摘要:
A reduced driving voltage polymer dispersed liquid crystal display (10) has a transparent polymer matrix (20) disposed between two substrates (12, 14). Droplets of a nematic liquid crystal fluid (22) are uniformly dispersed throughout the polymer matrix. Particles of an optically transparent material (24) that is a weak conductor are uniformly dispersed throughout the polymer matrix to reduce the electrical potential across the polymer. The enhanced conductivity of the polymer matrix allows the display to be operated at a reduced voltage.
摘要:
A conformal shield (10) includes a conformal shield base (15), and a conductive layer (16). The conformal shield base (10) has a first conformable insulating material (12) having a characteristic softening point at a first temperature. A second conformable insulating material (14), which has a characteristic softening point at temperature higher than the first temperature, is overlaid on the first conformable insulating material (12). The conductive layer (16) is disposed on the conformal shield base (15) to form the shield (10).
摘要:
A tacking agent is provided for use in temporarily adhering electronic components and providing fluxing properties for soldering electronic assemblies. The tacking agent comprises a fluxing agent and a tackifier. The fluxing agent is composed of one or more carboxylic acids having the formula ##STR1## where R is an alkyl group containing from 1 to 6 carbon atoms, R' is selected from the group consisting of hydrogen and hydroxyl, and R" is selected from the group consisting of hydrogen, hydroxyl and carboxyl. The tackifier comprises one or more alcohols, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, or polymers. The tacking agent is deposited onto a printed circuit board or other substrate, the electronic components are placed into the deposited tacking agent and soldered. During solder reflow the fluxing agent provides fluxing action for the soldering process, and the tackifier volatilizes, leaving little or no residue on the printed circuit board.
摘要:
Briefly, according to the invention, a transfer molding compound is made from an epoxide resin, a cyanate ester, and a catalyst. The molding compound is used to encapsulate semiconductor devices to fabricate individual packages or to encapsulate devices mounted directly on a circuit carrying substrate.
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:
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.