Patent Application
20090267629
The present invention generally relates to the field of integrated circuit devices (IC) testing. More particularly, the present invention relates to a contact in a test socket which interfaces with pads/leads of the IC devices with a printed circuit board of a test handler that protects both the IC pads/leads and contacts of the test socket from damage and extensive wear as well as allows good contact for the test to take place.
IC devices have many applications in today's industry. In order to provide for efficient, reliable and uninterrupted operation, such devices must be tested to ensure the device meets the high quality required of the electronics industry. Testing and burn-in of the IC device typically requires the devices to be actuated by engagement of their pads/leads, with corresponding contacts of a test socket. The contacts of the test socket, in turn, electronically communicate with terminals of a printed circuit board of a test socket of a test handler which is adapted to test the IC device in question. It is desirable that such IC devices could be tested either in manual mode or automatic mode of testing. In methods known in the art, “pick and place”, “turret” or “gravity feed” handling mechanism employs the modification of existing manual test sockets, in order to provide dedicated test sockets that are specifically adapted to interface with the test handler.
This type of test socket typically comprises of socket housing and an optional cover assembly for the manual mode testing. The socket housing is provided with an array of compliant contacts for electronically engaging the IC while the cover assembly is hinged at the socket housing. When a device is positioned in the test socket, the cover assembly is latched at the socket housing. The IC devices are aligned within the socket housing by various means to guide the pads/leads into engagement with the corresponding contacts within the test socket cavity.
In practice, contacts in test sockets are generally formed having W-shaped arms. The extremities of the upper and lower arms of the W-shaped body act as contacts that interconnect the pads/leads of the IC with the printed circuit board of the test handler. It is within the socket housing that the tips of the contacts are held. The contact is profiled appropriately for interfacing with the device by engagement of the contact tip and the pads/leads to provide the desired sliding action.
New IC devices such as the QFN/MLP have pads/leads where in the molding process of the same often has excessive molding flash or a solder mask that may impede good electrical contact required in the testing process. This often interferes with the contact probe thereby causing a test failure. A narrower solder mask in certain IC package designs also provides impediments to good contact and increases test failures due to the narrower test pads/leads. As such, the test yield is lost and re-test is needed, with the W-shaped preferably designed with narrower contact tip to enable to penetrate the narrower/recess or flat devices pads/leads for a good test. Therefore, there arises an un-met need for a new contact which can serve a plurality of IC devices having various pads/leads profiles and configurations.
The present invention discloses an improved test contact which functions to electronically interface the pads/leads of an IC device to be tested, with corresponding terminals of a printed circuit board. The device according to the present invention enables testing of similar pad configurations without the need to change the whole socket.
Accordingly, it is the primary object of the present invention to provide a contact for electronically interfacing pads/leads of an integrated circuit device with corresponding terminals of a printed circuit board for testing of the same.
It is another object of the present invention to provide a contact that is mechanically and thermally stable for providing acceptably high accuracy testing and yet suitable for various pads/leads configurations.
It is yet another object if the present invention to provide a contact having a sliding action with the pads/leads for substantially improved penetration for better contact and also resistance against wear and tear.
These and other objects of the present invention are accomplished by,
In a test socket (1) for testing integrated circuit devices (2) of the like, a contact (11) is provided for electronically interfacing pads/leads (21) of said integrated circuit devices (2) to be tested with corresponding terminals (31) on a printed circuit board (3), said contact (11) comprises of:
The contact (11) is retained in the test socket for interfacing the pads/leads of the IC devices with a printed circuit board (3) of the test socket during testing. The contact has features that look substantially similar with the letter of W. The first arm (13) of the contact is adapted for electronically engaging pads/leads (21) of the IC devices to be tested. For improved engagement, the first arm (13) is provided with a first engaging means (15) having a sliding means in the form of tip projecting from top most of the first arm (13) as seen in
The second arm (14) is provided with the second engaging means (16) for electronically engaging the contact (11) to the corresponding terminals (31) of the printed circuit board (3) of the test socket (1). The first engaging means (15) provides improved sliding action with the IC pads/leads (21), and in the especially preferred mode of the invention, has a thickness less than that of the body of the contact (11) thereby providing means to avoid electrical contact impediments that present or formed on, or in-between the pads/leads. The curved exterior surfaces of contact (11) that formed along the first engaging means (15) and both arms of the body also help protect the pads/leads (21) and contacts (31) of the test socket from damage and extensive wear. A planar contact section (19) positioned to operatively engage with the pads/leads (21) provides additional good contact to the test socket. Further, the thickness of the first engaging means (15), at least at the contact section (19), is best if it is thinner than the thickness of the first arm (13). This feature is best shown in
Other aspects of the present invention and their advantages could be readily discerned after studying the Details Description in conjunction with the accompanying drawings in which:
a shows side view of the contact of the present invention with the top projecting from the first arm and a contact section of the tip that has a generally planar shape profile.
b depicts an end view of the contact and shows the preferred embodiment of the engaging tip having a narrower contact tip thickness.
Referring first to
The first arm (13) is adapted for electronically engaging the pads/leads (21) of the IC devices (2) to be tested to the contact (11). The tip of the first arm (13) has a first engaging means (15) that is provided with a sliding means for improved sliding action with the pads/leads (21). A good sliding action is generally achieved when the contact pressure between the pads/leads (21) and the sliding means is just right and this is provided by the biasing action of the elastomer (23) that imparts the desired contact for a good electric flow but not particularly excessive to be detrimental to the terminals (31) through good rolling action, as well as to the pads/leads (21) of the IC devices. Preferably, the sliding means is made from a resilient material such as Beryllium Copper and to be able to vary and compensate the contact pressure to accommodate for the different types of lead profiles and configurations.
Still referring to
Referring now to
While the preferred embodiment of the present invention and their advantages have been disclosed in the above Detailed Description, the invention is not limited thereto but only by the scope of the appended claim.
| Number | Date | Country | Kind |
|---|---|---|---|
| PI20081225 | Apr 2008 | MY | national |
