In the electronic industry electronic circuits have become more and more compact to the point that cartridges such as small portable circuit cards have been developed that can be removably inserted into electronic equipment typically for temporary use. In particular, external circuit cards have been developed which approximate the size of credit cards, though somewhat thicker, and which incorporate a circuit board sandwiched between metal or plastic covers, and an electrical connector for connection to external electronic equipment. International standards known as the Personal Computer Memory Card International Association (PCMCIA) standards were established to encourage uniformity among different manufacturers in the field of small circuit cards.
Cartridges enclosing storage devices for programs such as games have been in use for many years particularly for video games and some microcomputers. Because of their relatively large size physical durability was not a property that was difficult to develop for cartridges. Space was available to build the necessary strength into the components and housings. However, for a circuit card package the size of a credit card physical construction techniques are more limited.
Memory card devices are illustrated in U.S. Pat. No. 4,924,076, issued May 8, 1990 and assigned to Mitsubishi Denki Kabusihiki Kaisha, Japan. The devices illustrated incorporate semiconductor devices mounted in an internal base and enclosed in a plastic package formed from two bonded plastic sections.
Another reference, U.S. Pat. No. 4,798,946, issued Jan. 17, 1989, and assigned to the assignee of the previous mentioned patent describes a plastic package for containing an IC card, which essentially constructs a plastic box from halves glued along mating edges.
The applicant has not found any references to circuit cards or cartridges produced by others that would meet the specifications outlined by the Personal Computer Memory Card International Association (PCMCIA), in September 1991, relating to torque, bend, flex and warpage of credit card sized memory cards. Plastic components do not generally provide sufficient electrical shielding to protect internal electronic components from static electricity, while adhesives used to bond them may fail under stress from heat, humidity and other factors.
Similarly, designs known to the applicant incorporating electronic cards retained by plastic perimeter frames and sandwiched between planar plastic or metal sheets bonded to the frame have not been able to meet the PCMCIA specifications.
U.S. Pat. No. 4,386,388 issued May 31, 1983 and assigned to Northern Telecom Limited describes a printed circuit board assembly which uses a sheet aluminum cover which loosely encloses a circuit board; abutting edges of the cover are held in a contiguous relationship by inturned edges of the cover which engage small notches in end plates on the circuit board. While this assembly may be satisfactory for larger circuit boards, sufficient strength or stiffness is not likely possible for circuit boards approaching the size of credit cards.
Realizing the deficiencies of the prior art known to the applicant herein, a compact circuit card assembly was developed which became the subject matter of Canadian Patent Application 2057518 filed on Dec. 9, 1991. This assembly is convenient from a manufacturing perspective and is physically durable even if constructed in a small size satisfying the PCMCIA standards.
A preferred form of the circuit card included an internal circuit module which included a circuit component assembly and an electrical connector attached to the component assembly. A protective metal covering of thin stainless steel closely girded and substantially enclosed the module in a one piece substantially rigid jacket, while an opening was provided in the jacket to expose an electrical connector so the card could be connected to external equipment such as a computer. The circuit module was constructed with a perimeter frame of plastic, which carried a circuit board, electronic components, and an electrical connector. Recesses were provided in the frame for locating the metal covering on the frame while projecting edges or corners of the frame provide concealment for jacket edges and provided impact absorbing corners for the card. No adhesives were necessary to bond the jacket to the frame or other components of the card. Memory cards constructed as described were found to able to satisfy the PCMCIA standards version 1 and 2 and were quite durable.
Credit card sized circuit cards described under the PCMCIA standard version 1 have found substantial acceptance in the electronic industry, but were found wanting in some instances in terms of physical space for components and adaptability to perform additional functions that are desirable. Accordingly PCMCIA standard version 2 was adopted which provided for slightly thicker cards and the option of extending the length of the card to add a rear section that can be considerably thicker than the front portion of the card. Although substantially all of the front portion of the card could be inserted into an electronic device such as a computer for use the rear portion can be quite bulbous and is not conveniently housed within the electronic device with which it is intended to be used. Accordingly when an extended card is in use the rear portion of the card is exposed to possible stresses or damage while in use, (unlike the nonextended version) so it is important that the entire card is strongly constructed, preferably in a unitary structure.
While it is possible to manufacture a circuit card satisfying the PCMCIA standard version 2 in a single unit; this would require a completely new and different assembly line than required for a version 1 or 2 non-extended card. Accordingly it appears useful to construct an extended card in two sections that can be joined together in tandem to produce the final extended card. The front or base portion of the card could be made on an assembly line designed to handle the non-extended cards, and the extensions could be assembled on an additional assembly line or contracted to a vendor. In addition the base portion could be designed to provide basic electronic and memory functions while the extensions could be designed for specific functions such as LAN communications, infrared communications, audio functions, etc., to work with and complement the functions provided by the base. In this manner customized extended card assemblies could be produced without the necessity of constructing a different full extended card for each function. One base card could be used with any one of a number of extension cards.
Electrical and mechanical connection of circuit cards is known in the literature; however because of the small size of the circuit cards conforming to the PCMCIA standards the applicant was not able to find any connection means capable of providing secure mechanical and electrical connection between components of the card system while providing a rugged supporting connection between base and extension components.
U.S. Pat. No. 5,113,317 issued May 12, 1992 to Allen-Bradley Company describes a piggy-back support for an auxiliary circuit card so that one card may be inserted along rails contained on one side of a host card to provide support for the auxiliary card. This reference does not appear useful in the PCMCIA circuit card field because of the extra thickness required by the piggy-back configuration.
U.S. Pat. No. 4,941,841 issued Jul. 17, 1990 to Julius Darden et al describes an adapter and removable slide-in cartridge for an information storage system. The apparatus disclosed in this reference forms a fairly bulky system compared to the size range required in the PCMCIA circuit card field.
U.S. Pat. No. 4,179,178 issued Dec. 18, 1979 to RCA Corporation describes a plug in circuit cartridge with electrostatic charge protection which uses a pair of actuator pins which extend beyond an electrical connector to engage corresponding apertures in a mating assembly to contact a shield device on the mating assembly to raise the shield to permit engagement of the electrical connector. There is no disclosure of the connection of one cartridge to another. The apparatus disclosed is designed to connect a portable cartridge such as a video game cartridge to an electronic device such as a player capable of using it.