阅读说明：本技术 用于铝结合的可印刷表面处理 (Printable surface treatment for aluminum bonding ) 是由 M·R·维森 C·陈 D·P·卡迪瓦拉 S·K·莎玛 于 2018-04-05 设计创作，主要内容包括：提供了用于将金属与铝表面连接的组合物和方法。该组合物被制备成水溶液或悬浮液,和可使用传统印刷技术施加到铝表面。可调整该可印刷的组合物的流变性以提供凝胶或乳油。如果需要,可以在与批量生产的设备的塑料/聚合物部件例如铝RFID天线相容的低温下进行固化步骤。(Compositions and methods for joining metals to aluminum surfaces are provided. The composition is prepared as an aqueous solution or suspension and can be applied to the aluminum surface using conventional printing techniques. The rheology of the printable composition can be adjusted to provide a gel or cream. If desired, the curing step may be performed at a low temperature that is compatible with the plastic/polymer components of mass-produced devices, such as aluminum RFID antennas.)

1. A printable composition that provides printable surface activation for metal bonded aluminum or aluminum alloys, wherein the printable composition comprises an aqueous solvent or a mixed aqueous solvent.

2. The printable composition of claim 1 further comprising an organic amine.

3. A printable composition as claimed in claim 2, wherein the organic amine is selected from the group consisting of ethanolamine and dodecylamine.

4. A printable composition as claimed in any one of claims 1 to 3, which further comprises a fatty acid.

5. A printable composition as claimed in claim 4, wherein the fatty acid is palmitic acid or a salt of palmitic acid.

6. A printable composition as claimed in any one of claims 1 to 5 wherein the printable composition is in the form of a gel or cream.

7. A printable composition as claimed in any one of claims 1 to 6 wherein the printable composition is compatible with printing techniques selected from the group consisting of screen printing, stencil printing, gravure printing, and pad printing.

8. The printable composition of claim 1 comprising a hydrofluorinated amine formulated into a gel in an aqueous solvent free of organic solution.

9. The printable composition of claim 1 comprising a mixture of fatty acids, fatty acid salts, amine fluorides, acidic amine fluorides, and amine tetrafluoroborates in an aqueous solution free of organic solvents and formulated into a gel.

10. A printable composition as claimed in claim 1, which comprises a mixture of fatty acids, fatty acid salts, amine fluorides, amine fluoride acids and amine tetrafluoroborates in aqueous solution, wherein the rheology is adjusted for printing techniques by the addition of organic co-solvents.

11. The printable composition of claim 11 wherein said co-solvent is selected from the group consisting of hydrocarbons, halogenated hydrocarbons, and alcohols.

12. The printable composition of claim 11 further comprising a surfactant.

13. A method of bonding a metal to aluminum, comprising:

Depositing a printable composition to an aluminum surface to form a coated aluminum surface, wherein the printable composition comprises an aqueous solvent or a mixed aqueous solvent; and

Attaching the metal to the coated aluminum surface.

14. The method of claim 13, wherein the depositing is performed using a printing technique.

15. The method of claim 14, wherein the printing technique is selected from the group consisting of screen printing, pad printing, ink jet printing, stencil printing, and gravure printing.

16. The method of any one of claims 13 to 15, further comprising the step of curing the coated aluminum surface.

17. The method of any one of claims 13 to 16, wherein the joining is performed by a technique selected from the group consisting of welding, ultrasonic welding and soldering.

18. The method of one of claims 13 to 17, wherein the printable composition further comprises an organic amine.

19. The method of claim 18, wherein the organic amine is selected from the group consisting of ethanolamine and dodecylamine.

20. The method of one of claims 13 to 19, wherein said printable composition further comprises a fatty acid.

21. The method of claim 20, wherein the fatty acid is palmitic acid or a salt of palmitic acid.

22. The method of any one of claims 13 to 21, wherein said printable composition is in the form of a gel or an emulsifiable concentrate.

23. The method of any one of claims 13 to 22 wherein said printable composition comprises an amine hydrofluoride in an aqueous solvent free of organic solution and formulated as a gel.

24. The method of one of claims 13 to 22, wherein said printable composition comprises a mixture of fatty acids, fatty acid salts, amine fluorides and amine tetrafluoroborates in an aqueous solution free of organic solvents and formulated into a gel.

25. The method of one of claims 13 to 22, wherein said printable composition comprises a mixture of fatty acids, fatty acid salts, amine fluorides and amine tetrafluoroborates in an aqueous solution, wherein rheology is adjusted for printing techniques by adding an organic co-solvent.

26. The method of claim 25, wherein the co-solvent is selected from the group consisting of hydrocarbons, halogenated hydrocarbons, and alcohols.

27. The method of one of claims 13 to 26, wherein said printable composition further comprises a surfactant.

Technical Field

The field of the invention is metal bonding, more specifically aluminum bonding.

Background

The following description includes information that may be useful for understanding the present invention. It is not an admission that any of the information provided herein is prior art or that any publication specifically or implicitly referenced is prior art to the presently claimed invention.

Aluminum has the advantages of being lightweight, readily available, recyclable, and reasonably conductive. Aluminum is also very corrosion resistant due to the rapid formation of a robust oxide layer on the exposed aluminum surface. Unfortunately, as described by Babcock et al (see Ref 1), oxide layers interfere with the connection to other metals. While other metals may be problematic in combination with aluminum, the ability to bond the metal to the aluminum is important in order to manufacture electronic devices (particularly RFID tags). Low cost RFID tags typically have an aluminum antenna. Antennas are often bonded to other electronic devices for signal communication, which in turn requires bonding of metal to aluminum metal. The aluminum surface has a top oxide layer. Therefore, a proper surface treatment of aluminum is required to enable the aluminum to be combined with other metals.

Various surface treatments have been developed for application to aluminum to facilitate bonding to other metals by welding, e.g., Elbreder et al³. These surface treatment chemistries for aluminum typically include inorganic compounds, such as metal halides, Eichhorn et al⁴And high temperatures are required to facilitate bonding between the aluminum and the desired bonding metal (e.g., weld metal or alloy)Appropriate binding reactions. Inorganic fluorine salts and/or organic amine fluorides or acidic fluorides have been used to activate the surface of aluminum for bonding to metals/solder^5-14. There are also methods that do not use fluoride/fluoroborate salts, such as the waxy formulations described in references 15-20).

However, these formulations may not be suitable for use on devices that include temperature sensitive materials or components. Typical consumer RFID tags are low cost, mass-produced items that include aluminum/aluminum alloy antennas and typically use plastic/polymer substrates. Such plastic substrates typically degrade at elevated temperatures. Low temperatures, for example in the range of 70 ° to 250 ℃, are preferred to maintain the integrity of the plastic substrate during the surface activation treatment.

Similarly, it is not clear whether such wax-like formulations are suitable for high-speed manufacturing processes typically used in RFID tags. Application to a surface in these methods typically involves rapid and scalable methods of the entire surface, such as dipping, painting, spraying, etc.; it is unclear whether the wax-like substance can be applied in this manner. Alternatively, printing (e.g., screen printing, stencil printing, gravure printing, pad application, roll-to-roll printing, and/or ink jet printing) may be used to activate portions of the surface. However, it is not clear whether such printing techniques can be applied to existing aluminium binding formulations on an industrial scale.

Such printing techniques require a paste, suspension or solution that dries quickly after application. It may be desirable to use an appropriate solvent or carrier (e.g., organic or mixed aqueous solvent) to carry out the technique. Another important feature of printable, e.g. screen-printable or stencil-printable, surface-activated chemistry for aluminum bonding to metals is compatibility with solvents, which allows adjustment of the rheology of the printing ink (see Durairaj)²³And Hsu²⁴). It is unclear whether these solvents are compatible with existing aluminum bonding formulations.

Screen printable solder pastes/fluxes with solder metal powders have been developed^21,22. A limitation of these and similar fluxes having solder metal powder as part of their composition is their useLimited to the specific solder-metal/alloy composition of the formulation. On the other hand a suitable printable surface activation treatment should provide the user with the freedom to use any solder in the metal bonding to the aluminium.

All publications mentioned herein are incorporated herein by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

Thus, there remains a need for compositions and methods for low temperature, scalable bonding of aluminum to other metals.

Disclosure of Invention

The present subject matter provides compositions and methods that allow for the bonding of metals to aluminum. The compositions of the present concepts may be formulated without the use of organic solvents and may be applied in the use of conventional printing processes. The application and curing steps may be performed at temperatures compatible with the plastics/polymers used in mass-produced consumer devices such as aluminum antennas for RFID tags.

One embodiment of the inventive concept is a printable composition that provides printable surface activation for metal bonded aluminum or aluminum alloys, wherein the printable composition comprises an aqueous solvent or a mixed aqueous solvent. The printable composition may also comprise organic amines (e.g. ethanolamine and/or dodecylamine) and/or fatty acids (e.g. palmitic acid or salts of palmitic acid). The printable composition may be formulated as a gel or cream to facilitate printing by certain techniques. Suitable printing techniques for the application of the printable composition include screen printing, stencil printing, gravure printing and pad printing). One example of such a printable composition includes an amine hydrofluoride in an aqueous solvent that does not include an organic solvent and is formulated into a gel. Another example of such a printable composition includes a mixture of fatty acids, salts of fatty acids, amine fluorides, acid amine fluorides, and amine tetrafluoroborates in an aqueous solvent that does not include an organic solvent and is formulated into a gel. Another example of such a printable composition includes a mixture of fatty acids, salts of fatty acids, amine fluorides, acidic amine fluorides, and amine tetrafluoroborates in an aqueous solvent. The rheology of these printable compositions can be adjusted for use in printing techniques by the addition of organic co-solvents (e.g., hydrocarbons, halogenated hydrocarbons, and/or alcohols). In some embodiments, the printable composition includes a surfactant.

Another embodiment of the inventive concept is a method of bonding metal to aluminum by depositing a printable composition (as described above) onto an aluminum surface to form a coated aluminum surface and attaching the metal to the coated aluminum surface. The printable composition may be deposited using printing techniques such as screen printing, pad printing, ink jet printing, stencil printing, and/or gravure printing. In some embodiments, the method also includes the step of curing the coated aluminum surface. The metal may be joined to the coated aluminum surface by any suitable method, including welding, ultrasonic welding, and/or soldering.

Various objects, features, aspects and advantages of the present subject matter will become more apparent from the following detailed description of preferred embodiments.

Drawings

FIG. 1 provides a photograph of surface activated gravure printed areas on an aluminum substrate.

Fig. 2 provides a photograph of surface mount components reflow soldered to an aluminum substrate after treating the aluminum surface with a gravure-printed surface activation ink.

Figure 3 provides a photograph of a copper wire welded to an aluminum substrate via a gravure printing surface applied to the aluminum.

Figure 4 provides a photograph of an aluminum antenna laminated on a polyethylene sheet. The square bond pads provide connection points to external circuitry.

Figure 5 provides a photograph of an aluminum antenna laminated on a polyethylene board after DDAHF has been applied to the bonding pad by screen printing.

Fig. 6 depicts a thermogram of printable aluminum surface treatment ink.

Detailed Description

The present subject matter provides devices, systems, and methods in which printable surface activation of aluminum or aluminum alloys for metal bonding is based on water as a solvent. In some preferred embodiments, the printable surface activation is achieved by screen, stencil, gravure or pad printing. In some preferred embodiments, surface activation is achieved by using amine hydrofluoride, which can be gelled using water as a solvent. In some preferred embodiments, surface activation is achieved by a mixture of fatty acids, their salts, amine fluorides, acidic amine fluorides, and amine tetrafluoroborates, which can be gelled by water as a solvent.

It should be appreciated that the compositions and methods of the inventive concept provide a convenient and scalable process for combining aluminum with other metals under cryogenic conditions that are compatible with many plastics and produce little to no volatile organics.

In some embodiments, numbers expressing quantities of ingredients, properties (e.g., concentrations, reaction conditions, and so forth) used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term "about". Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Numerical values presented in some embodiments of the invention can contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

As used in this specification and throughout the claims that follow, the meaning of "a", "an", and "the" includes plural references unless the context clearly dictates otherwise. In addition, the meaning of "in … …" as used in this specification includes "in … …" and "on … … (on)" unless the context clearly dictates otherwise.

Unless the context dictates otherwise, all ranges set forth herein should be construed as inclusive of their endpoints, and open-ended ranges should be construed as inclusive of only commercially practical values. Similarly, all numerical lists should be considered as containing intermediate values, unless the context dictates otherwise.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each separate value within the range is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided with respect to certain embodiments herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

The following discussion provides many example embodiments of the inventive subject matter. While each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment includes elements A, B, and C, and a second embodiment includes elements B and D, then even if not explicitly disclosed, the inventive subject matter is considered to include A, B, C, or other remaining combinations of D.

Groupings of optional elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member may be individually referenced and claimed, or may be in any combination with other members of the group or other elements found herein. For convenience and/or patentability reasons, one or more group members may be included or deleted from a group. When any such inclusion or deletion occurs, the specification is considered to include the modified group, thereby fulfilling the written description of all markush groups used in the appended claims.

The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements. But the inventive subject matter is considered to include all possible combinations of the disclosed elements and thus if one embodiment includes elements A, B, and C, and a second embodiment includes elements B and D, the inventive subject matter is considered to include A, B, C, or other remaining combinations of D, even if not explicitly disclosed.

As used herein, and unless the context dictates otherwise, the term "connected" is intended to include both direct connections (in which two elements that are connected to each other are in contact with each other) and indirect connections (in which at least one additional element is located between the two elements). Thus, the terms "connected to" and "connected with … …" are used synonymously.

For surface activation of aluminum for metal bonding, the present inventors eliminated the use of organic solvents in screen printing ink formulations, making these formulations compatible with the use of plastic substrates and/or parts. The compositions of the present inventive concept utilize water as a solvent to achieve rheology compatibility with a variety of printing techniques (e.g., screen printing, stencil printing, roll printing, ink jet printing, etc.) without the need for organic solvents.

The compositions of the present inventive concept can provide printable formulations that act as surface-activated fluxes for bonding metals to aluminum, such as by soldering. The elimination of organic solvents advantageously provides a "green technology" for surface activation of aluminum for metal bonding. This is particularly advantageous in the production of RFID tags, which are produced in large quantities (e.g., millions of units per year). The organic solvent is eliminated and the subsequent curing step does not involve any significant release of organic fumes or vapors.

In some embodiments, compositions of the present concepts may include a mixed aqueous solvent (e.g., an aqueous solvent system including an organic solvent component). In such mixed aqueous solvents, water may be present in a concentration range of 0.001% to 99% v/v (preferably 0.001% to 10% v/v). In such mixed aqueous solvent systems, suitable organic solvents may be water miscible, such as low molecular weight alcohols, ketones, ethers, esters, and aldehydes. Such organic solvents may be present only during certain steps during the production of the printable formulation of the inventive concept, or may be present in the final formulation.

The compositions of the inventive concept may include organic amines and/or organic amine derivatives. These organic amines may comprise carbon chains from 2 to 12 carbon lengths and include at least one amine group. In some embodiments, the organic amine may include additional substituents, such as hydroxyl groups, carboxyl groups, and/or halogens. In some embodiments, the organic amine may be present as a free base. In other embodiments, the organic amine may be present as a salt (e.g., tetrafluoroborate) or as a complex with an inorganic acid (e.g., HCl or HF). Suitable organic amines include ethanolamine and dodecylamine.

The compositions of the inventive concept may include fatty acids and/or fatty acid derivatives. These fatty acids may be saturated or unsaturated. Suitable saturated fatty acids include propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, arachidic acid, heneicosanoic acid, behenic acid, tricosanoic acid, lignoceric acid, pentacosanoic acid, hexacosanoic acid, heptacosanoic acid, nonacosanoic acid, hentriacontanoic acid, lacceric acid, tridecanoic acid (pseudollitic acid), tetradecanoic acid (geddic acid), pentacosanoic acid (cephaloplastic acid), hexacosanoic acid (hexatriacontanoic acid), heptadecanoic acid (heptadecanoic acid), and triacontanoic acid (octatriacontanoic acid). Suitable unsaturated fatty acids include alpha linoleic acid, stearidonic acid, eicosapentaenoic acid (eicosapentaenoic acid), docosahexaenoic acid, linoleic acid, elaidic acid, gamma-linolenic acid, dihomo-gamma-linolenic acid (dihomo-gamma-linolenic acid), arachidonic acid, docosatetraenoic acid (docosatetraenoic acid), palmitoleic acid, vaccenic acid, eicosenoic acid (paulinic acid), oleic acid, elaidic acid, macrocephalic acid, erucic acid, nervonic acid, and eicosatrienoic acid (mead acid). These fatty acids may be in the form of the free acid or in the form of a salt (e.g., ammonium, sodium or potassium salt). In some embodiments, the fatty acid is palmitic acid or a palmitate ester.

the compositions of the present concepts may have rheological properties that allow them to be printed by conventional and scalable printing techniques. This advantageously minimizes the consumption of these compositions by facilitating their directional application only to the portion of the aluminum surface that joins other metals. Suitable printing techniques include screen printing, stamping, ink jet printing, and roll printing. Suitable rheological properties of the compositions of the inventive concept depend on the printing technique employed. Such as screen printing, stencil printing, pad printing, and roll printing may utilize gels, creams, and relatively viscous solutions or emulsions. An example of a printable composition pad print of the present subject matter is shown in fig. 2, which is deposited on an aluminum surface using stencil printing. On the other hand, ink jet printing and other droplet dispensing techniques may require compositions having relatively low viscosities and good flow characteristics. The rheological properties of the compositions of the present concepts are a function of the components selected during manufacture, the concentration of such components, the solvent system used, and/or the process steps (e.g., mixing or blending). In some embodiments, the compositions of the present concepts may have non-newtonian characteristics (e.g., fluid but with a viscosity that varies depending on applied pressure or mechanical stress). The viscosity of the compositions of the present concepts may range from 1.1Cp to about 10,000 Cp.

The rheological properties of the compositions of the inventive concept can be modified from the basic formulation to suit the specific printing technique by the addition of organic compounds and/or solvents. Suitable organic solvents include ketones, ether esters, aldehydes, hydrocarbons, and/or halogenated hydrocarbons. Likewise, in some embodiments, the compositions of the present concepts may include one or more surfactants to adjust the rheological properties. Suitable surfactants include anionic surfactants, cationic surfactants, zwitterionic surfactants, and nonionic surfactants.

In the method of the inventive concept, the composition of the inventive concept is contacted with an aluminum surface. For example by printing. In some embodiments, an aluminum surface as provided may be used. In other embodiments, the aluminum surface may be treated, for example, by degreasing and/or removing some or all of the aluminum oxide layer prior to contacting it with the compositions of the present concepts. In some embodiments, the composition is applied to the aluminum surface prior to contact with other metals to be joined to the aluminum. In other embodiments, the composition is applied to a non-aluminum metal, which in turn is in contact with the aluminum surface, such that the composition of the inventive concept is located between the two metals. In still other embodiments, the non-aluminum metal is in close contact with the aluminum surface and the composition of the inventive concept is injected or otherwise introduced into the intervening space.

In a preferred embodiment, the composition of the inventive concept is selectively applied to portions of the aluminum surface to which other metals are to be joined using a printing process. For example, aluminum deposited on a plastic or polymer substrate provides an exposed aluminum surface that may be suitable for printing. Thus, using an "ink" comprising the composition of the present concepts, a piece of aluminum equipment can be deposited on plastic or polymer and printed (e.g., by screen printing, pad printing, or ink jet printing). Such printing may involve all or one or more selected portions of each aluminum device, for example in electrical contacts. After the ink is applied, the printable aluminum surface may be subjected to a curing process. Such curing may be used to remove the solvent from the printable ink composition. The curing process may involve incubation at elevated temperatures (e.g., from about 30 ℃ to about 500 ℃) and/or reduced pressures (from about 0.1kPa to about 100 kPa). Curing conditions may be selected to be compatible with the substrate supporting the aluminum surface to be printed. For example, if the aluminum substrate is supported by a polyethylene substrate, the curing conditions may utilize a temperature and exposure time that maintains the integrity of the polyethylene substrate. In some embodiments, for example where it is desired to remove the support substrate after printing, the curing conditions may be selected to melt, fracture, pulverize, or otherwise eliminate the support substrate while maintaining the aluminum surface.

After printing and in some embodiments after the curing step, the non-aluminum metal may be attached to the aluminum surface. This may be accomplished by any suitable method, including welding, ultrasonic welding, and/or soldering. In some embodiments, additional protective coatings may be applied to the joined metal surfaces to improve mechanical stability and/or protect against corrosion and environmental effects. For example, after a non-aluminum metal is attached to an aluminum surface, a protective coating of polymer, rubber, lacquer, and/or wax may be applied to the attached metal. Fig. 3 provides an example of a metal attached to an aluminum surface after deposition of the printable composition of the inventive subject matter onto the aluminum, showing surface mounting of a metal covered electronic component to an aluminum surface treatment area by reflow soldering. Another example is provided in fig. 4, which shows the attachment of copper wires to the treated area of an aluminum surface by welding.

The following examples illustrate water-based screen-printable surface-activated formulations that are metal-bonded to aluminum (e.g., soldered to selected aluminum bonding pads).