Magnetic particle containing material for fastening together parts or substrates

The field to which the disclosure generally relates to magnetic particle containing materials that may be used to fasten together substrates.

Soldering is a process in which two or more metal substrates are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point. In a conventional soldering process, heat is applied to the substrates to be joined, causing the solder to melt and be drawn into the joint by capillary action and to bond to the substrates to be joined by wetting action. A solder flux agent or material is typically used to assist the flow of the solder into the desired location.

Metal substrates may alternatively be joined together using polymeric adhesive materials. Conventionally, this is done by applying the adhesive between the metal substrates. The substrates may also be fastened in a similar manner to a conventional soldering process.

In one exemplary embodiment, a high melting temperature fastening material may be prepared containing magnetic particles that is used to fasten two or more substrates together to form an integrated part. The magnetic particles in the fastening material may allow a molten mixture of the fastening material to be drawn to a desired location through use of a magnet, electromagnet or magnetic field.

Other exemplary embodiments of the invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while disclosing exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Exemplary embodiments of the invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a schematic perspective partial section view of a method for coupling a pair of substrates in a clamping device;

FIG. 2 illustrates the coupling of a magnetic mold base to the bottom of the coupled substrates contained in the clamping device of FIG. 1 and the addition of high temperature fastening material having magnetic particles according to an exemplary embodiment of the present invention; and

FIG. 3 illustrates a method for drawing the high temperature fastening materials within the adjacent holes in the pair of substrates in FIG. 2 to form an integrated part;

FIG. 4 illustrates the removal of the integrated part of FIG. 3 ;

FIG. 5 illustrates an alternative arrangement for forming an integrated part according to another exemplary embodiment;

FIG. 6 illustrates a schematic perspective view for recovering excess high temperature fastening materials used in for forming an integrated part as in FIGS. 1-4 ;

FIG. 7 illustrates another exemplary alternative arrangement for forming the integrated as in FIGS. 1-4 ; and

FIG. 8 illustrates another exemplary alternative arrangement for recovering excess high temperature fastening material used in forming an integrated part as in FIGS. 1-4 .

The following description of the embodiment(s) is merely exemplary (illustrative) in nature and is in no way intended to limit the invention, its application, or uses.

Referring now to FIGS. 1-4 , one exemplary method for fastening together two distinct parts or substrates 12 , 14 to form an integrated part 10 may be depicted. Although two substrates are shown in FIGS. 1-4 , the use of a solder including magnetic particles may be used to fasten two parts together such as, but not limited to, an electronic component and a circuit board. In one embodiment, the solder composition is free, or substantially free, of a flux agent.

In one embodiment, as shown first in FIG. 1 , two substrates 12 , 14 may first be aligned such that their respective mating surfaces 16 , 18 are mated and such that through holes 20 , 22 are aligned as desired. A clamping device 30 having a right half 32 and left half 34 may then be positioned on either side of the substrates 12 , 14 and acts to clamps the substrates 12 , 14 to form a coupled substrate 50 such that the mating surfaces 16 , 18 are in contact with one another wherein the holes 20 , 22 form a continuous cavity or cavities 38 .

As shown in FIGS. 2 and 3 , the coupled substrates 50 may then be placed onto a magnetic mold base 60 . In this arrangement, the left half 34 of the clamping device 30 may be in close contact with a respective top surface 62 of the magnetic mold base 60 . The magnetic mold base 60 may include depressed areas 61 corresponding to the continuous cavity 38 .

A fastening material 40 in a molten or liquid state containing magnetic particles 42 may then be introduced onto a non-mated surface 50 of the substrate 12 opposite the magnetic mold base 60 . As best shown in FIG. 3 , the magnetic particles 42 in the molten material 40 aid in drawing the material 40 through the holes 20 , 22 and into the depressions 61 , therein filling the respective cavities 38 . Once the molten material 40 fills the cavity 38 and depressions, it is allowed to cool and harden, therein reversibly coupling the substrates 12 , 14 to form an integrated part 10 .

The drawing rate of the molten material 40 towards the magnetic mold base 60 is a function of the size of the cavities 38 , the viscosity of the molten material 40 , the force of gravity and the strength of the magnetic field created by the magnetic mold base 60 .

At this point, as shown in FIG. 4 , the clamping device 30 and mold base 60 may be removed. Excess fastening material 45 not contained within the cavities 38 that has settled into the depressions 61 or remained on the non-mated surface 50 may be recovered through use of an external magnet 55 and recycled as shown best in FIG. 5 . The external magnet 55 may be a permanent magnet or an electromagnet.

In an alternative exemplary arrangement to the arrangement as shown in FIG. 3 , as shown in FIG. 6 , the mold base 70 is not a magnetic mold base 60 , but instead may be formed of any non-magnetized material. The mold base includes depressions 71 along a top surface 72 similar to depressions 61 as described above. In this exemplary embodiment, a magnet 55 may be brought in close proximity to the bottom surface 75 of the mold base 70 in order to draw the fastening material 40 through the holes 20 , 22 as described above. The magnet 55 , whether a permanent magnet or electromagnet, may then be removed after the fastening material 40 is sufficiently drawn through the holes 20 , 22 and cooled. Alternatively, a magnetic field may be created by a coil or other means to cause the solder including magnetic particles to flow to a desired location.

In still another alternative exemplary arrangement to supplement the introduction of the fastening material 40 as in FIG. 3 , as shown in FIG. 7 , a heater 80 may be placed in close proximity to the magnetic mold base 60 and non-mated surface 50 . The heater 80 , whether an induction heater or a radiant heater, may aid in maintaining the fastening material 40 in a molten or liquid state as it is drawn through the holes 20 , 22 towards the magnetic mold base 60 . In addition, the presence of the magnetic particles 42 in the solder may facilitate the original heating of the fastening material 40 from a solid state to the molten state.

In yet another alternative exemplary arrangement to FIG. 4 , as shown in FIG. 8 , a heater 80 such as the heater 80 from FIG. 6 may be placed in close proximity to the integrated part 10 to remove any excess fastening material 45 . The heater 80 may act to melt the excess fastening material 45 back to a molten state, wherein it can easily be scraped or otherwise removed from any surface of the integrated part 10 as described above.

In one exemplary embodiment for any of the exemplary embodiments of FIGS. 1-8 above, the fastening material 40 may be a high melting temperature solder alloy of bismuth, indium, and/or tin containing magnetic particles that is coupled to a substrate material that forms the outer surfaces of the substrates 12 , 14 . The substrate materials 12 , 14 may include any material to which solder may be applied, including but not limited to metal substrate materials such as copper or steel. If permanently magnetizable particles are used as the magnetic particles 42 , the flux density of the magnetic field used during the process will determine, in part, the ultimate shear strength of the bond between the substrates 12 , 14 created by the fastening material 40 located within the cavities 38 . A shear strength enhancement may also occur if “soft” magnetic particles, as opposed to permanent magnetic particles, are used if the liquid portion of the solder or adhesive solidifies while the magnetic field is applied.

Exemplary alloys of bismuth, indium, and/or tin that may be utilized in the high temperature alloy fastening material 40 include Indalloy 174, Indalloy 162, and Indalloy 19, each having compositions described below in Table 1 (percentages are weight percents):

Exemplary magnetic materials 42 that may be used with the exemplary alloys include iron powders (I.P.) such as CM (average particle size 8 micron) or HS (average particle size 2 micron), or combinations thereof, both supplied by BASF Corp. of Mt. Olive, N.J. These exemplary magnetic materials 42 may be surface treated with phenyl phosphonic acid (PPA), 14MAG124 (a magnetorheological fluid) or with silica (SiO 2 ) to reduce oxidation at elevated temperatures. These magnetic materials 42 may be washed with solvents prior to introduction to the material 40 to remove residual oils from the iron powders.

Exemplary formulations of fastening materials 40 including one of the high temperature alloys of Table 1 with the exemplary magnetic materials 42 which were hand mixed with a spatula for a predetermined amount of time. These exemplary formulation are provided in Table 2:

In another exemplary formulation for the fastening material 40 , the fastening material 40 may be a high melting temperature polymeric material containing the afore-mentioned magnetic particles 42 . Exemplary thermoplastic polymers that may be utilized include nylon, polypropylene, polystyrene, or polyethylene.

The method for bonding together the substrates 12 , 14 to form an integrated part 10 , as shown in FIGS. 1-7 and described above, is equally appropriate for use with the high melting temperature polymeric material containing the aforementioned magnetic particles 42 as with the high temperature metal solder including the magnetic particles 42 and will not be repeated herein.

This bonding method of the exemplary embodiments provides a number of benefits. For example, pieces of either similar or dissimilar substrates can be fastened together quickly and easily. Also, multiple fastening operations can be performed at one time. Further, either temporary or permanent fasteners can be installed using the same exemplary method. Also, bonds of varying strength may be realized through the use of different integrated part 10 materials, different sized holes, and differing magnetic flux density. Finally, the fastening process can be readily reversed by heating of the fastening material 40 above its melting point and applying a magnet to remove the molten fastening material.

The above description of embodiments of the invention is merely exemplary in nature and, thus, variations thereof are not to be regarded as a departure from the spirit and scope of the invention.

In select exemplary embodiments the magnetic particles in the solder composition may be present in an amount ranging from about 0.01-50 weight (wt.) percent; about 1-10 wt. percent; about 2-6 wt. percent or about 3-20 wt. percent.