Surface mount resistors and methods of manufacturing same
10083781 ยท 2018-09-25
Assignee
Inventors
Cpc classification
H01C7/06
ELECTRICITY
H01C7/18
ELECTRICITY
H01C17/00
ELECTRICITY
H01C1/148
ELECTRICITY
H01C1/142
ELECTRICITY
H01C1/144
ELECTRICITY
International classification
H01C1/02
ELECTRICITY
H01C1/144
ELECTRICITY
H01C1/148
ELECTRICITY
H01C7/18
ELECTRICITY
H01C17/00
ELECTRICITY
Abstract
Resistors and a method of manufacturing resistors are described herein. A resistor includes a resistive element and a plurality of conductive elements. The plurality of conductive elements are electrically insulated from one another via a dielectric material and thermally coupled to the resistive element via an adhesive material disposed between each of the plurality of conductive elements and a surface of the resistive element. The plurality of conductive elements is coupled to the resistive element via conductive layers and solderable layers.
Claims
1. A resistor comprising: a resistive element having an upper surface, a bottom surface, a first side surface, and an opposite second side surface; and a first conductive element and a second conductive element joined to the upper surface of the resistive element by an adhesive, wherein a gap is provided between the first conductive element and the second conductive element, and wherein the positioning of the first conductive element and the second conductive leaves exposed portions of the upper surface of resistive element adjacent the first side surface and the second side surface of the resistive element; a first conductive layer covering the exposed portion of the upper surface of resistive element adjacent the first side surface, and in contact with the first conductive element; a second conductive layer covering the exposed portion of the upper surface of resistive element adjacent the second side surface, and in contact with the second conductive element; a third conductive layer positioned along the bottom surface of the resistive element, adjacent the first side of the resistive element; a fourth conductive layer positioned along the bottom surface of the resistive element, adjacent the second side of the resistive element; wherein the first conductive layer, second conductive layer, third conductive layer, and fourth conductive layer do not cover the first side surface or second side surface of the resistive element; a dielectric material covering upper surfaces of the first conductive element and the second conductive element and filling the gap between the first conductive element and the second conductive element; and, a dielectric material deposited on a surface of the resistor.
2. The resistor of claim 1, further comprising: a first solderable layer covering a first side of the resistor, the first solderable layer in contact with the first conductive layer, the resistive element, and the third conductive layer; and, a second solderable layer covering a second side of the resistor, the second solderable layer in contact with the second conductive layer, the resistive element, and the fourth conductive layer.
3. The resistor of claim 2, wherein the first solderable layer covers at least a portion of the upper surface of the first conductive element, and at least a portion of a bottom surface of the third conductive layer.
4. The resistor of claim 3, wherein the second solderable layer covers at least a portion of the upper surface of the second conductive element, and at least a portion of a bottom surface of the fourth conductive layer.
5. The resistor of claim 1, wherein the first conductive element and the second conductive element are joined to the resistive element by an adhesive.
6. The resistor of claim 5, wherein the adhesive is positioned only between the first and second conductive elements and the resistive element.
7. The resistor of claim 5, wherein at least a portion of the adhesive is positioned adjacent the first side surface of the resistive element, and wherein the first conductive layer is in contact with a portion adhesive joining the resistive element to the first conductive element.
8. The resistor of claim 7, wherein at least a portion of the adhesive is positioned adjacent the second side surface of the resistive element, and wherein the second conductive layer is in contact with a portion adhesive joining the resistive element to the second conductive element.
9. The resistor of claim 1, wherein the first conductive layer and the second conductive layer each have an upper portion that is stepped, angled or rounded.
10. The resistor of claim 1, wherein a first dielectric material covers at least a portion of the top of the resistor, and a second dielectric material covers at least a portion of the bottom of the resistor.
11. The resistor of claim 1, wherein the first conductive layer and the third conductive layer are formed as a single conductive layer.
12. The resistor of claim 11, wherein the second conductive layer and the fourth conductive layer are formed as a single conductive layer.
13. The resistor of claim 1, wherein the resistive element comprises copper-nickel-manganese (CuNiMn), nickel-chromium-aluminum (NiCrAl), or nickel-chromium (NiCr).
14. The resistor of claim 1, wherein the resistive element has a thickness of about 0.001 to about 0.015.
15. The resistor of claim 1, wherein the conductive elements comprise copper or aluminum.
16. A method of manufacturing a resistor, the method comprising: laminating a conductor to an upper surface of a resistive element using an adhesive; masking and patterning the conductor to divide the conductor into a plurality of conductive elements; selectively removing portions of the adhesive material from the resistive element; plating exposed portions of the upper surface of the resistive element with one or more conductive layers to electrically couple the resistive element to the plurality of conductive elements; plating one or more conductive layers on a bottom surface of the resistive element; and depositing a dielectric material on at least the plurality of conductive elements to electrically isolate the plurality of conductive elements from each other; wherein the conductive layers on the upper surface and bottom surface of the resistive element do not cover a first side surface or a second side surface of the resistive element.
17. The method of claim 16, further comprising the step of plating solderable layers to the side surfaces of the resistor.
18. The method of claim 17, wherein the solderable layers are in contact with the resistive element, the conductive elements, the conductive layers, and the adhesive.
19. A resistor comprising: a resistive element; first and second conductive elements that are electrically insulated from one another by a dielectric material, the first and second conductive elements thermally coupled to an upper surface of the resistive element via an adhesive material; wherein the first conductive element has a first outer edge in alignment with a first outer edge of the resistive element so as to form a generally planar first side surface, and the second conductive element has a second outer edge in alignment with a second outer edge of the resistive element so as to form a generally planar second side surface; a first conductive layer disposed so as to directly contact the first side surface and extend along at least a portion of a bottom surface of the resistive element; a second conductive layer disposed so as to directly contact the second side surface and extend along at least a portion of the bottom surface of the resistive element; and, first and second solderable layers forming lateral sides of the resistor.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein:
(2)
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(8)
DETAILED DESCRIPTION
(9) Certain terminology is used in the following description for convenience only and is not limiting. The words right, left, top, and bottom designate directions in the drawings to which reference is made. The words a and one, as used in the claims and in the corresponding portions of the specification, are defined as including one or more of the referenced item unless specifically stated otherwise. This terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. The phrase at least one followed by a list of two or more items, such as A, B, or C, means any individual one of A, B or C as well as any combination thereof.
(10)
(11) As shown in
(12) The conductive elements 110a and 110b may be laminated to or otherwise bonded, joined or attached to the resistive element 120 via an adhesive material 130, which may comprise, by way of non-limiting example, materials such as DUPONT? PYRALUX?, or other acrylic, epoxy, or polyimide adhesives in sheet or liquid form. As shown in
(13) A first conductive layer 150a and a second conductive layer 150c are provided in the spaces s and s, adjacent the top surface 122 of the resistive element 120 and along the outer side edges (or outer side surfaces) of the conductive elements 110a and 110b in order to provide an electrical connection with them. Preferably, the first conductive layer 150a and the second conductive layer 150c are plated to the top surface 122 of the resistive element and along the outer side edges (or outer side surfaces) of the conductive elements 110a and 110b. In a preferred embodiment, copper may be used for the conductive layers. However, any platable and highly conductive metals may be used, as will be appreciated by those of skill in the art.
(14) As shown in
(15) The aligned outer side edges (or outer side surfaces) of the resistive element 120 and the outer side edges (or outer side surfaces) of the conductive layers 150a, 150b, 150c, 150d, form solderable surfaces configured to receive solderable layers. Solderable layers 160a and 160b may be separately attached at the lateral ends 165a and 165b of the resistor 100A to allow the resistor 100A to be soldered to a circuit board, which is described in more detail below with respect to
(16) A dielectric material 140 may be deposited on a surface or surfaces of the resistor 100, for example, by coating. The dielectric material 140 may fill spaces or gaps to electrically isolate components from each other. As shown in
(17)
(18) The conductive elements 110a and 110b are coupled to the resistive element 120 via the adhesive 130 and connected to the resistive element at its lateral or outer side ends or surfaces via the conductive layer 150a and 150c. It is appreciated that the conductive elements 110a and 110b may be thermally and/or mechanically and/or electrically coupled/connected or otherwise bonded, joined or attached to the resistive element 120. It is further appreciated that the conductive elements 110a and 110b may be thermally and/or mechanically and/or electrically coupled/connected or otherwise bonded, joined or attached to the conductive layers 150a and 150c. Of particular note, the conductive layer 150a and 150c makes the electrical connection between the resistive element 120 and the conductive elements 110a and 110b from the surface 122 of the resistive element that is farthest from the circuit board 170 when the resistor 100B is mounted thereon. The thermal, electrical, and/or mechanical coupling/connection between the resistive element 120 and the lateral end of each of the conductive elements 110a and 110b may enable the conductive elements 110a and 110b to be used both as supports for the resistive element 120 and also as a heat spreader. Use of the conductive elements 110a and 110b as a support for the resistive element 120 may enable the resistive element 120 to be made thinner as compared to self-supporting resistive elements, enabling the resistor 100B to be made to have a resistance values of 1 m? to 20? using foil thicknesses between about 0.015 and about 0.001. In addition to providing support for the resistive element 120, efficient use of the conductive elements 110a and 110b as a heat spreader may enable the resistor 100B to dissipate higher powers as compared to resistors that do not use a heat spreader. For example, a typical power rating for a 2512 size metal strip resistor is 1 W. Using the embodiments described herein, the power rating for a 2512 size metal strip resistor may be 3 W.
(19) Further, making the electrical connection between the resistive element 120 and the conductive elements 110a and 110b on a surface of the resistive element that is farthest from the circuit board 170 may avoid exposure of the resistive-element-to-conductive-element-connection to the solder joint between the resistor 100 and the circuit board 170, which may reduce or eliminate risk of failure of the resistor due to the thermal coefficient of expansion (TCE). Further, the use of a conductive layer, such as 150b and 150d, on the side of the resistive element that is closest to the PCB may aid in creating a strong solder joint and centering the resistor on the PCB pads during solder reflow.
(20) Examples of other resistor designs and methods of manufacturing them are described below with respect to
(21)
(22) The conductive elements 110a and 110b and the resistive element 120 may be masked, as desired, to create a plating pattern and then may be plated (235). The plating may be used, for example, to deposit one or more of the conductive layers 150a, 150b, 150c and 150d. Once the plating is completed, the masking may be removed so that the resistive element may be calibrated (240), for example, by thinning a resistive foil to a desired thickness or by manipulating the current path by cutting through the resistive foil in specific locations based, for example, on the target resistance value for the resistor. A dielectric material 140 is deposited on the top, bottom, or both top and bottom surfaces of the resistor 100. The dielectric material 140 is preferably deposited on exposed upper surfaces of the conductive elements 110a and 110b (245), for example, by coating. The dielectric material 140a may fill any space between the conductive elements 110a and 110b to electrically isolate them from one another. A plate formed by the method may then be singulated into individual pieces to form individual resistors 100 (250). Solderable layers 160a and 160b may then be attached to, or formed on, the lateral edges 165a and 165b of the individual resistors 100, for example, by plating (255).
(23)
(24) As shown in
(25) The conductive elements 310a and 310b may be laminated to or otherwise joined or attached to the resistive element 320 via an adhesive material 330. As shown in
(26) The conductive elements 310a and 310b are shaped such that each conductive element 310a and 310b extends along a portion of the top surface 322 of the resistive element 320, from an outer edge of the gap 390 to a respective outer edge of the adhesive 330, and each has a portion that angles outwardly and downwardly toward the resistive element 320, to be positioned in the spaces s and s and directly contacting the top surface 322 of the resistive element 320. The angled portions of the conductive elements 310a and 310b are preferably positioned and arranged to provide for intimate contact, electrically, thermally and mechanically, between of the conductive elements 310a and 310b and the surface 322 of the resistive element 320 in the area designated as s, and to provide for intimate contact, electrically, thermally and mechanically, between the conductive elements 310a and 310b and the surface 322 of the resistive element 320 in the area designated as s. The shape of the upper portions 312a and 312b of the conductive elements 310a and 310b can be varied, and can range from a barely perceptible step, to a rounding such as a rounded edge, to an angle having a slope that could be from a few degrees to somewhat less than 90 degrees, so long as the areas provide for intimate contact as described.
(27) As shown in
(28) The outer side edges (or outer side surfaces) of the resistive element 320, the outer sides of the conductive elements 310a, 310b, and the outer side edges (or outer side surfaces) of conductive layers 350a and 350b, form solderable surfaces configured to receive solderable layers. Solderable layers 360a and 360b may be attached at the lateral ends 365a and 365b of the resistor 300 to allow the resistor 300 to be soldered to a circuit board. As shown in
(29) A dielectric material 340 may be deposited surfaces of the resistor 300, for example, by coating. The dielectric material 340 may fill spaces or gaps to electrically isolate components from each another. As shown in
(30)
(31) The conductive elements 310a and 310b and the resistive element 320 may be masked, as desired, to create a plating pattern and then may be plated (435). The plating may be used, for example, to deposit one or more of the conductive layer 350a and 350b on the surface 324 of the resistive element 320. Once the plating is completed, the masking may be removed so that the resistive element may be calibrated (440), for example, by thinning a resistive foil to a desired thickness or by manipulating the current path by cutting through the resistive foil in specific locations based, for example, on the target resistance value for the resistor. The conductive elements 310a and 310b may then be swaged to cover the portions of the surface 322 of the resistive element 320 that were exposed by the selective removing of the adhesive material 330 (445).
(32) A dielectric material 340 may be deposited on one or both of the bottom surface 324 of the resistive element 320, and the conductive elements 310a and 310b (450), for example, by coating. The dielectric material 340a may fill any space between the conductive elements 310a and 310b to electrically isolate them from one another. A plate formed by the method may then be singulated into individual pieces to form individual resistors 300 (455). Solderable layers 360a and 360b may then be attached to, or formed on, the lateral edges 365a and 365b of the individual resistors 300, for example, by plating (460).
(33)
(34) As shown in
(35) The conductive elements 510a and 510b may be laminated to or otherwise joined or attached to the resistive element 520 via an adhesive material 530. As shown in
(36) A first conductive layer 550a and a second conductive layer 550b are provided in spaces s and s, along the outer side edges (or outer side surfaces) of the resistive element 520, the adhesive 530 and each of the conductive elements 510a and 510b in order to make an electrical connection between them. Preferably, the first conductive layer 550a and the second conductive layer 550b are plated to the bottom surface 524 of the resistive element 520 and along the outer edges of the resistive element 520 and the conductive elements 510a and 510b.
(37) The aligned outer side edges (or outer side surfaces) of the resistive element 520, adhesive material 530, and conductive layers 550a, 550b, form solderable surfaces configured to receive solderable layers. Solderable layers 560a and 560b may be separately attached at the lateral ends 565a and 565b of the resistor 500 to allow the resistor 500 to be soldered to a circuit board. As shown in
(38) A dielectric material 540 may be deposited on surfaces of the resistor 500, for example, by coating. The dielectric material 540 may fill spaces or gaps to electrically isolate them from one another. As shown in
(39)
(40) The conductive elements 510a and 510b and the resistive element 520 may be masked, as desired, to create a plating pattern and then may be plated (630). The plating may be used, for example, to deposit one or more of the conductive layer 550a and 550b. Once the plating is completed, the masking may be removed so that the resistive element may be calibrated (635), for example, by thinning a resistive foil to a desired thickness or by manipulating the current path by cutting through the resistive foil in specific locations based, for example, on the target resistance value for the resistor. A dielectric material 540 may be deposited on one or both of the resistive element 520, and the conductive elements 510a and 510b (640) (e.g., by coating). The dielectric material 540a may fill any space between the conductive elements 510a and 510b to electrically isolate them from one another. A plate formed by the method may then be singulated into individual pieces to form individual resistors 500 (645). Solderable layers 560a and 560b may then be attached to, or formed on, the lateral edges 565a and 565b of the individual resistors 500, for example, by plating (650). In the embodiments illustrated in
(41) Although the features and elements of the present invention are described in the example embodiments in particular combinations, each feature may be used alone without the other features and elements of the example embodiments or in various combinations with or without other features and elements of the present invention.