The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Referring now to
The substrate 12 is shown disposed on top of backplate 14. However, the substrate 12 may be otherwise configured with or without a backplate. The substrate 12 may employ a known substrate material, such as low temperature co-fired ceramic (LTCC) or FR4, and may be a rigid or non-rigid substrate. The substrate 12, described in one exemplary embodiment as a printed circuit board, has first electrical circuitry formed on the top surface thereof including contact pads 16. The contact pads 16 have an exposed surface for contacting second electrical circuitry to form the electrical connections according to the present invention. The substrate 12 may further include electrical circuitry extending through the substrate including circuitry formed in intermediate layers and on the bottom surface. It is also contemplated that one or more electrical devices may be connected via one or more electrical connector assemblies 15 to the top, bottom and/or side walls of the substrate 12, without departing from the teachings of the present invention.
The electrical connector assembly 15 provides for easy to assemble and reliable solderless electrical connections between the circuit board 12 and other electrical device(s). The electrical connector assembly 15 includes flexible electrical circuitry shown having a plurality of flexible circuit elements 20 that are shown held together via a polyimide material 24. The flexible circuit elements 20 are disposed adjacent to and aligned with the contact pads 16 on circuit board 12, and are forced into pressure contact therewith by way of a holder compressing an elastomer 30 against the flexible circuit elements 20.
The flexible electrical circuitry 20 may include a polyimide flexible circuit, according to one embodiment. A polyimide flexible circuit can be formed using sculptured flexible circuit technology, which is commonly known to those in the art. The flexible circuitry 20 may be formed by chemically milling a sheet of copper to the shape and dimensions that are desired. A layer of polyimide film 24 is then applied to each side of the etched copper to form the flexible circuit. This enables the resulting circuitry to have rigid terminal pins 22 that are integral extensions of the thin flexible conductor elements 20. The thin flexible conductor elements 20 near one end physically contact the contact pads 16 on circuit board 12, while the rigid terminal pins 22 at the other end are shown extending within a shroud 25 having a receptacle 26 for receiving the contact terminals of another electrical device, such as a surface mount device, to form electrical connection(s) therewith. The flexible circuit elements 20, terminal pins 22, polyimide 24 and shroud 25, essentially form the wiring harness 21.
The flexible circuit elements 20 may be formed as copper runners on the polyimide 24 layer. According to one example, the flexible circuit elements 20 may each have a thickness in the range of about two to four mils. Referring to
The elastomer 30 is illustrated having a plurality of downward extension members 32 for engaging the plurality of dimples 28 in each of the flexible circuit elements 20. The extension members 32 essentially extend below the main body of the elastomer 30 at locations intended to engage the dimples 28 and compress the circuit elements 20 into contact with respective contact pads 16. One example of an elastomer 30 is a silicone elastomer. The elastomer 30 is a compressible material that, when held in place, results in a compressive force that maintains pressure against the circuit elements 20 to maintain a good electrical contact with contact pads 16. The elastomer 30 also has a plurality of openings 34 extending therethrough for allowing a mold compound to enter and lock the elastomer 30 securely in place in a compressed state. The elastomer 30 may be configured in various shapes and sizes.
The electrical connector assembly 15 further includes a holder for securing the compressed elastomer 30 in place to provide a pressure contact between the flexible circuit elements 20 and the respective contact pads 16 on the circuit board 12. According to one embodiment, the holder is a mold compound 18 that essentially molds the elastomer 30 in a compressed state against the circuit board 12. In one exemplary embodiment, the mold compound 18 may include an overmolding material, such as an epoxy mold compound that bonds the assembly 15 together. The overmolding material 18 also serves to provide an overmolded package 10. The overmolding material 18 is essentially disposed in any location and shape sufficient to operate as a holder to secure the elastomer 30 in a compressed state against the substrate 12. According to one exemplary embodiment, the overmolding material 18 may be an epoxy mold compound such as thermoset materials commercially available as Cookson 200SH-01 or Henkle MG33F-0602. The overmolding material 18 essentially cures to adhere the components of the assembly together.
Referring to
During assembly of the overmolded package 10 and its electrical connector assembly 15, the backplate 14, circuit board 12 and connector assembly 15 are enclosed by a mold which is then filled with the mold compound. One example of a mold is illustrated surrounding package 10 in
The resultant structure of the overmolded package 10 is locked together after the compound is cured. The terminal pins 22 within shroud 25 are adapted to matingly engage terminal connectors of another electrical device that would extend within the female receptacle 26 of shroud 25. The terminal pins 22 thereby serve to form electrical connections with other devices according to any known connector assembly.
Accordingly, the electrical connection assembly 15 according to the present invention advantageously provides for a reliable and easy to manufacture electrical connection that does not require a solder joining process. The resulting electrical connector assembly 15 consumes a small amount of space and is cost affordable.
It will be understood by those who practice the invention and those skilled in the art, that various modifications and improvements may be made to the invention without departing from the spirit of the disclosed concept. The scope of protection afforded is to be determined by the claims and by the breadth of interpretation allowed by law.