Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1999-05-12
2001-11-13
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S754090, C324S758010
Reexamination Certificate
active
06316952
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for connecting an integrated circuit to an external system, such as a test and burn-in system. More particularly, the present invention relates to the use of flexible conductive structures for performing test and burn-in of integrated circuit packages with ball grid arrays.
2. Description of the Related Art
Integrated circuit packages generally include internal and external structures utilized to electrically connect integrated circuits to external circuitry. One known type of integrated circuit package is a ball grid array (“BGA”) package. BGA packages include an array of solder balls in a selected pattern on an external portion of the package. The solder balls are placed on metallic portions of external circuitry, such as a circuit board, and heated. Upon solidifying, the solder balls form conductive metal-to-metal bonds with the circuitry.
BGA packages are referred to in U.S. Pat. No. 5,796,163 (Glenn et al.), U.S. Pat. No. 5,716,222 (Murphy), and U.S. Pat. No. 5,831,832 (Gillette et al.). In Murphy and Gillette et al., the solder balls have rigid, solderable coverings. A potential problem with such a design is the creation of defects caused by fitting the coverings over the solder balls. Another potential problem is a loosening of the fit of the coverings over the solder balls, thus diminishing the electrical connections therebetween.
Prior to releasing an integrated circuit package for public use, it may be necessary to test and/or “burn-in” the integrated circuit. The procedure may be used to stabilize the characteristics of the integrated circuit die and reveal any defects therein.
One method for testing an integrated circuit package having a ball grid array is through the use of a plurality of silicon pillars on a test apparatus. The silicon pillars, which are electrically conductive, are placed in contact with the solder balls of the integrated circuit package to test or burn-in the package. The pillars provide electrical connections between the test apparatus and the individual elements of the ball grid array. A problem with utilizing silicon pillars, however, is their lack of flexibility. Due to their lack of flexibility, the silicon pillars may damage the solder balls on contact, thereby creating defects in the integrated circuit package. Damage sustained by the solder balls is due to excessive deformation, which results in decreased ability to solder.
U.S. Pat. No. 5,475,317 (Smith) refers to a conductive elastomeric probe which is screened onto bond pads used to test a singulated bare die. The elastomeric probes are used to ensure electrical connectivity. The invention described in Smith is directed to the testing of dies earlier on in the processing of the dies. The Smith patent does not suggest testing of dies which are further along the processing line, and it does not discuss the testing of dies which utilize solder balls.
SUMMARY OF THE INVENTION
The present invention addresses the problem of damage to solder balls in a ball grid array caused by inflexible electrical connections. The present invention relates to an apparatus for processing an integrated circuit die having a ball grid array of solder balls. The apparatus has a supporting surface and a plurality of flexible supports for receiving the solder balls.
The present invention also relates to a flexible support system for supporting solder balls located on an integrated circuit die. The flexible support system includes at least one support which flexes, thereby enabling it to impart significantly less deformation to the solder balls than that imparted by a rigid system.
The present invention also relates to a method of processing an integrated circuit die having a ball grid array of solder balls. The method includes the steps of moving the die toward a test and burn-in apparatus which has a supporting surface and a plurality of flexible supports, placing the die into electrical connection with the apparatus, and testing the die.
The present invention also relates to a method of receiving solder balls located on integrated circuit dies. The method includes the steps of positioning the dies such that the solder balls are above flexible support systems and lowering the dies such that the solder balls come into contact with the system, the system flexing in response to the contact.
These and other advantages will become apparent from the following detailed description of preferred embodiments of the invention.
REFERENCES:
patent: 5475317 (1995-12-01), Smith
patent: 5533515 (1996-07-01), Coller et al.
patent: 5716222 (1998-02-01), Murphy
patent: 5746616 (1998-05-01), Mar
patent: 5796163 (1998-08-01), Glenn et al.
patent: 5810609 (1998-09-01), Faraci et al.
patent: 5831832 (1998-11-01), Gillette et al.
patent: 6020747 (2000-02-01), Bahns et al.
patent: 6043670 (2000-03-01), Degani et al.
patent: 6046597 (2000-04-01), Barabi
patent: 6046598 (2000-04-01), Miyaji et al.
patent: 6086386 (2000-07-01), Fjelstad
patent: 6094057 (2000-07-01), Hiruta et al.
Ahmad Syed Sajid
Akram Salman
Dickstein , Shapiro, Morin & Oshinsky, LLP
Metjahic Safet
Micro)n Technology, Inc.
Sundaram T. R.
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