the holding current (Hold Current, I) of the circuit protection element _hold ), so that circuit protection components can be applied to electronic product applications that need to carry a higher rated current. In addition, the invention sets a plurality of right notches 65, 66 and a plurality of left notches 67, 68 on both sides of the circuit protection element 300, which can disperse the influence of thermal expansion stress and avoid the problem of poor resistance reproducibility caused by element deformation. Further, the present invention encapsulates the circuit protection element with a packaging tape 90 or an insulating frame 91, which not only isolates the influence of environmental factors, but also further stabilizes the overall structure of the circuit protection element.

The technical content and technical features of this creation have been disclosed above, but those skilled in the art may still make various substitutions and modifications based on the teachings and disclosures of this creation without departing from the spirit of this creation. Therefore, the scope of protection of this creation should not be limited to those disclosed in the embodiments, but should include various replacements and modifications that do not deviate from this creation, and are covered by the scope of the following patent applications.

1, 2, 3, 4, 5, 6, 7: steps 10: The first thermal element 11: The first positive temperature coefficient material layer 12: The first upper conductive layer 13: The first lower conductive layer 20: The second thermal element 21: The second positive temperature coefficient material layer 22: The second upper conductive layer 23: The second lower conductive layer 30: Multi-layer structure of insulating material 31: upper insulating layer 32: Intermediate insulating layer 33: Lower insulating layer 41: The first electrode layer 42: Second electrode layer 51: The first outer electrode 52: Second external electrode 61: right gap 62: left gap 63: Right lead 64: Left lead 65: First Right Gap 66: Second Right Gap 67: First Left Gap 68: Second Left Gap 70: insulating material 80: Structural strengthening metal film 90: Encapsulation tape 91: Insulation frame 100, 200, 300, 400, 500: circuit protection components 101: upper surface 102: lower surface 103: Peripheral wall 110: The first positive temperature coefficient material layer plate 120: The first upper conductive layer plate 130: The first lower conductive layer plate 210: second positive temperature coefficient material layer plate 310: upper insulating layer sheet 320: middle insulating layer plate 330: lower insulating layer sheet 410: The first electrode layer plate 420: second electrode layer plate d1, d2, d3, d4: cutting lines D: distance H: via hole L1: first length L2: second length L3: third length L4: fourth length L5: fifth length O: open S1: right wall S2: left wall S3: Rear side wall S4: front side wall W1: first width W2: second width

FIG. 1 shows a perspective view of a circuit protection element of the first embodiment of the present invention; FIG. 2 shows a three-dimensional exploded schematic diagram of the circuit protection component of FIG. 1; Fig. 3 shows a cross-sectional view of the circuit protection element of Fig. 1; Fig. 4 shows a partially enlarged view of the cross-sectional view of the circuit protection element of Fig. 3; Fig. 5 shows the top view of the circuit protection element of Fig. 1; Fig. 6 shows a top view of the circuit protection element of the second embodiment of the present invention; FIG. 7 shows a three-dimensional exploded schematic diagram of a circuit protection component of a third embodiment of the present invention; Fig. 8 shows the manufacturing process of the circuit protection element of the present invention; Fig. 9 shows a cross-sectional view of a circuit protection element of a fourth embodiment of the present invention; Fig. 10 shows a three-dimensional exploded schematic view and a combined schematic view of the circuit protection element of the fourth embodiment of the present invention; and FIG. 11 shows a three-dimensional exploded schematic view and an assembled schematic view of a circuit protection component according to a fifth embodiment of the present invention.

10: The first thermal element

11: The first positive temperature coefficient material layer

12: The first upper conductive layer

13: The first lower conductive layer

20: The second thermal element

21: The second positive temperature coefficient material layer

22: The second upper conductive layer

23: The second lower conductive layer

30: Multi-layer structure of insulating material

31: upper insulating layer

32: Intermediate insulating layer

33: Lower insulating layer

41: The first electrode layer

42: Second electrode layer

51: The first outer electrode

52: Second external electrode

61: right gap

62: left gap

63: Right lead

64: Left lead

70: insulating material

80: Structural strengthening metal film

100: circuit protection components

L1: first length

L2: second length

L3: third length

O: open

Claims (20)

A circuit protection element has an upper surface, a lower surface opposite to the upper surface, and a peripheral wall connecting the upper surface and the lower surface, the circuit protection element comprising: A first thermal element, comprising a first upper conductive layer, a first lower conductive layer and a first positive temperature coefficient (Positive Temperature) stacked between the first upper conductive layer and the first lower conductive layer Coefficient, PTC) material layer; A second heat-sensitive element, including a second upper conductive layer, a second lower conductive layer, and a second positive temperature coefficient material layer stacked between the second upper conductive layer and the second lower conductive layer; A multilayer structure of insulating material, having an upper insulating layer, a middle insulating layer and a lower insulating layer, wherein: The upper insulating layer extends beyond the first upper conductive layer, thereby completely covering the first upper conductive layer and partially covering the first positive temperature coefficient material layer; the intermediate insulating layer is laminated between the first lower conductive layer and the second upper conductive layer, and connects the first thermosensitive element and the second thermosensitive element; and The lower insulating layer extends beyond the second lower conductive layer, thereby completely covering the second lower conductive layer and covering part of the second positive temperature coefficient material layer; A first electrode layer and a second electrode layer are attached to the upper insulating layer and the lower insulating layer respectively, and the first electrode layer is electrically connected to the first upper conductive layer and the second upper conductive layer, and the second electrode layer is electrically connected with the first lower conductive layer and the second lower conductive layer; and A first external electrode is arranged on the first electrode layer and extends beyond the peripheral wall along a first horizontal direction parallel to the first electrode layer. The circuit protection device according to claim 1, further comprising a right notch and a left notch, wherein the upper insulating layer is attached between the first electrode layer and the first upper conductive layer, so that the first electrode layer and the The first upper conductive layer is separated by a distance, and the first electrode layer and the first upper conductive layer extend parallel to each other to the right gap, and are electrically connected through the right gap. According to the circuit protection element of claim 2, the distance is 0.02 mm to 0.06 mm. The circuit protection device according to claim 2, wherein an opening is formed directly above where the upper insulating layer covers part of the first positive temperature coefficient material layer and does not cover the first electrode layer, so that the first electrode layer does not extend to the left gap, so that the first electrode layer is not electrically connected to the left gap. The circuit protection device according to claim 4 further includes an insulating material filled into the opening. The circuit protection device according to claim 4, wherein the right gap has a right conducting member, so that the first electrode layer, the first upper conductive layer and the second upper conductive layer are electrically connected, and the left gap has a left The conductive element is used to electrically connect the second electrode layer, the first lower conductive layer and the second lower conductive layer. The circuit protection device according to claim 6, further comprising a structure strengthening metal film, the structure strengthening metal film covering the surface of the first electrode layer, the surface of the second electrode layer, the surface of the right conducting element and the left conducting element surface, so that the first electrode layer, the second electrode layer, the right conductive element and the left conductive element are isolated from ambient gas. According to the circuit protection element of claim 7, the peripheral wall has a left side wall, a right side wall, a front side wall and a rear side wall, the left side wall is opposite to the right side wall, and the front side wall is opposite to the rear side wall, wherein the left The notch is located on the left side wall, and the right notch is located on the right side wall. The circuit protection device according to claim 8, wherein the first external electrode extends beyond the right side wall along the first horizontal direction. The circuit protection element according to claim 9, wherein the circuit protection element has a first length parallel to the first horizontal direction, and the first external electrode has a second length beyond the right side wall from the right side wall, and Taking the sum of the first length and the second length as 100%, the second length accounts for 31% to 53%. The circuit protection device according to claim 10, wherein the second length is 4 mm to 8 mm. The circuit protection device according to claim 11, wherein the upper surface of the circuit protection device has a circuit protection device upper surface area, and the first external electrode has a first outer electrode upper surface area, and the first outer electrode upper surface area is divided by the The ratio of the upper surface area of the circuit protection element is 1.37 to 1.64. The circuit protection device according to claim 9, further comprising a second external electrode disposed on the second electrode layer covering the structural strengthening metal film, wherein the first external electrode is parallel to the first electrode layer along a second The horizontal direction extends beyond the front sidewall, and the second external electrode extends beyond the rear sidewall parallel to the first external electrode. The circuit protection device according to claim 9, further comprising a second external electrode disposed on the second electrode layer covering the structural strengthening metal film, and extending beyond the left sidewall in a direction opposite to the first horizontal direction. According to the circuit protection element of claim 14, it further comprises a packaging tape, and the packaging tape is wound along the direction of the upper surface, the front side wall, the lower surface, and the rear side wall with the circuit protection element as the axis, so that the The circuit protection element only exposes the right side wall, the left side wall, part of the first external electrode and part of the second external electrode. The circuit protection device according to claim 14 further includes an insulating frame covering the circuit protection device, so that only part of the first external electrode and part of the second external electrode are exposed by the circuit protection device. The circuit protection device according to claim 1, further comprising a plurality of right notches and a plurality of left notches opposite to the right notches, respectively disposed on a right side wall and a left side wall of the peripheral wall, wherein the first external electrode is along the The first horizontal direction extends beyond the right side wall. The circuit protection device according to claim 17, further comprising a second external electrode disposed on the second electrode layer and extending beyond the left sidewall parallel to the second electrode layer in a direction opposite to the first horizontal direction. The circuit protection element according to claim 18 further comprises a packaging tape, the packaging tape is wound around the circuit protection element, so that the circuit protection element only exposes the right side wall, the left side wall, and part of the first outer surface. electrode and part of the second external electrode. The circuit protection device according to claim 18 further includes an insulating frame covering the circuit protection device, so that only part of the first external electrode and part of the second external electrode are exposed by the circuit protection device.

Images