CN111590232B - Welding material and preparation method thereof - Google Patents

Abstract

The invention provides a welding material and a preparation method thereof, relating to the technical field of welding. The welding material provided by the invention comprises the following components in percentage by weight: 59-91% of bismuth-based alloy, 5-30% of wave-absorbing material, 0.1-6% of rheological modifier and 2-5% of reinforcing and toughening material. The technical scheme of the invention can melt the welding material in a microwave heating mode, and is beneficial to improving the welding effect of the liquid metal circuit.

Description

Welding material and preparation method thereof

Technical Field

The invention relates to the technical field of welding, in particular to a welding material and a preparation method thereof.

Background

The technology of manufacturing electronic circuits by using liquid metal through the additive manufacturing method has the advantages of high processing speed, low cost, high efficiency, no pollution and the like, and is increasingly widely applied. The materials used in the additive manufacturing method are mostly alloy materials mainly composed of liquid metal with a melting point of 40 ℃ to 120 ℃ (for example, indium tin eutectic alloy with a melting point of 108 ℃, bismuth indium tin eutectic alloy with a melting point of 58 ℃).

In addition, the inventor finds that the conventional welding process mostly adopts contact heating, namely, the welding material is melted by means of heat conduction, which easily causes poor welding effect, and the specific reasons are as follows: if the melting points of the welding material and the main circuit material are completely consistent, the heating environment of the welding pad part of the main circuit and the welding material is consistent, and when the welding material reaches a molten state, the welding pad of the main circuit is completely melted, so that the circuit is easily damaged; if the melting point of the welding material is lower than that of the main circuit material, the difference of the melting points easily causes poor compatibility at the interface joint of the main circuit material and the welding material, and the main circuit material and the welding material are not easy to be stably connected.

Disclosure of Invention

The invention provides a welding material and a preparation method thereof, which can melt the welding material in a microwave heating mode and is beneficial to improving the welding effect of a liquid metal circuit.

In a first aspect, the invention provides a welding material, which adopts the following technical scheme:

the welding material comprises the following components in percentage by weight: 59-91% of bismuth-based alloy, 5-30% of wave-absorbing material, 0.1-6% of rheological modifier and 2-5% of reinforcing and toughening material.

Optionally, the bismuth-based alloy consists of bismuth, indium, tin, or the bismuth-based alloy consists of bismuth, indium, tin, and at least one of zinc and cobalt.

Further, the welding material comprises, in weight percent: 15% -35% of bismuth, 20% -35% of indium, 5% -16% of tin, 0% -5% of zinc and 0% -2% of cobalt, wherein the bismuth, the indium, the tin, the zinc and the cobalt form the bismuth-based alloy.

Optionally, the wave-absorbing material includes one or more of silicon carbide, carbon black, graphite, spinel type ferrite, carbonyl iron, carbonyl nickel and carbonyl cobalt.

Optionally, the rheology modifier is lithium magnesium silicate and/or fumed silica.

Further, the welding material comprises, by weight, 0% -2% of lithium magnesium silicate and 0.1% -4% of fumed silica.

Optionally, the reinforcing and toughening material comprises one or more of cage polysilsesquioxane, carbon fiber, single-walled carbon nanotube and graphene oxide.

Optionally, the welding material further comprises 1-7 wt% of an antioxidant aid.

Further, the antioxidant auxiliary agent is one of pimelic acid and glutaric acid.

In a second aspect, the present invention provides a method for preparing a welding material, which is used for preparing the welding material described in any one of the above aspects, and adopts the following technical scheme:

the preparation method of the welding material comprises the following steps:

step S1, under the protection of vacuum or inert gas, heating each raw material of the bismuth-based alloy to be above a melting point, weighing each raw material according to a proportion, mixing, fully stirring the mixture, and then gradually cooling;

step S2, heating the bismuth-based alloy to a molten state, adding the wave-absorbing material, the rheological modifier and the reinforcing and toughening material which are weighed in advance, and stirring;

step S3, transferring the mixture obtained in the step S2 to a ball milling tank under the protection of inert gas, and adding grinding balls for ball milling;

and step S4, adding an antioxidant aid, and continuing ball milling to obtain the welding material.

The invention provides a welding material and a preparation method thereof, and specifically, the welding material comprises the following components in percentage by weight: 59% -91% of bismuth-based alloy, 5% -30% of wave-absorbing material, 0.1% -6% of rheological modifier and 2% -5% of reinforcing and toughening material, the wave-absorbing material in the welding material can absorb microwave well, the welding material can be heated and melted by the microwave, and the liquid metal circuit absorbs the microwave very weakly (the reflection wave to the microwave can reach 95% -99%), therefore, the melting point of the welding material can be consistent with the main circuit material of the liquid metal circuit, not only can the main circuit be prevented from being damaged, but also the compatibility of the main circuit material and the interface combination part of the welding material can be improved, so that the two can be stably connected, and the welding effect of the liquid metal circuit can be improved. When the welding material is used for welding the liquid metal circuit, after the welding material absorbs microwave energy to generate heat, the welding material can quickly reach a molten state and partially transfer the heat when contacting with a bonding pad of the liquid metal circuit, so that the bonding pad is partially molten to weld.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a flowchart of a method for manufacturing a solder material according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the technical features in the embodiments of the present invention may be combined with each other without conflict.

The embodiment of the invention provides a welding material, which comprises the following components in percentage by weight: 59-91% of bismuth-based alloy, 5-30% of wave-absorbing material, 0.1-6% of rheological modifier and 2-5% of reinforcing and toughening material.

The bismuth-based alloy is a welding main body material, and the melting point of the bismuth-based alloy is matched with that of a main body circuit material in the liquid metal circuit; the wave-absorbing material is used for absorbing microwaves, converting the energy of the microwaves into heat energy and heating the welding material; the rheological modifier is used for enabling the welding material to still keep certain plasticity after being melted, the phenomenon that the viscosity is reduced too remarkably and flows randomly and can not be controlled along with the temperature rise in the melting process of the welding material can not occur, and in addition, when the rheological modifier with the specific gravity lower than that of the bismuth-based alloy is selected, the rheological modifier can be enriched on the surface of the melted welding material to realize the oxygen blocking when the welding material is melted, so that the antioxidation effect is realized; the reinforced and toughened material is used for improving the pit impact capability and the shear resistance capability of the welding material by depending on the characteristics of the molecular structure of the reinforced and toughened material.

The welding material can be heated and melted by microwave, and the liquid metal circuit absorbs the microwave very weakly (the reflection wave to the microwave can reach 95% -99%), so that the melting point of the welding material can be consistent with that of the main circuit material of the liquid metal circuit, the main circuit can be prevented from being damaged, the compatibility of the interface joint of the main circuit material and the welding material can be improved, the main circuit material and the welding material can be stably connected, and the welding effect of the liquid metal circuit can be improved. When the welding material is used for welding the liquid metal circuit, after the welding material absorbs microwave energy to generate heat, the welding material can quickly reach a molten state and partially transfer the heat when contacting with a bonding pad of the liquid metal circuit, so that the bonding pad is partially molten to weld.

It should be noted that if the weight percentage of one or more of the wave-absorbing material, the rheology modifier and the reinforcing and toughening material in the welding material deviates from the above range, the performance of the welding material is reduced. Specifically, if the weight percentage of the wave-absorbing material in the welding material is lower than the above range, the heating efficiency is too low, and if the weight percentage of the wave-absorbing material in the welding material is higher than the above range, the overall conductivity of the welding material is reduced; if the weight percentage of the rheological modifier in the welding material is lower than the range, the rheological modifier cannot form a completely coated film on the surface of the molten welding material, the oxygen isolation effect is poor, and if the weight percentage of the rheological modifier in the welding material is higher than the range, the compatibility of the welding material and a main circuit material of a liquid metal circuit is poor, and the conductivity of the liquid metal circuit is remarkably reduced; if the weight percentage of the reinforcing and toughening material in the welding material is less than the above range, the impact resistance and shear resistance of the welding material are not good, and if it is more than the above range, the conductivity of the whole welding material is reduced.

Illustratively, the weight percentage of the bismuth-based alloy in the weld material may be 59%, 60%, 70%, 80%, 90%, or 91%, preferably 70% to 90%; the weight percentage of the wave-absorbing material can be 5%, 10%, 15%, 20%, 25% or 30%; the weight percentage of rheology modifier may be 0.1%, 1%, 2%, 3%, 4%, 5%, or 6%; the weight percentage of the reinforcing and toughening material can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

The following embodiment of the present invention illustrates specific materials of bismuth-based alloy, wave-absorbing material, rheology modifier and reinforcing and toughening material in the welding material.

Optionally, in the embodiment of the present invention, the bismuth-based alloy is composed of bismuth, indium, and tin, or the bismuth-based alloy is composed of bismuth, indium, and tin, and at least one of zinc and cobalt, so that the elemental composition in the bismuth-based alloy is consistent with the elemental composition in the main circuit material commonly used for the liquid metal circuit, and the compatibility is good. Of course, other elements such as lead, mercury, cadmium and the like can be added into the bismuth-based alloy according to actual needs.

Further, the welding material may include, in weight percent: 15% to 35% bismuth (e.g. 15%, 20%, 25%, 30% or 35%), 20% to 35% indium (e.g. 20%, 25%, 30% or 35%), 5% to 16% tin (e.g. 5%, 8%, 10%, 12%, 14% or 16%), 0% to 5% zinc (e.g. 0%, 1%, 2%, 3%, 4% or 5%) and 0% to 2% cobalt (e.g. 0%, 0.5%, 1%, 1.5% or 2%), where the bismuth, indium, tin, zinc and cobalt are not present as a simple substance, but rather form a bismuth-based alloy, in the form of a bismuth-based alloy.

Optionally, in the embodiment of the present invention, the wave-absorbing material includes one or more of silicon carbide, carbon black, graphite, spinel-type ferrite, carbonyl iron, carbonyl nickel, and carbonyl cobalt, so that the wave-absorbing material has a good microwave absorption effect and is easily and uniformly mixed with the bismuth-based alloy.

Optionally, in the embodiment of the present invention, the rheology modifier is magnesium lithium silicate and/or fumed silica, so that while the rheology modifier performs a rheology modification function (even if the welding material is melted, a certain plasticity can be maintained, and a phenomenon that the viscosity of the welding material is too significantly reduced to freely flow and be uncontrollable due to temperature rise in the melting process of the welding material is avoided), the rheology modifier can also perform an oxidation resistance function because the specific gravity of the magnesium lithium silicate and the fumed silica is lower than that of the bismuth-based alloy.

Further, the solder material may include 0% to 2% by weight of lithium magnesium silicate (e.g., 0%, 0.5%, 1%, 1.5%, or 2%), 0.1% to 4% fumed silica (e.g., 0.1%, 1%, 2%, 3%, or 4%).

Optionally, in the embodiment of the present invention, the reinforcing and toughening material includes one or more of cage polysilsesquioxane, carbon fiber, single-walled carbon nanotube, and graphene oxide, so that the reinforcing and toughening effect is better.

In addition, the welding material in the embodiment of the invention also can comprise an antioxidant auxiliary agent, and the antioxidant auxiliary agent can reduce oxidized metal, so that the welding material has good conductivity and welding effect. Optionally, the welding material comprises 1-7% of antioxidant aid by weight percentage. Furthermore, the antioxidant auxiliary agent is one of pimelic acid and glutaric acid, and the melting point of pimelic acid is about 105 ℃ and the melting point of glutaric acid is about 95 ℃, so that the antioxidant auxiliary agent is in a solid state and has good compatibility and migration resistance in the daily storage process of the welding material, and the antioxidant auxiliary agent is molten in a fluid state in the heating process and has good reduction capability.

Optionally, in order to increase the compatibility of the reinforcing and toughening material and the rheology modifier with the bismuth-based alloy, the welding material may further include an amino coupling agent, and the amount of the amino coupling agent may be 5% of the total mass of the reinforcing and toughening material and the rheology modifier, so as to further enhance the composite effect.

In addition, an embodiment of the present invention further provides a method for preparing a solder material, which is used to prepare the solder material described in any one of the above embodiments, specifically, as shown in fig. 1, fig. 1 is a flowchart of a method for preparing a solder material provided in an embodiment of the present invention, where the method for preparing a solder material includes:

and step S1, heating the raw materials of the bismuth-based alloy to be above the melting point under vacuum or inert gas protection, weighing the raw materials according to the proportion, mixing, fully stirring the mixture, and then gradually cooling.

For example, stirring for 1 to 2 hours, and cooling at a rate of 0.01 to 5 ℃/min, preferably 0.1 to 1 ℃/min. The selection of the cooling rate in the step can ensure sufficient cooling efficiency, and can effectively inhibit segregation caused by too high cooling rate and too large cooling crystallization driving force, so that the segregation easily causes uneven strength of the solder, the melting temperature interval is easily increased, and the fluidity of the solder at the same temperature is reduced.

And step S2, heating the bismuth-based alloy to a molten state, adding the wave-absorbing material, the rheological modifier and the reinforcing and toughening material which are weighed in advance, and stirring.

Optionally, mixing for 30-120 min under overhead stirring at 300-2000 r/min.

In this step, the order of adding the powder is preferably: adding the reinforcing and toughening material and the rheological modifier with smaller specific gravity, stirring for a period of time (such as 20 min-90 min), adding the wave-absorbing material, and stirring for a period of time (such as 10 min-30 min). The reason for adopting the adding sequence is that the reinforcing toughening material and the rheological modification material have low specific gravity and poor compatibility with the bismuth-based alloy, and if the reinforcing toughening material and the rheological modification material are added later, the condition of uneven dispersion or phase separation is easily generated, and the later addition of the wave-absorbing material can meet the requirement of effective dispersion in a short time and can also ensure that the wave-absorbing material cannot be oxidized and denatured to lose efficacy in a charging link without inert gas protection.

If the welding material further comprises an amino coupling agent, the amino coupling agent can be added to the bismuth-based alloy together with the reinforcing and toughening material and the rheology modifier.

And step S3, transferring the mixture obtained in the step S2 to a ball milling tank under the protection of inert gas, and adding grinding balls for ball milling.

For example, one of agate and corundum is selected to be a ball milling tank, and agate, corundum or zirconia grinding balls are added to the ball milling tank to perform ball milling for 10 to 120min under the condition of 800 to 1500 r/min.

In step S3, the protection of the inert gas can effectively inhibit the oxidation of the bismuth-based alloy during the high-temperature ball milling process.

Since the bismuth-based alloy, the wave-absorbing material, the rheological modifier and the reinforcing and toughening material are mixed in the step S2, and ball milling is performed in the step S3, the metal and the inorganic non-metal material (the wave-absorbing material, the rheological modifier and the reinforcing and toughening material) with large specific gravity difference can be uniformly dispersed with high efficiency (in a short time), and adverse effects caused by oxidation can be avoided as much as possible.

And step S4, adding an antioxidant aid, and continuing ball milling to obtain the welding material.

Preferably, the antioxidant is added after the ball milling rotation speed in step S3 is reduced.

In addition, in order to facilitate the use of the welding material, the welding material obtained in step S4 may be prepared into a wire shape by extrusion and injection molding.

The following embodiments of the present invention provide several alternative specific formulations of the solder material to facilitate understanding and implementation by those skilled in the art.

Example 1

Name (R)	Added amount (g)	Mass percent
			Bismuth (III)	20	30.30％
Indium (In)	20	30.30％
			Tin (Sn)	10	15.15％
Zinc	1	1.52％
			Cobalt	0	0.00％
Lithium magnesium silicate	0	0.00％
			Fumed silica	2	3.03％
Carbon fiber	2	3.03％
			Single-walled carbon nanotubes	1	1.52％
Pimelic acid	2	3.03％
			Carbonyl nickel	5	7.58％
Silicon carbide	3	4.55％

Example 2

Name (R)	Added amount (g)	Weight percent of
			Bismuth (III)	22	28.39％
Indium (In)	25	32.26％
			Tin (Sn)	11	14.19％
Zinc	0	0.00％
			Cobalt	0	0.00％
Lithium magnesium silicate	2	2.58％
			Fumed silica	1	1.29％
Carbon fiber	3.5	4.52％
			Pimelic acid	2	2.58％
Cobalt carbonyl	6	7.74％
			Graphene oxide	5	6.45％

Example 3

Name (R)	Added amount (g)	Weight percent of
			Bismuth (III)	18	27.91％
Indium (In)	20	31.01％
			Tin (Sn)	6	9.30％
Zinc	2	3.10％
			Cobalt	1	1.55％
Lithium magnesium silicate	1	1.55％
			Fumed silica	0.5	0.78％
Cage polysilsesquioxane	3	4.65％
			Pimelic acid	2	3.10％
Silicon carbide	6	9.30％
			Graphite	3	4.65％
Carbonyl iron	2	3.10％

The properties of the above examples are shown in the following table:

in the table, the lower melting point refers to the start melting temperature, and the lower melting point refers to the end melting temperature.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A welding material, characterized in that the welding material comprises, in weight percent: 59-91% of bismuth-based alloy, 5-30% of wave-absorbing material, 0.1-6% of rheological modifier and 2-5% of reinforcing and toughening material.

2. The solder material according to claim 1, wherein the bismuth-based alloy is composed of bismuth, indium, and tin, or the bismuth-based alloy is composed of bismuth, indium, and tin, and at least one of zinc and cobalt.

3. The welding material of claim 2, wherein the welding material comprises, in weight percent: 15% -35% of bismuth, 20% -35% of indium, 5% -16% of tin, 0% -5% of zinc and 0% -2% of cobalt, wherein the bismuth, the indium, the tin, the zinc and the cobalt form the bismuth-based alloy.

4. The welding material of claim 1, wherein the wave-absorbing material comprises one or more of silicon carbide, carbon black, graphite, spinel type ferrite, carbonyl iron, nickel carbonyl, and cobalt carbonyl.

5. The welding material of claim 1, wherein the rheology modifier is lithium magnesium silicate and/or fumed silica.

6. The welding material of claim 5, wherein the welding material comprises, in weight percent, 0% to 2% lithium magnesium silicate, 0.1% to 4% fumed silica.

7. The welding material of claim 1, wherein the reinforcing and toughening material comprises one or more of cage polysilsesquioxane, carbon fiber, single-walled carbon nanotube, and graphene oxide.

8. The welding material according to any one of claims 1 to 7, further comprising 1 to 7 weight percent of an antioxidant auxiliary.

9. The welding material of claim 8, wherein the antioxidant additive is one of pimelic acid and glutaric acid.

10. A method of producing a solder material for use in producing a solder material according to any one of claims 1 to 9, the method comprising:

step S1, under the protection of vacuum or inert gas, heating each raw material of the bismuth-based alloy to be above a melting point, weighing each raw material according to a proportion, mixing, fully stirring the mixture, and then gradually cooling;

step S2, heating the bismuth-based alloy to a molten state, adding the wave-absorbing material, the rheological modifier and the reinforcing and toughening material which are weighed in advance, and stirring;

step S3, transferring the mixture obtained in the step S2 to a ball milling tank under the protection of inert gas, and adding grinding balls for ball milling;

and step S4, adding an antioxidant aid, and continuing ball milling to obtain the welding material.

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