Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
1999-12-16
2001-04-10
Patel, Tulsidas (Department: 2839)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C439S331000, C361S767000
Reexamination Certificate
active
06213787
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to making connections between integrated circuit array packages (IC) and circuit boards.
As is known in the art, integrated circuit (IC) packages can have anywhere from a few to in excess of one thousand pins. The IC packages are often soldered directly to a circuit board to assure a relatively permanent connection between the IC package and board. However, in some applications, it may be desired that the package be mounted indirectly to the board through an electrical socket. In this way, the integrated circuit can be replaced or removed for testing without the need for reheating solder joints which may, in some cases, cause damage to the integrated circuit and board.
Certain socket adapters, including those used for pin grid arrays (PGAs), ball grid arrays (BGAs) and land grip arrays (LGAs), utilize a male terminal which is received within a female socket. The female sockets generally include spring contacts to ensure reliable electrical and mechanical connections between the male terminal and female socket. If the package has a small number of pins the forces associated with each pin and socket terminal are relatively insignificant. However, for IC packages and sockets/adapters having a larger number of pins, the aggregate force of the many pin/socket terminal connections can become quite high.
SUMMARY OF THE INVENTION
This invention features an intercoupling component (e.g., socket or adapter) which provides a reliable, non-permanent and low-loss electrical interconnection between electrical contacting areas of an array package and connection regions of a substrate (e.g., printed circuit board), particularly for high density integrated circuit packages having many electrical contacting areas (e.g., greater than 200). The term “integrated circuit array package” is intended to mean those packages, including PGA, BGA and LGA packages having electrical contacting areas in the form of pins, balls, and contact pads, respectively. The term “substrate” is intended to mean any base member having electrical contact areas including printed circuit boards, IC chip substrates or the packages supporting such chip substrates.
In one aspect of the invention, the intercoupling component includes socket terminal assemblies, a socket support member including first openings configured to receive a corresponding one of the socket terminal assemblies, and a stiffening member, mechanically coupled to the socket support member, including second openings configured to receive a corresponding one of the socket terminal assemblies. Each socket terminal assembly includes a socket body having an end configured to contact the corresponding connection region of the substrate and an opposite end with an opening configured to receive an end of a pin.
The stiffening member virtually eliminates any possibility of the socket support member bending or becoming bowed due to large forces generated when the numerous pins are depressed within the sockets. Bowing can generate pulling forces, which can cause separation of the solder joint from the printed circuit board. Because the amount of force, and potential for “bowing” increases with the number of contacts (e.g., pins, balls, lands) of the integrated circuit package, the stiffening member is particularly important for packages having a large number of contacts.
Embodiments of this aspect of the invention may include one or more of the following features.
The stiffening member is formed of a material (e.g., aluminum) having an elastic modulus characteristic greater than 5 MPsi (5×10
6
Psi) and preferably greater than 10 MPsi. The stiffening member has a thickness in a range between 0.020 inches and 0.200 inches.
The intercoupling component further includes an insulative member positioned between the stiffening member and the connection regions of the substrate. In certain embodiments, the insulative member encapsulates the stiffening member. In embodiments in which the stiffening member is formed of an electrically conductive member, the insulative member electrically isolates the stiffening member from electrically conductive areas of the printed circuit board. Thus, the opportunity for inadvertent electrical “short circuits” is minimized.
The stiffening member includes guide elements for aligning the electrical contacting areas of the integrated circuit package with the corresponding connection region of the substrate. For example, the guide elements can be in the form of upstanding sidewalls along which peripheral edges of the IC package are guided to align solder balls of a BGA package over corresponding converter socket terminals.
In certain embodiments, each socket terminal assembly includes a contact spring (e.g., resilient spring fingers), disposed at the opening of the socket body. The contact spring is configured to provide a “wiping”, reliable electrical contact in which the frictional force sufficient to retain the pin within the socket body is in a direction substantially transverse to the upward force applied by the resilient member. For example, the contact spring includes resilient spring fingers which frictionally engage the lower end of the pin.Each socket terminal assembly includes a resilient member, disposed within the opening, to apply, in response to a downward force applied to the pin, an upward force to the pin sufficient to overcome the frictional force of the contact spring. The resilient member for applying the upward force, on the other hand, is in the form of a coiled conductive spring, or alternatively, in the form of an elastomeric material (e.g., rubber). The frictional force applied by the contact spring is in a direction substantially transverse to the direction of the upward force applied by the resilient member.
The end of the socket body is configured to contact the corresponding connection region of the substrate is ball-shaped, for example, formed as a solder ball.
The intercoupling component further includes an electrically insulative retaining sheet (e.g., a polyimide film) coupled to a corresponding pin, having a plurality of holes arranged in a pattern corresponding to the pattern of the connection contacts, each hole adapted to retain the pins.
The intercoupling component further includes a member for applying a downward force on the contact area of the integrated circuit package and to each pin to cause the resilient member to compress. The member for applying the downward force is a heat sink threadingly received within a cover positioned over the integrated circuit package. The socket support member includes alignment elements to align the contacting area of the integrated circuit package to corresponding ones of the connection regions.
Other features of the invention will be apparent from the following description of the preferred embodiments and from the claims.
REFERENCES:
patent: 4442938 (1984-04-01), Murphy
patent: 5038467 (1991-08-01), Murphy
patent: 5151040 (1992-09-01), Tanaka
patent: 5287617 (1994-02-01), Murphy
patent: 5481435 (1996-01-01), Werther
patent: 5917703 (1999-06-01), Murphy
Advanced Interconnections, Catalog No. 14, p. 162, 1996.
Advanced Interconnections Corporation
Fish & Richardson P.C.
Patel Tulsidas
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