摘要:
Solder pastes having vehicles including formic acid-soluble organic acids as fluxing agents are described. Fluxing agents may be compounds of the formula: ##STR1## where R is an electron withdrawing group. In one embodiment, R is selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl. Other suitable formic-acid fluxing agents include, but are not limited to, adipic acid, acrylic acid, polyacrylic acid, methacrylic acid and polymethacrylic acid. The compounds clean oxides from the printed circuit boards (PCBs) under assembly and then volatilize leaving a residue to be cleaned away. The cleaning step involves rinsing with formic acid. No undesired residue remains indicating that the organic acids of the invention are effective in cleaning boards. Such acid fluxing agents can be used mixed with typical solder components, such as lead/tin solder pastes, or applied topically to solders, such as solder balls; both techniques permit the assembly of PCBs more easily with high quality bonds, and with little or no residue. Malic acid is a preferred organic acid fluxing agent. The formic acid cleaning step may be followed by a water rinse.
摘要:
Solder pastes having vehicles including blends of low boiling point alcohols and relatively high boiling point alcohols are described which leave residues which may be cleaned using only water are described. The low boiling point alcohols have a boiling point range of between about 65.degree. and about 150.degree. C. whereas the high boiling point alcohols have a boiling point in rhe range of about 150.degree. to about 270.degree. C. The solder pastes also use water-soluble organic acids as fluxing agents such as compounds of the formula: ##STR1## where R is an electron withdrawing group such as fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl. Other suitable formic-acid fluxing agents include, but are not limited to, adipic acid, polyacrylic acid, methacrylic acid and polymethacrylic acid. The compounds clean oxides from the printed circuit boards (PCBs) under assembly and then volatilze leaving a residue to be cleaned away. The cleaning step involves rinsing with water. No undesired residue remains indicating that the organic acids of the invention are effective in cleaning boards. Malic acid is a preferred organic acid fluxing agent.
摘要:
Fluxing compositions containing compounds that generate acids upon photoinitiation from a light source such as Hg/Xe ultraviolet (UV) light sources are described. The acids clean oxides from the printed circuit boards (PCBs) under assembly and then volatilize with little or no need for a cleaning step, or cleaning only with water. The compounds that release an oxide removing agent, sometimes called a "photoacid" include metal and organic onium salts and furyl compounds bearing a carbonyl group. Such fluxing compositions can be used mixed with typical solder formulations, such as lead/tin solders, or applied topically thereto; both techniques permit the assembly of PCBs more easily and with high quality bonds.
摘要:
Fluxing compositions are described containing as fluxing agents compounds of the formula: ##STR1## where R is an electron withdrawing group. In one embodiment, R is selected from the group consisting of fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl. The compound cleans oxides from the printed circuit boards (PCBs) under assembly and then volatilize with little or no need for a cleaning step, or cleaning only with water or formic acid. Very little or no undesired residue remains. Such acid fluxing agents can be used mixed with typical solder formulations, such as lead/tin solder pastes, or applied topically to solders, such as solder balls; both techniques permit the assembly of PCBs more easily with high quality bonds, and with little or no residue. Malic acid is a preferred organic acid fluxing agent.
摘要:
Solder paste vehicles using blends of monofunctional and polyfunctional alcohols are described. The blend may have a major portion of a low viscosity, monofunctional alcohol solvent and a minor portion of a high viscosity polyfunctional alcohol thickener. The monohydric solvent has a room temperature viscosity of at least 3 centipoise and from about 3 to 18 carbon atoms and may include such materials as 2-butanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-dodecanol, 2-ethoxyethanol, 2-(2-ethoxyethoxy)ethanol, 2-(2-butoxyethoxy)ethanol, n-hexadecanol, n-octadecanol, benzyl alcohol and mixtures thereof. The polyalcohol has a room temperature viscosity of between about 26 to about 1500 cp and includes compounds such as 1,2-ethanediol; 1,2-propanediol; 1,3-propanediol; 1,2-butanediol; 1,3-butanediol; 1,4-butanediol; 1,2-pentanediol; 1,5-pentanediol; 2,4-pentanediol; 2,5-hexane-diol; glycerol; 1,2,4-butanetriol; 2,2'-(ethylenedioxy)diethanol; 1,12-dodecane-diol; 1,16-hexanedecanediol and mixtures thereof. These blends give improved solubility of organic acid fluxing agents, provide relatively high viscosities of the solder paste and permit lower amounts of solvent to be used.
摘要:
A solder paste is formulated by combining a solder paste vehicle, a resin, and solder alloy particles. The solder paste vehicle is made by combining mono and polyfunctional alcoholic solvents with a fluxing agent. The solder particles are first reacted with a formate ion produced by formic acid, formaldehyde, paraformaldehyde, or mixtures thereof, in order to create a metal-formate complex that functions as an oxygen scavenger on the surface of the solder alloy particles.
摘要:
A manifold (10) for use in a gas solder-reflow oven (50) comprises a hollow tube made from a transition metal having an open end (18) for receiving gas, a closed end (16), and a plurality of holes (12).
摘要:
A first conductive layer 12 is deposited on the substrate 14. Next, a second conductive layer 16 with a circuit pattern is deposited on the first layer 12. Finally, the first conductive layer 12 not residing under the second conductive layer 16 is etched off, leaving the second layer 16 above the first layer 12.
摘要:
A membrane electrode assembly consists of a polymer electrolyte membrane (100) with an electrode on each side. The polymer electrolyte membrane has an integral sensor (115) disposed on the surface. The sensor monitors the physical, thermal, chemical or electrical state of the membrane electrode assembly. Information obtained from the sensor is used to identify a defective membrane electrode assembly, and the operation of the fuel cell is altered based on the identified defective membrane electrode assembly.
摘要:
Thermally conductive particles (14) for use in a polymeric resin are provided. The particles (10) are aluminum nitride coated with copper (12). The thermally conductive particles (14) are incorporated into a polymer (38) in order to provide, for example, a thermally conductive adhesive (36). The thermally conductive adhesive is used to bond an electronic component (32) to a circuit carrying substrate (34) in order to dissipate heat from the electronic component.