Integrated circuit devices generally include an integrated circuit (IC) chip and a lead frame which are sealed within a protective enclosure. Such IC chip packages, as they are often called, find wide use in consumer electronics, computers, automobiles, telecommunications, military applications, etc. The lead frame electrically couples the IC chip to circuitry (e.g., printed circuit board) external to the package. The lead frame is typically formed from a highly electrically and thermally conductive material, such as copper or copper alloys. The lead frame material is typically stamped or etched into a plurality of leads, and a central area, called a die attach pad, onto which the IC chip is attached. The IC chip is electrically connected to the leads, usually by wire bonding, and the device is encapsulated by a molded structure. Then, the IC chip package is mounted to another component, such as a circuit board, and electrically coupled thereto.
One type of IC chip package-is a quad flat no-lead package. This surface mount chip package includes one or more IC dies encapsulated in mold resin, and a plurality of perimeter leads on the bottom and/or sides thereof for connecting the one or more IC dies to contacts on an associated circuit board or other component.
Disclosed examples include an integrated circuit chip package and method for making the same, wherein the package includes plated conductive leads. In one example, a method for making an integrated circuit chip package comprises providing a premolded lead frame assembly having opposing first and second sides, the premolded lead frame assembly including an array of lead frames at least partially surrounded by a first molded structure, each lead frame including a die attach pad and a plurality of conductive lead structures spaced apart from the die attach pad, the first molded structure interposed at least between adjacent conductive lead structures along a parting line, forming a trench (ditch) in at least one of the plurality of conductive lead structures along the parting line, the trench opening to the second side of the premolded lead frame assembly, plating at least the trench, coupling an integrated circuit die to the die attach pad on the first side of the premolded lead frame assembly, wirebonding the integrated circuit die to the plurality of conductive lead structures on the first side of the premolded lead frame assembly, forming a second molded structure over the die and plurality of conductive lead structures, and singulating the integrated circuit chip package, the singulating including severing the first molded structure, the second molded structure and the plurality of conductive lead structures along the parting line resulting in an integrated circuit chip package having at least one conductive lead with a side portion and a plated recessed portion.
In the drawings, like reference numerals refer to like elements throughout, and the various features are not necessarily drawn to scale. In the following discussion and in the claims, the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are intended to be inclusive in a manner similar to the term “comprising”, and thus should be interpreted to mean “including, but not limited to . . . ” Also, the term “couple” or “couples” is intended to include indirect or direct electrical or mechanical connection or combinations thereof. For example, if a first device couples to or is coupled with a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via one or more intervening devices and connections.
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In process step 308, the array of lead frames is premolded by forming a first molded structure. The first molded structure generally occupies the interstitial regions between the die pads, conductive lead structures and/or any other components of the lead frames.
In process step 312, a trench is formed in the plurality of conductive lead structures of each lead frame along a parting line between adjacent lead frames. As will be described in more detail, the trench can be formed in any suitable manner, including by laser cutting, sawing or an etching process as disclosed herein.
After forming the trench, the conductive lead structures and/or die pads etc. are plated with a suitable material, such as tin etc. in process step 316.
Once plated, IC dies are then mounted (coupled) to the die attach pads in process step 320 and then wirebonded to the conductive lead structures in process step 324. A second molded structure is then formed over the IC dies and lead frames in process step 328.
In process step 332, individual IC chip packages are singulated by separating the same along parting lines to result in the structure shown in
The method 300 will now be described in connection with remaining
As noted above, the premolded lead frame assembly 402 includes first molded structure 220. As shown in
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As compared to other methods of forming a recessed, wettable conductive lead, the present disclosure utilizes only a single plating step after trench formation. In addition, as compared to approaches that do not utilize a premolded lead frame, the first molded structure 220 of the present disclosure acts to block molding material leakage around the conductive lead structures during encapsulation of the IC die with the second molded structure 224. That is, unlike other approaches, the second molded structure 224 is blocked from flowing into the trenched region of the conductive lead structures 406 by the first molded structure 220. This feature facilitates full width trenches that produce conductive leads 112 with full width recessed portions 216 that are less likely to capture burrs and other debris during singulation as compared to partial width trenching (slotted leads) techniques that result in recessed regions of reduced size.
The above examples are merely illustrative of several possible embodiments of various aspects of the present disclosure, wherein equivalent alterations and/or modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. Modifications are possible in the described embodiments, and other embodiments are possible, within the scope of the claims.
Under 35 U.S.C. §119, this application claims priority to, and the benefit of, U.S. Provisional Patent Application No. 62/416,605, entitled “Plated Ditch Pre-Mold Lead Frame for Wettable Flank QFN”, filed on Nov. 2, 2016, the entirety of which is hereby incorporated by reference.
Number | Date | Country | |
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62416605 | Nov 2016 | US |