Abstract: Provided are a composition for an anisotropic conductive adhesive, a method of forming a solder bump and a method of forming a flip chip using the same. The composition for an anisotropic conductive adhesive includes a low melting point solder particle and a thermo-curable polymer resin. The anisotropic conductive adhesive includes forming a mixture by mixing a polymer resin and a curing agent, and mixing a deforming agent, a catalyst or a reductant with the mixture.

Abstract: A method of bonding an electrical component to a substrate includes applying solder paste on to a substrate. Solder preform has an aperture is formed therethrough and is then urged into contact with the solder paste, such that solder paste is urged through the aperture. An electrical component is then urged into contact with the solder preform and into contact with the solder paste that has been urged through the aperture, thereby bonding the electrical component, the solder preform, and the substrate together to define a reflow subassembly.

Abstract: A system includes a device of the surface-mounting type having an insulating package provided with a mounting surface and a contact pin exposed on the mounting surface. The device is attached to an insulating board including a gluing surface and an opposite surface. The process for manufacturing the system includes forming through holes a contact region on the gluing surface. The mounting surface is glued to the gluing surface with the contact pin aligned with the contact region. Wave soldering is performed to electrically join the device to the board by hitting the opposite surface with a wave of soldering paste to form, by capillary action with the soldering paste ascending in the through holes up to the overflow on the gluing surface, a conductive contact electrically connecting the contact pin of the electronic device through a solder connection to the contact region of the electronic board.

Abstract: A method of joining at least two parts includes steps of dispersing a joining material comprising a multi-phase magnetic metal-aluminum powder at an interface between the at least two parts to be joined and applying an alternating magnetic field (AMF). The AMF has a magnetic field strength and frequency suitable for inducing magnetic hysteresis losses in the metal-aluminum powder and is applied for a period that raises temperature of the metal-aluminum powder to an exothermic transformation temperature. At the exothermic transformation temperature, the metal-aluminum powder melts and resolidifies as a metal aluminide solid having a non-magnetic configuration.

Abstract: A flux composition is provided, comprising, as initial components: a carboxylic acid; and, a polyamine fluxing agent represented by formula I: with the proviso that when the polyamine fluxing agent represented by formula I is according to formula Ia: then zero to three of R1, R2, R3 and R4 is(are) a hydrogen. Also provided is a method of soldering an electrical contact using the flux composition.

Abstract: A flux composition is provided, comprising, as an initial component: a carboxylic acid; and, a fluxing agent represented by formula I: wherein R1, R2, R3 and R4 are independently selected from a hydrogen, a substituted C1-80 alkyl group, an unsubstituted C1-80 alkyl group, a substituted C7-80 arylalkyl group and an unsubstituted C7-80 arylalkyl group; and wherein zero to three of R1, R2, R3 and R4 is(are) a hydrogen. Also provided is a method of soldering an electrical contact using the flux composition.

Abstract: A flux composition is provided, comprising, as initial components: a carboxylic acid; and, an amine fluxing agent represented by formula I: Also provided is a method of soldering an electrical contact using the flux composition.

Abstract: A curable flux composition is provided, comprising, as initial components: a resin component having at least two oxirane groups per molecule; a carboxylic acid; and, an amine fluxing agent represented by formula I: and, optionally, a curing agent. Also provided is a method of soldering an electrical contact using the curable flux composition.

Abstract: A curable flux composition is provided, comprising, as initial components: a resin component having at least two oxirane groups per molecule; a carboxylic acid; a fluxing agent represented by formula I: wherein R1, R2, R3 and R4 are independently selected from a hydrogen, a substituted C1-80 alkyl group, an unsubstituted C1-80 alkyl group, a substituted C7-80 arylalkyl group and an unsubstituted C7-80 arylalkyl group; and wherein zero to three of R1, R2, R3 and R4 is(are) a hydrogen; and, optionally, a curing agent. Also provided is a method of soldering an electrical contact using the curable flux composition.

Abstract: A conductive ball mounting method for mounting conductive balls on a mount using an arraying mask, in which the mount includes mounting positions formed in a predetermined pattern, and the arraying mask is provided above the mount and includes through holes provided in positions corresponding to the mounting positions. The method includes providing a ball suction unit for sucking solder balls, the ball suction unit including a ball holding member capable of holding the conductive balls, sucking up the conductive balls below the ball suction unit, holding the conductive balls on a lower surface of the ball holding member while sucking up the conductive balls, and after the holding the conductive balls, falling the conductive balls held by the ball holding member to the mount.

Abstract: A method for joining two ceramic parts, or a ceramic part and a metal part, and the joint formed thereby. The method provides two or more parts, a braze consisting of a mixture of copper oxide and silver, a diffusion barrier, and then heats the braze for a time and at a temperature sufficient to form the braze into a bond holding the two or more parts together. The diffusion barrier is an oxidizable metal that forms either a homogeneous component of the braze, a heterogeneous component of the braze, a separate layer bordering the braze, or combinations thereof. The oxidizable metal is selected from the group Al, Mg, Cr, Si, Ni, Co, Mn, Ti, Zr, Hf, Pt, Pd, Au, lanthanides, and combinations thereof.

Abstract: An electro-conductive bonding material includes: metal components of a high-melting-point metal particle that have a first melting point or higher; a middle-melting-point metal particle that has a second melting point which is first temperature or higher, and second temperature or lower, the second temperature is lower than the first melting point and higher than the first temperature; and a low-melting-point metal particle that has a third melting point or lower, the third melting point is lower than the first temperature.

Abstract: The invention relates to a strip or sheet of aluminium alloy, comprising at least 80% by weight of aluminium and 0.01 to 0.5% yttrium and/or 0.05 to 0.5% bismuth, coated on at least one face with a brazing alloy. Said sheets and strips are used for the production of pieces by non-flux brazing.

Abstract: A method of controlling a bump printing apparatus includes securing a board having air holes therein to a printing table by vacuum suction using suction nozzles; bringing a mask into close contact with the board; printing solder bumps by compressing and moving a solder paste across an upper surface of the mask using a squeegee; spraying air through spray nozzles to separate the mask from the board; and terminating air spraying using the spray nozzles and terminating air suction using the suction nozzles to remove the board.

Abstract: A method for soldering an LED to a circuit board includes firstly providing a solder-applying pattern overlaying the circuit board. First holes and second holes are defined in the solder-applying patter. Then, solder pastes are filled in the first holes and the second holes. The solder-applying pattern is removed and a plurality of first solder poles and second solder poles are remained on the circuit board. An LED is then put on the first solder poles and the second solder poles. The first solder poles and the second solder poles are heated to form a first solder ball and a second solder ball respectively after the heated first and second solder poles are cooled. The first and second solder balls electrically connect positive and second electrodes of the LED with the circuit board.

Abstract: The present invention relates to a method of manufacturing a solar cell electrode, comprising: preparing a semiconductor substrate having a preformed electrode on a front side, a back side, or both of the front and the back side of the semiconductor substrate; applying a conductive paste onto the preformed electrode, wherein the conductive paste comprises a conductive powder, an amorphous saturated polyester resin with glass transitional temperature (Tg) of 50° C. or lower, and an organic solvent; drying the applied conductive paste; putting a tab electrode on the dried conductive paste; and soldering the tab electrode.

Abstract: Interconnect and/or reflow methods of the present disclosure achieve high aspect ratio interconnects, for example interconnects having an aspect ratio as high as 4, in addition to wider interconnect height tolerances among interconnects (for example, interconnects having a height variability of up to about 30%) while still achieving reliable electrical connections. Moreover, flip-chip interconnects configured in accordance with principles of the present disclosure can provide improved z-axis spacing between die-to-die and/or die-to-substrate flip chip stacks, for example z-axis spacing as large as 600 ?m. In this manner, additional spacing can be achieved for MEMS devices and/or similar components that are extendable and/or deformable out of the die plane.

Abstract: The method and apparatus serve to treat a multi-walled glass body, in particular a glass body (20) with a glass membrane (25) for a chemical sensor or measuring probe, wherein a portion of at least one wall or of an interior tube (21) is to be fused, and wherein the fusing can have the purpose of closing off a first chamber (291). A glass element (286) which serves to absorb radiation energy is inserted in the vicinity of the portion (210) of either the wall or of the interior tube (21) that is to be fused. The glass element (286) is exposed to the radiation energy of at least one energy radiator (17), whereby the glass element (286) and the portion (210) of either the wall or the interior tube (21) are fused together.

Abstract: A circuit board, associated assembly, and method of manufacture. The circuit board comprises an elongated groove, extending into the circuit board, for accommodating a footing of a large component such as an RF shield. The groove allows solder paste to be deposited therein via a stencil, to a depth greater than the stencil thickness. Thus the same stencil can be used for depositing solder paste for both small and large components.

Abstract: A method for repairing a gas turbine engine component includes applying a braze slurry to a first portion of the component, applying a pre-sintered preform to a second portion of the component that is different than the first portion, and brazing the component.

Abstract: A cold formation method of composite silver nanoparticles has been established. Thus, provided are composite silver nanoparticles comprising a silver core, which is made up of aggregated silver atoms and has an average particle diameter of from 1 to 20 nm, and an organic coating layer formed thereon which comprises at least one member selected from an alcohol molecule derivative having 1 to 12 carbon atoms, an alcohol molecule residue or an alcohol molecule; a composite silver nanopaste which contains at least the composite silver nanoparticles and a solvent and/or a viscosity grant agent added thereto; a method of producing the same; an apparatus for producing the same; a method of bonding the same; and a method of patterning the same.

Abstract: A camera module includes a lens module, a circuit board and solder balls. The lens module includes a lens holder, a liquid crystal lens, and wires. The lens holder includes an outer surface, a first end portion, and a second end portion at opposite sides of the lens holder. The lens holder defines wire grooves in the first and second end portions and the outer surface. The liquid crystal lens is received in the first end portion. The wires are formed on the first end portion The outer surface and the second end portion in the wire grooves are electrically connected to the liquid crystal lens. Each wire includes a solder terminal. The circuit board includes solder pads each corresponding to the solder terminal The solder balls each interconnect the solder pad and the corresponding solder terminal and are formed by low-temperature solder paste composed of tin and bismuth.

Abstract: A process for manufacturing a device comprising at least a support and a component, joined together by at least one braze, includes a brazing operation which is carried out starting from a metal oxalate. Advantageously, it is a silver oxalate or a mixture of silver and copper oxalates, the component and/or the support being covered with a film comprising gold or copper in contact with said braze and the component possibly being a power component.

Abstract: Braze materials and processes for using braze materials, such as for use in the manufacturing, coating, repair, and build-up of superalloy components. The braze material contains a plurality of first particles of a metallic material having a melting point, and a plurality of second particles comprising at least one nonmetallic material chosen from the group consisting of oxides, carbides, and nitrides of at least one metal. The nonmetallic material is more susceptible to heating by microwave radiation than the metallic material of the first particles, and the nonmetallic material is present in the braze material in an amount sufficient to enable the first particles to completely melt when the first and second particles are subjected to heating by microwave radiation.

Abstract: Disclosed is a print technology in which a solder pool staying on the surface of a mask is driven by means of a squeegee, and solder is applied onto a substrate onto which the lower surface of a mask is placed. A forward print process where solder is applied by driving a squeegee in a predetermined forward direction relative to a mask, and a backward print process where the solder is applied by driving the squeegee in a returning direction opposite to the forward direction are switched alternately. When the squeegee passes through the solder pool on the downstream side in a moving direction before switching in the course of switching from any one of the forward and backward print processes to the other one of these processes, the amount of solder in the solder pool is measured. Based on the amount of solder thus measured, the necessity of replenishing solder is determined. The solder pool is supplemented with solder, based on the result of the decision on whether solder replenishment is required.

Abstract: A module includes a substrate including a first copper surface and a semiconductor chip. The module includes a first sintered joint bonding the semiconductor chip directly to the first copper surface.

Abstract: Metal nanoink (100) for bonding an electrode of a semiconductor die and an electrode of a substrate and/or bonding an electrode of a semiconductor die and an electrode of another semiconductor die by sintering under pressure is produced by injecting oxygen into an organic solvent (105) in the form of oxygen nanobubbles (125) or oxygen bubbles (121) either before or after metal nanoparticles (101) whose surfaces are coated with a dispersant (102) are mixed into the organic solvent (105). Bumps are formed on the electrode of the semiconductor die and the electrode of the substrate by ejecting microdroplets of the metal nanoink (100) onto the electrodes, the semiconductor die is turned upside down and overlapped in alignment over the substrate, and then, the metal nanoparticles of the bumps are sintered under pressure by pressing and heating the bumps between the electrodes. As a result, generation of voids during sintering under pressure is minimized.

Abstract: A component assembly for use in living tissue comprises: a ceramic part; a metal part, e.g., a titanium metal; and a palladium (Pd) interlayer for bonding said ceramic part to the metal part. By applying sufficient heat to liquify a palladium-titanium interface, the Pd interlayer is used to braze the ceramic part to the titanium part to yield a hermetic seal.

Abstract: Disclosed are an apparatus for adhering solder powder to finely adhere the solder powder to an electronic circuit board and a method for adhering solder powder to the electronic circuit board.

Abstract: A method for forming bumps 19 on electrodes 32 of a wiring board 31 includes the steps of: (a) supplying a fluid 14 containing conductive particles 16 and a gas bubble generating agent onto a first region 17 including the electrodes 32 on the wiring board 31; (b) disposing a substrate 40 having a wall surface 45 formed near the electrodes 32 for forming a meniscus 55 of the fluid 14, so that the substrate 40 faces the wiring board 31; and (c) heating the fluid 14 to generate gas bubbles 30 from the gas bubble generating agent contained in the fluid 14.

Abstract: A method are provided to deposit conductive bonding material into cavities in a mold. A fill head is placed in substantial contact with a mold that includes cavities. The fill head includes a sealing member that substantially encompasses an entire area to be filled with conductive bonding material. The fill head and mold are transitioned so that the fill head is situated substantially directly above the mold and so that the plurality of cavities are facing in an upward direction with respect to the sealing member. The conductive bonding material is forced out of the fill head toward the mold. The conductive bonding material is provided into at least one cavity of the cavities contemporaneous with the at least one cavity being in proximity to the fill head.

Abstract: A solder is provided that produces a more impact resistant solder joint that is usable in high-end applications. The solder joint has a strong interconnection that can perform all of the normal functions of a solder joint while being more impact resistant. Furthermore, the solder joint retains its capabilities over the service life of a high-end product such as a computer or a cell phone. The solder meets the requirements of the soldering industry both today and into the future, including but not limited to an ability to be printed or dispensed with standard methods and conformity to health and safety standards.

Abstract: The invention relates to a method for applying a connection material with a specified shape on at least one surface of at least one workpiece, wherein the connection material and the surface have complementary wetting or wettable properties, and wherein the connection material (3) is deposited on at least one of the surfaces (2) and a shaping device (10, 10?) is arranged at least for the period of a flowable state of the connection material adjacent to the connection material as well as at least partially surrounding this material on the surface (2), wherein this device has a surface (11, 12) that is non-wettable with respect to the wetting properties of the connection material and that is designed for the forced guidance of the flow of the still flowable connection material in the region of the non-wettable surface that thus assumes a specified shape; and the shaped connection material is hardened.

Abstract: Regarding electronic component mounting in which an electronic component having plural solder bumps for external connection on its lower surface is mounted on a board, in an electronic component mounting operation of previously measuring the height position of solder paste on the board on which the solder paste has been printed, and mounting the electronic component on the board on which the solder paste has been printed by a loading head, whether the transfer of the solder paste to the solder bumps is necessary or not is judged on the basis of the measurement result of the height of the solder paste. In case that it is judged that the transfer is necessary, the transfer of the solder paste is executed, and thereafter the electronic component is mounted on the board. Hereby, it is possible to prevent the poor joint in case that a thin-sized semiconductor package which causes easily warp deformation is mounted on the board by soldering.

Abstract: An amorphous braze foil (1) produced by a melt-spin process has an upper side and a lower side. The upper side and the lower side are thinly coated with a film of metallic Ni-based, Co-based, or Ni—Co-based braze powder (2) with a particle size in the nanometer range, wherein both the braze foil (1) and also the braze powder (2) additionally include grain boundary stabilizing elements as alloying elements. In addition, melting point depressants can be present in the braze foil or in the nano braze powder (2) in a commercially common quantity or with a considerably increased proportion. With the braze foil (1) coated in this manner, both the melting temperature of the braze material and also the probability of recrystallization are advantageously reduced when brazing in the adjacent base material (10).

Abstract: The present invention provides electrically and thermally conductive compositions for forming interconnections between electronic elements. Invention compositions comprise three or more metal or metal alloy particle types and an organic vehicle comprising a flux that is application specific. The first particle type includes a reactive high melting point metal that reacts with a reactive low melting point metal(s) in the other particles to form intermetallic species. The reactive low melting point metal(s) of the invention are provided in two distinct particle forms. The first reactive low melting point metal particle includes a carrier that facilitates the reaction with the reactive high melting point metal. The second reactive low melting point metal particle acts primarily as a source of the reactive low melting point metal.

Abstract: A system and method for supporting an electronic component attached to a circuit board. Solder paste is applied to a solder pad underneath and aligned with a non-wetting region of an electronic component to form a support formed of solder to prevent electronic component lead flexing. The amount of solder for forming the support and the size of the solder pad are selected to bring the support into contact with, or in close proximity to, the non-wetting region.

Abstract: Methods and apparatus are provided for solder bonding entities to solid materials. One or more through apertures are formed in a solid material. Solder paste is introduced into each through aperture. Respective entities having solderable surface features are disposed in overlying alignment with the through apertures. The arrangement is heated causing molten solder paste to wet the solderable surface features and the solid material. Cooling results in the electrical and mechanical bonding of the entities to the solid material. Devices having substantially planar form factors and without lead wires can be electrically and mechanically secured to a supporting conductive stratum.

Abstract: A sintering method allows components to be joined to each other in a stable way at a processing temperature of less than 200° C., producing stable contact points having low porosity and high electrical and thermal conductivity. The method includes (a) providing a sandwich arrangement having at least a first component, a second component, and a metal paste located between the first and second components, and (b) sintering the sandwich arrangement. The metal paste includes (A) 75-90 wt. % of at least one metal present in the form of particles having an organic compound-containing coating, (B) 0-12 wt % of at least one metal precursor, (C) 6-20 wt % of at least one solvent, and (D) 0.1-15 wt % of at least one sintering agent selected from (i) salts of C1-C4 organic acids, (ii) esters of C1-C4 organic acids, and (iii) carbonyl complexes.

Abstract: A sintering method is provided which allows components to be joined to each other in a stable way, wherein the processing temperature is less than 200° C. and stable contact points are produced, which have low porosity and also high electrical and thermal conductivity. The method for joining components includes (a) providing a sandwich arrangement having at least (a1) one component 1, (a2) one component 2, and (a3) a metal paste located between component 1 and component 2, and (b) sintering the sandwich arrangement. The metal paste contains (A) 75-90 weight percent of at least one metal present in the form of particles having a coating containing at least one organic compound, (B) 0-12 weight percent of at least one metal precursor, (C) 6-20 weight percent of at least one solvent, and (D) 0.1-15 weight percent of at least one sintering agent selected from the group comprising (i) organic peroxides, (ii) inorganic peroxides, and (iii) inorganic acids.

Abstract: A solder paste including a metal component consisting of a first metal powder and a second metal powder having a melting point higher than that of the first metal, and a flux component. The first metal is Sn or an alloy containing Sn, and the second metal is a metal or alloy which forms an intermetallic compound having a melting point of 310° C. or higher with the first metal and has a lattice constant difference, i.e. a difference in between the lattice constant of the intermetallic compound and the lattice constant of the second metal component, of 50% or greater.

Abstract: A method for attaching a porous metal layer to a dense metal substrate, wherein the method is particularly useful in forming orthopedic implants such as femoral knee components, femoral hip components, and/or acetabular cups. The method, in one embodiment thereof, comprises providing a solid metal substrate; providing a porous metal structure; contouring a surface of the porous metal structure; placing the porous structure against the substrate such that the contoured surface of the porous metal structure is disposed against the substrate, thereby forming an assembly; applying heat and pressure to the assembly in conjunction with thermal expansion of the substrate in order to metallurgically bond the porous structure and the substrate; and removing mass from the substrate after the porous structure is bonded to the substrate, thereby finish processing the assembly.

Abstract: An aluminum-boron-carbon (ABC) ceramic-metal composite bonded to a metal or metal-ceramic composite other than ABC composite is made by forming a porous body comprised of particulates being comprised of a boron-carbon compound that has a particulate layer of titanium diboride powder on the surface of the porous body. The porous body is infiltrated with aluminum or alloy thereof resulting in the simultaneous infiltration of the TiB2 layer, where the layer has an aluminum metal content that is at least about 10 percentage points greater by volume than the (ABC) composite. The ABC composite is then fused to a metal or metal-ceramic body through the infiltrated layer of titanium diboride, wherein the metal-ceramic body is a composite other than an aluminum-boron-carbon composite.

Abstract: A method of joining at least two parts includes steps of dispersing a joining material comprising a multi-phase nanocrystalline magnetic metal-aluminum powder at an interface between the at least two parts to be joined and applying an alternating magnetic field (AMF). The AMF has a magnetic field strength and frequency suitable for inducing magnetic hysteresis losses in the metal-aluminum powder and is applied for a period that raises temperature of the metal-aluminum powder to an exothermic transformation temperature. At the exothermic transformation temperature, the metal-aluminum powder melts and resolidifies as a metal aluminide solid having a non-magnetic configuration.

Abstract: Polymer compositions containing a polymer matrix, a graphene that is covalently bonded to the polymer matrix and metal particles are described herein. A combined concentration of the metal particles and the graphene in the polymer matrix exceeds an electrical percolation threshold. In general, the graphene has a carbon:oxygen ratio of at least about 20:1 so as to impart a high electrical conductivity thereto. The polymer compositions can be used as a lead-free solder material, in which case they can allow multiple rework operations to take place at a connection. Methods for making and using such electrically conductive polymer compositions are also described.

Abstract: A composition may have metal nanoparticles having a diameter of 20 nanometers or less and have a fusion temperature of less than about 220° C. A method of fabricating the metal nanoparticles may include preparing a solvent, adding a precursor with a metal to the solvent, adding a first surfactant, mixing in a reducing agent, and adding in a second surfactant to stop nanoparticle formation. Copper and/or aluminum nanoparticle compositions formed may be used for lead-free soldering of electronic components to circuit boards. A composition may include nanoparticles, which may have a copper nanocore, an amorphous aluminum shell and an organic surfactant coating. A composition may have copper or aluminum nanoparticles. About 30-50% of the copper or aluminum nanoparticles may have a diameter of 20 nanometers or less, and the remaining 70-50% of the copper or aluminum nanoparticles may have a diameter greater than 20 nanometers.

Abstract: A semiconductor apparatus includes a semiconductor chip, a post electrode positioned on the front surface electrode, and a metal particle layer having metal particles bonded actively to each other. The front surface electrode and the post electrode are bonded with each other through the metal particle layer. A method of manufacturing a semiconductor apparatus includes the steps of coating metal particles protected with organic coating films to at least one of the front surface electrode of a semiconductor chip or the post electrode; pressing and heating the metal particles between the front surface electrode of the semiconductor chip and post electrode for breaking the organic coating films and for exposing the metal particles; and actively bonding the exposed metal particles to each other for bonding the front surface electrode and post electrode.

Abstract: An automatic soldering system includes a conveyance mechanism, a vehicle, a first part assembling mechanism, a first soldering mechanism, a turn-over mechanism, a second part assembling mechanism, a second soldering mechanism, and a control system. The vehicle is conveyed by the conveyor mechanism for carrying a workpiece. The first part assembling mechanism and the first soldering mechanism assemble and solder a first part to the primary workpiece carried by the vehicle. The turn-over mechanism turns the vehicle that is conveyed by the conveyor mechanism and carries the primary workpiece having the first part assembled thereto by a predetermined angle. The second part assembling mechanism and the second soldering mechanism assemble and solder and position a second part to the primary workpiece. The control system is electrically connected to and thus controls the first part and second part assembling mechanisms, the first and second soldering mechanisms, and the turn-over mechanism.

Abstract: The invention relates to a soldering work piece made of aluminium and/or aluminium compounds, to a soldering method, in addition to a heat exchanger soldered in said manner. One surface of the soldering work piece is provided with an artificially applied oxide layer.

Abstract: Disclosed is a heat exchanger comprising a boiling passage and cooling passage defined by opposite sides of metal walls. Layers of brazing material between the metal walls and a spacer member bond components of the heat exchanger together. An enhanced boiling layer (EBL) comprising metal particles bonded to each other and to a boiling side of the metal wall provides nucleate boiling pores to improve heat transfer. The EBL has a melting temperature that is higher than the melting temperature of the brazing material. Also disclosed is a process for assembling the heat exchanger.