Overcurrent safety construction for a printed circuit board

• US 4,379,318 A
• Filed: 09/16/1980
• Issued: 04/05/1983
• Est. Priority Date: 09/21/1979
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Ootsuka, Tetsuo
• Primary Examiner(s): Salce, Patrick R.
• Application Number:
  US06/187,713
• Time in Patent Office: 931 Days
• Field of Search: 361/104, 361/103, 361/397, 361/400, 361/402, 361/405, 361/404, 361/406, 361/409, 361/430, 361/401, 337/1, 337/290, 337/295-297, 337/232, 307/303, 307/310, 307/202.1, 29/577 R, 29/577 C, 29/585, 29/829, 29/840, 29/846, 29/847, 29/849, 29/852, 29/740, 29/623, 357/51, 357/5, 357/45
• US Class Current: 361/104
• CPC Class Codes: H05K 1/0293 Individual printed conductors which are adapted for modification, e.g. fusable or breakable conductors, printed switches
• CPC Class Codes: H05K 1/11 Printed elements for providing electric connections to or between printed circuits
• CPC Class Codes: H05K 2201/0305 Solder used for other purposes than connections between PCB or components, e.g. for filling vias or for programmable patterns
• CPC Class Codes: H05K 2201/09381 Shape of non-curved single flat metallic pad, land or exposed part thereof; Shape of electrode of leadless component
• CPC Class Codes: H05K 2201/10181 Fuse
• CPC Class Codes: H05K 2203/173 Adding connections between adjacent pads or conductors, e.g. for modifying or repairing
• CPC Class Codes: H05K 2203/175 Configurations of connections suitable for easy deletion, e.g. modifiable circuits or temporary conductors for electroplating; Processes for deleting connections
• CPC Class Codes: H05K 3/3447 Lead-in-hole components H05K3/3415 takes precedence
• CPC Class Codes: H05K 3/3468 Applying molten solder
• CPC Class Codes: Y10T 29/49107 Fuse making
• CPC Class Codes: Y10T 29/49124 On flat or curved insulated base, e.g., printed circuit, etc.
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

In a printed circuit board, a safety means is provided to prevent the circuit elements such as semiconductor devices, resistors, and the like from suffering damage due to overcurrent flow. The safety means thus improved has a narrow gap provided within a metal foil pattern on the surface of the printed circuit board and a low-melting point metal such as solder bridges this gap to connect the metal foil.

Claims

1. A method of manufacturing a printed circuit board having an overcurrent safety construction for protecting electrical components of the printed circuit board against overcurrent damage, which comprises the steps of:

(a) forming a metal foil pattern on the board and simultaneously forming a narrow gap in said metal foil between the position at which said pattern is to be connected to a power source and the position at which said components to be protected are to be mounted on said board;

(b) mounting said circuit components on said board; and

(c) dipping the printed circuit board in a reservoir of molten solder so as to form simultaneously a bridge across the gap and connections to said components in circuit mounted on the board.

2. The method as set forth in claim 1 wherein the step of forming a narrow gap comprises forming said narrow gap in the form of non-aligned line segments.