Apparatus for irradiation of printed wiring boards and the like

• US 5,040,236 A
• Filed: 07/18/1990
• Issued: 08/13/1991
• Est. Priority Date: 07/18/1990
• Status: Expired due to Fees

• Current Assignee: ARGUS International, Inc.
• Original Assignee: ARGUS International, Inc.
• Inventors: Costello, Bernard J.
• Primary Examiner(s): Reynolds, Bruce A.
• Assistant Examiner(s): Jeffery, John A.
• Application Number:
  US07/554,272
• Time in Patent Office: 391 Days
• Field of Search: 392/417-419, 392/407, 392/420, 219/388, 219/503, 219/495, 198/848, 198/803.14, 198/803.15, 414/157, 414/159
• US Class Current: 392/417
• CPC Class Codes: F26B 15/18 the objects or batches of materials being carried by endless belts
• CPC Class Codes: F26B 3/28 by radiation, e.g. from the sun
• CPC Class Codes: F27B 9/066 heated by lamps
• CPC Class Codes: H05K 2203/1509 Horizontally held PCB
• CPC Class Codes: H05K 2203/1572 Processing both sides of a PCB by the same process; Providing a similar arrangement of components on both sides; Making interlayer connections from two sides
• CPC Class Codes: H05K 3/0082 characterised by the exposure method of radiation-sensitive masks
• CPC Class Codes: H05K 3/28 Applying non-metallic protective coatings H05K3/0091 takes precedence; methods for intermediate insulating layers for build-up multilayer circuits H05K3/4673

Abstract

An open-weave conveyor moves a printed wiring board through a region of radiant energy. The conveyor has a plurality of supporting projections extending from the major surface of the conveyor to minimize engagement between the conveyor and the board, providing at least three projections supporting each board above the open-weave conveyor to eliminate a shadow effect caused by radiation blocked by conveyor strands. Guides move the conveyor along an arcuate path away from the printed wiring board in the radiation region, assuring irradiation of the entire printed wiring board surface. This technique is advantageous for simultaneously irradiating both sides of a board during a dry film solder masking technique. The solder mask is radiated to promote cross-linking of the film polymer. To reduce thermal shock and abrupt temperature rise in the workpiece, the ultraviolet source includes a water envelope to absorb infrared radiation. A series of irradiation devices, one with and one without the aforementioned water envelope, may be utilized. A liquid component utilized in the dry film solder masking tecnique to fill voids and irregularities in the printed wiring board surface irradiated in this manner remains stable, preventing the overlaying film from cracking during a semi-curing step followed by further UV processing which provides a full cure. A lamp regulator permits smooth regultion of radiant energy while eliminating the need to regulate or change capacitors. A sensor monitors the UV lamp output to adjust and maintain the desired radiation operating levels.

Claims