CN110994100A - Surface-mounted type load sheet for 5G communication and preparation method thereof - Google Patents
Surface-mounted type load sheet for 5G communication and preparation method thereof Download PDFInfo
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- CN110994100A CN110994100A CN201911375503.6A CN201911375503A CN110994100A CN 110994100 A CN110994100 A CN 110994100A CN 201911375503 A CN201911375503 A CN 201911375503A CN 110994100 A CN110994100 A CN 110994100A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/24—Terminating devices
- H01P1/26—Dissipative terminations
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P11/00—Apparatus or processes specially adapted for manufacturing waveguides or resonators, lines, or other devices of the waveguide type
Abstract
The invention discloses a surface-mounted type load sheet for 5G communication and a preparation method thereof, and belongs to the technical field of aluminum nitride ceramic substrate load sheets for 5G communication. The front side of the aluminum nitride ceramic substrate is printed with a front side circuit, a resistor and a grounding wire, the front side circuit, the resistor and the grounding wire are printed with a first black protective film, a second black protective film and an identification point for three times, wherein the second black protective film has a retraction distance relative to the front end and the rear end of the first black protective film and is perforated to expose the identification point, the back side of the aluminum nitride ceramic substrate is attached with a back side grounding conductor in an SMT patch mode, and the front end and the rear end are respectively formed into end grounding through a double-sided vacuum sputtering process. The load sheet can meet the application requirement of 5G communication, can meet the requirements on flatness, vacuum sputtering consistency and good appearance in the production process on the basis of realizing miniaturization and high-frequency load, can improve the yield of products, and can meet the automatic production requirement of customers.
Description
Technical Field
The invention relates to an aluminum nitride ceramic substrate load sheet and a preparation method thereof, in particular to a surface-mounted type load sheet for 5G communication and a preparation method thereof, and belongs to the technical field of parts for 5G communication.
Background
The aluminum nitride ceramic substrate load sheet is mainly used for absorbing reverse input power in a communication component in a communication base station, and if the load sheet cannot bear required power, the load can be burnt out, so that the whole equipment is burnt out. At present, most communication base stations use high-power ceramic load sheets to absorb reverse input power in communication components, the basic size is required to be smaller and smaller, the power required to be absorbed is larger and larger, and the product characteristics such as standing-wave ratio are required to be smaller and better.
With the progress of the communication era, 5G base stations have entered into a substantial station distribution stage, and most of the 5G base stations adopt a 64-channel design, so that the transmission speed of the network can be greatly increased through the multi-channel design. On each channel, a power absorbing load is required at the multiport of the circulator. Most of the prior and current terminal clients mostly adopt foreign power absorption loads on the power amplifier board, and some of the power amplifier boards are difficult to be matched with software and hardware of a domestic 5G communication system; the current domestic load chip still has great defects in miniaturization and high-frequency load. Therefore, it is an urgent technical problem to provide a small-sized load sheet with high frequency load to meet the requirement of 5G base station, and to provide an optimized method for preparing a load sheet for 5G communication.
Disclosure of Invention
In order to solve the technical problem, the invention provides a surface-mounted type load sheet for 5G communication and a preparation method thereof.
The technical scheme of the invention is as follows:
the invention discloses a surface-mounted type 5G load sheet for communication, which comprises an aluminum nitride ceramic substrate with the size of 1.5 multiplied by 3.0 multiplied by 0.385mm, wherein two ends of the aluminum nitride ceramic substrate in the length direction are respectively a front end and a rear end,
a front circuit in a square frame shape is printed at the front end of the front surface of the aluminum nitride ceramic substrate, a resistor is printed on the front surface of the aluminum nitride ceramic substrate, and the resistor is connected with the front circuit to form a load circuit; a square grounding wire is printed at the rear end of the front surface of the aluminum nitride ceramic substrate, and the grounding wire is connected with the resistor to form a grounding end of the load circuit;
the front surface of the aluminum nitride ceramic substrate is provided with a first black protective film, the first black protective film covers a local front surface circuit, the whole resistor and a local grounding wire, and the front end and the rear end of the first black protective film are respectively retracted by 0.1-0.2mm relative to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate so as to expose the local front surface circuit and the local grounding wire; the upper surface layer of the first black protective film is provided with a mark point; a second black protective film is arranged on the upper surface layer of the first black protective film, the second black protective film is corresponding to the opening at the mark point to expose the mark point, and the front end and the rear end of the second black protective film are respectively retracted by 0.1-0.2mm relative to the front end and the rear end of the first black protective film to expose partial first black protective film;
an input pad is printed at the front end of the back of the aluminum nitride ceramic substrate, and a back grounding conductor is attached to the rear end of the back of the aluminum nitride ceramic substrate in an SMT (surface mount technology) patch mode;
the front end and the rear end of the aluminum nitride ceramic substrate are respectively provided with end grounds through a double-sided vacuum sputtering process, wherein the end ground of the front end is communicated with the front circuit and the input bonding pad, and the end ground of the rear end is communicated with the grounding wire and the back grounding conductor.
The further technical scheme is as follows:
the front end and the rear end of the first black protective film, which are opposite to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate, are respectively retracted by 0.1 mm; and the front end and the rear end of the second black protective film are respectively retracted by 0.1mm relative to the front end and the rear end of the first black protective film.
The further technical scheme is as follows:
the resistance value of the resistor is 50 +/-1 ohm.
The further technical scheme is as follows:
the front circuit adopts a leadless design mode.
The further technical scheme is as follows:
the second black protective film is consistent with the marking point in thickness.
The further technical scheme is as follows:
the absorption load power of the surface-mounted type 5G communication load sheet is 8W, the frequency covers DC-6GHz, and the standing wave characteristic of the surface-mounted type 5G communication load sheet reaches-20.83 dB max in the frequency.
The invention also discloses a preparation method of the surface-mounted type 5G load sheet for communication, which mainly comprises the following steps:
s1, cleaning the substrate: selecting an aluminum nitride ceramic substrate with the size of 1.5 multiplied by 3.0 multiplied by 0.385mm, cleaning the surface of the aluminum nitride ceramic substrate by adopting alcohol with the volume percent of more than 95%, and printing a conductor within 2 hours after the alcohol is volatilized;
s2, printing front circuit and ground line: adopting a thick film printing process, printing a front circuit and a grounding wire on the front surface of the aluminum nitride ceramic substrate treated in the step S1 by using silver paste through screen printing, and sequentially standing, pre-baking and sintering at high temperature after printing;
s3, printing a resistor: adopting a screen printing process, further printing resistors on the front circuit and the grounding wire which are processed in the step S2 by using the resistor paste through a screen, and sequentially standing, pre-baking and sintering at high temperature after printing;
s4, resistance adjustment: adopting a laser resistance value debugging mode for the resistor formed by sintering in the step S3 to enable the resistance value of the resistor to reach 50 +/-1 ohm;
s5, printing a first black protective film: printing a first black protective film on the local front circuit, the whole resistor and the local grounding wire on the front surface of the aluminum nitride ceramic substrate processed in the step S4 by adopting a thick film printing process, wherein the front end and the rear end of the first black protective film are respectively retracted by 0.1mm relative to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate so as to expose the local front circuit and the local grounding wire, and after printing is finished, sequentially carrying out placement, keeping and drying to form a dry first black protective film;
s6, printing identification points: printing mark points on the upper surface layer of the first black protective film formed in the step S5 by adopting a thick film printing process, and after printing is finished, sequentially placing, leveling and drying to form dry mark points;
s7, printing a second black protective film: printing a second black protective film on the upper surface layer of the first black protective film formed in the step S5 by using a thick film printing process, wherein the second black protective film is opened corresponding to the mark point to expose the mark point, the front end and the rear end of the second black protective film are respectively retracted by 0.1mm relative to the front end and the rear end of the first black protective film to expose a part of the first black protective film, and after printing is finished, the first black protective film, the mark point and the second black protective film are sequentially placed, leveled and dried to form a cured first black protective film, a cured second black protective film and a cured second black protective film;
s8, molding of input pads and back ground conductors: printing an input pad on the back of the cleaned aluminum nitride ceramic substrate by using silver paste through a thick film printing process, and sequentially standing, pre-baking and sintering at high temperature after printing is finished; mounting the back grounding conductor by adopting an SMT (surface mount technology) mounting mode;
s9, ground-end molding: and (3) synchronously sputtering and coating films at one time at the front end and the rear end of the aluminum nitride ceramic substrate processed in the step S8 by adopting a double-sided vacuum sputtering process to form end grounding, wherein the end grounding at the front end is communicated with the front circuit and the input bonding pad, and the end grounding at the rear end is communicated with the grounding wire and the back grounding conductor.
The further technical scheme is as follows:
the silver paste adopted by the front circuit, the grounding wire and the input pad in the steps S2 and S8 mainly comprises the following components in percentage by mass: 70-80 wt.% of silver powder with the diameter of 800-1000nm, 4-5 wt.% of glass powder, 5-10 wt.% of binder, 0.05-0.08 wt.% of sintering promoter and the balance of organic solvent.
The glass powder can be glass powder with the diameter of 1-2 μm, and the content of the main components in the glass powder is as follows: 30-40 wt.% of aluminum oxide, 1-2 wt.% of calcium oxide, 0.5-1.0 wt.% of bismuth oxide and the balance of silicon oxide, wherein the sum of the weight percentages of the components of the glass powder is 100 wt.%.
The binder is organic cellulose binder, and may be at least one of ethyl cellulose, nitrocellulose, and hydroxymethyl cellulose.
The sintering accelerant is a ruthenium-containing compound or an iridium-containing compound.
The organic solvent is at least one of alcohol organic solvent and ester organic solvent, such as terpineol, butyl benzyl alcohol, tributyl phosphate, etc.
The further technical scheme is as follows:
in the steps S2 and S8, the front circuit, the grounding wire and the input bonding pad are all selected from a screen printing plate with the tension of 24-26N when in printing, and the temperature is 23-27 ℃ when the screen printing plate is used; after the printing is finished, standing for 15-20min, pre-baking at 170 ℃ of 165-plus-material for 15-20min and high-temperature sintering at 900 ℃ of 850-plus-material for 15-20min are carried out in sequence.
The further technical scheme is as follows:
the resistance slurry adopted by the resistance in the step S3 is a thixotropic slurry with the viscosity of 50000-55000cps, and the thixotropic slurry mainly comprises the following components in percentage by mass: 55-60 wt.% of silver powder with the diameter of 300-500nm, 3-6 wt.% of glass micropowder with the diameter of 200-300nm, 5-10 wt.% of organic cellulose binder, 0.5-1.0 wt.% of fumed silica thixotropic agent and the balance of organic solvent, wherein the glass micropowder comprises 30-50 wt.% of silicon oxide and 50-70 wt.% of aluminum oxide.
The organic cellulose binder can be selected from conventional organic cellulose, such as at least one of ethyl cellulose, nitrocellulose, and hydroxymethyl cellulose.
The organic solvent can be at least one of alcohol organic solvent and ester organic solvent, such as terpineol, butyl benzyl alcohol, tributyl phosphate, etc.
The further technical scheme is as follows:
in the step S3, the resistor is printed by a 400-mesh 420-mesh steel wire screen plate, the temperature of the steel wire screen plate is 23-27 ℃, and after the printing is finished, the resistor is sequentially placed for 10-15min, pre-dried at the temperature of 175 ℃ for 15-20min and sintered at the temperature of 850 ℃ for 15-20 min.
The further technical scheme is as follows:
the first black protective film in the step S5, the mark point in the step S6 and the second black protective film in the step S7 adopt a screen printing plate with the tension of 24-26N during printing, the temperature during screen printing is 23-27 ℃, after printing is finished, standing is sequentially carried out for 20-23min, pre-drying is carried out for 20-25min at the temperature of 100-105 ℃ until surface drying is carried out, and then, high-temperature baking is carried out for 50-60min at the temperature of 200-210 ℃ until solid drying is carried out.
The marking points are used for distinguishing the electrode direction of the product, and are printed by white slurry to form contrast with the color of the black protective film. The slurry used for the first black protective film, the second black protective film and the mark point is a slurry conventionally used for manufacturing protective films and mark points in the field, and a commercially available product can be selected, which are all technical solutions well known to those skilled in the art, and is not described in detail in this application.
The beneficial technical effects of the invention are as follows:
(1) the aluminum nitride ceramic substrate adopted in the invention has the size of 1.5 multiplied by 3.0 multiplied by 0.385mm, is smaller than the conventionally used aluminum nitride ceramic substrate for the load sheet, and can meet the requirement of miniaturization of the load sheet;
(2) the front circuit adopts a leadless design, and can increase the capacitance of the front bonding pad part, thereby improving the radio frequency performance;
(3) in the invention, the following advantages exist in printing the protective film and the mark points:
a. in the invention, a mode of printing two layers of black protective films is adopted; different from the traditional method that only one black protective film is printed;
b. in the printing process, a first layer of black protective film is printed, after the first layer of black protective film is dried, identification points are printed on the first layer of black protective film, then a second layer of black protective film is printed on the first layer of black protective film, and the identification points are exposed by opening holes; the traditional mark points are directly printed on only one black protective film; the printing method can ensure that products are not uneven due to the height of the identification points when the products are stacked in the jig during subsequent vacuum sputtering, so that the same distance can be ensured between every two products;
c. in the invention, the front end and the rear end of the first layer of black protective film are respectively retracted by a certain distance relative to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate, the front end and the rear end of the second black protective film are respectively retracted by a certain distance relative to the front end and the rear end of the first black protective film, and especially the inward retraction design of the front end and the rear end of the second black protective film is an innovative point of the invention; this is to form a height difference between the second black protective film and the first black protective film, so that during subsequent vacuum sputtering, it can be ensured that the sputtered layer can be sputtered onto the electrode and the first black protective film, and at the same time, the sputtered layer can be blocked by the second black protective film, so that the uniformity of sputtering can be ensured.
The three-point design can improve the consistency of vacuum sputtering and the appearance yield by 15 percent;
(4) the back conductors are mounted in a separated mode and are matched with the SMT mounting mode, so that a customer can conveniently and directly mount the back conductors, and the automatic production of the customer is met;
(5) in the invention, the end grounding adopts a double-sided vacuum sputtering process, the sputtering of the two-sided end heads is completed at one time, and the production efficiency can be improved; and because the back adopts surface mounting technology, it has certain pressure in automated production, uses vacuum sputtering can guarantee the planarization of product, can not because the pressure that produces in the automated production process is with product fracture.
Drawings
FIG. 1 is a schematic front view of the present invention;
FIG. 2 is a schematic view of the backside structure of the present invention;
FIG. 3 is a schematic view of the cross-sectional structure A-A of FIG. 1 according to the present invention;
wherein:
1-an aluminum nitride ceramic substrate; 2-front side circuit;
3-a ground wire; 4-resistance;
5-a first black protective film; 6-second black protective film;
7-identification points; 8-back ground conductor;
9-input pad; the 10-terminal is grounded.
Detailed Description
In order to make the technical means of the present invention clearer and to make the technical means of the present invention capable of being implemented according to the content of the specification, the following detailed description of the embodiments of the present invention is made with reference to the accompanying drawings and examples, which are provided for illustrating the present invention and are not intended to limit the scope of the present invention.
The following embodiment describes in detail a surface mount type 5G communication load sheet including an aluminum nitride ceramic substrate 1 having a size of 1.5 × 3.0 × 0.385mm, both ends in the longitudinal direction of the aluminum nitride ceramic substrate being a front end and a rear end, respectively.
A front circuit 2 in a square frame shape is printed at the front end of the front surface of the aluminum nitride ceramic substrate 1, and the front circuit 2 adopts a leadless design mode. The front surface of the aluminum nitride ceramic substrate is printed with a resistor 4, the resistance of the resistor 4 is adjusted to 50 +/-1 ohm by laser resistance value after sintering, and the resistor is connected with a front surface circuit to form a load circuit. A square grounding wire 3 is printed at the rear end of the front surface of the aluminum nitride ceramic substrate 1, and the grounding wire is connected with the resistor to form a grounding end of the load circuit.
A first black protective film 5 is arranged on the front surface of the aluminum nitride ceramic substrate 1, the first black protective film covers a local front surface circuit, the whole resistor and a local grounding wire, and the front end and the rear end of the first black protective film, which are opposite to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate, are respectively retracted by 0.1mm so as to expose the local front surface circuit and the local grounding wire; the upper surface layer of the first black protective film is provided with identification points 7 for distinguishing the electrode direction of the product; be equipped with second black protection film 6 on the upper surface of first black protection film, this second black protection film corresponds 7 punchments of identification point and makes the identification point exposes, and around this second black protection film both ends relative first black protection film both ends around equally divide and contract 0.1mm respectively in order to expose local first black protection film, foretell second black protection film 6 is unanimous with the thickness of thickness and identification point 7.
An input pad 9 is printed at the front end of the back surface of the aluminum nitride ceramic substrate 1, and a back surface grounding conductor 8 is attached to the back end of the back surface of the aluminum nitride ceramic substrate in an SMT patch manner.
The front end and the rear end of the aluminum nitride ceramic substrate 1 are respectively formed with terminal grounds 10 by a double-sided vacuum sputtering process, wherein the terminal ground of the front end communicates with the front surface circuit and the input pad, and the terminal ground of the rear end communicates with the ground line and the rear surface ground conductor.
The size of the surface-mounted type 5G load chip for communication is 1.5 multiplied by 3.0 multiplied by 0.385mm, the absorbed load power is 8W, the frequency covers DC-6GHz, and the standing wave characteristic of the surface-mounted type 5G load chip reaches-20.83 dB max in the frequency.
The following examples are provided to illustrate the preparation of the surface-mounted type 5G carrier sheet for communication.
75 wt.% of silver powder with the average diameter of 1 μm, 5 wt.% of glass powder with the average diameter of 1.5 μm, 10 wt.% of binder (formed by mixing ethyl cellulose and hydroxymethyl cellulose according to the mass ratio of 1: 1), 0.05 wt.% of ruthenium dioxide and the balance of butyl benzyl alcohol, wherein the glass powder comprises the following main components: 30 wt.% of aluminum oxide, 1 wt.% of calcium oxide, 0.5 wt.% of bismuth oxide and the balance of silicon oxide, and the sum of the weight percentages of the components of the glass powder is 100 wt.%. The preparation is carried out by adopting a technical scheme well known by the technical personnel in the field, the details are not repeated in the specific embodiment, and the fineness of the slurry ground by a three-roll grinder is less than or equal to 5 mu m.
80 wt.% of silver powder with the average diameter of 800nm, 4 wt.% of glass powder with the average diameter of 1.0 μm, 8 wt.% of binder (formed by mixing ethyl cellulose and hydroxymethyl cellulose according to the mass ratio of 1: 1), 0.06 wt.% of ruthenium dioxide and the balance of terpineol, wherein the glass powder comprises the following main components: 35 wt.% of aluminum oxide, 2 wt.% of calcium oxide, 0.8 wt.% of bismuth oxide and the balance of silicon oxide, and the sum of the weight percentages of the components of the glass powder is 100 wt.%. The preparation is carried out by adopting a technical scheme well known by the technical personnel in the field, the details are not repeated in the specific embodiment, and the fineness of the slurry ground by a three-roll grinder is less than or equal to 5 mu m.
60 wt.% silver powder with an average diameter of 450nm, 5 wt.% glass micropowder with a diameter of 300nm, 10 wt.% organic cellulose based binder (nitrocellulose), 0.5 wt.% fumed silica and the balance terpineol, wherein the glass micropowder comprises 40 wt.% silica and 60 wt.% alumina. The preparation is carried out by adopting a technical scheme which is well known to a person skilled in the art, and the detailed description in the specific embodiment is omitted. The viscosity of the slurry is 51040cps, and the fineness of the slurry ground by a three-roller grinder is less than or equal to 2 μm.
55 wt.% of silver powder with the average diameter of 500nm, 6 wt.% of glass micropowder with the diameter of 200nm, 8 wt.% of organic cellulose binder (formed by mixing ethyl cellulose and nitrocellulose according to the mass ratio of 1: 2), 0.8 wt.% of fumed silica and the balance of butyl benzyl alcohol, wherein the glass micropowder comprises 50 wt.% of silicon oxide and 50 wt.% of aluminum oxide. The preparation is carried out by adopting a technical scheme which is well known to a person skilled in the art, and the detailed description in the specific embodiment is omitted. The viscosity of the slurry is 54130cps, and the fineness of the slurry ground by a three-roller grinder is less than or equal to 2 μm.
Detailed description of the preferred embodiment 1
The preparation method of the 5G communication load sheet 1 comprises the following steps:
s1, cleaning the substrate: selecting an aluminum nitride ceramic substrate with the size of 1.5 multiplied by 3.0 multiplied by 0.385mm, cleaning the surface of the aluminum nitride ceramic substrate by adopting alcohol with the volume percent of more than 95%, and printing a conductor within 2 hours after the alcohol is volatilized;
s2, printing front circuit and ground line: adopting a thick film printing process, carrying out screen printing at 25 +/-2 ℃ by using a silver paste 1 through a screen with the tension of 25 +/-1N, printing a front circuit and a grounding wire on the front surface of the aluminum nitride ceramic substrate treated in the step S1, and standing for 15min, prebaking at 165 ℃ for 20min and sintering at 850 ℃ for 15min in sequence after printing is finished to form a solidified front circuit and a solidified grounding wire;
s3, printing a resistor: adopting a screen printing process, selecting a 400-mesh steel wire mesh screen plate, further printing resistors on the front circuit and the grounding wire processed in the step S2 by using the resistor slurry 1 through the steel wire mesh screen plate at the temperature of 25 +/-2 ℃, and standing for 15min, pre-baking for 20min at 170 ℃ and sintering for 15min at high temperature of 850 ℃ after printing is finished to obtain cured resistors;
s4, resistance adjustment: adopting a laser resistance value debugging mode for the resistor formed by sintering in the step S3 to enable the resistance value of the resistor to reach 50 +/-1 ohm;
s5, printing a first black protective film: adopting a thick film printing process, selecting a screen with the tension of 25 +/-1N to perform screen printing at the environment of 25 +/-2 ℃, printing a first black protective film on a local front circuit, a whole resistor and a local grounding wire on the front surface of the aluminum nitride ceramic substrate treated in the step S4, respectively retracting the front end and the rear end of the first black protective film by 0.1mm relative to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate to expose the local front circuit and the local grounding wire, after finishing printing, sequentially placing and keeping flat for 20min, pre-baking at 100 ℃ for 25min to surface dry, then baking at 200 ℃ for 50min to actual dry to form a dry first black protective film;
s6, printing identification points: adopting a thick film printing process, selecting a screen with the tension of 25 +/-1N to perform screen printing at the environment of 25 +/-2 ℃, printing white identification points on the upper surface layer of the first black protective film formed in the step S5, sequentially placing and keeping flat for 20min after printing is finished, pre-drying at 100 ℃ for 25min to dry, and then baking at 200 ℃ for 50min to dry to form dry white identification points;
s7, printing a second black protective film: performing screen printing at 25 +/-2 ℃ by using a screen with the tension of 25 +/-1N by adopting a thick film printing process, printing a second black protective film on the upper surface layer of the first black protective film formed in the step S5, wherein the second black protective film corresponds to the opening at the identification point to expose the identification point, the front end and the rear end of the second black protective film are respectively retracted by 0.1mm relative to the front end and the rear end of the first black protective film to expose a local first black protective film, after printing is finished, sequentially placing and keeping flat for 20min, pre-baking at 100 ℃ for 25min to be surface-dried, then baking at 200 ℃ for 50min to be solid-dried to form a dry second black protective film;
s8, molding of input pads and back ground conductors: printing an input pad on the back surface of the cleaned aluminum nitride ceramic substrate by using silver paste 1 and adopting a thick film printing process, wherein during printing, the input pad is printed by a screen printing plate with the tension of 25 +/-1N at the temperature of 25 +/-2 ℃, and after printing, standing for 15min, prebaking at 165 ℃ for 20min and sintering at 850 ℃ for 15min in sequence; mounting the back grounding conductor by adopting an SMT (surface mount technology) mounting mode;
s9, ground-end molding: and (3) synchronously sputtering and coating films at one time at the front end and the rear end of the aluminum nitride ceramic substrate processed in the step S8 by adopting a double-sided vacuum sputtering process to form end grounding, wherein the end grounding at the front end is communicated with the front circuit and the input bonding pad, and the end grounding at the rear end is communicated with the grounding wire and the back grounding conductor.
The size of the prepared load sheet 1 for 5G communication is 1.5 multiplied by 3.0 multiplied by 0.385mm, the absorbed load power can reach 8W, the frequency can cover DC-6GHz, and the standing wave characteristic can reach-20.83 dB max in the frequency. Meanwhile, in the vacuum sputtering step, the products cannot be uneven in height when being stacked in the jig, and the same distance can be reserved among the products; in addition, the sputtering consistency, the smoothness and the good appearance can be ensured during vacuum sputtering, and the condition of product fracturing can not occur, so that the yield of the product is improved by 15%.
Specific example 2
The procedure for the preparation of the 5G communication support sheet 2 was as described in example 1. The difference lies in that:
In step S3, resistance paste 2 is used, the selected steel wire mesh plate is 420 meshes, and the process after printing is as follows: after the printing is finished, standing for 10min, prebaking at 175 ℃ for 15min and sintering at 800 ℃ for 20min in sequence.
In step S5, step S6, and step S7, the process after the printing is completed is: after printing is finished, the materials are sequentially placed and left flat for 23min, pre-dried for 20min at 105 ℃ until the surfaces are dry, and then baked at high temperature of 210 ℃ for 60min until the surfaces are dry.
The size of the 5G communication load sheet 2 prepared by the method is 1.5 multiplied by 3.0 multiplied by 0.385mm, the absorbed load power can reach 8W, the frequency can cover DC-6GHz, and the standing wave characteristic can reach-20.83 dB max in the frequency. Meanwhile, in the vacuum sputtering step, the products cannot be uneven in height when being stacked in the jig, and the same distance can be reserved among the products; in addition, the sputtering consistency, the smoothness and the good appearance can be ensured during vacuum sputtering, and the condition of product fracturing can not occur, so that the yield of the product is improved by 16%.
Comparative example 1
The preparation procedure of the loading sheet 1 for comparative example mainly included the following steps:
s1, same as step S1 in example 1;
s2, same as step S2 in example 1;
s3, same as step S3 in example 1;
s4, same as step S4 in example 1;
s5, printing only one black protective film: adopting a thick film printing process, selecting a screen with the tension of 25 +/-1N to perform screen printing at the environment of 25 +/-2 ℃, printing a first black protective film on a local front circuit, a whole resistor and a local grounding wire on the front surface of the aluminum nitride ceramic substrate treated in the step S4, sequentially placing and keeping flat for 20min after printing is finished, pre-drying at 100 ℃ for 25min till surface drying, and then baking at 200 ℃ for 50min till full drying to form a dry black protective film;
s6, printing identification points: printing white mark points on the black protective film in the step S5 as described in the step S6 in embodiment 1;
s7, forming the input pad and the back ground conductor in the same manner as in S8 described in embodiment 1;
s8, the end grounding formation is performed in the same manner as in the step S9 described in embodiment 1.
The size of the prepared comparative load sheet 1 is 1.5 multiplied by 3.0 multiplied by 0.385mm, the absorbed load power can reach 8W, the frequency can cover DC-6GHz, the standing wave characteristic can reach-20.83 dB max in the frequency, and the performance can meet the requirement; however, in the subsequent vacuum sputtering step, when the products are stacked in the jig, the white mark points protrude out of only one layer of black protective film, so that the height is uneven, and the same distance is difficult to keep between every two products; in addition, the uniformity and the good appearance of sputtering can not be ensured during vacuum sputtering, and compared with the yield of the load sheet obtained by the method, the yield is not improved, but is reduced by 2 percent on the original basis.
Comparative example 2:
s1, same as step S1 in example 1;
s2, same as step S2 in example 1;
s3, same as step S3 in example 1;
s4, same as step S4 in example 1;
s5, printing a first black protective film: other process steps in the printing process are the same as the step S5 in embodiment 1, and only the front and rear ends of the first black protective film are not retracted;
s6, printing identification points: printing white mark points on the black protective film in the step S5 as described in the step S6 in embodiment 1;
s7, printing a second black protective film: the other process steps in the printing process are the same as the step S7 in embodiment 1, and only the front and rear ends of the second black protective film, which are not opposite to the front and rear ends of the first black protective film, are respectively retracted by 0.1 mm;
s8, forming the input pad and the back ground conductor in the same manner as in S8 described in embodiment 1;
s9, the end grounding formation is performed in the same manner as in the step S9 described in embodiment 1.
The dimensions and basic properties of the comparative support sheet 2 prepared above were all on par with those of the specific example 1; however, in the subsequent vacuum sputtering step, since no height difference is generated between the first black protective film and the second black protective film, when vacuum sputtering cannot be guaranteed, the sputtering layer can be sputtered onto the electrode and the first black protective film while being blocked by the second black protective film, so that the sputtering consistency cannot be guaranteed, and the product yield is reduced by 5% on the original basis.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (12)
1. A surface-mounted type 5G load sheet for communication is characterized in that: comprises an aluminum nitride ceramic substrate (1) with the size of 1.5 multiplied by 3.0 multiplied by 0.385mm, the two ends of the aluminum nitride ceramic substrate in the length direction are respectively a front end and a rear end,
a front circuit (2) in a square frame shape is printed at the front end of the front surface of the aluminum nitride ceramic substrate, a resistor (4) is printed on the front surface of the aluminum nitride ceramic substrate, and the resistor is connected with the front circuit to form a load circuit; a square grounding wire (3) is printed at the rear end of the front surface of the aluminum nitride ceramic substrate, and the grounding wire is connected with the resistor to form a grounding end of a load circuit;
a first black protective film (5) is arranged on the front surface of the aluminum nitride ceramic substrate, the first black protective film covers a local front surface circuit, the whole resistor and a local grounding wire, and the front end and the rear end of the first black protective film are respectively retracted by 0.1-0.2mm relative to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate so as to expose the local front surface circuit and the local grounding wire; the upper surface layer of the first black protective film is provided with a mark point (7); a second black protective film (6) is arranged on the upper surface layer of the first black protective film, the second black protective film corresponds to the opening at the mark point to expose the mark point, and the front end and the rear end of the second black protective film are respectively retracted by 0.1-0.2mm relative to the front end and the rear end of the first black protective film to expose partial first black protective film;
an input pad (9) is printed at the front end of the back of the aluminum nitride ceramic substrate, and a back grounding conductor (8) is attached to the rear end of the back of the aluminum nitride ceramic substrate in an SMT (surface mount technology) patch mode;
the front end and the rear end of the aluminum nitride ceramic substrate are respectively provided with an end ground (10) through a double-sided vacuum sputtering process, wherein the end ground of the front end is communicated with the front circuit and the input bonding pad, and the end ground of the rear end is communicated with the grounding wire and the back grounding conductor.
2. The surface-mounted type 5G communication load chip according to claim 1, wherein: the front end and the rear end of the first black protective film (5) are respectively retracted by 0.1mm relative to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate (1); and the front end and the rear end of the second black protective film (6) are respectively retracted by 0.1mm relative to the front end and the rear end of the first black protective film (5).
3. The surface-mounted type 5G communication load chip according to claim 1, wherein: the resistance value of the resistor (4) is 50 +/-1 ohm.
4. The surface-mounted type 5G communication load chip according to claim 1, wherein: the front circuit (2) adopts a wire-free design mode.
5. The surface-mounted type 5G communication load chip according to claim 1, wherein: the thickness of the second black protective film (6) is consistent with that of the mark point (7).
6. The surface-mount 5G communication load chip according to any one of claims 1 to 5, wherein: the absorption load power of the surface-mounted type 5G communication load sheet is 8W, the frequency covers DC-6GHz, and the standing wave characteristic of the surface-mounted type 5G communication load sheet reaches-20.83 dB max in the frequency.
7. A method for preparing a surface-mounted 5G communication load sheet as claimed in claim 6, comprising the following steps:
s1, cleaning the substrate: selecting an aluminum nitride ceramic substrate with the size of 1.5 multiplied by 3.0 multiplied by 0.385mm, cleaning the surface of the aluminum nitride ceramic substrate by adopting alcohol with the volume percent of more than 95%, and printing a conductor within 2 hours after the alcohol is volatilized;
s2, printing front circuit and ground line: adopting a thick film printing process, printing a front circuit and a grounding wire on the front surface of the aluminum nitride ceramic substrate treated in the step S1 by using silver paste through screen printing, and sequentially standing, pre-baking and sintering at high temperature after printing;
s3, printing a resistor: adopting a screen printing process, further printing resistors on the front circuit and the grounding wire which are processed in the step S2 by using the resistor paste through a screen, and sequentially standing, pre-baking and sintering at high temperature after printing;
s4, resistance adjustment: adopting a laser resistance value debugging mode for the resistor formed by sintering in the step S3 to enable the resistance value of the resistor to reach 50 +/-1 ohm;
s5, printing a first black protective film: printing a first black protective film on the local front circuit, the whole resistor and the local grounding wire on the front surface of the aluminum nitride ceramic substrate processed in the step S4 by adopting a thick film printing process, wherein the front end and the rear end of the first black protective film are respectively retracted by 0.1mm relative to the front end and the rear end of the front surface of the aluminum nitride ceramic substrate so as to expose the local front circuit and the local grounding wire, and after printing is finished, sequentially carrying out placement, keeping and drying to form a dry first black protective film;
s6, printing identification points: printing mark points on the upper surface layer of the first black protective film formed in the step S5 by adopting a thick film printing process, and after printing is finished, sequentially placing, leveling and drying to form dry mark points;
s7, printing a second black protective film: printing a second black protective film on the upper surface layer of the first black protective film formed in the step S5 by using a thick film printing process, wherein the second black protective film is opened corresponding to the mark point to expose the mark point, the front end and the rear end of the second black protective film are respectively retracted by 0.1mm relative to the front end and the rear end of the first black protective film to expose a part of the first black protective film, and after printing is finished, the first black protective film, the mark point and the second black protective film are sequentially placed, leveled and dried to form a cured first black protective film, a cured second black protective film and a cured second black protective film;
s8, molding of input pads and back ground conductors: printing an input pad on the back of the cleaned aluminum nitride ceramic substrate by using silver paste through a thick film printing process, and sequentially standing, pre-baking and sintering at high temperature after printing is finished; mounting the back grounding conductor by adopting an SMT (surface mount technology) mounting mode;
s9, ground-end molding: and (3) synchronously sputtering and coating films at one time at the front end and the rear end of the aluminum nitride ceramic substrate processed in the step S8 by adopting a double-sided vacuum sputtering process to form end grounding, wherein the end grounding at the front end is communicated with the front circuit and the input bonding pad, and the end grounding at the rear end is communicated with the grounding wire and the back grounding conductor.
8. The method for preparing a surface-mounted 5G communication load sheet according to claim 7, wherein the method comprises the following steps: the silver paste adopted by the front circuit, the grounding wire and the input pad in the steps S2 and S8 mainly comprises the following components in percentage by mass: 70-80 wt.% of silver powder with the diameter of 800-1000nm, 4-5 wt.% of glass powder, 5-10 wt.% of binder, 0.05-0.08 wt.% of sintering promoter and the balance of organic solvent.
9. The method for preparing a surface-mounted 5G communication load sheet according to claim 7, wherein the method comprises the following steps: in the steps S2 and S8, the front circuit, the grounding wire and the input bonding pad are all selected from a screen printing plate with the tension of 24-26N when in printing, and the temperature is 23-27 ℃ when the screen printing plate is used; after the printing is finished, standing for 15-20min, pre-baking at 170 ℃ of 165-plus-material for 15-20min and high-temperature sintering at 900 ℃ of 850-plus-material for 15-20min are carried out in sequence.
10. The method for preparing a surface-mounted 5G communication load sheet according to claim 7, wherein the method comprises the following steps: the resistance slurry adopted by the resistance in the step S3 is a thixotropic slurry with the viscosity of 50000-55000cps, and the thixotropic slurry mainly comprises the following components in percentage by mass: 55-60 wt.% of silver powder with the diameter of 300-500nm, 3-6 wt.% of glass micropowder with the diameter of 200-300nm, 5-10 wt.% of organic cellulose binder, 0.5-1.0 wt.% of fumed silica thixotropic agent and the balance of organic solvent, wherein the glass micropowder comprises 30-50 wt.% of silicon oxide and 50-70 wt.% of aluminum oxide.
11. The method for preparing a surface-mounted 5G communication load sheet according to claim 7, wherein the method comprises the following steps: in the step S3, the resistor is printed by a 400-mesh 420-mesh steel wire screen plate, the temperature of the steel wire screen plate is 23-27 ℃, and after the printing is finished, the resistor is sequentially placed for 10-15min, pre-dried at the temperature of 175 ℃ for 15-20min and sintered at the temperature of 850 ℃ for 15-20 min.
12. The method for preparing a surface-mounted 5G communication load sheet according to claim 7, wherein the method comprises the following steps: the first black protective film in the step S5, the mark point in the step S6 and the second black protective film in the step S7 adopt a screen printing plate with the tension of 24-26N during printing, the temperature during screen printing is 23-27 ℃, after printing is finished, standing is sequentially carried out for 20-23min, pre-drying is carried out for 20-25min at the temperature of 100-105 ℃ until surface drying is carried out, and then, high-temperature baking is carried out for 50-60min at the temperature of 200-210 ℃ until solid drying is carried out.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114284665A (en) * | 2022-01-20 | 2022-04-05 | 苏州市新诚氏通讯电子股份有限公司 | High-power microwave load sheet and preparation method thereof |
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| CN207993600U (en) * | 2018-04-03 | 2018-10-19 | 广东风华高新科技股份有限公司 | A kind of chip resistor and the resistive element for including the chip resistor |
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| CN110994100B (en) | 2020-11-20 |
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