# Patent

## Title
Deep drawn electrical contacts and method for making

## Abstract

A method for making a contact begins by providing a sheet of material. A portion of the sheet is deep drawn to form a cavity having at least one sidewall, the cavity extending away from a rim formed by a non-drawn portion of the sheet. At least one spring member is defined from the at least one sidewall and is bent such that at least a portion of the at least one spring member extends beyond the rim.

## Background
CROSS REFERENCE TO RELATED APPLICATION(S)
This application claims the benefit of U.S. Provisional Application No. 60/554,818, filed on Mar. 19, 2004, which is incorporated by reference as if fully set forth herein.


FIELD OF INVENTION
The present invention is related to electrical contacts. More particularly, the present invention is directed to an eyelet contact which is suitable for use with an interposer, a printed circuit board (PCB), or the like. The present invention also includes a method for making an eyelet contact.
BACKGROUND
There are currently many different types of connector technologies that produce a vast array of connectors for all different types of connector applications. Current connector technologies are deficient in that they are made on a “macro-scale”, in which individual pieces of the connector are formed separately and are then integrated together in a final assembled contact. However, such schemes are cumbersome at best, and can result in a defective contact when the integration does not proceed as planned. Further, such schemes do not scale; as the pitch of contacts becomes smaller, the problems associated with current technologies greatly increase. Accordingly, a new technology that avoids the disadvantages with current technologies is desired.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a sheet of material for making a contact in accordance with the present invention.
FIG. 2 is a perspective view of the sheet of FIG. 1, which has been deep drawn to form a contact having a lip and a body.
FIG. 3 is a perspective view of the contact of FIG. 2 with the bottom removed.
FIG. 4 is a perspective view of the contact and definition of the spring member.
FIG. 5 is a perspective view of the contact showing the spring member being bent above the rim of the body.
FIG. 6 is a perspective view of the contact showing the forming of the distal end of the spring member.
FIG. 7 is a perspective view of an array of contacts made in accordance with the teachings of the present invention.
FIG. 8 is a perspective view of an alternative embodiment of the present invention including a plurality of spring members.
FIG. 9 is a perspective view of an alternative embodiment of the present invention including additional openings.
FIG. 10 is a flow diagram of a method of forming a contact in accordance with the present invention.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described with reference to the drawing figures wherein like numerals represent like elements throughout. The terms “down”, “up”, “bottom”, “side”, or “top” as used hereinafter are used only for convenience to differentiate certain aspects of the contact in the orientation shown in the figures. It should be understood that these terms are not meant to limit the functional aspects of the elements to which the terms apply.
The present invention provides an eyelet contact and a method for making the same. The present invention may be utilized with an interposer, on a printed circuit board (PCB), as part of another type of contact, incorporated directly into an electronic device, or may be utilized in a variety of other applications.
Referring to FIG. 1, a sheet 10 of material is shown, which is used to form a contact 8. Preferably, the sheet 10 is formed from a conductive and resilient material such as copper (Cu) or beryllium copper (BeCu), brass, phosphorus bronze, stainless steel, or other types of laminated or non-laminated material. Although the sheet 10 is shown as being configured in a generally circular shape having a certain thickness, those of skill in the art should realize that this is for convenience of explanation and the shape and/or thickness of the sheet 10 will vary depending upon the particular application and the desired physical characteristics of the contact. Such physical characteristics, for example, may include the impedance of the contact, the desired normal force to be applied by the contact, and the working range of the contact. Other characteristics may be related to a variety of plating schemes, or contact schemes such as multiple contact members for higher power application, contact geometry to cradle solder ball technology, or variable heights between contacts in the array for “make first-break last” applications.
Referring to FIG. 2, the sheet 10 has been deep drawn to form the contact 8 having a cavity, using a deep drawing process, leaving a lip 12 at the top of a deep drawn body 14. Deep drawing is a well-known process to those of skill in the metallurgical arts and, therefore, a detailed description of the process will not be set forth in detail hereinafter. Generally, however, deep drawing selectively stretches a sheet of material to form a desired three-dimensional shape. The cylindrical shape as shown in FIG. 2 and the subsequent figures is for example only and the shape may be any shape desired for the particular application. For example, the body 14 may be substantially rectilinear in shape, or may be drawn deeper or shallower than shown.
The body 14 generally comprises one or more walls 16 and a bottom 18. Although the body 14 shown in the figures is substantially cylindrical and comprises a single continuous wall 16, if the body 14 is a cubic or other three-dimensional shape, there may be a plurality of sidewalls 16. Likewise, although a bottom 18 is shown, a deep drawing process may be used such that there is no bottom 18 to the body 14.
If the body 14 includes a bottom 18, the bottom 18 may optionally be removed as shown in FIG. 3. This step is preferably used when it is desired to have a contact 8 with an extended operating range. As such, removing the bottom 18 from the body 14 would have certain operational advantages, although this step is optional and is not required for the contact 8 to operate properly.
Referring to FIG. 4, two cuts are made in the wall 16 to form a spring member 20 and an opening 22. The spring member 20 is bent away from the wall 16 and then back upon itself and in a generally vertical position extending toward and/or through the top of the body 14 and above the lip 12 as shown in FIG. 5. Although the spring member 20 is shown as extending above the lip 12, this is not required. Accordingly, the spring member 20 may also extend upward toward the opening defined by the lip 12, but still be located below the lip 12.
Referring to FIG. 6, the distal end of the spring member 20 is then bent or otherwise formed in a desired configuration. The desired configuration shown in FIG. 6 is an arch. The distal end of the spring member 20 configured in an arch forms a compliant contact area 24 for mating with a corresponding contact of an electronic device or other device. The corresponding contact may be a generally flat land (such as found on a land grid array (LGA)), a pin, a solder ball (such as found on a ball grid array (BGA)), or any other type of contact system. Although the spring member 20 is shown as bending away from the middle of the contact 8, the spring member 20 may bend toward the center of the contact 8. Additionally, either the entire spring member 20 or the distal end of the spring member 20 may be formed as desired to achieve certain a configuration or specific physical characteristics.
For example, it is possible to form compound springs by having one spring member, when displaced some distance, hit a lower spring member and take advantage of the compound force that results when a first spring member contacts a second spring member, which results in different spring rates.
As a further example, an angular spring member configuration typically urges the point of contact more forcefully into a corresponding flat land, whereas a rounded arch will glide more easily over a land. These configurations each provide distinct wiping performances.
Due to its configuration, the contact 8 shown in FIG. 6 is able to accommodate a wide range of pin connector lengths since the bottom 18 has been removed. A long mating contact, such as a pin, may be inserted into the contact 8 without bottoming out. This provides the ability to mate with different configurations of contacts.
It should be noted that although FIGS. 1-6 were described with reference to forming a single contact, it is envisioned that an array of contacts will be simultaneously formed as shown in FIG. 7. The individual contacts may thereafter be singulated using either mechanical or other known techniques, such as photolithographic mask and etch technology.
Referring to FIG. 8, a contact 28 having two spring members 20a, 20b is shown. Although there is only one spring member 20 shown in FIG. 6 and two spring members 20a, 20b shown in FIG. 8, there may be more spring members as required by the particular application. The spring members 20a, 20b as configured in FIG. 8 include a large gap therebetween, although this is not required. The spring members 20a, 20b are configured with at least one contact area 24a, 24b respectively, as desired in order to properly mate with a corresponding contact.
Although the two spring members 20a, 20b are shown as being substantially similar in length, this is not required. As aforementioned, the particular length and shape of the spring members 20a, 20b may change depending upon the application. In addition, it is possible to have compound spring performance characteristics by having one spring member, for example 20a, with a higher profile and a second spring member 20b with a lower profile. Alternatively, it is possible to provide the contact areas 24a and 24b extending in the same direction, for example, with the first contact area 24a of the first spring member 20a extending over and spaced apart from the second contact area 24b of the second spring member 20b so that the first spring member 20a, when displaced a predetermined distance, hits the second spring member 20b and therefore provides a compound force that results when one spring member contacts another spring member. This provides a different spring rate.
Although not shown, further forming operations may split the spring members 20 into two or more contact areas 24. This would be particularly advantageous in an application where the multiple contact areas 24 can be specifically tailored to the configuration of the corresponding contact. For example, for a solder ball in a BGA, the distal ends may be configured to “cradle” the solder ball.
In an alternate embodiment as shown in FIG. 9, in addition to the opening 22 which is formed as part of making the spring members 20a, 20b, a contact 38 made in accordance with this embodiment of the invention includes additional openings 23 to give the body 14 greater pliancy. This is particularly beneficial in an application in which the contact 38 is inserted into a via (or through hole) in a PCB or other device. The extra pliancy provided by the additional openings 23 may permit the contact 38 to be friction-fitted to a PCB or device without requiring an additional bonding material.
Referring to FIG. 10, a method 200 for forming a contact in accordance with the present invention is shown. The method 200 begins with deep drawing a conductive material (step 202). The bottom of the body is then removed (step 204), although this step is optional. At least a portion of a sidewall of the body is slit to form at least one spring member (step 206). The spring member is then bent backward upon itself such that the spring member extends toward, or over, the rim of the contact (step 208). The distal end of the spring member is then shaped as desired (step 210).
Although the present invention has been described in detail, it is to be understood that the invention is not limited thereto, and that various changes can be made therein without departing from the scope of the invention, which is defined by the attached claims.

## Claims

1. An electrical contact, comprising:
a hollow tubular body with a first end and a second end, with at least one linear sidewall;
a rim formed on either the first end or the second end, the rim extends perpendicularly from the at least one linear sidewall, forming a thickness which is less than the length of the hollow tubular body; and
at least one spring member formed from the at least one linear sidewall, the at least one spring member is bent such that at least a portion of the at least one spring member extends beyond the end on which the rim is provided.

2. An electrical contact, comprising:
a hollow tubular body with a first end and a second end, with at least one linear sidewall;
a rim formed on either the first end or the second end, the rim extends perpendicularly from the at least one linear sidewall, forming a thickness which is less than the length of the hollow tubular body; and
at least one spring member formed from the at least one linear sidewall, the at least one spring member is bent such that at least a portion of the at least one spring member extends beyond the end on which the rim is provided to form a contact surface.

3. An electrical contact, comprising:
a hollow tubular body with a first end and a second end, with at least one linear sidewall;
a rim formed on either the first end or the second end, the rim extends perpendicularly from the at least one linear sidewall, forming a thickness which is less than the length of the hollow tubular body; and
at least one spring member formed from the at least one linear sidewall, the at least one spring member is bent such that at least a portion of the at least one spring member extends beyond the end on which the rim is provided to form an arched contact surface.

4. An electrical contact, comprising:
a hollow tubular body with a first end and a second end, with at least one linear sidewall;
a rim formed on either the first end or the second end, the rim extends perpendicularly from the at least one linear sidewall, forming a thickness which is less than the length of the hollow tubular body; and
at least one spring member formed from the at least one linear sidewall, the at least one spring member is bent such that at least a portion of the at least one spring member extends beyond the end on which the rim is provided to form an angled contact surface.

5. An electrical contact, comprising:
a hollow tubular body with a top end and a bottom end, with at least one linear sidewall, a portion of the bottom end is removed from the electrical contact;
a rim formed on either the top end or the bottom end, the rim extends perpendicularly from the at least one linear sidewall, forming a thickness which is less than the length of the hollow tubular body; and
at least one spring member formed from the at least one linear sidewall, the at least one spring member is bent such that at least a portion of the at least one spring member extends beyond the end on which the rim is provided to form a contact surface.

6. An electrical contact, comprising:
a hollow cylindrical body with a first end and a second end, with at least one linear sidewall;
a rim formed on either the first end or the second end, the rim extends perpendicularly from the at least one linear sidewall, forming a thickness which is less than the length of the hollow cylindrical body; and
a spring member formed from the at least one linear sidewall, the spring member is bent such that at least a portion of the spring member extends beyond the end on which the rim is provided to form a contact surface.

7. An electrical contact, comprising:
a hollow tubular body with a first end and a second end, with at least two linear sidewalls;
a rim formed on either the first end or the second end, the rim extends perpendicularly from the at least two linear sidewalls, forming a thickness which is less than the length of the hollow tubular body; and
at least one spring member formed from at least one of said linear sidewalls, the at least one spring member is bent such that at least a portion of the at least one spring member extends beyond the end on which the rim is provided to form a contact surface.

8. An electrical contact, comprising:
a hollow tubular body with a first end and a second end, with at least two linear sidewalls;
a rim formed on either the first end or the second end, the rim extends perpendicularly from the at least two linear sidewalls, forming a thickness which is less than the length of the hollow tubular body; and
at least two spring members, each of said at least two spring members formed from a corresponding one of said at least two linear sidewalls, said each of the at least two spring members is bent such that at least a portion of each of said at least two spring members extends beyond the end on which the rim is provided to form a contact surface.