Contactor for testing electronic device

An electronic device having a structure that electrically connects the contactor to an electronic device during a testing process is disclosed. The contactor includes a holder for accommodating the electronic device during the testing process; a flexible circuit, having a first set of contacts electrically connected to the corresponding electrode terminals of the electronic device, and a second set of contacts electrically connected to a control unit that sends test signals during the test process; an elastomer, for adjusting the pressure between the first set of contacts of the flexible circuit and the corresponding electrode terminals of the electronic device while being pressed together; and an alignment tool, for aligning the first set of contacts with the corresponding electrode terminals of the electronic device. The electrode terminals of the electronic device are located on the same surface of the electronic device and the flexible circuit is detachable from the contactor.

FIELD OF THE INVENTION

The present invention relates to contactors for testing an electronic device. More particularly, the present invention relates to a contactor for characteristic testing of a semiconductor integrated circuit device such as a chip-scale package (CSP) devices, a flip-chip device, or a ball grid array (BGA) device.

BACKGROUND OF THE INVENTION

In recent years, a reduction in thickness and in weight of portable electronic equipment and IoT device increases the demand for miniaturization of the package of semiconductor integrated circuit devices. The chip-scale package (CSP) is one of the best package methods for an IC to fit the miniaturization requirement of an IoT device. In a CSP, the die may be mounted on an interposer where pads or balls are formed on, similar to that of flip-chip ball grid array (BGA) packaging, or the pads may be etched or printed directly onto the wafer.

An IC tester is used for performing a characteristic test by supplying electric power and electric signals to the packaged IC. A contactor such as an IC socket is often used as an interface to connect an IC to the IC tester. Conventional contactors use probe pins, each incorporating a coil spring to contact with the terminals of a packaged IC. The probe pins are movable in a vertical direction to adjust the contact pressure.

U.S. Pat. No. 6,636,057 disclosed one conventional electrical socket having a pin and a spring. U.S. Pat. No. 7,471,096 disclosed another conventional electrical socket having a conductive elastic contact pin. As shown inFIG. 1, the contactor10includes a plurality of contact pieces11. each of the contact pieces11comprises a contact pin11cand a first contact portion11aprovided in an upper portion of contact pin11c. The lower end of the contact pin11cserves as a second contact portion11b, which is brought into contact with a terminal13aformed and arranged on the substrate13. The contact pin11cis bent beforehand in an elbow shape to be easily deformed when being pressed from both ends. Both prior arts provided a reliable connection for a device under test to connect with a tester.

Mis-test may be aroused by many possible causes, including dirt and oxides, that accumulate on the device pin and socket pin. Misalignment will also result in mis-test, as misalignment causes a part to be damaged, lost or falsely tested. U.S. Pat. No. 6,636,057 mentioned a knurl formed on the terminal contact surface to maintain a secure electrical connection thereof. However, both prior arts are silent about the maintenance or replacement of the pins. In fact, these pins must be replaced after a certain number of uses, usually tens of thousands of uses. In addition, the cost to manufacture the pins is high, particularly for today's high-density packages, and the replacement is time-consuming work.

Therefore, in order to resolve the problems mentioned above, a low-cost and easy-to-replace tool for the contactor is desired.

SUMMARY OF THE INVENTION

This paragraph extracts and compiles some features of the present invention; other features will be disclosed in the follow-up paragraphs. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims.

In order to settle the problems mentioned above, a contactor for testing an electronic device is provided. The contactor comprises: a holder, having a concave portion for holding and fixing the electronic device during a testing process; a flexible circuit, having a first set of contacts electrically connected to the corresponding electrode terminals of the electronic device, and a second set of contacts electrically connected to a control unit that sends test signals during the testing process; an elastomer, for adjusting the pressure between the first set of contacts of the flexible circuit and the corresponding electrode terminals of the electronic device while being pressed together; and an alignment tool, for aligning the first set of contacts with the corresponding electrode terminals of the electronic device. The electrode terminals of the electronic device are located on the same surface of the electronic device. The flexible circuit is detachable from the contactor.

Preferably, the electronic device may be a chip-scale package (CSP) device, a flip-chip device, or a ball grid array (BGA) device. The contactor may further comprises a press-down cover above the concave portion of the holder to fasten the electronic device to the flexible circuit. The contactor may further comprise a substrate for the holder to fix thereto, wherein the substrate comprises a set of connectors for the second set of contacts to connect to the control unit. The connectors may be flexible flat cable (FFC) connectors, and the second set of contacts may be in the form of FFC contacts. The substrate may be a printed circuit board (PCB) where the control unit is mounted thereon.

According to the present invention, the first set of contacts are plated with gold or gold alloy. The elastomer comprises a set of protrusions corresponding to the first set of contacts to provide extra force to enhance the pressure between the first set of contacts and corresponding electrode terminals of the electronic device. The first set of contacts may be in the form of via holes. The alignment tool may comprise a set of locating pins formed on the holder and a movable frame with a set of corresponding locating holes formed thereon to be engaged with the locating pins. There is also a set of corresponding locating holes formed on the flexible circuit and the elastomer, respectively, for engaging with locating pins. The alignment tool may comprise a movable frame and a set of linear actuators for adjusting position between the movable frame and the holder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically with reference to the following embodiment.

Please refer toFIG. 2toFIG. 4.FIG. 2shows a contactor20for testing an electronic device21to make an electrical connection to a plurality of electrode terminals211of the electronic device21. In the first embodiment, the electronic device21is a chip-scale package (CSP) device27. The electronic device21may be a device having all the electrode terminals211located on the same surface, e.g., a CSP device, a flip-chip device, or a ball grid array (BGA) device.FIG. 3is the top view of a portion of the contactor20.FIG. 4is a cross-section view along the AA′ line inFIG. 3.FIG. 5is a cross-section view along the BB′ line inFIG. 3. It should be understood that the components are slightly separated inFIG. 5merely to clearly express the relative positions of each component. The contactor20includes: a holder22, a flexible circuit23, an elastomer24, and an alignment tool25.

The holder22has a concave portion221for holding and fixing the CSP device27during a testing process. In the present embodiment, the holder22has a press-down cover22a, an upper part22b, a middle part22c, and a lower part22d, as shown inFIG. 4. The press-down cover22ais placed above the CSP device27to fasten the CSP device27to the flexible circuit23. It should be noticed that the press-down cover22ais neglected inFIG. 2andFIG. 3. The CSP device27includes a set of electrode terminals271at the bottom side thereof. An alternative device, e.g., a picker of a robotic arm, may be used to press down the CSP device27. In the present embodiment, the electrode terminals271are solder balls. The holder22may be composed of several parts but not limited to the press-down cover22a, the upper part22b, the middle part22c, and the lower part22d. As shown inFIG. 5, a first opening22eis located at the center of the upper part22bforming the concave portion221of the holder22. The middle part22chas a recession22ffor the flexible circuit23to fit therein. The middle part22calso has a second opening22gfor the elastomer24to be placed into. The upper part22bcan be left up easily for a user to exchange the flexible circuits. A hinge22hmay be used to connect the upper part22band the middle part22c. The holder22is fixed on a substrate26, e.g. a printed circuit board (PCB). In the present embodiment, the holder22is fixed on a PCB26by the lower part22dand the middle part22c, as shown inFIGS. 4 and 5. There may be clip locks (not shown) located on the opposite side of the hinge22hof the holder22for hooking the upper part22bto the middle part22c, as shown inFIGS. 2 and 4. Any tool that can lock the upper part22bto the middle part22cduring the testing process and can be easily unlocked when replacing the flexible circuit23can be used here. The middle part22cand the lower part22dmay be fixed together by screws (not shown).

The flexible circuit23may be formed by etching a copper foil cladding from insulating polymer bases into circuit patterns and then covering the circuit patterns with a polymer coating to protect it. The flexible circuit23has two sets of contacts that are not covered by the polymer coating. The contacts can be plated with gold or gold alloy to increase durability. The contacts can be plated with other common plating materials, such as tin, nickel, silver, electroless nickel with immersion gold (ENIG), electroless nickel/palladium immersion gold (ENEPIG). Platinum group metals may be plated on the contacts to protect against corrosion.

The first set of contacts231are used to electrically connect to the corresponding electrode terminals271of the CSP device27. Therefore, the first set of contacts231, formed on a top surface of the flexible circuit23, has a pattern that is the same as the distribution of the corresponding electrode terminals271of the CSP device27. The size of each contact is the same as or slightly larger than the size of the corresponding electrode terminals271of the CSP device27. The second set of contacts232are electrically connected to a control unit29that sends test signals during the testing process. The control unit29may be mounted on a PCB26, and a plurality of traces (not shown) are formed on the PCB26to connect the second set of contacts232to corresponding pins of the control unit29. In another embodiment, the control unit29may be assembled in another device and connect to the second set of contacts232on the PCB26via a connector (not shown), e.g. a USB interface. The flexible circuit23is detachable from the contactor20and the PCB26. For example, there may be connectors261mounted on the PCB26and connect the flexible circuit23to corresponding traces. The connectors261make it easy to replace a worn flexible circuit23with a new one. The connectors261may be flexible flat cable (FFC) connectors. The second set of contacts232may be in the form of regular FFC contacts that fit corresponding connectors261. For example, the connector is a 20-pins connector having a pitch of 0.5 mm.

The elastomer24is placed beneath the flexible circuit23. The elastomer24is designed to adjust the pressure between the first set of contacts231of the flexible circuit23and the corresponding electrode terminals271of the CSP device27while being pressed together. The center of the CSP device27, the first set of contacts231, and the elastomer24are approximately aligned vertically. The elastomer24may have a larger area than the size of the CSP device27from the top view. The elastomer24may include a set of protrusions24acorresponding to the first set of contacts231to provide extra force to enhance pressure between the first set of contacts231and corresponding electrode terminals271of the CSP device27. Therefore, a secure electrical connection between the CPS device and the flexible circuit23will be established while being pressed together. The protrusions24amay have a crater formed at the center of the tip for the electrode terminals271better fit therein.

Various types of tools can be used as the alignment tool25, as long as they meet the accuracy and precision requirement of the contactor20. In the present embodiment, the alignment tool25includes a set of locating pins251(or locating pillars) onto the holder22and a movable frame252with a first set of corresponding locating holes252aformed thereon to be engaged with the locating pins251. There are also a second set of corresponding locating holes253formed on the flexible circuit23, and a third set of corresponding locating holes254formed on the elastomer24to engage with the locating pins251. The size of an inner opening252bof the movable frame252has the same as or slightly larger than the size of the CSP device27for the CSP device27to fit therein. The height of the movable frame252(H2) is slightly less than a total height of the CSP device27(H1), as shown inFIG. 5. Therefore, the electrode terminals271of the CSP device27will be slightly protruded beyond the lower surface of the movable frame252to contact the first set of contacts when the press-down cover22aof the contactor20is pressed down. The alignment tool is used to align the first set of contacts231with the corresponding electrode terminals271of the CSP device27.

Please refer toFIG. 6AandFIG. 6B.FIG. 6Ashows a side view of an electronic device and a flexible circuit23in a second embodiment, andFIG. 6Bshows a top view of the flexible circuit23inFIG. 6A. The electronic device is a BGA device28in the second embodiment. Only a portion of the flexible circuit23around the first set of contacts231is shown in the figures. The first set of contacts231are in the form of via holes, i.e., plated through-holes. The via has a diameter smaller than the diameter of the electrode terminals281of the BGA device28, and maybe plated with gold or gold alloy. The via holes make it easier for the electrode terminals281to fit therein. In other words, the soldering balls will engage the corresponding holes while the BGA device28is pressed down by the press-down cover22aof the holder22. The traces23amay be formed on both the top and bottom layers of the flexible circuit23, and are used to connect the first set of contacts to the second set of contacts. Protective layers are formed on both sides of the flexible circuit23except the location of the first and second sets of contacts, in order to protect the traces23a.

In another embodiment, the holder22may include different types of alignment tools. For example, a set of linear actuators are placed around the holder22to adjust the position of the movable frame252and to align the first set of contacts231with the corresponding electrode terminals211of the electronic device21. Please refer toFIG. 7AandFIG. 7B.FIG. 7Ashows a top view of the movable frame252and the holder22with the linear actuators25a.FIG. 7Bshows a cross-section view of a portion of the holder22and one of the linear actuators25abuilt therein. In the present embodiment, a pair of leadscrew25band nut25cis used to form the linear actuator25a. Other types of linear actuators, e.g., ball screws, piezoelectric actuation, etc., may also be used here. The accuracy and resolution of the linear actuator are designed to fit the dimension of the package. For example, the singulation tolerance of the finished devices27may vary +/−50 μm, which results in a variation of the BGA location tolerance of the same amount.

While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention needs not to be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, which are to be accorded with the broadest interpretation to encompass all such modifications and similar structures.