Patent Application
20220301747
This application claims the priority benefit of TW application serial No. 109125235 filed on Jul. 27, 2020, and the priority benefit of TW application serial No. 110110044 filed on Mar. 19, 2020, the entirety of which is hereby incorporated by reference herein and made a part of specification.
The present invention relates to a resistor, more particularly a high-power resistor.
With reference to
After printing the printed conductive layers 82 and before sintering the printed conductive layers 82, edges of the printed conductive layers 82 are prone to tilting and collapsing due to material property reasons. The tilting and collapsing of edges of the printed conductive layers 82 makes the printed resistor layer 81 clad on the tilted edges of the printed conductive layers 82, forming a tilted surface 810 upon sintering. Since both the printed resistor layer 81 and the two printed conductive layers 82 are only about 50 nanometers (nm) to 15 micrometers (μm) thick, widths of contact surfaces between the printed resistor layer 81 and the two printed conductive layers 82 are also about 50 nm to 15 μm. When a high current passes through the contact surfaces between the printed resistor layer 81 and the two printed conductive layers 82, the tilted surface 810 will easily heat up due to high resistance created by small electricity pathways of the contact surfaces. After heating up and cooling down repeatedly, stress and strain of repeated expanding and shrinking can cause dislocations between the printed resistor layer 81 and the two printed conductive layers 82, decreasing reliability of the chip resistor.
With reference to
To overcome the drawbacks of an unstable structure connecting a printed resistor layer of a conventional chip resistor and two printed conductive layers, the present invention provides a high-power resistor. The high-power resistor of the present invention includes:
a substrate, having a first surface;
a resistor layer, mounted on the first surface of the substrate;
two edge electrodes, mounted on the resistor layer; and
a seed layer, mounted between the resistor layer and the two edge electrodes, and being electrically conductive.
In a manufacturing process of the high-power resistor, after the resistor layer is mounted on the substrate, the seed layer is mounted on the resistor layer before further mounting the two edge electrodes on the seed layer. Since the seed layer is mounted first on the resistor layer, a cladding process such as rack plating is used for mounting the edge electrodes on the seed layer. As a result, the two edge electrodes are located on the resistor layer and are mounted overlapping the resistor layer, rather than only contacting side surfaces of the resistor layer. In the high-power resistor of the present invention, a contacting surface between one of the two edge electrodes and the resistor layer is a projected area of one of the two edge electrodes perpendicular to the substrate. The contacting surface is much bigger than contacting side surfaces of the printed resistor layer and the printed conduction layers from the prior art. As a result, a current flows between the edge electrodes and the resistor layer with less electrical resistance in the high-power resistor of the present invention.
Since the manufacturing process of the high-power resistor excludes mounting the printed resistor layer and the printed conductive layers, sintering can be avoided, and since the contacting surface between the edge electrodes and the resistor layer becomes bigger, tilting and collapsing of the contacting surface from circuit printing and sintering can also be avoided, ensuring manufacturing stability, precision, and better efficiency.
The high-power resistor of the present invention is made by the aforementioned manufacturing process. The edge electrodes connecting an external power source is mounted overlapping the resistor layer via the seed layer on the resistor layer. The contacting surface between one of the two edge electrodes and the resistor layer is the projected area vertically projected from one of the two edge electrodes to the substrate. The projected area is far bigger than contacting side surfaces of the printed resistor layer and the printed conduction layers from the prior art.
When high-power electricity passes through the resistor layer, heat generated by large passing current between the resistor layer and the two edge electrodes can be equally dissipated in all directions on the contact surface. With the contact surface being bigger, the contact surface prevents damage due to excessive high temperatures, enabling the high-power resistor to tolerate greater electric power. Furthermore, by having the seed layer, the two edge electrodes and the resistor layer benefit for having stable structures and having stable electrical connections. The seed layer decreases electrical resistance between the two edge electrodes and the resistor layer, making the high-power resistor performing stably, and making the high-power resistor more tolerant of electrical resistance fluctuations for the resistor layer and the two edge electrodes.
With reference to
preparing a substrate 10;
mounting a resistor layer 20 on a first surface 11 of the substrate 10;
mounting a seed layer 21 on the resistor layer 20;
mounting two edge electrodes 31 on the seed layer 21;
removing parts of the seed layer 21 and parts of the resistor layer 20 to form a resistor pattern from the remained seed layer 21 and the remained resistor layer 20; and
removing parts of the remained seed layer 21 exposed by the two edge electrodes 31 to expose the remained resistor layer.
With reference to
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More particularly, after the seed layer 21 covers the resistor layer 20, the exposed parts of the seed layer 21 reserved for mounting the two edge electrodes 31 are lithographically created through the patterned photoresist layer 33A covered on the seed layer 21. The exposed parts of the seed layer 21 reserved for mounting the two edge electrodes 31 each has an area of dimension 0.7 millimeters (mm)*0.7 mm to 1.5 mm*1.5 mm in another embodiment of the present invention. Once the areas cleared, the two edge electrodes 31 are mounted in the areas by plating. Further, rack plating is used to make the two edge electrodes 31 thick. A thickness d1 for the two edge electrodes 31 can reach 30 to 100 micrometers (micron; μm) or even greater. Therefore, the areas are basically contact areas. The seed layer 21 is used as an intermedia in the contact areas between the two edge electrodes 31 and the resistor layer 20, and the seed layer 21 has a dimension of 0.7 millimeters (mm)*0.7 mm to 1.5 mm*1.5 mm.
The two edge electrodes 31 are mounted overlapping the resistor layer 20 with the contact area, and the contact area is an overlapping surface 311 of the two edge electrodes 31. Comparing to side surfaces connecting the printed resistor layer and the printed conduction layer of a conventional chip resistor with a width of 50 nanometers (nm) to 15 μm, the overlapping surface 311 of the present invention has greater surface area to conduct electricity. Furthermore, since after mounting the seed layer 21 the present invention uses rack plating, the thickness of the two edge electrodes 31 of the present invention is far greater than the printed conduction layer. Overall, since the overlapping surface 311 is greater and the thickness of the two edge electrodes 31 is thicker, the edge electrodes 31 have better heat dissipating properties. When a high current passes through the high-power resistor, the heat generated by the high current from the overlapping surface 311 is dissipated from the two edge electrodes 31 directly, preventing the heat from damaging the high-power resistor with high temperature, and improving a power tolerance of the high-power resistor.
Furthermore, when mounting the two edge electrodes 31, two bottom electrodes 32 are simultaneously mounted on the second surface 12 of the substrate 10. With reference to
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After the edge two electrodes 31 are mounted on the seed layer 21, a next step is to remove any remains of the seed layer 21 and the resistor layer 20 other than the resistor pattern on the first surface 11 of the substrate 10. First the first patterned photoresist layer 34 covers on the seed layer 21, wherein the first patterned photoresist layer 34 covers a pattern needed to be preserved for forming the resistor pattern. Then parts of the seed layer 21 exposed through the first patterned photoresist layer 34 and parts of the resistor layer 20 are removed, preserving only parts of the seed layer 21 and parts of the resistor layer 20 for forming the resistor pattern. Further, parts of the seed layer 21 and parts of the resistor layer 20 are removed separately by etching, and in the end, the first patterned photoresist layer 34 is also removed.
When the remains of the seed layer 21 and the resistor layer 20 are removed, simultaneously removes remains of the seed layer 21 and the resistor layer 20 on the second surface 12 of the substrate 10. Since only the bottom electrodes 32 on the second surface 12 needs to be preserved, when etching to remove the seed layer 21 and the resistor layer 20 on the first surface 11, parts of the seed layer 21 and parts of the resistor layer 20 exposed by the two bottom electrodes 32 are simultaneously removed.
With reference to
with reference to
with reference to
After forming the resistor pattern for the seed layer 21 and the resistor layer 20 on the first surface 11, a next step is to remove the seed layer 21 redundant in the resistor pattern. Therefore the next step is to cover the two edge electrodes 31 and parts of the first surface 11 exposed by the resistor pattern with the second patterned photoresist layer 35, and then to etch the seed layer 21 covered by the resistor pattern away, and to expose the resistor layer 20 in the resistor pattern. Further, etching methods are utilized to remove the seed layer 21 and to expose the resistor layer 20 in the resistor pattern. As such, the resistor layer 20 with a desired electrical resistance is complete in the high-power resistor of the present invention. The high-power resistor of the present invention includes the substrate 10, the resistor layer 20, the two edge electrodes 31, and the seed layer 21. The substrate 10 has the first surface 11, the resistor layer 20 is mounted on the first surface 11, the two edge electrodes 31 are mounted on the resistor layer 20, and the seed layer 21 is mounted between the resistor layer 20 and the two edge electrodes 31.
With reference to
With further reference to
forming a first protective layer 41 on the resistor layer 20, wherein the first protective layer 41 covers a surface area of the resistor layer 20 between the two edge electrodes 31, and wherein a height of an edge 411 of the first protective layer 41 contacting the two edge electrodes 31 is lower than a height of a top surface 312 of the two edge electrodes 31; and
forming a second protective layer 42 on the first protective layer 41.
The high-power resistor further includes the first protective layer 41 and the second protective layer 42. The first protective layer 41 covers the resistor layer 20 between the two edge electrodes 31, and the height of the edge 411 of the first protective layer 41 along the two edge electrodes 31 is lower than the height of the two edge electrodes 31. The second protective layer 42 is mounted on the first protective layer 41, covering the first protective layer 41.
The first protective layer 41 and the second protective layer 42 are used to cover the resistor layer 20, protecting the resistor layer 20 from physical or chemical harms. In particular, the first protective layer 41 and the second protective layer 42 are used to insulate the resistor layer 20 from contacting air, since air contains erosive water vapor. The first protective layer 41 and the second protective layer 42 are made out of materials such as synthetic resin, and in particular, electrically insulating synthetic resin having a curing temperature between 150° C. to 450° C. In the present invention, the first protective layer 41 and the second protective layer 42 are free to be made out of other materials. Furthermore, in the present embodiment, the first protective layer 41 covers a surface of the resistor layer 20 and is cured, and then the second protective layer 42 covers the first protective layer 41 and is also cured, sealing any potential gaps around the first protective layer 41, and completely insulating the resistor layer 20 from any outside air.
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The substrate 10 further has the two side surfaces 13, the first surface 11, and the second surface 12 facing opposite direction to the first surface 11. The high-power resistor further includes the two bottom electrodes 32, the side surface seed layers 51, the two first conducting layers 52, and the two second conducting layers 53. The two bottom electrodes 32 are mounted on the second surface 12. The side surface seed layers 51 are mounted on the two side surfaces 13, stretching from the first surface 11 to the second surface 12, and electrically connecting the two edge electrodes 31 and the two bottom electrodes 32. The two first conducting layers 52 are mounted on the two side surfaces 13, and the two second conducting layers 53 are mounted on the two first conducting layers 52.
A goal is to form an electrical connection between the two edge electrodes 31 and the two bottom electrodes 32. To achieve the goal, first the side surface seed layers 51 are mounted on the two side surfaces 13 of the substrate 10. The side surface seed layers 51 are made with metallic materials such as tin, silver, nickel, copper, or palladium, and by process of coating, deposition, or sputtering. This way the side surface seed layers 51 can cover the two side surfaces 13 of the substrate 10, can stretch to the first surface 11 and the second surface 12, and can coat the two side surfaces 13 of the two edge electrodes 31 and the two bottom electrodes 32, achieving the goal of electrically connecting the two edge electrodes 31 and the two bottom electrodes 32.
Additionally the two first conducting layers 52 and the two second conducting layers 53 are mounted on the side surface seed layers 51, ensuring good electrical connection between the two edge electrodes 31 and the two bottom electrodes 32. The two second conducting layers 53 are mounted on a Tin layer outside of the two first conducting layers 52 by a plating method such as barrel plating, mainly for wielding the high-power resistor through the tin layer with an external circuit board. The present embodiment is characterized in that the side surface seed layers 51 are mounted on the two side surfaces 13 of the substrate 10, causing the two first conducting layers 52 to be closely connecting the two side surfaces 13 of the substrate 10 via an intermedia as the side surface seed layers 51.
With reference to
With reference to
R3=(R1′*R2)/(R1′+R2)+R1″+(R1′*R2)/(R1′+R2).
To put simply, the current passing through the two edge electrodes 31 and the resistor layer 20 encounters equivalent resistance of individual resistances first connected in parallel then in series, improving power tolerance for the high-power resistor.
The following tables demonstrate test results for reliability tests of the high-power resistor of the present invention. In the reliability tests, resistors specified for 0.5 Watt (W) power and of 6 ohms (Ω), 11Ω, 110Ω, and 280Ω resistance (R) are being tested. The testing conditions are to put the resistors under 0.5 W, 0.75 W, 1 W, and 2 W designated power for 60 seconds of constant voltage (CV) and of constant current (CC) for reliability tests. The reliability test examines whether the high-power resistor of the present invention performs stably under the above specified testing conditions. The test results are written either as PASS or N/A. While PASS means passing the test, N/A means the resistor broke during the test and therefore failed the test.
The following tables 1A and 1B demonstrate test results of 30 resistors of
6Ω resistance.
The following tables 2A and 2B demonstrate test results of 30 resistors of 11Ω resistance.
The following tables 3A and 3B demonstrate test results of 30 resistors of 110Ω resistance.
The following tables 4 demonstrate test results of 30 resistors of 280Ω resistance.
From the results of 6Ω resistors detailed in tables 1A and 1B, all 30 sets of 6Ω resistors passed the reliability tests of 0.5 W, 0.75 W, 1 W, and 2 W designated power and of constant voltage and constant current. From the results of 11Ω resistors detailed in tables 2A and 2B, all 30 sets of 11Ω resistors passed the reliability tests of 0.5 W, 0.75 W, 1 W, and 2 W designated power and of constant voltage and constant current. From the results of 110Ω resistors detailed in tables 3A and 3B, all 30 sets of 110Ω resistors passed the reliability tests of 0.5 W, 0.75 W, and 1 W designated power and of constant voltage and constant current. For 2 W designated power, all 30 sets of 110Ω resistors passed the reliability tests of constant voltage. However 10 sets of 110Ω resistors broke during the test of 2 W designated power and of constant current (designating as N/A in the corresponding tables). From the results of 280Ω resistors detailed in tables 4, all 30 sets of 280Ω resistors passed the reliability tests of 0.5 W and 0.75 W designated power and of constant voltage and constant current. However 3 sets of 280Ω resistors broke during the test of 1 W designated power and of constant voltage, and 17 sets of 280Ω resistors broke during the test of 1 W designated power and of constant current. Since some of the 30 sets of 280Ω resistors failed the reliability test at 1 W designated power, the reliability test at 2 W designated power is canceled.
In conclusion, all sets of 6Ω and 11Ω resistors can stably perform under power up to 2 W. All sets of 110Ω resistors can stably perform under power up to 1 W, and at 2 W power with constant current, parts of the sets of 110Ω resistors will break. All sets of 280Ω resistors can stably perform under power up to 0.75 W. At 1 W power with constant voltage, parts of the sets of 280Ω resistors will break, and at 1 W power with constant current, all of the sets of 280Ω resistors will break.
In other words, in embodiments with low resistance values (at 6Ω and 11Ω), the high-power resistor of the present invention can stably perform under power 4 times higher than specified. In embodiments with high resistance values (at 110Ω and 280Ω), the high-power resistor can stably perform under power 2 times higher than specified.
Furthermore, the high-power resistor of the present invention forms the seed layer 21 as the intermedia between the resistor layer 20 and the two edge electrodes 31. This causes the two edge electrodes 31 to tightly connect the resistor layer 20, the thickness of the two edge electrodes 31 to be more than a conventional thickness of a printed conduction layer, and the electrical conductivity to be very good between the resistor layer 20 and the two edge electrodes 31. Therefore, the high-power resistor of the present invention demonstrates practical improvements to prior arts.
To better demonstrate how the high-power resistor of the present invention is able to dissipate heat and avoid damages caused by excessive high temperatures when conducting high power, the following table 5 and
The high-power resistor samples are divided into a first set and a second set. Though the first set and the second set of the high-power resistor samples differ in thickness of the two edge electrodes 31, the first set and the second set have the same contact areas between two edge electrodes 31 and the resistor layer 20. The thickness of the two edge electrodes 31 is 20 μm for the first set, and the thickness of the two edge electrodes 31 is 35 μm for the second set. Margins of error for the thickness of the two edge electrodes 31 is less than 5.25%, and margins of error of precisions between the first set and the second set is less than 0.1%.
By varying the conducting powers (W) supplied to the first set and the second set, each of the high-power resistor samples has averaged temperature measured and recorded in Table 5 for comparisons. As the conducting powers increase, averaged temperatures of the high-power resistor samples also increase. However, when the conducting powers exceeds 0.25 W, the high-power resistor samples with thicker thickness of the two edge electrodes 31 tend to have more controlled temperature rises. In other words, when the conducting powers exceeds 0.25 W, the second set of the high-power resistor samples evidently has less averaged temperature than the first set.
With reference to
The above only describes the various embodiments of the present invention, rather than limitations to the present invention. Although the embodiments of the present invention are revealed, any technical personnel in related fields are free to utilize the revealed technical detail stated above and make slight equivalent changes as different embodiments of the present invention within the boundary of what is claimed for the present invention. All equivalent changes made in relation to what is claimed for the present invention are all encompassed by what is claimed for the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 110110044 | Mar 2021 | TW | national |
