Abstract: Apparatus for dispensing liquids, such as viscous liquids used during the manufacture of electronic component assemblies. The apparatus includes a valve body having a liquid passage with a valve seat and an outlet. A needle is mounted for reciprocating movement between open and closed positions in the liquid passage and with respect to the valve seat to dispense liquid from the outlet. An armature is connected for reciprocating movement with the needle and a magnetic element is mounted outside the liquid passage and movable between a first position that attracts the armature and moves the needle into the open position and a second position at which the armature and the needle are forced to the closed position by way of a return spring. An actuator is operatively connected to the magnetic element to move the magnetic element between the first and second positions.

Abstract: A method of dispensing encapsulant material on a wire bonded die comprises dispensing a series of discrete, single-point droplets and a series of continuous beads within an area bounded by a dam. The encapsulant material spreads out from the droplets and the continuous beads to form an encapsulating layer over the wire bonded die in an area defined by the dam.

Abstract: A dispensing pump for dispensing liquid, particularly suitable for dispensing two-part epoxy for encapsulation of integrated circuits, includes a pumping chamber in communication with a nozzle via a three way valve, the pumping chamber including an outlet, an internal volume, a pair of spaced directional seals located away from the outlet, an open volume reciting between the seals and an external port opening the open volume to atmosphere. A stepped plunger extends axially within the pumping chamber, with a first portion sized to be received and aligned through the first directional seal, the plunger being movable to move the first portion toward the outlet to close off the internal volume at the second seal. The second portion of the plunger is relatively smaller in transverse cross-sectional dimension than the inside diameter of the second seal, to cooperate with the port to promote fluid removal from the internal volume during initial filling and priming of the pumping chamber.

Abstract: A dispensing pump for dispensing liquid, particularly suitable for dispensing two-part epoxy for encapsulation of integrated circuits, includes a pumping chamber in communication with a nozzle via a three way valve, the pumping chamber including an outlet, an internal volume, a pair of spaced directional seals located away from the outlet, an open volume residing between the seals and an external port opening the open volume to atmosphere. A stepped plunger extends axially within the pumping chamber, with a first portion sized to be received and aligned through the first directional seal, the plunger being movable to move the first portion toward the outlet to close off the internal volume at the second seal. The second portion of the plunger is relatively smaller in transverse cross-sectional dimension than the inside diameter of the second seal, to cooperate with the port to promote fluid removal from the internal volume during initial filling and priming of the pumping chamber.