CANTILEVER CONTACTS

RELATED APPLICATION

This application claims priority to United States Provisional Application Number 62/611,844 that was filed on December 29, 2017. The entire content of the application referenced above is hereby incorporated by reference herein.

TECHNICAL FIELD

Test contactor mounting assemblies and related methods.

TECHNICAL BACKGROUND

Test contactors are used on printed circuit boards to test various parameters and/or components of semiconductor devices. Electronic devices have become smaller yet more powerful, resulting crowded and complex circuit boards. For example, modem automobiles are using RADAR equipment for collision avoidance, parking assist, automated driving, cruise control, etc. The radio frequencies used in such systems are typically 77 GHz (W-band). Next generation IC's will push operating frequencies to even higher levels. Semiconductor devices that operate at these frequencies need to be tested, but existing test contactor technology cannot operate in the W-band due to extreme transmission line impedance mismatches.

One way of testing the printed circuit boards includes using test contactors that include deflecting contacts, for example as shown in US 10,037,933. To support the contacts, a flat elastomer is provided. The elastomer provides a non-linear force to the contacts. In addition, the elastomer becomes permanently deformed and loses resiliency over time. Accordingly, what is needed is a contact assembly with a support member that is reliable over time, and provides a linear support force.

SUMMARY

In one or more embodiments, a test socket assembly includes a socket housing having one or more spring probes therein. The test socket further includes a lead frame assembly including one or more cantilever members extending from a first fixed end portion to a second movable end portion. The second movable end portion is movable from a first unflexed position to a second flexed position, and the lead frame assembly disposed within the socket housing.

At least one linear spring damper is disposed within the socket housing adjacent the lead frame assembly and supports the cantilever members. The at least one linear spring damper extends from a first end to a second end, where the second end is disposed adjacent to the second movable end portion of the one or more cantilever members.

In one or more embodiments, the socket housing has a linear pocket therein, and the linear spring damper is received in the pocket.

In one or more embodiments, the at least one linear spring damper includes a coil spring surrounding a post.

In one or more embodiments, the coil spring is compressed when the second movable end portion is disposed in the second flexed position.

In one or more embodiments, the second end of the at least one linear spring damper is electrically non-conductive.

In one or more embodiments, the at least one linear spring damper is defined in part by a spring damper longitudinal axis, and the one or more cantilever members is defined in part by a cantilever member axis, and the spring damper longitudinal axis is perpendicular to the cantilever member axis when the one or more cantilever members is in the first unflexed position.

In one or more embodiments, the at least one linear spring damper provides a linear force along the spring damper longitudinal axis to the second movable end portion of the one or more cantilever members.

In one or more embodiments, the test probe assembly further includes an outer metal socket housing, where the lead frame assembly is disposed within the outer metal socket housing.

In one or more embodiments, the test probe assembly further includes an outer plastic socket housing, the lead frame assembly is disposed within the plastic socket housing.

In one or more embodiments, a test socket assembly includes a socket housing, and a lead frame assembly. The lead frame assembly includes one or more cantilever members extending from a first fixed end portion to a second movable end portion. The second movable end portion is movable from a first unflexed position to a second flexed position. The lead frame assembly is disposed within the socket housing.

The test socket assembly further includes at least one linear spring damper disposed within the socket housing adjacent the lead frame assembly and supports the cantilever members. The at least one linear spring damper extends from a first end to a second end, the second end is disposed adjacent to the second movable end portion of the one or more cantilever members.

The at least one linear spring damper is defined in part by a spring damper longitudinal axis, and the one or more cantilever members is defined in part by a cantilever member axis. The spring damper longitudinal axis is perpendicular to the cantilever member axis when the one or more cantilever members is in the first unflexed position. The at least one linear spring damper provides a linear force along the spring damper longitudinal axis to the second movable end portion of the one or more cantilever members.

In one or more embodiments, the at least one linear spring damper includes a coil spring surrounding a post.

In one or more embodiments, the coil spring is compressed when the second movable end portion is disposed in the second flexed position.

In one or more embodiments, the second end of the at least one linear spring damper is electrically non-conductive.

In one or more embodiments, a method includes a method for testing a device under test with a test socket assembly includes disposing a device under test in a test socket assembly, where the test socket assembly comprises a socket housing having spring probes therein, a lead frame assembly including one or more cantilever members extending from a first fixed end portion to a second movable end portion, at least one linear spring damper disposed within the socket housing adjacent the lead frame assembly and supporting the cantilever members. The at least one linear spring damper extends from a first end to a second end, the second end is disposed adjacent to the second movable end portion of the one or more cantilever members.

The at least one linear spring damper is defined in part by a spring damper longitudinal axis, and the one or more cantilever members is defined in part by a cantilever member axis, and the spring damper longitudinal axis is perpendicular to the cantilever member axis when the one or more cantilever members is in the first unflexed position. The method further includes contacting the device under test with the spring probes, contacting the device under test with the cantilever members and flexing and deflecting the cantilever members, providing a linear force along the spring damper longitudinal axis from the at least one linear spring damper to the second movable end portion of the one or more cantilever members, and sending signals to and from the device under test.

In one or more embodiments, the second end of the at least one linear spring damper is electrically non-conductive. In one or more embodiments, the method further includes penetrating a portion of the device under test with the cantilever members. In one or more embodiments, the method further includes supporting an intermediate portion of the cantilever members with the socket housing.

These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims and their equivalents.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates an exploded perspective view of a test socket assembly as constructed in one or more embodiments.

FIG. 2 illustrates a perspective view of a portion of a test socket assembly as constructed in one or more embodiments.

FIG. 3 illustrates an exploded view of FIG. 2.

FIG. 4 illustrates a cross-sectional view of a portion of a test socket assembly as constructed in one or more embodiments.

FIG. 5 illustrates a side view of a portion of a test socket assembly and a lead frame assembly in an unflexed position as constructed in one or more embodiments.

FIG. 6 illustrates a side view of a portion of a test socket assembly and a lead frame assembly in an unflexed position as constructed in one or more embodiments.

FIG. 7 illustrates a side view of a portion of a test socket assembly and a lead frame assembly in a flexed position as constructed in one or more embodiments.

FIG. 8 illustrates a side view of a linear spring damper as constructed in one or more embodiments.

DETAILED DESCRIPTION

The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the apparatus may be practiced. These embodiments, which are also referred to herein as“examples” or“options,” are described in enough detail to enable those skilled in the art to practice the present embodiments. The embodiments may be combined, other embodiments may be utilized or structural or logical changes may be made without departing from the scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense and the scope of the invention is defined by the appended claims and their legal equivalents.

In this document, the terms“a” or“an” are used to include one or more than one, and the term“or” is used to refer to a nonexclusive“or” unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. FIGs. 1 and 2 illustrate a test socket assembly 100, including a socket alignment frame 190, a lead frame assembly 140, spring probes 120, a socket frame 180, a socket housing 110, a printed circuit board 122, and a retainer plate 108. The test socket assembly 100 is an integrated circuit test socket that combines spring probes in an insulative socket housing with a conductive structure that includes a lead frame assembly 140 with cantilever members 150 that carry very high speed signals in coplanar waveguide structures and coaxial connectors that interface with test equipment. Retainer plate hardware and alignment frame hardware are also optionally provided.

The test socket assembly 100 is used with a device under test 200. The test socket assembly 100 uses vertical compliance to integrate with robotic chip handling equipment and to achieve reliability. The spring probes 120 are compliant for the power, ground and low speed signal connections, such as balls, and the microwave structures flex into the linear spring damper 130. The microwave structures terminate in precision coaxial connectors or waveguides. The device under test 200 (FIG. 1) engages both spring probes and ends of the cantilever members 150 of the lead frame assembly 140.

FIGs. 2 - 7 illustrate the lead frame assembly 140 in greater detail. The lead frame assembly 140 includes an electrically conductive sheet with holes, slots, and cantilever members 150 that make the impedance controlled microwave structures (such as a coplanar waveguide). Microwave structures are formed to high speed signal positions of the device under test, and are routed to the edge of the lead frame assembly 140 or to an interior position in the grounding portion of the lead frame. On a back side of the lead frame is a thin, flexible polymer, which can be attached with an adhesive, to maintain the shape and position of all of the individual lead frame parts. Other holes can be fabricated in the ground plane and can be used for mechanical fastening and/or alignment to the socket housing.

The lead frame assembly 140 includes one or more cantilever members 150 which flex relative to the remaining portion of the assembly 140. The cantilever members 150 include members which interface with the device under test 200 (FIG. 2). In one or more embodiments, the cantilever members 150 are impedance controlled microwave structures. The members include end portions of the cantilever members 150, in one or more examples. In one or more examples, the cantilever members 150 have mechanical structures designed to align and/or penetrate the ball grid array solder balls, which assist in making reliable electrical contacts. In one or more examples, the members include parallel edges, recessed overall triangle shape, recessed sharp bumps, a hole or opening with internal sharp features, such as projections, or a combination thereof. In one or more embodiments, the cantilever members 150 include coupling members of the transmission line signals. In one or more embodiments, the coupling members are delay lines or phase shifting lines.

In one or more embodiments, the lead frame microwave structures are terminated externally to precision microwave coaxial connectors. In one or more embodiments, the lead frame is impedance matched at the transition to the coaxial connectors 182 for optimal RF performance. The lead frame can include a flat configuration with axially terminating connectors. In one or more embodiments, the lead frame has a gradual radius downward, so that coaxial connectors can be mounted below the socket housing, allowing for improved socket density in test handling conditions.

Several options for the signal lines are as follows. For instance, in one or more embodiments, the lead frame signal lines are configured in a coplanar waveguide transmission line structure.

In one or more embodiments the lead frame assembly 140 includes one or more cantilever members 150. The one or more cantilever members 150 extend from a first fixed end portion 152 to a second movable end portion 154, and has an intermediate portion therebetween 156. The cantilever members 150 are defined in part by a cantilever member longitudinal axis 158. The socket housing 110 supports the intermediate portion 156 of the cantilever members 150. The second movable end portion of the cantilever members 150 is movable from a first unflexed position (FIGs. 5 and 6) to a second flexed position (FIG. 7), as supported by the socket housing. For example, as the DUT is placed in the test socket assembly 100 and contacted with the cantilever members 150 of the lead frame assembly 140, the second movable end portion of the cantilever members flexes.

In one or more embodiments, the lead frame assembly 140 is replaceable such that it can be removed from the socket assembly without damaging the socket assembly and replaced with another lead frame assembly.

In one or more embodiments, the socket assembly has an outer body constructed of a conductive metal shell. The shell acts as a mounting point for connectors and acts as an electrical ground. In one or more embodiments, the outer body is of plastic, and can be optionally coated with material, such as metallic material. The socket assembly further includes a socket housing 110 that is non-conductive and houses the spring probes (FIG. 1). The spring probes contact digital signals, power, and ground pins on the device under test. A retainer plate on the bottom of the body 110 captivates the spring probes. As discussed above, the lead frame assembly 140 is installed on the body 110 with spring probes 120 and at least one linear spring damper 130, where the lead frame assembly 140 is adjacent to the linear spring damper 130. For example the lead frame assembly 140 is positioned on top of the linear spring damper 130, and in a further option positioned directly adjacent and directly on top of the linear spring damper 130. The linear spring damper 130 is disposed in a pocket 112 in the plastic socket housing 110, such as a linear pocket. The linear spring damper 130 provides resiliency to the ground and microwave structures. In one or more embodiments, the linear spring damper 130 has one or more holes sizes and positioned to receive the spring probes 120 therethrough. In one or more embodiments, the linear spring damper 130 is resilient so that the microwave structures and ground planes offer compliance.

The flexing of the cantilever by itself results in a very low normal force which degrades reliability in contact to the DUT. The linear spring damper pushes against the cantilever members 150, adding additional force to contact without increasing stress. The linear spring damper 130 is sized such that the RF signal traveling through the cantilever members will not couple and resonate with the coil spring. The linear spring damper 130 provides a linear force along a sping damper longitudinal axis to the second movable end portion of the one or more cantilever members. The linear force is a force exerted on an object with a contant acceleration with a linear trajectory.

The linear spring damper 130 is provided, where the lead frame assembly 140 is adjacent to the linear spring damper 130. For example the lead frame assembly 140 is positioned on top of the linear spring damper 130, and in a further option positioned directly adjacent and directly on top of the linear spring damper 130. The linear spring damper 130 is disposed in a pocket in the plastic socket housing. The linear spring damper 130 provides resiliency to the cantilever members 150 at the end of the signal leads.

In one or more embodiments, the linear spring damper 130 is disposed adjacent the lead frame assembly 140 and provides support and a linear force to the lead frame assembly 140, for example to the second movable end portion of the one or more cantilever members. The linear spring damper 130 extends from a first end 132 to a second end 134, and extends longitudinally along a longitudinal axis 136. The linear spring damper 130 contracts and extends along the longitudinal axis 136. The second end 134 of the at least one linear spring damper 130 is disposed adjacent to the second movable end portion 154 of the one or more cantilever members 150, and the second end 134 of the at least one linear spring damper is electrically non- conductive. In one or more embodiments, the spring damper longitudinal axis 136 is perpendicular to the cantilever member axis 158 when the one or more cantilever members is in the first unflexed position.

The linear spring damper 130 includes a coil spring 138, and insert 139 as shown in FIGs. 5 - 8. The coil 138, in one or more embodiments, is a compression spring, or a helical coil, made from a resilient metal such as stainless steel. The insert 139 includes a non- conductive post.

During use of the test socket assembly, a method for testing a device under test with a test socket assembly includes disposing a device under test in a test socket assembly, where the test socket assembly comprises a socket housing having spring probes therein, a lead frame assembly including one or more cantilever members extending from a first fixed end portion to a second movable end portion, at least one linear spring damper disposed within the socket housing adjacent the lead frame assembly and supporting the cantilever members. The at least one linear spring damper extends from a first end to a second end, the second end is disposed adjacent to the second movable end portion of the one or more cantilever members. The at least one linear spring damper is defined in part by a spring damper longitudinal axis, and the one or more cantilever members is defined in part by a cantilever member axis, and the spring damper longitudinal axis is perpendicular to the cantilever member axis when the one or more cantilever members is in the first unflexed position. The method further includes contacting the device under test with the spring probes, contacting the device under test with the cantilever members and flexing and deflecting the cantilever members, providing a linear force along the spring damper longitudinal axis from the at least one linear spring damper to the second movable end portion of the one or more cantilever members, and sending signals to and from the device under test.

In one or more embodiments, the second end of the at least one linear spring damper is electrically non-conductive. In one or more embodiments, the method further includes penetrating a portion of the device under test with the cantilever members. In one or more embodiments, the method further includes supporting an intermediate portion of the cantilever members with the socket housing.

Advantageously, the linear spring damper has a spring rate that is linear, which makes it easier to predict the forces in assembly. The linear spring damper is low stress and performance does not degrade over time or over a wide range of testing temperatures. In addition, the linear spring damper has lower tolerances, providing a relatively constant rate of force. Socket performance can be adjusted in the field by adding or removing linear spring dampers to increase or decrease actuation force. Over time, as the linear spring dampers are used, the linear spring dampers do not create debris. In addition, the volume occupied by the linear spring dampers beneath the cantilever members is relatively small. The remaining volume is air. This gives a high-frequency signal a very low effective dielectric constant and low signal loss.

The socket assembly is a test socket that is compatible with semiconductor back-end manufacturing, yet is capable in operating at the W-band frequencies. The spring probes provide for reliable testing and are combined with impedance matched transmission line contacts to device contact points. The linear spring damper improves the overall performance of the test socket by increasing its life during use, and extends the operation temperature range.

The linear spring damper further improves the electrical environment, and simplifies the overall design, assembly, and maintenance of the test socket.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. It should be noted that embodiments discussed in different portions of the description or referred to in different drawings can be combined to form additional embodiments of the present application. The scope should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.