Patent Application
20090253287
1. Field of the Invention
The present invention relates to the art of electrical connectors, and more particularly to a land grid array (LGA) contact of an electrical connector.
2. Description of the Related Art
Various types of connectors have been developed for electrical connections between an IC package and a printed circuit board, such as Pin Grid Array (PGA) connectors, Ball Grid Array (BGA) connectors, Land Grid Array (LGA) connectors, etc., which are named by conductive elements of the IC packages that the connectors electrically connect. Contacts resided within the respective connectors are accordingly classified as PGA contacts, BGA contacts, LGA contacts and so on.
U.S. Pat. No. 7,189,080 discloses an electrical connector with LGA contacts. The LGA contact includes a base with a retaining portion, and a pair of spring arms extending from a top and a bottom sides of the base. Each of the spring arms includes a contacting section at a free end thereof, adapted for electrically contacting an IC package and a printed circuit board, respectively. The contacting section is split into dual-structure contact regions. The contact is approximately symmetrical in an up and down direction, so the contact can give equal forces on the IC package and the printed circuit board, respectively. However, contact pitch in such electrical connector becomes more and more smaller, correspondingly, pads on the IC package may change to smaller size, and simultaneity, a size of the pad on the printed circuit board may not change. At this time, the contact disclosed in U.S. Pat. No. 7,189,080 may not be advisable.
Accordingly, a new contact that solves the above problems is desirable.
A contact, adapted for electrically connecting an IC package and a printed circuit board, comprises: a base, being a board-like shape; an upper spring arm being formed with an upper waist portion extending from a top edge of the base and a top end for electrically contacting with the IC package; and a lower spring arm being formed with a lower waist portion extending from a bottom edge of the base and a bottom end for electrically contacting with the printed circuit board, the bottom end having a width larger than that of the top end, and the lower waist portion having a width larger than that of the upper waist and defining a slot in a middle thereof.
Other features and advantages of the present invention will become more apparent to those skilled in the art upon examination of the following drawings and detailed description of preferred embodiments, in which:
Reference is now made to the drawings to describe the invention in detail.
Present invention substantially regard to improved LGA contacts used in an electrical connector (not shown) with which further comprises an insulative housing (not shown). The insulative housing (not shown) defines a plurality of passageways (not shown) for receiving the LGA contacts which approximately has same configure with conventional insulative housing used in such electrical connector, so herein after we will not give further detail descriptions about the insulative housing (not shown).
Referring to
The base 11 of the contact 1 is in a rectangle piece-shape, the upper spring arm 12 stretches from a top edge of the base 11, the lower spring arm 13 stretches from a bottom edge of the base 11, and the retaining portions 14 downwardly stretch from two lateral ends of the base 11. The contact 1 is approximately in a U-shape, taken from a lateral side.
The upper spring arm 12 comprises an upper waist portion 120 connecting with the base 11, a top end 122 and an inclined linking portion 124 linking the upper waist portion 120 and the top end 122. The upper waist portion 120 firstly upright and then Obliquely extends from the top edge of the base 11. The upper spring arm 12 further defines a gap 126 downwardly extending from a middle part of a top edge thereof and passing through the top end 122 and a part of the linking portion 124. The gap 126 divides the top end 122 into dual contacting regions 128 besides the gap 126. The two contacting regions 128 are approximately in an arc configure and used for electrically contacting with the same pad (not shown) of an IC package (not shown), so that the contact 1 can reliably electrically connect with the IC package (not shown).
The lower spring arm 13 comprises a lower waist portion 130 connecting with the base 11, a bottom end 132 and a linking portion 134 linking the lower waist portion 130 and the bottom end 132. The lower waist portion 130 firstly upright and then Obliquely extends from the bottom edge of the base 11. The lower spring arm 13 defines a through slot 136 to separate the lower spring arm 13 into two branches with same configure and form two contacting regions 138 on the bottom end 132. The two contacting regions 138 are used for electrically contacting with the same pad (not shown) of a printed circuit board (not shown), so that the contact 1 can reliably electrically connect with the printed circuit board (not shown).
The two retaining portions 14 are provided on two lateral sides of the base 11, the retaining portion 14 has an arc nick 140 on an out side surface thereof and an engaging portion 142 vertically and downwardly extending for being interferingly retained in the insulative housing (not shown) of the electrical connector (not shown).
Since the pad of the IC package (not shown) is small relative to the pad of the printed circuit board (not shown), so a width A of the top end 122 of the upper spring arm 12 is smaller than a width B of the low end 132 of the lower spring arm 13 to prevent the contacting regions 128 of the upper spring arm 12 from sliding out of an area of the pad of the IC package (not shown). So, a spring constant of the top end is small, to improve this point, the upper spring arm 12 is approximately formed in one-piece shape with an integral waist portion 122. However, the lower spring arm 13 is divided into two-piece shape by the through slot 136 in a middle thereof, this configure with the gap 136 reduces a whole spring constant of the lower spring arm 13. For avoiding the spring constant of lower spring arm 13 smaller than that of the upper spring arm 12, a width D of the lower waist portion 132 is disposed larger than a width C of the upper waist portion 122 to increase the spring constant of the lower spring arm 13. By this manner, the upper spring arm 12 and the lower spring arm 13 obtain the same spring constants. When the contact 1 Synchronously contacts with the IC package (not shown) and the printed circuit board (not shown) from a top and a bottom sides, the contacts 1 will be pressed, for the upper spring arm 12 and the lower spring arm 13 has same spring constants, the upper spring arm 12 and the lower spring arm 13 produce equal forces on the IC package (not shown) and the printed circuit board (not shown), respectively, so the contact 1 will be balanced during this process.
While the present invention has been described with reference to preferred embodiments, the description of the invention is illustrative and is not to be construed as limiting the invention. Various of modifications to the present invention can be made to preferred embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.
