TWI603347B - Wafer resistance terminal electrode structure - Google Patents

Description

Chip resistor end electrode structure

The present invention relates to a wafer resistor terminal structure, and more particularly to a current conduction path using a different structure and using a new structure protection layer and a resistor layer size instead of a conventional current protection layer and a resistance layer having the same current conduction path. In particular, it can improve the resistance value variability of the chip resistor, thereby increasing the chip resistor yield of the narrow distributed resistance value, which can effectively improve the resistor electrical yield product and greatly reduce the cost of the front end electrode material. By.

The resistance value of the chip resistor is mainly determined by the material and geometry of the resistor layer, and then connected to the printed circuit board (PCB) through electroplating nickel and tin after being turned on through the front metal terminal electrode. Basically, the terminal electrode of the chip resistor can be divided into three parts, namely a front end electrode, a side end electrode and a back end electrode, wherein the side end electrode and the back end electrode are only used for the post process electroplating of nickel and tin seed layers. In addition to the use of the front-end electrode for the post-process electroplating nickel and tin seed layer, it is also necessary to be responsible for the connection of the resistance layer conduction path, that is, the connection of the resistance layer and the electroplated nickel tin and soldering to the PCB board. For example, US Patent No. 6,153,256, and the Republic of China No. I423271 and No. 350071; of course, there is also a technique of using a silver electrode on the back side to connect a resistive layer, such as the Patent No. I294129 of the Republic of China, the principle and the above-mentioned front end electrode The connection resistance layer is the same. In order to form an ohmic contact with the resistive layer, the conductivity of the front end electrode must be much lower than the resistive layer resistivity to form an ohmic contact, otherwise the parasitic resistance will affect the final resistance value of the resistor. This precision control of the resistance value must be in a small range (±1~3%), or a low resistance value resistor. The high conductivity of the front side electrode is required to be strict; however, when the resistance element has a higher resistance value The lower the resistance, the lower the front electrode resistance must be lower and lower than the resistance layer, and the front end electrode is a paste silver ink composed of a silver conductor, glass and an organic adhesive (US 6,153,256 and the Republic of China No. I423271) Case), if the resistance is low, it is necessary to increase the solid content of metallic silver in the metal silver paste. However, the higher the metal silver content is, the more expensive the price is, resulting in a substantial increase in the material cost of the front end electrode. In addition, for the low-resistance resistor, even if the resistance of the front-end electrode is lower than that of the resistive layer, it will effectively affect the final resistance of the entire resistor, resulting in difficulty in controlling the resistance of the narrow-varying low-resistance resistor. Therefore, the user-like users cannot meet the needs of the user in actual use.

The main object of the present invention is to overcome the above problems encountered in the prior art and to provide a way to change the current conduction path by different sizes of the protective layer and the resistive layer, and to turn on the electroplated layer from the path through which the front end electrode is turned on. The chip resistance end electrode structure of the new path of the resistance layer.

A secondary object of the present invention is to provide a plating metal nickel with a conductivity superior to that of printed metal silver. Therefore, by directly connecting a low resistance resistive layer with electroplated nickel, the parasitic resistance effect of the resistance layer resistance can be greatly reduced, and the effect is low. The resistance layer of the resistance value is particularly important, and the wafer resistance terminal electrode structure can effectively improve the electrical test yield of the resistor.

Another object of the present invention is to provide a seed layer function when the front side of the metal silver is not required to conduct the function of the resistive layer, and is only used for the subsequent electroplating of nickel. It can be used for electroplating nickel. In addition to the low-cost low-silver content of printed metallic silver, other low-conductivity low-cost metals can be used, which can effectively reduce the wafer resistor terminal structure of the wafer resistor material cost.

For the purpose of the above, the present invention is a wafer resistor terminal structure comprising a substrate having a front surface, a back surface and two side surfaces; and two front end electrodes formed on the front surface of the substrate and spaced apart from each other One side of the substrate is coincident; two back end electrodes are formed on the back surface of the substrate and spaced apart from each other to coincide with one side of the substrate; a first resistive layer is formed on the front surface of the substrate and located on the front surface of the substrate Between the terminal electrodes, the two ends of the first resistive layer partially overlap at least a portion of the two front end electrodes; a first protective layer is over the first resistive layer, and the first protective layer is Dimensions different from the size of the first resistive layer to expose both end portions of the first resistive layer; and two side end electrodes respectively formed on the two sides of the substrate and respectively with the front and back ends of the same side The electrodes are connected and partially overlapped over the exposed portions of the first resistive layer, such that the current conducting path directly conducts the first resistive layer through the two side terminal electrodes.

In the above embodiment of the present invention, the method further includes: a second resistive layer formed on the back surface of the substrate and located between the two back end electrodes, and the two ends of the second resistive layer partially overlap the two back ends At least a portion of the electrode; and a second protective layer overlying the second resistive layer, and the second protective layer is different in size from the second resistive layer such that both ends of the second resistive layer Partially exposed.

In the above embodiment of the present invention, the two side end electrodes are respectively formed on two sides of the substrate and are respectively connected to the front and back end electrodes of the same side, and partially overlap the two ends of the first and second resistance layers. Above the exposed portion, the current conducting path is conducted through the two side end electrodes to directly conduct the first and second resistance layers.

In the above embodiment of the present invention, the first and second protective layers are smaller than the first and second resistive layers by at least 1 micrometer (μm).

In the above embodiment of the present invention, the two front end electrodes are metal electrodes having a lower conductivity and lower cost than silver.

In the above embodiment of the present invention, the two side end electrodes are selected from the group consisting of copper, nickel, tin or a combination thereof.

In the above embodiment of the present invention, the second plating layer is further formed from the side surface of the side electrode of the same side.

In the above embodiment of the present invention, the first protective layer has an inner coating layer mainly composed of glass and connected to the surface of the first resistance layer, and an epoxy resin as a main component and a surface of the inner coating layer. Connect the outer coating.

11‧‧‧Substrate

111‧‧‧ positive

112‧‧‧Back

113‧‧‧ side

12‧‧‧ front side electrode

13‧‧‧back electrode

14‧‧‧First resistance layer

15‧‧‧First protective layer

151‧‧‧Inner coating

152‧‧‧Overcoat

16‧‧‧ Side electrode

17‧‧‧Electroplating

18‧‧‧second resistance layer

19‧‧‧Second protective layer

S301 ~ s310‧‧‧ steps

Fig. 1 is a schematic view showing the manufacturing process of the first embodiment of the present invention.

Fig. 2 is a schematic view showing the comparison of the current conduction paths of the present invention.

Fig. 3 is a cross-sectional view showing the structure of a resistor end electrode of a wafer according to a second embodiment of the present invention.

Fig. 4 is a schematic view showing the comparison of the resistance value distribution of the present invention.

Please refer to FIG. 1 to FIG. 4 , which are schematic diagrams of the manufacturing process of the first embodiment of the present invention, a comparison diagram of the current conduction path of the present invention, and a cross section of the resistor end electrode structure of the second embodiment of the present invention. A schematic diagram and a comparison diagram of the resistance value distribution of the present invention. As shown in the figure, the present invention is a wafer resistor terminal structure. In the first embodiment, the substrate includes a substrate 11, two front end electrodes 12, two back end electrodes 13, a first resistive layer 14, and a first protection. The layer 15 and the two side end electrodes 16 are formed as shown in Fig. 2(b).

The substrate 11 mentioned above has a front surface 111, a back surface 112 and two side surfaces 113.

The two front end electrodes 12 are formed on the front surface 111 of the substrate 11 and are spaced apart from each other to overlap with one side surface 113 of the substrate 11.

The two back end electrodes 13 are formed on the back surface 112 of the substrate 11 and are spaced apart from each other to coincide with one side surface 113 of the substrate 11.

The first resistive layer 14 is formed on the front surface 111 of the substrate 11 and located between the two front end electrodes 12, and both end portions of the first resistive layer 14 partially overlap at least a portion of the two front end electrodes 12.

The first protective layer 15 is overlapped on the first resistive layer 14 , and the first protective layer 15 is different in size from the first resistive layer 14 , so that both ends of the first resistive layer 14 are exposed. . The first protective layer 15 has a size smaller than the first resistive layer 14 by at least 1 micrometer (μm), and the first protective layer 15 has a glass as a main component and is connected to the surface of the first resistive layer 14. The inner coating layer 151 and the outer coating layer 152 are mainly composed of an epoxy resin and connected to the surface of the inner coating layer 151.

The two side end electrodes 16 are respectively formed on the two side faces 113 of the substrate 11 and are respectively connected to the front and back end electrodes 12 and 13 of the same side, and partially overlap the exposed portions of the first resistance layer 14 And causing the current conduction path to directly conduct the first resistance layer 14 through the two side terminal electrodes 16.

The wafer resistor terminal structure may further include a second plating layer 17 formed upward from the surface of the side terminal electrode 16 on the same side. If so, a new wafer resistor terminal structure is constructed by the above disclosed process.

The second resistor layer 18 and a second protection layer 19 are formed on the substrate 11 as shown in FIG. The back surface is located between the two back end electrodes 13, and the two ends of the second resistive layer 18 partially overlap at least a portion of the two back end electrodes 13; and the second protective layer 19 overlaps the second resistive layer 18, and the second protective layer 19 is smaller than the second resistive layer 18 by at least 1 μm or more, so that both ends of the second resistive layer 18 are exposed. In this structure, the two side end electrodes 16 are respectively formed on two sides of the substrate 11 and are respectively connected to the front and back end electrodes 12 and 13 of the same side, and partially overlap the first and second resistance layers 14 , Above the exposed portions of the two ends of the 18, the current conducting path is conducted through the two side end electrodes 16 to directly conduct the first and second resistive layers 14, 18.

The process of the above-mentioned chip resistor end electrode structure is performed by using an alumina ceramic substrate with a thick film printing process, sequentially through the end electrode printing and sintering, resistive layer printing and sintering, inner coating printing and sintering of the protective layer, laser cutting, protection The outer layer of the coating is printed and sintered, the letter layer printing, the folding strip, the end electrode side guiding printing, the dicing, the electroplating and the like to form a wafer resistor terminal structure. As shown in FIG. 1, the process of the chip resistor terminal electrode structure (the first embodiment is taken as an example) of the present invention is mainly implemented by the following steps:

In the terminal electrode printing and sintering step s301, first, the two rear end electrodes 13 are printed on the back surface 112 of the substrate 11, and the two front end electrodes 12 are printed on the front surface 111 of the substrate 11; the substrate 11 is then sent to the sintering furnace. The high temperature sintering operation at 850 ° C enables the back end electrode 13 and the front end electrode 12 to be sintered with the substrate 11; wherein the front end electrode 12 is a metal electrode having a lower conductivity and lower cost than silver, such as aluminum or copper. Etc., it is also possible to use low cost, low silver content printed metallic silver.

In the resistive layer printing and sintering step s302, a first resistive layer 14 is printed on the substrate 11 between the adjacent front end electrodes 12, and the first resistive layer 14 is connected to the front end electrode 12 at both ends; It is sent to a sintering furnace to perform a high-temperature sintering operation at 850 ° C, so that the first resistance layer 14 can be sintered with the substrate 11.

The inner coating layer 151 of the first protective layer 15 is printed on the first resistive layer 14 which is sintered, and the inner coating layer 151 is smaller in size than the first resistive layer. 14. The two ends of the first resistive layer 14 are exposed; the substrate 11 is sent to a sintering furnace for high-temperature sintering at 600 ° C, so that the inner coating 151 of the first protective layer 15 can be combined with the first resistor. The layer 14 is sintered; wherein the inner coating layer 151 of the first protective layer 15 is an insulator composed mainly of glass.

In the laser cutting step s304, the substrate 11 is sent to the laser cutting device, and the first resistive layer 14 is cut on the inner coating layer 151 of the first protective layer 15 by laser light, and cut out at the appropriate place of the first resistive layer 14. An adjustment groove of an appropriate shape ("I", "L" or "one" shape) is used to trim the resistance value of the first resistance layer 14.

a protective layer outside the coating printing and sintering step s305, on the surface of the inner protective layer 151 of the first protective layer 15 is reprinted to form a first protective layer 15 outer coating 152 to form a complete first protective layer 15; Then, the substrate 11 is sent to a sintering furnace for sintering at 200 ° C, so that the outer protective layer 15 of the first protective layer 15 can be sintered with the inner coating 151; wherein the outer coating 152 and the inner coating 151 The two ends of the first resistive layer 14 are exposed to the same size, and the outer coating layer 152 of the first protective layer 15 is an insulating material composed mainly of epoxy resin.

The word layer printing step s306, on the first protective layer 15, is printed with an associated identification code representing the resistance of the chip, such as a model number, a resistance value, and the like.

In the folding step s307, the sheet-like substrate 11 is sent to a rolling device, and the substrate 11 is split into strips by a roll division method.

In the terminal electrode side printing step s308, the electrode on both sides of the strip-shaped substrate 11 is printed with a conductive material, so that the front end electrode 12 and the back end electrode 13 on the same side of the substrate 11 are connected to each other to form a wafer. The side end electrode 16 of the resistor; the strip substrate 11 which finished the side electrode side printing is sent to the sintering furnace for sintering at 200 ° C, so that the side end electrode 16 after the side guide printing can be combined with the front end electrode 12 The back end electrode 13 is sintered; wherein the side end electrode 16 is a conductive material selected from copper, nickel, tin or a combination thereof.

In the granulation step s309, the strip substrate 11 sintered by the side end electrode 16 is completed, and the strip substrate 11 is again divided by the rolling device, and the strip substrate 11 is folded, so that the connected wafer resistor terminal electrode structure is divided into many independent and has two front surfaces. The terminal electrode 12, the two back end electrodes 13, the two side end electrodes 16, a first resistance layer 14, and a granular body including the protective layer 15 of the undercoat layer 151 and the overcoat layer 152.

In the electroplating step s310, the wafer resistor end electrode structure formed into a granular shape is sent to the plating bath for electroplating operation, and a plating layer 17 is plated on the outside of the side end electrode 16 of the wafer resistor conductive material, thereby completing the fabrication of the wafer resistor terminal electrode structure. .

As shown in FIG. 2(b), the present invention proposes that the new wafer resistor terminal structure changes the current conduction path by the difference between the size of the protection layer and the resistance layer, and turns on the original structure as shown in FIG. 2(a) through the printed front end electrode. The resistive layer path becomes a new path of the plating resistive layer as shown in Fig. 2(b). As a result, the three-terminal electrode of the resistor, the front end electrode, the side end electrode and the back end electrode are all used for the post-process electroplating of the nickel and tin seed layers. The new structure simplifies the function of the front-end electrode, so that the front-end electrode has the same electrical conductivity as the side-end electrode and the back-end electrode, and only needs to satisfy the post-process electroplating nickel and tin seed layer, and does not have to follow the resistance layer resistance in order to form an ohmic contact. The rate changes and changes.

As shown in Fig. 4, Fig. (a) shows the distribution of the resistance values of the original structural protective layer and the same size of the resistive layer, and Fig. (b) shows the distribution of the resistance values of the new structural protective layer and the resistive layer of the present invention. It can be seen from the results that the present invention can improve the resistance of the chip resistor by changing the structure mode, using a current conduction path with a different size of the new structure protection layer and the resistance layer, instead of the current conduction path of the same size of the conventional structure protection layer and the resistance layer. Value variability, which in turn increases wafer resistor yield for narrowly distributed resistance values.

Therefore, the present invention utilizes a new chip resistor terminal structure, and changes the current conduction path by the difference between the size of the protection layer and the resistance layer, and changes from the path of the on-resistance through the printed front-end electrode to the new path of the on-resistance layer. This new structure has the following two major advantages:

1. The conductivity of electroplated metal nickel is better than that of printed metal silver. Therefore, the direct connection of the low-resistance resistive layer by electroplating nickel can greatly reduce the parasitic resistance effect of the resistance layer resistance. This effect is especially important for the low-resistance resistive layer. Improving the electrical test yield of resistors has greatly helped. Wherein, the use of the metal nickel to connect the resistance layer, even if the resistance layer of the low resistance value, the resistivity is still much lower than the resistivity of the resistance layer, and therefore does not effectively affect the final resistance of the entire resistor, resulting in a narrow change Low resistance resistors are easy to control.

2. When the front side printing metal silver does not need to be used to turn on the resistance layer function, it is only used to make the seed layer function when electroplating nickel. The front end electrode conductivity requirement only needs to be able to be electroplated nickel, except low Printed metallic silver with a low silver content can be used, and other low-cost metals with lower conductivity (such as aluminum and copper) can be used, which greatly helps to reduce the cost of wafer resistor materials.

In summary, the present invention is a chip resistor terminal structure, which can effectively improve various shortcomings of the conventional use, and replaces the conventional structure protection layer and the resistor by using a new structure protection layer and a resistance layer with different current conduction paths. The current conduction path with the same layer size can really improve the resistance value variability of the chip resistor, thereby increasing the chip resistor yield of the narrow distributed resistance value, which can effectively improve the resistor electrical yield product and greatly reduce the front side. The cost of the end electrode material, in turn, makes the invention more progressive, more practical, and more in line with the needs of the user. It has indeed met the requirements of the invention patent application, and has filed a patent application according to law.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto; therefore, the simple equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the invention are modified. All should remain within the scope of the invention patent.

11‧‧‧Substrate

111‧‧‧ positive

112‧‧‧Back

113‧‧‧ side

12‧‧‧ front side electrode

13‧‧‧back electrode

14‧‧‧First resistance layer

15‧‧‧First protective layer

151‧‧‧Inner coating

152‧‧‧Overcoat

16‧‧‧ Side electrode

17‧‧‧Electroplating

Claims (6)

A chip resistor terminal structure comprises: a substrate having a front surface, a back surface and two side surfaces; and two front end electrodes formed on the front surface of the substrate and spaced apart from each other to coincide with one side of the substrate; The back end electrodes are formed on the back surface of the substrate and spaced apart from each other to coincide with one side of the substrate; a first resistance layer is formed on the front surface of the substrate and between the two front end electrodes, and the first A second resistive layer partially overlaps at least a portion of the two front end electrodes; a second resistive layer is formed on the back surface of the substrate and between the two back end electrodes, and the two ends of the second resistive layer The portion partially overlaps at least a portion of the two back end electrodes; a first protective layer overlying the first resistive layer, and the first protective layer is different in size from the first resistive layer, such that An end portion of the first resistive layer is exposed, wherein the first protective layer has a size smaller than the first resistive layer by at least 1 micrometer (μm) or more; and a second protective layer overlaps the second resistive layer, and The second The size of the protective layer is different from the size of the second resistive layer, so that both end portions of the second resistive layer are exposed; and the two side end electrodes are respectively formed on two sides of the substrate and are respectively opposite to the same side The back end electrodes are connected and partially overlap the two ends of the first and second resistance layers Above the exposed portion, the current conducting path is conducted through the two side end electrodes to directly conduct the first and second resistance layers. The wafer resistor terminal structure of claim 1, wherein the second protective layer has a size smaller than the second resistor layer by at least 1 micrometer (μm). The chip resistor end electrode structure according to claim 1, wherein the two front end electrodes are metal electrodes having a lower conductivity and lower cost than silver. The wafer resistor end electrode structure according to claim 1, wherein the two side end electrodes are selected from the group consisting of copper, nickel, tin or a combination thereof. The wafer resistor terminal structure of claim 1, further comprising a second plating layer formed upward from the side electrode surface of the same side. The wafer resistor terminal structure of claim 1, wherein the first protective layer has an inner coating layer mainly composed of glass and connected to the surface of the first resistor layer, and an epoxy resin A main component and a coating attached to the surface of the inner coating.