CN118215233A - Technological method for surface mounting of ceramic substrate - Google Patents
Technological method for surface mounting of ceramic substrate Download PDFInfo
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- CN118215233A CN118215233A CN202410273484.0A CN202410273484A CN118215233A CN 118215233 A CN118215233 A CN 118215233A CN 202410273484 A CN202410273484 A CN 202410273484A CN 118215233 A CN118215233 A CN 118215233A
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- China
- Prior art keywords
- ceramic substrate
- bonding pad
- bottom plate
- welding
- positioning tool
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- 239000000758 substrate Substances 0.000 title claims abstract description 90
- 239000000919 ceramic Substances 0.000 title claims abstract description 89
- 238000000034 method Methods 0.000 title claims abstract description 44
- 238000003466 welding Methods 0.000 claims abstract description 38
- 229910000679 solder Inorganic materials 0.000 claims abstract description 26
- 238000005476 soldering Methods 0.000 claims abstract description 24
- 238000012360 testing method Methods 0.000 claims abstract description 24
- 239000011800 void material Substances 0.000 claims abstract description 14
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 12
- 239000010959 steel Substances 0.000 claims abstract description 12
- 238000004140 cleaning Methods 0.000 claims abstract description 10
- 239000004593 Epoxy Substances 0.000 claims abstract description 6
- 238000009434 installation Methods 0.000 claims abstract description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 18
- 229910052802 copper Inorganic materials 0.000 claims description 18
- 239000010949 copper Substances 0.000 claims description 18
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 239000000463 material Substances 0.000 description 6
- 238000001035 drying Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 230000004907 flux Effects 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- 239000002390 adhesive tape Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229920001721 polyimide Polymers 0.000 description 2
- 238000011179 visual inspection Methods 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Landscapes
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Abstract
The invention discloses a process method for mounting the surface of a ceramic substrate, which adopts a welding mode of one-time integral reflow soldering and comprises the following steps: step one, cleaning the surface of a ceramic substrate and pre-baking the ceramic substrate; step two, using a steel mesh to print solder paste on the T surface and the B surface of the ceramic substrate respectively; step three, providing a bottom plate, placing the ceramic substrate on the bottom plate, and performing contact installation on the B surface of the ceramic substrate and the bottom plate by using a positioning tool and an epoxy plate to obtain a test assembly; and fourthly, placing the test assembly on a carrier, and carrying out component mounting and reflow soldering. According to the process method for mounting the ceramic substrate on the surface, the void ratio of the whole welding spot is not more than 16%, so that the void ratio of the welding spot is greatly reduced, an effective welding method is provided for the high-heat-conductivity printed board assembly of the power supply controller for the spacecraft, and the welding reliability of the printed board assembly is improved.
Description
Technical Field
The invention relates to the technical field of electronic assembly, in particular to a process method for surface mounting of a ceramic substrate.
Background
The printed board material used in large quantities on the current control products is traditional FR4, has the characteristics of low heat conductivity coefficient, low thermal expansion coefficient and the like, is suitable for low-power products with low requirements, and gradually cannot meet the power requirements of high-power products along with the increasing power requirements and the increasing integration degree of the control products. In order to solve the heat dissipation problem of the printed board for mounting the power component, a high-heat-conductivity substrate material, such as a high-heat-conductivity ceramic substrate material, is selected from the source. Ceramic substrates have been widely used as materials for printed boards in various industries at home and abroad, and the ceramic substrates have excellent electrical insulation properties, high thermal conductivity, excellent soldering property and high adhesion strength, and have great current carrying capacity. At present, in order to ensure high reliability of heat conduction in aerospace, national defense and the like, high-heat-conduction alumina ceramic substrate materials, even ceramic substrate materials with better heat conduction such as aluminum nitride, silicon nitride and the like are adopted.
Since ceramic substrates have lower mechanical properties than metal plates, FR4 printed boards, ceramic plates cannot be directly fixed to structural frames by mechanical fastening. The method comprises the steps of directly welding a ceramic substrate and a metal bottom plate, and then mechanically installing the metal bottom plate and a frame. At present, vacuum welding equipment such as vacuum reflow welding or vacuum vapor welding is mainly used for welding in the industry, but the vacuum welding equipment is high in price, and the equipment vacuumizes in the working process to require a closed environment, so that batch production line type continuous production cannot be realized. The hot air reflow soldering equipment is mature in application, but after the large-area ceramic substrate and the metal base plate are soldered by adopting the hot air reflow soldering equipment, the vacuum effect is avoided due to normal pressure soldering, the void ratio of the welding spots is larger, and the requirement that the void ratio of the welding spots in GJB548C is not more than 50% is exceeded, so that reports on soldering the large-area ceramic substrate and the metal base plate by adopting the hot air reflow soldering equipment are rare.
Disclosure of Invention
The invention aims to overcome the defect of larger void ratio of welding spots caused by adopting a method for welding a ceramic substrate at normal pressure in the prior art.
In order to achieve the above purpose, the invention provides a process method for mounting a ceramic substrate on a surface, wherein the process method adopts a welding mode of one-time integral reflow soldering, and comprises the following steps:
step one, providing a ceramic substrate, wherein the ceramic substrate is provided with a T surface and a B surface, and the ceramic substrate is subjected to surface cleaning and pre-baking;
step two, using a steel mesh to print solder paste on the T surface and the B surface of the ceramic substrate respectively;
step three, providing a bottom plate, placing the ceramic substrate on the bottom plate, and performing contact installation on the B surface of the ceramic substrate and the bottom plate by using a positioning tool and an epoxy plate to obtain a test assembly;
and fourthly, placing the test assembly on a carrier, and carrying out component mounting and reflow soldering.
Preferably, in the first step, the surface cleaning and pre-baking specifically means cleaning the surface of the ceramic substrate with absolute ethyl alcohol, and then drying with an oven.
Preferably, in the second step, the solder paste covers up to 80% of the printing area of the bonding pad on the ceramic substrate.
Preferably, in the second step, the B-surface of the ceramic substrate is disposed in a grid shape.
Preferably, in the second step, the steel mesh is set to a grid-shaped small bonding pad shape with a size corresponding to the bonding pad, that is, a cross groove opening is opened on the basis of the grid-shaped bonding pad, so that the printed solder paste forms a 'field' -shaped shape on the small bonding pad, the size of the small bonding pad is 1 mm-3 mm, and the spacing between the small bonding pads is 0.8 mm-2 mm.
Preferably, in the third step, before the ceramic substrate is placed on the bottom plate, the ceramic substrate is placed in the groove on the positioning tool.
Preferably, the size of the boss in the groove is 1mm smaller than the size of the ceramic substrate, so that the positioning tool does not interfere with the bonding pad on the ceramic substrate.
Preferably, in step four, the test assembly is secured using copper tape.
Preferably, the fixing specifically means that one end of the copper strip is fixed in a groove of the positioning tool, and the other end of the copper strip is fixed on a bonding pad on the ceramic substrate.
Preferably, the test assembly has an overall solder joint void ratio of no greater than 16%.
Compared with the prior art, the invention has the beneficial effects that at least comprises:
The technological method for mounting the ceramic substrate on the surface provides an effective welding method for the high-heat-conductivity printed board assembly of the power supply controller for the spacecraft, the steel mesh for printing is arranged into grids with the size corresponding to the bonding pad, and the cross slot openings are opened on the basis of the grids, so that the printed solder paste forms a 'field' -shaped shape on the small bonding pad, the exhaust channel of the soldering flux in the solder paste is increased, the void ratio of the whole welding point is not more than 16%, the standard requirement of less than 25% is met, the void ratio of the welding point is greatly reduced, and the welding reliability of the printed board assembly is improved.
Drawings
Fig. 1 is a schematic diagram of a pad structure according to the present invention.
Fig. 2 is a schematic view of the steel mesh structure of the present invention.
Fig. 3 is a schematic structural diagram of the positioning tool of the present invention.
FIG. 4 is a schematic structural view of the test assembly of the present invention.
Fig. 5 is an enlarged detail view of the positioning tool of the present invention.
Wherein, 1-carrier, 2-location frock, 3-cushion.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings and examples. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
In the present invention, unless otherwise indicated, terms such as "upper, lower, inner, outer" and the like are used merely to denote orientations of the term in a normal use state or are commonly understood by those skilled in the art, and should not be construed as limitations of the term.
Definition: according to the IPC-A-610 standard, the void ratio of the welding spot is as follows: for surface-welded (Surface Mount Technology, SMT) pads, the cavity diameter should be less than 50% of the pad diameter. For a Through-Hole Technology (THT) weld spot, the Hole diameter should be less than 25% of the weld spot diameter.
The invention provides a process method for mounting a ceramic substrate on the surface, which adopts a welding mode of one-time integral reflow welding and comprises the following steps:
Step one, providing a ceramic substrate, wherein the ceramic substrate is provided with a T surface and a B surface, absolute ethyl alcohol is used for cleaning the surface of the ceramic substrate, a bonding pad is arranged on the ceramic substrate, the surplus on the surface of the bonding pad is removed, and an oven is used for pre-baking; providing a bottom plate, wiping the bottom plate by using absolute ethyl alcohol, drying by using compressed air after wiping, and carrying out nickel plating treatment on the surface of the bottom plate to increase weldability.
And secondly, respectively performing solder paste printing on the T surface and the B surface of the ceramic substrate by using a steel mesh.
And thirdly, placing the ceramic substrate on the bottom plate, and performing contact installation on the B surface of the ceramic substrate and the bottom plate by using a positioning tool and an epoxy plate with the thickness of 1mm to obtain a test assembly, wherein the ceramic substrate is ensured to be 1mm away from the edge of the bottom plate.
And fourthly, placing the test assembly on a carrier, and carrying out component mounting and reflow soldering.
In some embodiments, in order to ensure the temperature required by the process, a furnace temperature testing step is further included before the first step, and a furnace temperature tester is used for testing the temperature, so that the temperatures of the welding area between the B surface of the ceramic substrate (i.e. the surface where the ceramic substrate and the bottom plate are installed) and the bottom plate and each point on the T surface of the ceramic substrate meet the process requirements in the welding process.
In some embodiments, when the steel mesh shown in fig. 2 is used to print solder paste on the T-side and the B-side of the ceramic substrate, the following conditions should be satisfied by the solder paste after printing: the printing area of the solder paste covering the bonding pad should reach more than 80%, the dislocation of the solder paste and the bonding pad is less than 0.2mm, and the dislocation of the bonding pad of the fine-pitch device should be less than 0.1mm; the solder paste has no collapse and fracture, and the edges of the solder paste are neat. Before the ceramic substrate is placed on the bottom plate, the ceramic substrate is placed in a groove on the positioning tool, and the size of a boss in the groove is 1mm smaller than that of the ceramic substrate, so that the positioning tool and the bonding pad do not interfere.
The steel mesh is arranged into a grid-shaped (matrix-shaped) small bonding pad shape with the size corresponding to the bonding pad shown in fig. 1, namely, a cross groove opening is formed on the basis of the grid-shaped shown in fig. 1, so that the printed solder paste forms a 'field' -shaped shape on the small bonding pad, the size of the small bonding pad is 1-3 mm, the spacing between the small bonding pads is 0.8-2 mm, and the purpose is to reserve an exhaust channel for the soldering flux in the solder paste on the bonding pad in the welding process, so that the soldering flux is discharged as much as possible, and the phenomenon that a large amount of soldering flux is detained on the bonding pad to influence solder wetting to form a cavity is avoided.
In some embodiments, when mounting and reflow soldering components, as shown in fig. 4, a test component is placed on a carrier 1, one end of a copper strip is mounted on a bonding pad of the ceramic substrate, the other end of the copper strip is fixed through a groove on a positioning tool 2, as shown in fig. 5, a detailed enlarged view of the groove of the positioning tool 2 is shown, two ends below the positioning tool are respectively provided with a cushion block 3, and the copper strip is fixed on the positioning tool 2 by using a polyimide adhesive tape, so that the copper strip is prevented from shifting out of the bonding pad in the reflow soldering process. The depth of the copper strip embedded into the solder paste is not less than 25% of the thickness of the copper strip by visual inspection through a 3-5-fold magnifying glass.
And after the reflow soldering is finished, carrying out X-ray detection on the test assembly, and judging the void ratio of the welding spots.
Examples
The embodiment provides a process method for mounting a ceramic substrate on the surface, which comprises the following steps:
Step one, providing a ceramic substrate, and using a furnace temperature tester to perform temperature test, wherein the temperatures of a welding area between the B surface of the ceramic substrate and a welding bottom plate and each point on the T surface of the ceramic substrate are all between 210 ℃ and 230 ℃ in the welding process.
And secondly, cleaning the surface of the ceramic substrate by using absolute ethyl alcohol, removing the surplus on the surface of the bonding pad on the ceramic substrate, drying at 110 ℃ by using an oven after the removal, wiping the welded bottom plate by using absolute ethyl alcohol, and drying by using compressed air after the wiping.
And thirdly, printing solder paste on the T surface and the B surface of the ceramic substrate respectively by using a steel mesh, wherein the printing area of the solder paste covering the bonding pad is 90%, the dislocation of the solder paste and the bonding pad is less than 0.2mm, and the dislocation of the bonding pad of the fine-pitch device is less than 0.1mm. And placing the ceramic substrate into a groove of a positioning tool, wherein the size of a boss in the groove is 1mm smaller than that of the ceramic substrate.
And fourthly, installing the B surface of the ceramic substrate in contact with the bottom plate, centering the ceramic substrate on the bottom plate, and using a positioning tool and an epoxy plate with the thickness of 1mm to ensure that the ceramic substrate is 1mm away from the edge of the bottom plate so as to obtain the test assembly.
Step five, component mounting and reflow soldering are carried out, the test assembly is placed on a carrier, one end of a copper belt is mounted on a bonding pad of the ceramic substrate, the other end of the copper belt is fixed through a groove on the positioning tool, and the copper belt is fixed on the positioning tool by using a polyimide adhesive tape, so that the copper belt is prevented from shifting in the reflow soldering process. The depth of the copper strip embedded into the solder paste is not less than 25% of the thickness of the copper strip by visual inspection through a magnifying glass of 3-5 times.
And step six, after the reflow soldering is finished, carrying out X-ray detection on the test assembly, wherein the maximum void ratio of the whole welding spot is 16%, and the standard requirement of less than 25% is met.
In summary, the process method for surface mounting of the ceramic substrate adopts a welding mode of one-time integral reflow soldering, and comprises the following steps: step one, providing a ceramic substrate, and cleaning and pre-drying the surface of the ceramic substrate; step two, a bonding pad is arranged on the ceramic substrate, and tin paste printing is respectively carried out on the T surface and the B surface of the ceramic substrate by using a steel mesh; providing a bottom plate, placing the ceramic substrate on the bottom plate, and performing contact installation on the B surface of the ceramic substrate and the bottom plate by using a positioning tool and an epoxy plate to obtain a test assembly; and fourthly, placing the test assembly on a carrier, and carrying out component mounting and reflow soldering. The whole welding spot void ratio of the test assembly subjected to surface mounting according to the process method is 16% at maximum, an effective welding method is provided for the high-guide-plate printed board assembly of the power supply controller for the spacecraft, the welding spot void ratio is greatly reduced, and the welding reliability of the printed board assembly is improved.
What is not described in detail in this specification is prior art known to those skilled in the art. It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Many modifications and substitutions of the present invention will become apparent to those of ordinary skill in the art upon reading the foregoing. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims (10)
1. The technological method for mounting the ceramic substrate surface is characterized by adopting a welding mode of one-time integral reflow welding, and comprises the following steps of:
step one, providing a ceramic substrate, wherein the ceramic substrate is provided with a T surface and a B surface, and the ceramic substrate is subjected to surface cleaning and pre-baking;
step two, using a steel mesh to print solder paste on the T surface and the B surface of the ceramic substrate respectively;
Step three, providing a bottom plate, placing the ceramic substrate on the bottom plate, and performing contact installation on the B surface of the ceramic substrate and the bottom plate by using a positioning tool and an epoxy plate to obtain a test assembly;
and fourthly, placing the test assembly on a carrier, and carrying out component mounting and reflow soldering.
2. The method according to claim 1, wherein in the first step, the surface cleaning and pre-baking means cleaning the surface of the ceramic substrate with absolute ethanol and then baking the surface with an oven.
3. The method according to claim 1, wherein in the second step, the solder paste covers up to 80% of the printed area of the bonding pad on the ceramic substrate.
4. The method according to claim 1, wherein in the second step, the B-side of the ceramic substrate is arranged in a lattice shape.
5. The process for surface mounting a ceramic substrate according to claim 3, wherein in the second step, the steel mesh is set into a grid-shaped small bonding pad shape with a size corresponding to the bonding pad, that is, a cross groove opening is opened on the basis of the grid-shaped bonding pad, so that the printed solder paste forms a 'field' -shaped shape on the small bonding pad, the size of the small bonding pad is 1 mm-3 mm, and the spacing between the small bonding pads is 0.8 mm-2 mm.
6. The method of claim 1, wherein in step three, the step of placing the ceramic substrate in the recess in the positioning tool is further included before placing the ceramic substrate on the base plate.
7. The method of claim 6, wherein the boss in the recess is 1mm smaller than the ceramic substrate so that the positioning tool does not interfere with the bonding pad on the ceramic substrate.
8. The method according to claim 1, wherein in the fourth step, the test component is fixed using a copper tape.
9. The method according to claim 8, wherein the fixing means fixing one end of the copper strip in a groove of the positioning tool, and fixing the other end of the copper strip on a bonding pad on the ceramic substrate.
10. The method of claim 1, wherein the test assembly has an overall solder joint void ratio of no more than 16%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410273484.0A CN118215233A (en) | 2024-03-11 | 2024-03-11 | Technological method for surface mounting of ceramic substrate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410273484.0A CN118215233A (en) | 2024-03-11 | 2024-03-11 | Technological method for surface mounting of ceramic substrate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118215233A true CN118215233A (en) | 2024-06-18 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410273484.0A Pending CN118215233A (en) | 2024-03-11 | 2024-03-11 | Technological method for surface mounting of ceramic substrate |
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| Country | Link |
|---|---|
| CN (1) | CN118215233A (en) |
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2024
- 2024-03-11 CN CN202410273484.0A patent/CN118215233A/en active Pending
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