A method for producing chip scale ic packages includes the step of mounting a lead frame panel on a temporary support fixture in order to provide support and protection during the manufacturing process. An embodiment of the temporary support fixture includes a sheet of sticky tape secured to a rigid frame. The rigid frame maintains tension in the sheet of sticky tape to provide a stable surface to which the lead frame panel can be affixed. Installation of ic chips and encapsulation in protective casings is performed as in conventional ic package manufacturing. If encapsulant material is to be dispensed over the ic chips, an encapsulant dam can be formed around the lead frame panel to contain the flow of encapsulant material. The temporary support fixture can be used in any ic package manufacturing process in which lead frames require supplemental support.
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3. A fixture for providing temporary support to a lead frame during an ic package manufacturing process comprising an adhesive pad attached to a rigid frame such that said adhesive pad is held in tension by said rigid frame to provide a stable support surface for said lead frame, wherein said rigid frame comprises a stainless steel ring having an opening of a diameter larger than said lead frame.
1. A fixture for providing temporary support to a lead frame during an ic package manufacturing process comprising an adhesive pad attached to a rigid frame, said rigid frame having an opening larger than said lead frame so as to accommodate said lead frame entirely within an outer periphery of said rigid frame, and such that said adhesive pad is held in tension by said rigid frame to provide a stable support surface for said lead frame.
4. The fixture of
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6. A fixture as in
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0. 9. A fixture as recited in
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1. Field of the Invention
The present invention relates to integrated circuit packages, and more specifically, to the production of a chip scale integrated circuit package using a lead frame.
2. Related Art
typicalGenerally, an integrated circuit (IC) package encapsulates an IC chip, or die, in a protective casing and also provides power and signal distribution between the IC chip and an external printed circuit board (PCB). A metal lead frame can be used to provide the electrical paths for that distribution. A lead frame panel suitable for use in accordance with the present invention is illustrated in FIG. 1a. For production purposes, a lead frame panel 110 made up of multiple lead frames 120 is etched or stamped from a thin sheet of metal, as shown in FIG. 1a. An IC chip 130 is then mounted and wire bonded to each lead frame 120, as shown in FIG. 1b. Wire bonding is typically performed using fine gold wires 140. Each IC chip 130 is then encapsulated in a protective casing 160 which may be formed by dispensing and molding a layer of encapsulant material over all IC chips 130. Next, lead frames 120 are cut apart, or singulated to produce individual IC packages 190.
As seen in
The present invention embodiment shown in
The embodiment of the present invention shown in
Similarly, numerous implementations of adhesive pad 220 are possible. Any material compatible with the IC package assembly process and capable of providing the necessary support to the lead frame panel and IC chips can be used. The sticky tape mentioned previously is a convenient choice due to widespread current usage and availability. The use of one-sided sticky tape enables pad 220 to be applied to the bottom surface of frame 210 and provide an adhesive surface for mounting of lead frame panel 110, without requiring additional attachment materials or components. Pad 220 can also be patterned by removing selected portions in order to facilitate subsequent assembly operations such as electrical interconnection formation. Removal of pad 220 once packaging is complete can be performed in various ways, depending on the nature of the adhesive material used. A light adhesive material may allow pad 220 to simply be peeled away from frame 110. An alternative bonding agent requires exposure to UV light before removal of pad 220 can take place.
In this manner a lead frame BGA IC package can be produced using a temporary support structure. This enables the production of IC packages using lead frames that would otherwise be too fragile to withstand conventional manufacturing processes. It should be noted that while particular embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that many modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. For example, the wafer saw operation of step 370 can be performed prior to removal of support fixture 200 from lead frame panel 110. Also, solder balls 150 could be applied to lead frames 120 in step 370 prior to singulation. Alternatively, appropriately located openings in adhesive pad 220 would allow solder balls 150 to be applied without removing pad 220. Certain lead frame designs may even allow patterning of pad 220 such that removal is unnecessary. Finally, while the present invention has been described with reference to chip scale IC package manufacturing, it can be applied to any IC package manufacturing process involving lead frames, including non-chip scale and non-BGA IC packages such as SOP's, PLCC's, and PTH packages.
Mostafazadeh, Shahram, Smith, Joseph O.
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