TW201928356A - Contact probe with compression spring assembly - Google Patents

Abstract

The present invention relates to a contact probe with compression spring assembly that is able to achieve high spring force without compromising spring life span. Said contact probe comprises of a barrel, a first plunger, a second plunger and a compression spring assembly, whereby the compression spring assembly include at least one inner compression spring and at least one outer compression spring. Said inner compression spring has a first winding direction and said outer compression spring has a second winding direction, wherein the first winding direction is different from the second winding direction.

Description

Contact probe with compressive spring assembly

The invention provides a contact probe with a compressive spring component, which can obtain a high spring force without affecting the life of the spring. The contact probe comprises a piston cylinder, a first plunger, a second plunger and a compression spring assembly. The compression spring assembly includes at least one internal pressure spring and at least one external pressure spring. The at least one internal pressure The spring has a first winding direction, and the at least one external pressure spring has a second winding direction, wherein the first winding direction is different from the second winding direction.

Contact probes are used to test sockets or contactors to provide an electrical connection between a test circuit board and a device under test (DUT), such as an electronic packaging device. The electrical interface of a spring contact probe for providing electrical connection is well known in the art. Generally, a spring contact probe includes a cylindrical piston barrel, a plunger, and a spring, wherein the spring and the plunger are disposed in the cylindrical piston barrel, and then the spring contact probe is assembled into a test socket or contact. Device.

In the electrical test of the DUT, the plunger slides axially along the cylindrical piston barrel, and the spring is compressed, thereby bringing the plunger into contact with the corresponding contact element. One end of the contact probe is in electrical contact with the contact point of the DUT, and the other end of the contact probe is in contact with the circuit board of the test equipment. The measurement is performed according to predetermined parameters and specifications.

In a mass production test environment, low and stable contact resistance requires high spring force. However, the traditional single spring design has limitations in terms of spring characteristics. Increasing the spring force will shorten the life expectancy of the spring. For example, under the desired working stroke conditions, the plunger compresses a single spring to the desired working stroke to obtain the required spring force. In the working stroke, the preloaded spring force is about 50% of the required spring force, and the spring life is about 100,000 cycles. For a contact probe, the spring life of 100,000 cycles is not enough. If possible, the design life of the spring is about 1,000,000 cycles, or the length of the spring can be increased to extend the life of the spring, but in electrical testing, the high-frequency bandwidth requirements will be affected. Therefore, the length of the contact probe must be kept to a minimum. Avoid attenuation of high-frequency signals. However, it is a challenge to design a short contact probe without affecting the spring force and life. On the other hand, the thickness of the test socket is also reduced due to the use of short pins. For this reason, when the socket is connected to the load board, (PCB), there will be a problem that the preload will deform the socket. Reducing the preload is also an important factor in using short pins.

Therefore, it would be very advantageous to have a contact probe capable of overcoming the disadvantages described above. The present invention provides a contact probe with a compressive spring assembly for short needles to achieve the required high spring force and high bandwidth requirements.

An object of the present invention is to provide a contact probe having a compressive spring assembly for electrical testing.

Another object of the present invention is to provide a contact probe having a double spring design.

Another object of the present invention is to provide a contact probe capable of satisfying a high sales force.

Another object of the present invention is to provide a contact probe with a short length capable of meeting the requirements of high frequency bandwidth.

It is another object of the present invention to provide a contact probe having improved spring life.

Another object of the present invention is to provide a contact probe suitable for a mass production test environment.

Another object of the present invention is to provide a contact probe having a required spring force according to a required application.

Additional objects of the present invention will become apparent based on the detailed description of the present invention or the practical application of the present invention.

To achieve the foregoing object, the present invention is a contact probe with a compressive spring assembly, including:

A piston barrel having a first end, a second end, and a through hole extending from the first end to the second end;

A first plunger disposed at the first end;

A second plunger provided at the second end; and

A compression spring assembly is provided on the piston barrel, and is characterized by:

The compression spring assembly includes at least two springs, wherein the at least two springs include at least one internal pressure spring and at least one external pressure spring.

In order to make the foregoing features and advantages of the present invention more comprehensible, embodiments are described below. It will be described in detail with the accompanying drawings.

The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of the preferred embodiments with reference to the drawings.

The invention relates to a contact probe (100) for a test socket and a contactor, which is used to provide electrical contact between an electronic test device and an electronic component such as an electronic packaging device under test. More specifically, the present invention relates to a contact probe (100) having a compressive spring assembly (300), which can obtain a high spring force without affecting the spring life.

Please refer to FIG. 1A, which is a side view of the contact probe (100) of the present invention, and further refer to FIG. 1B, which is a cross-sectional view of the contact probe (100) of the present invention. The contact probe (100) includes a piston barrel (200), a first plunger (400), a second plunger (450), and a compression spring assembly (300). 2 to 4 are side and perspective views of the piston cylinder (200), the compressive spring assembly (300), the first plunger (400), and the second plunger (450). The contact probe (100) has a length of about 1 mm to 4 mm. In an exemplary embodiment, the contact probe (100) may have a length of about 2 mm in a BGA application of about 0.4 mm, and for a BGA application of a 0.4 mm pitch, the length of the contact probe (100) is about 2 mm, the size of the contact probe (100) can be changed from one embodiment of the invention to another without departing from the scope of the invention.

2A and 2B, the piston cylinder (200) is a cylindrical housing (201) and has a first end (203), a second end (205) and a first end (203). ) Extending to the through hole (207) of the second end (205). A first end (203) of the piston barrel (200) is used to receive the first plunger (400), and a second end (205) of the piston barrel (200) is used to receive the second plunger (450), The through hole (207) of the piston cylinder (200) is used to receive the compression spring assembly (300).

3A to 3D, the compression spring assembly (300) includes at least two springs, wherein the two springs include at least one internal pressure spring (301) (as shown in FIGS. 3A and 3B) and at least one An external pressure spring (303) (as shown in FIGS. 3C and 3D), the internal pressure spring (301) and the external pressure spring (303) are disposed in the piston cylinder (200). In an embodiment of the present invention, the wire diameter and spring force of the external pressure spring (303) are larger than the wire diameter and spring force of the internal pressure spring (301), and the diameter of the internal pressure spring (301) is smaller than the external pressure. The diameter of the spring (303) allows the internal pressure spring (301) to be installed in the external pressure spring (303). The spring can be made of a conductive material, such as steel wire or stainless steel wire. The design of the compression spring, such as the total number, length, and shape of the coils, can be changed to provide different amounts of compression and spring force for different test applications.

4A and 4B, the first plunger (400) has a first contact portion (401), an extension portion (403), a shoulder portion (405) and a tapered portion (407). The first plunger (400) is slidably disposed in the first end (203) of the piston cylinder (200), so that it moves longitudinally relative to the piston cylinder (200). The cone of the first plunger (400) The shaped portion (407) is engaged with one end of the compression spring, and the first contact portion (401) is engaged with an external circuit element during an electrical test, such as a circuit board pad, and the diameter of the tapered portion (407) must be substantially equal to Or smaller than the inner diameter of the external pressure spring (303), and the diameter of the shoulder (405) is slightly smaller than the inner diameter of the piston barrel (200).

The second plunger (450) is shown in Figures 4C and 4D. The second plunger (450) has a second contact portion (451) and a connecting portion (453). The second plunger (450) is provided at the second end (205) of the piston cylinder (200), wherein the connection portion (453) is engaged with the other end of the compression spring, and the second contact portion (451) is Engages with contact elements of electronic packaging equipment during testing. The second contact portion (451) of the second plunger (450) shown in FIGS. 4C and 4D is a four-point crown for ball grid array (BGA) and quad flat leadless (QFN) testing. Other types of contact include 9 Dot crowns, needles, etc. The shape of the contact portion can be selected to suit a particular application. It should be understood that the types of contact portions listed above are for illustration purposes only and are not intended to be limiting. The first plunger (400) is configured to retract and extend from the piston barrel (200) during operation to allow the contact probe (100) to move relative to an external element while still To ensure electrical continuity between the first plunger (400) and the second plunger (450), even if the first plunger (400) and the second plunger (450) are both movable, the present The invention is also true.

Please refer to FIG. 5, which is a partial cross-sectional view of the contact probe (100) of the present invention. The internal pressure spring (301) and the external pressure spring (303) are disposed in the piston barrel (200). The external pressure spring (303) is concentratedly disposed around the internal pressure spring (301). The internal pressure spring (301) ) Has a first winding direction, and the external pressure spring (303) has a second winding direction, the first winding direction is different from the direction of the second winding direction to prevent the internal pressure spring (301) and the external pressure The spring (303) is entangled. In the embodiment of the present invention, the internal pressure spring (301) is a clockwise spring, the external pressure spring (303) is a counterclockwise spring, and vice versa.

6A to 6C are partial cross-sectional views of the contact probe (100) according to the first embodiment of the present invention, wherein the compressive spring assembly (300) is in three different states. As shown in FIG. 6A, the compression spring assembly (300) is in an assembled state in which a small force is applied to the compression spring assembly (300). The tapered portion (407) of the first plunger (400) and the internal pressure spring (301), the shoulder (405) of the first plunger (400) is in contact with the external pressure spring (303), and FIG. 6B shows the contact probe (100) in a preloaded stroke state. The internal pressure spring (301) and the external pressure spring (303) are both compressed by the first plunger (400) until a predefined working stroke, and a preloaded spring force is obtained from the two springs. FIG. 6C shows the contact probe (100) under the required working stroke conditions. The desired spring force is obtained from the internal pressure spring (301) and the external pressure spring (303), both of which are detected by the first spring. The plunger (400) is compressed until the required working stroke. FIG. 7 shows a curve of spring force and compression stroke of the compressive spring assembly (300) in the first embodiment of the present invention. According to the curve, a desired high spring force is obtained by using the compressive spring assembly (300) of the present invention. The life cycle of the external pressure spring (303) is longer than the traditional single spring design because the spring force in the desired working stroke is less than the traditional single spring design. Compared with the traditional single spring design, the internal pressure spring The life cycle of (301) has increased. Under the working stroke condition, the preloaded spring force is about 50% of the required spring force. However, the life of the spring exceeding 1,000,000 cycles is achievable.

8A to 8C are partial cross-sectional views of the contact probe (100) according to a second embodiment of the present invention, wherein the compressive spring assembly (300) is in three different states. Compared with the external pressure spring (303) in the first embodiment, the length of the external pressure spring (303) used in the second embodiment is shorter. FIG. 8A shows that the compression spring assembly (300) is in an assembled state where no load is applied to the external pressure spring (303) and a set load is applied to the internal pressure spring (301). The cone of the first plunger (400) The portion (407) is in contact with the internal pressure spring (301), and the external pressure spring (303) is at a distance from the first plunger (400). FIG. 8B shows the contact probe (100) under the condition of a preload stroke, and the internal pressure spring (301) is compressed by the first plunger (400) until a predefined preload working stroke, for example, during preload work At a stroke of 0.15 mm, the pre-loaded spring force is approximately 3.75 gf. The preload spring force comes from the internal pressure spring (301), and the external pressure spring (303) is only in contact with the first plunger (400). FIG. 8C shows the contact probe (100) under a desired working stroke condition. The desired spring force is obtained from the internal pressure spring (301) and the external pressure spring (303). A plunger (400) is compressed until the required working stroke. In one exemplary embodiment, if the desired working stroke is 0.3 mm, the required spring force is about 30 gf. FIG. 9 shows a curve of a spring force and a compression stroke of the compression spring assembly (300) of the present invention. According to the curve, a desired high spring force is obtained by using the compression spring assembly (300) of the present invention. The life cycle of (303) is basically the same as the traditional single spring design, but compared with the traditional single spring design, the life of the internal pressure spring (301) is increased, and the total life of the spring is basically the same as the traditional single spring design. Under the working stroke condition, the preset spring force is about 13% of the expected spring force, of which the preloaded spring force is about 55% of the required spring force under the working stroke condition, which is beneficial to reduce the preload force by 77%. A 77% reduction in the preload force of the traditional single spring design is beneficial.

Therefore, with the contact probe of the present invention, high-frequency bandwidth requirements can be achieved without affecting the performance of the spring force and the durability of the compression spring. In addition, by reducing the preloaded spring force, warpage of the test sleeve can be reduced.

Although the preferred embodiments of the present invention and its advantages have been disclosed in the foregoing detailed description, the present invention is not limited thereto but is limited only by the scope of the appended claims.

(100) ‧‧‧Contact Probe

(200) ‧‧‧Piston barrel

(201) ‧‧‧cylindrical shell

(203) ‧‧‧First End

(205) ‧‧‧Second End

(207) ‧‧‧through hole

(300) ‧‧‧Compression spring assembly

(301) ‧‧‧Inner pressure spring

(303) ‧‧‧Inner pressure spring

(400) ‧‧‧First plunger

(401) ‧‧‧First contact

(403) ‧‧‧Extension

(405) ‧‧‧Shoulder

(407) ‧‧‧Tapered

(450) ‧‧‧Second plunger

(451) ‧‧‧Second Contact Section

(453) ‧‧‧Connection

FIG. 1A is a side view of a contact probe according to the present invention. FIG. 1B is a cross-sectional view of a contact probe according to the present invention. Figures 2A and 2-B, collectively referred to as Figure 2, are side and perspective views of a piston barrel of the present invention. 3A to 3D, collectively referred to as FIG. 3, are side and perspective views of a compression spring assembly according to the present invention. 4A to 4D, collectively referred to as FIG. 4, are side and perspective views of a plunger of the present invention. FIG. 5 is a partial cross-sectional view of a contact probe according to the present invention. 6A to 6C are partial cross-sectional views of a contact probe according to a first embodiment of the present invention, in which a compressive spring assembly is in three different states. FIG. 7 is a curve diagram of a spring force and a compression stroke of a compression spring assembly in the first embodiment of the present invention. 8A to 8C are partial cross-sectional views of a contact probe according to a second embodiment of the present invention, in which a compressive spring assembly is in three different states. FIG. 9 is a graph of a spring force and a compression stroke of a compression spring assembly in a second embodiment of the present invention.

Claims (7)

A contact probe with a compressible spring assembly includes: a piston barrel (200) having a first end (203), a second end (205), and an extension from the first end (203) to the A through hole (207) of the second end (205); a first plunger (400) provided at the first end (203); a second plunger (450) provided at the second end (205) And a compression spring assembly (300) provided on the piston cylinder (200), characterized in that: the compression spring assembly (300) includes at least two springs, wherein the at least two springs include at least one internal pressure spring (301 ), And at least one external pressure spring (303). The contact probe with a compressible spring assembly according to claim 1, wherein the external pressure spring (303) is concentratedly disposed around the internal pressure spring (301). The contact probe with a compression spring assembly according to claim 1, wherein the internal pressure spring (301) has a first winding direction, and the external pressure spring (303) has a second winding direction, and the first winding The direction is different from the direction of the second winding direction. The contact probe with a compression spring assembly according to claim 1, wherein a diameter of a wire of the external pressure spring (303) is larger than a diameter of a wire of the internal pressure spring (301). The contact probe with a compression spring assembly according to claim 1, wherein the internal pressure spring (301) and the external pressure spring (303) are both compressed by the first plunger (400) until a desired work plan. The contact probe with a compression spring assembly according to claim 1, wherein under the condition of a preset stroke, from the internal pressure spring (301) or from the internal pressure spring (301) and the external pressure spring (303 ) To obtain the preloaded spring force. The contact probe with a compression spring assembly according to claim 1, wherein a required spring force is obtained from the internal pressure spring (301) and the external pressure spring (303) under a condition of a desired working stroke. .