A high-insulation preformed solder sheet and its preparation method

Abstract

This invention provides a high-insulation preformed solder pad, comprising a flux core layer and a solder alloy shell layer disposed around the flux core layer. An anti-oxidation film layer is provided around the solder alloy shell layer. By embedding the solid flux core layer within the solder alloy layer to form a sandwich-like shape, the flux is effectively protected from oxidation. This eliminates the need for pre-brazing flux application and post-brazing flux removal, reducing manufacturing costs and the void rate on the welded surface. Coating the solder alloy shell layer with an anti-oxidation film improves the high insulation of the solder metal outer layer and facilitates storage. Polysiloxane is stable and has good insulation properties. As an anti-oxidation film, it is modified with phenyl and polyether organic compounds, improving its stability and ductility on the solder metal surface, giving it excellent anti-oxidation capabilities. Furthermore, it leaves no residue after soldering and will not damage the surface of electronic products, achieving high-precision and high-reliability brazing.

Description

[0001] The present application is a divisional application, the original application has the application number of 2022103395642, the application date is April 1, 2022, and the invention patent name is: a preformed soldering sheet and a preparation method thereof. TECHNICAL FIELD

[0002] The present application belongs to the technical field of welding materials, and particularly relates to a high-insulation preformed soldering sheet and a preparation method thereof. BACKGROUND

[0003] At present, the most widely used welding material in electronic product packaging is soldering paste, but in the case where the amount of soldering paste is large and the printing method cannot meet the requirements, using a preformed soldering sheet coated with a fluxing agent on the surface to replace the soldering paste is a method.

[0004] At present, the preformed soldering sheets on the market are basically bare soldering sheets and preformed soldering sheets coated with a fluxing agent on the surface, but coating a layer of fluxing agent on the surface of the soldering sheet makes the fluxing agent film thin and fragile, or the components in the fluxing agent cannot be well utilized due to oxidation, and the preformed soldering sheet has a specific processing shape. Such soldering sheets are generally small in size and light in weight, and particularly in the electronic product packaging process, high-precision brazing is achieved by precisely controlling the content of solder metal. However, the surface of the solder metal of the current preformed soldering sheet is often exposed to the outside, which is prone to oxidation and other problems. Therefore, how to protect the solder metal from oxidation corrosion is extremely important, and there is an urgent need for a high-insulation preformed soldering sheet and a preparation method thereof. SUMMARY

[0005] The present application provides a preformed soldering sheet to solve the technical problem that the fluxing agent film is prone to brittle and improve the high insulation of the solder metal.

[0006] The second object of the present application is to provide a preparation method of a preformed soldering sheet.

[0007] To achieve the above-mentioned first object, the technical solution adopted by the present application is:

[0008] A high-insulation preformed soldering sheet, comprising a fluxing agent core layer and a solder alloy shell layer arranged on the side of the fluxing agent core layer, and an oxidation-resistant film layer arranged on the side of the solder alloy shell layer. The solid fluxing agent core layer is embedded in the solder alloy layer to form a sandwich-like structure, which can well protect the fluxing agent from oxidation, and there is no need to apply the fluxing agent before brazing or remove the fluxing agent after brazing, thereby reducing the manufacturing cost and the void ratio of the soldering surface after welding. By coating an oxidation-resistant film on the solder alloy shell layer, the high insulation of the outer layer of the solder metal is improved, and the preformed soldering sheet is easy to store.

[0009] The anti-oxidation film layer comprises the following components by percentage: 12.0-15.0% of modified polysiloxane, 5.0-8.0% of corrosion inhibitor, 3.0-8.0% of surfactant, 0.5-1.2% of antioxidant, 0.3-0.8% of film forming aid, and the balance of water.

[0010] The solder alloy shell comprises the following components: 2.3wt% of silver, 1.2wt% of copper, 0.1wt% of vanadium, 0.8wt% of rhodium, 0.6wt% of iridium, 2.8wt% of lutetium, and the balance of tin.

[0011] The high-insulation preformed soldering sheet as described above, the modified polysiloxane is phenyl-polyether co-modified polysiloxane, the polysiloxane is stable in nature and has good insulation, by modifying the polysiloxane with phenyl and polyether organic matters, the stability and ductility of the polysiloxane on the surface of the solder metal are improved, the polysiloxane has excellent anti-oxidation ability, and after soldering, there is no residue to harm the surface of the electronic product, realizing high-precision and high-reliability soldering.

[0012] The high-insulation preformed soldering sheet as described above, the ratio of the phenyl and polyether is 3:5-7.

[0013] The high-insulation preformed soldering sheet as described above, the corrosion inhibitor is any one of mercaptobenzothiazole, benzotriazole, and hexadecylamine, by using the organic corrosion inhibitor with surface activity, a monomolecular film can be formed on the surface of the solder alloy by the cooperation of the polysiloxane and the organic corrosion inhibitor, and the diffusion of oxygen in the air to the surface of the alloy is prevented, thus playing a corrosion inhibition role.

[0014] The high-insulation preformed soldering sheet as described above, the surfactant is any one of halogen-free active agent ST-200, halogen-free active agent FR-500, propylene glycol methyl ether, bromohexadecyl pyridine, and stearic acid amide.

[0015] The high-insulation preformed soldering sheet as described above, the flux core layer comprises the following components by percentage: 80-87% of rosin, 6-10% of activator, 3-8% of surfactant, and 2-4% of thixotropic agent; the rosin is prepared by compounding disproportionated rosin and hydrogenated rosin at a ratio of 2:4, by compounding the hydrogenated rosin and the disproportionated rosin, the spreading rate of the soldering sheet on the substrate can be improved, the soldering sheet has good wetting performance, the soldering point is full, the surface is bright, and the forming effect is better.

[0016] The high-insulation preformed soldering sheet as described above, the activator is one or a combination of more than one of glutaric acid, heptanedioic acid, and malic acid.

[0017] The high-insulation preformed soldering sheet as described above, the overall shape of the high-insulation preformed soldering sheet is square, circular, arc-shaped, ring-shaped, frame-shaped, or strip-shaped.

[0018] The high insulation preformed soldering sheet has a core layer with a thickness of 30-50 microns and a shell layer with a thickness of 0.3-0.8 mm.

[0019] To achieve the above-mentioned second object, the technical scheme adopted by the present application is:

[0020] The preparation method of the high insulation preformed soldering sheet as described in any of the above has the following steps:

[0021] S1, weighing the above-mentioned alloy components according to the weight percentage, and melting;

[0022] S2, cooling the molten solution and pressure casting in a mold to obtain a solder shell for standby;

[0023] S3, adding rosin into a container and heating to 120-140 DEG C, and after dissolving, adding a surfactant and stirring until completely dissolved;

[0024] S4, keeping the temperature at 120-140 DEG C, adding a thixotropic agent and stirring until completely dissolved;

[0025] S5, reducing the temperature to 60-80 DEG C, adding an antioxidant and an activator, and stirring for 40-60 min to obtain a liquid flux;

[0026] S6, cooling the liquid flux to room temperature, and rolling and forming to obtain a solid flux;

[0027] S7, embedding the solid flux into the solder shell, and stamping and forming to obtain a soldering sheet;

[0028] S8, coating the obtained soldering sheet with an oxidation-resistant film, and obtaining the same.

[0029] The present application has the following advantages over the prior art:

[0030] 1. The present application provides a high insulation preformed soldering sheet, which comprises a flux core layer and a solder alloy shell layer arranged on the periphery of the flux core layer, and an oxidation-resistant film layer arranged on the periphery of the solder alloy shell layer. The solid flux core layer is embedded in the solder alloy layer to form a sandwich, which can well protect the flux from oxidation, and there is no need to apply the flux before soldering or remove the flux after soldering, thereby reducing the manufacturing cost and the void ratio of the soldering surface after soldering. The soldering sheet is coated with an oxidation-resistant film on the solder alloy shell layer, which improves the high insulation of the outer layer of the solder metal and is easy to store. The polysiloxane has stable properties and good insulation, and is modified by using phenyl and polyether organic matters as the oxidation-resistant film, which improves the stability and ductility of the polysiloxane on the surface of the solder metal, and the polysiloxane has excellent oxidation resistance and no residue after soldering, and will not damage the surface of the electronic product, thereby realizing high-precision and high-reliability soldering.

[0031] 2、The flux selected as the core layer in the application can improve the spreading rate of the soldering sheet on the substrate by compounding hydrogenated rosin and disproportionated rosin, so that the soldering sheet has good wetting performance, the soldering point is full, the surface is bright, the forming effect is better, and the mechanical performance, electrical performance and light transmission performance of rosin can be improved, especially the wet state performance of rosin can be greatly improved, the permeability of rosin is provided, and the spreading rate of the soldering sheet on the substrate can be improved, so that the soldering sheet has good wetting performance.

[0032] 3、The preparation method of the high insulation preformed soldering sheet provided by the application has the advantages that the inner core layer of the flux and the outer shell of the soldering alloy are prepared in sequence, then the flux core layer is embedded in the alloy shell, and an oxidation-resistant film is coated, the process is simple and mild, no harmful gas is generated in the process, and the method is suitable for mass production. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced.

[0034] Figure 1 is a sectional view of the high insulation preformed soldering sheet of the application. DETAILED DESCRIPTION

[0035] The technical solutions of the application will be described below in combination with Examples 1-3.

[0036] Example 1

[0037] The high insulation preformed soldering sheet comprises a soldering alloy shell layer 2, a flux inner core layer 1 and an oxidation-resistant film layer 3, wherein the component ratio of the oxidation-resistant film layer is shown in Table 1, the component ratio of the flux is shown in Table 2, and the component ratio of the soldering alloy is shown in Table 3, and the preparation method comprises the following steps:

[0038] The components are weighed according to the weight percentages in Tables 1 and 2, and are ready for use, and the soldering alloy in Table 3 is smelted; the molten solution is cooled and pressure cast in a mold to form a soldering shell, which is ready for use; the modified polysiloxane and a small amount of water in Table 1 are added to a container, stirred and heated to 50℃, the corrosion inhibitor, the surfactant and the antioxidant are added and stirred at 600r for 10min, and finally the film-forming aid and the remaining water are added and stirred at 400r for 5min, which is ready for use;

[0039] The rosin is added into a container according to Table 2, heated to 120℃, after dissolving, the surfactant is added, stirred until completely dissolved; keep the temperature at 120℃, add the thixotropic agent and stir until completely dissolved; reduce the temperature to 60℃, add the antioxidant, activator, stir for 40min, get the liquid flux; cool the liquid flux to room temperature, roll and shape, get the solid flux; embed the solid flux into the solder shell, stamping, coat the preformed solder piece after shaping with a layer of antioxidant film, and the preformed solder piece is obtained.

[0040] Example 2

[0041] A high insulation preformed solder piece, comprising a solder alloy shell layer 2, a flux inner core layer 1 and an antioxidant film layer 3, wherein the component ratio of the antioxidant film layer is shown in Table 1, the component ratio of the flux is shown in Table 2, and the component ratio of the solder alloy is shown in Table 3, and the preparation method comprises the following steps:

[0042] The components are weighed according to the percentage in Table 1 and Table 2, and are ready for use. The solder alloy in Table 3 is melted; the molten solution is cooled and pressure cast in a mold to form a solder shell, which is ready for use; the modified polysiloxane and a small amount of water in Table 1 are added to a container, stirred and heated to 50℃, the corrosion inhibitor, surfactant and antioxidant are added and stirred at 600r for 10min, and finally the film forming aid and the remaining water are added and stirred at 400r for 5min, which is ready for use;

[0043] The rosin is added into a container according to Table 2, heated to 120℃, after dissolving, the surfactant is added, stirred until completely dissolved; keep the temperature at 120℃, add the thixotropic agent and stir until completely dissolved; reduce the temperature to 60℃, add the antioxidant, activator, stir for 40min, get the liquid flux; cool the liquid flux to room temperature, roll and shape, get the solid flux; embed the solid flux into the solder shell, stamping, coat the preformed solder piece after shaping with a layer of antioxidant film, and the preformed solder piece is obtained.

[0044] Example 3

[0045] A high insulation preformed solder piece, comprising a solder alloy shell layer 2, a flux inner core layer 1 and an antioxidant film layer 3, wherein the component ratio of the antioxidant film layer is shown in Table 1, the component ratio of the flux is shown in Table 2, and the component ratio of the solder alloy is shown in Table 3, and the preparation method comprises the following steps:

[0046] The components in Table 1 and Table 2 are weighed and prepared, and the solder alloy in Table 3 is melted; the molten solution is cooled and pressure cast in a mold to obtain a solder shell, which is prepared; the modified polysiloxane and a small amount of water in Table 1 are added to a container, heated and stirred to 50℃, and then the corrosion inhibitor, surfactant and antioxidant are added and stirred at 600r for 10min; finally, the film-forming aid and the remaining water are added and stirred at 400r for 5min, which is prepared;

[0047] The rosin in Table 2 is added to a container and heated to 120℃, and then the surfactant is added after dissolution, and stirred until completely dissolved; the temperature is maintained at 120℃, and the thixotropic agent is added and stirred until completely dissolved; the temperature is reduced to 60℃, and the antioxidant and activator are added and stirred for 40min to obtain a liquid flux; the liquid flux is cooled to room temperature, and then rolled and formed to obtain a solid flux; the solid flux is embedded in the solder shell, and then punched and formed, and then the preformed solder piece is coated with an antioxidant film to obtain the product.

[0048] Table 1: Component weight ratio of antioxidant film layer in Examples 1-3

[0049]

[0050] Table 2: Component weight ratio of flux in Examples 1-3

[0051]

[0052] Table 3: Component weight ratio of solder alloy in Examples 1-3

[0053] Components Proportions Tin 92.2％ Silver 2.3％ Copper 1.2％ Vanadium 0.1％ Rhodium 0.8％ Iridium 0.6％ Lutetium 2.8％

[0054] The high-insulation preformed solder piece obtained in Examples 1-3 is tested for performance, and the test results are shown in Table 4:

[0055] Table 4: Test results of Examples 1-3

[0056]

[0057]

[0058] As can be seen from the table, the application provides a high-insulation preformed soldering piece, which comprises a soldering flux core layer and a solder alloy shell layer arranged on the periphery of the soldering flux core layer, and an oxidation-resistant film layer is arranged on the periphery of the solder alloy shell layer; the solid soldering flux core layer is embedded in the solder alloy layer to form a sandwich biscuit shape, so that the soldering flux can be well protected from oxidation, and it is not necessary to apply the soldering flux before soldering or to remove the soldering flux after soldering, thereby reducing the manufacturing cost and the void ratio of the soldering surface after soldering; the solder alloy shell layer is coated with an oxidation-resistant film layer, so that the high insulation of the outer layer of the solder metal is improved, and the preformed soldering piece is easy to store; the polysiloxane has stable properties and good insulation, and is modified by using phenyl and polyether organic matters as the oxidation-resistant film, so that the stability and ductility of the polysiloxane on the surface of the solder metal are improved, the polysiloxane has excellent oxidation resistance, and there is no residue after soldering, so that the surface of the electronic product is not damaged, and high-precision and high-reliability soldering is realized.

[0059] The above only describes the preferred embodiments of the application and is not used to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A high insulation preformed soldering lug, characterized by, The solder alloy shell layer (2) is provided with an oxidation-resistant film layer (3) on the periphery thereof. The oxidation-resistant film layer (3) comprises the following components in percentage: 12.0-15.0% of modified polysiloxane, 5.0-8.0% of corrosion inhibitor, 3.0-8.0% of first surfactant, 0.5-1.2% of antioxidant, 0.3-0.8% of film-forming aid, and the balance of water. The solder alloy shell layer (2) comprises the following components: 2.3wt% of silver, 1.2wt% of copper, 0.1wt% of vanadium, 0.8wt% of rhodium, 0.6wt% of iridium, 2.8wt% of lutetium, and the balance of tin. The flux core layer (1) comprises the following components in percentage: 80-87% of rosin, 6-10% of activator, 3-8% of second surfactant, and 2-4% of thixotropic agent; the rosin is a compound of disproportionated rosin and hydrogenated rosin at a ratio of 2:4; The activator is any one of glutaric acid, heptanedioic acid, and malic acid; the second surfactant is any one of oleic acid amide, erucic acid amide, and sodium dodecyl sulfonate; and the thixotropic agent is any one of hydroquinone, dodecahydroxystearic acid, and modified hydrogenated castor oil. The first surfactant is any one of halogen-free activator ST-200, halogen-free activator FR-500, and propylene glycol methyl ether.

2. The high insulation preformed soldering lug according to claim 1, characterized in that: The modified polysiloxane is phenyl-polyether co-modified polysiloxane.

3. The high insulation preformed soldering lug according to claim 2, characterized in that: The ratio of the phenyl group to the polyether is 3:5-7.

4. The high insulation preformed solder patch of claim 1, wherein: The corrosion inhibitor is any one of mercaptobenzothiazole, benzotriazole, and hexadecylamine.

5. The high insulation preformed solder patch of claim 1, wherein: The high-insulation preformed soldering sheet has a square, circular, arc-shaped, ring-shaped, frame-shaped, or strip-shaped overall shape.

6. The high insulation preformed solder patch of claim 1, wherein: The thickness of the core layer (1) is 30-50μm, and the thickness of the shell layer (2) is 0.3-0.8mm.

7. The method of making a high insulation preformed solder patch according to any one of claims 1-6, wherein, The method comprises the following steps: S1, weighing the above-mentioned alloy components according to the weight percentage, and melting; S2, cooling the molten solution and pressure casting in a mold to obtain a solder shell for standby; S3, adding rosin to a container, heating to 120-140℃, and after dissolving, adding a surfactant and stirring until completely dissolved; S4, keeping the temperature at 120-140℃, adding a thixotropic agent and stirring until completely dissolved; S5, reducing the temperature to 60-80℃, adding an antioxidant and an activator, and stirring for 40-60min to obtain a liquid flux; S6, cooling the liquid flux to room temperature, and rolling and forming to obtain a solid flux; S7, embedding the solid flux into the solder shell, and stamping to obtain a soldering sheet; S8, coating the obtained soldering sheet with an oxidation-resistant film, and the process is completed.

Images