Abstract: Disclosed is a method for testing solder mask material for suitability with an electroless plating process. The Emix potential of the electroless bath is measured. A test substrate including the mask material is then immersed in an electrolyte, and a constant potential at least equal to the Emix potential is applied to a pair of electrodes also immersed in the electrolyte. The test substrate is then inspected to determine adherence of the mask material.

Abstract: Disclosed is a method for removal of contaminants and replenishment of an electroless copper plating solution in order to allow reuse of the solution. Copper oxide is dissolved in the spent solution and this is followed by an electrodialysis which removes formate and carbonate ions.

Abstract: A surface of a substrate 11 (FIG. 2) is uniformly coated with a liquid L by wetting the surface with the liquid and compressibly contacting the wetted surface with an applicator member 10 having an outer layer 14 of a compressible liquid absorbing material with inverse sponge characteristics and an inner layer 13 of compliant material. Preferably the member is a roller 10 having a silicone rubber or polyurethane inner layer and a chamois outer layer. A plurality of the rollers 10 are arranged to be in compressive contact with the surfaces of a plurality of substrates 11 as the substrates are being removed from the liquid L (arrow A), the movement of the substrates 11 causing rotation (arrow F) of the rollers to apply a uniform coating of the liquid on the contacted surfaces.

Abstract: In an improved method for depositing a metal on a substrate of the type in which a dielectric coated substrate is coated with a sensitizing solution containing a reductible metal salt, a primary reducing agent comprising 2,7 anthraquinone disulfonic acid and a secondary reducing agent, the substrate is exposed to ultraviolet light in an atmosphere having a temperature of at least 117.degree. F. (42.degree. C.) and a mass of water vapor of at least 3.8 mg of water per liter of dry air for at least 15 seconds. In an embodiment of the method the substrate is aerated in a moisture controlled atmosphere at room temperature for at least 30 minutes prior to exposing the substrate to ultraviolet light.

Abstract: A mask for selectively transmitting therethrough a desired light radiant energy is disclosed. The mask comprises a stress-relieved, essentially dimensionally stable base, comprising a copolymer of tetrafluoroethylene and hexafluoropropylene, which is capable of transmitting therethrough the light radiant energy. A blocking film is deposited on at least a portion of the base for blocking the transmission of the light radiant energy through the portion of the base.

Abstract: A surface of a substrate 11 (FIG. 2) is uniformly coated with a liquid L by wetting the surface with the liquid and compressibly contacting the wetted surface with an applicator member 10 having an outer layer 14 of a compressible liquid absorbing material with inverse sponge characteristics and an inner layer 13 of compliant material. Preferably the member is a roller 10 having a silicone rubber or polyurethane inner layer and a chamois outer layer. A plurality of the rollers 10 are arranged to be in compressive contact with the surfaces of a plurality of substrates 11 as the substrates are being removed from the liquid L (arrow A), the movement of the substrates 11 causing rotation (arrow F) of the rollers to apply a uniform coating of the liquid on the contacted surfaces.

Abstract: A mask for selectively transmitting therethrough a desired light radiant energy is disclosed. The mask comprises a stress-relieved, essentially dimensionally stable base, comprising a copolymer of tetrafluoroethylene and hexafluoropropylene, which is capable of transmitting therethrough the light radiant energy. A blocking film is deposited on at least a portion of the base for blocking the transmission of the light radiant energy through the portion of the base.

Abstract: A method for depositing a metal on a surface is disclosed. The method comprises coating the surface with a sensitizing solution comprising at least a reducible salt of a non-noble metal dissolved in a solvent comprising water and an alcohol having a total number of carbon atoms ranging from 2 to 8. The coated surface is treated to reduce the metal salt to metallic nuclei to form a catalytic layer thereon capable of directly catalyzing the deposition of a metal on said nuclei from an electroless metal deposition solution.

Abstract: A circuit pattern on a circuit board has at least one contact finger termination to be coupled to a connector contact. A conductive overlay is solder-bonded to the base metal of the contact finger. The overlay is a composite structure of a number of layers. A base layer of copper faces, and is solder-bonded, to the base. A surface layer of gold provides a contact area for the connector contact. A layer of nickel between the base layer and the surface layer acts as a barrier layer to prevent copper from migrating through the surface layer to deposit as a contaminant on the surface of the contact area.

Abstract: In a thermocompressive soldering process, a conductive overlay of a material such as gold is applied to a contact finger of a circuit board.In carrying out this process, the overlay is initially carried on an adhesively coated strip such as a polyimide tape. To transfer the overlay to the contact finger, it is aligned with the contact finger and temporarily attached to the circuit board. A heat conductive resilient sheet is then interposed between the circuit board and a thermode. The thermode is adjusted to engage the contact finger with a predetermined force. The force is resiliently distributed by the interposed sheet. Heat is then applied from the thermode through the resilient sheet to liquefy a solder coating on the overlay and to bond the overlay to the contact finger upon resolidification of the solder. The applied force is sustained during the application of head and during a subsequent cooling period during which the solder resolidifies.