Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – Distinct contact secured to panel circuit
Reexamination Certificate
1999-05-11
2001-04-17
Patel, Tulsidas (Department: 2839)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
Distinct contact secured to panel circuit
C439S931000, C174S256000
Reexamination Certificate
active
06217346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a solderless pin connection utilizing a press fit pin staked within a hole printed with polymer thick film.
2. Description of Related Art
Traditional printed circuit boards are manufactured by applying a layer of copper to a substrate and then etching the desired circuit into the layer of copper. This subtractive manufacturing process is step intensive and results in wasted materials. A perceived advantage of copper is its ability to maintain a soldered connection for electrical and mechanical connections. Staking a pin into a multi-processed copper plated through hole may result in a solder-free joint.
Soldered connections require additional complex and costly manufacturing steps and may result in unreliable connections. Waste from the soldering and plating processes is hazardous to the environment and expensive to dispose of safely. Further, manufacture of the plated through hole requires a lengthy process with many steps, including a drilled hole, that are critical to achieving a sound electrical connection. This lengthy plating process, combined with the assembly of the pin, may jeopardize the integrity of the plated through hole.
SUMMARY OF THE INVENTION
Polymer thick film (PTF) is a material and process used to create printed circuit boards and other products. Polymer thick film is an additive material and process for printed circuit board manufacturing that can improve reliability, product performance and quality and at the same time reduce overall component costs.
Polymer thick film comprises polymer resins filled with conductive particles that are screen printed and heat cured onto the surface of a printed circuit board substrate. A loading ratio can be varied to create materials having variable conductivities, depending on the application. The conductive particles can also be blended, such as a silver/carbon mixture, to achieve particular characteristics. Polymer thick film inks are used to create variable resistors, fixed resistors, conductors, insulating layers, switches and other devices on the surface of a printed circuit board.
According to this invention, a solderless pin connection for a printed circuit board is prepared using polymer thick film printed on a printed circuit board substrate. An inner surface of the substrate defines a hole, that may be drilled or punched into the substrate.
The polymer thick film is applied on a top surface of the substrate and along the inner surface. Additionally, the polymer thick film may be applied to a bottom surface of the substrate and in an additional layer along the inner surface.
A pin is subsequently press fit within the polymer thick film along the inner surface. The pin preferably has a pin diameter less than a diameter of the hole. The pin is retained within the hole using either the press fit connection, or preferably is staked into the hole using a mechanical connection such as barbs, a folded staked end portion of the pin, a shoulder positioned on the pin and/or teeth positioned on the shoulder.
The polymer thick film is preferably applied to the substrate by drawing the polymer thick film through the hole and along the inner surface from each side of the substrate. The resultant inner surface of the hole is consistently coated with the polymer thick film.
It is one object of this invention to provide a pin connection that does not require solder or traditional soldering procedures.
It is another object of this invention to provide a pin connection wherein a pin is press fit with respect to a substrate.
It is still another object of this invention to utilize polymer thick film with a pin connection.
It is yet another object of this invention to provide a pin connection that provides a reliable, consistent connection.
REFERENCES:
patent: 3912852 (1975-10-01), Simon
patent: 4181387 (1980-01-01), Walters
patent: 4230385 (1980-10-01), Ammon et al.
patent: 4656314 (1987-04-01), Durand
patent: 5480309 (1996-01-01), Arisaka
ITW Chronomatic, An Illinois Tool Works Company, “A Practical Guide to the Use of Polymer Thick Film (PTF) in Automotive Applications” (1991).
Illinois Tool Works Inc.
Patel Tulsidas
Pauley Petersen Kinne & Fejer
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