Gull-wing zig-zag inline lead package having end-of-package anchoring pins

Abstract

A semiconductor package having a gull-wing, zig-zag, inline-lead configuration and end-of-package anchoring devices for rigidly affixing the package to a circuit board such that each lead is in compressibe contact with its associated mounting pad on the board. The anchoring devices of a first embodiment comprise anchoring pins having fish-hook-type barbs which lock against the under side of the board when the pegs are inserted through holes in the board; a second embodiment utilizes anchoring pins which are adhesively bonded in recesses that have been drilled or molded into the board; a third embodiment utilizes anchoring pins, the ends of which can be bonded directly to planar peg-bonding regions on the surface of the board; and a fourth utilizes tapered anchoring ping which may be inserted with an interference fit into holes in the board. The invention eliminates the need for mechanical support of the packages during solder reflow operations used during board assembly and repair.

Description

of identical second-embodiment gull-wing ZIP packages 51 are shown bonded to opposite sides of a printed circuit board. It will be noted that, in this case, anchoring pins 52 do not extend from one side of circuit board 53 to the other. Anchoring pins 52 of this particular embodiment have rectangular-cross-section shanks 53. Quick-setting cyano-acrylic adhesive is utilized to bond the cylindrical nubs 54 of anchoring pins 52 in the depressions 55 on board 53. In this embodiment, depressions 55 serve merely as alignment recesses, being incapable of providing vertical support to the packages 51 and maintain the leads 18 in a state of compression against the board bonding pads 19 without the use of an adhesive to anchor the nubs 54 within the depressions 55. The advantage to this approach is that two different molds are not required to provide components to stuff both sides of a circuit board.

Referring now to FIG. 6, a pair of identical third-embodiment gull-wing ZIP packages 61 are shown anchored to opposite sides of a common printed circuit board 63. This embodiment does not require the drilling of anchoring pin holes in the printed circuit board. The third embodiment ZIP package 61 is virtually identical to the second embodiment version depicted in FIG. 5, with the exception that the cylindrical nubs 54 of anchoring pins 52 have been eliminated completely. The end sections 62 of packages 61 have a planar surfaces which are bonded directly to circuit board 63 with quick-setting adhesive. Adhesive displaced during the bonding process is represented by fillet 64.

Referring now to FIG. 7, a single fourth-embodiment gull-wing ZIP package 71 is shown mounted on a circuit board 72. The fourth embodiment ZIP package 71 is also virtually identical to the second embodiment version depicted in FIG. 5, with the exception that cylindrical nubs 54 of anchoring pins 52 have been replaced with tapered extensions 74. A pair of holes 75 have been drilled in circuit board 72. The holes are slightly larger in diameter than the tip of tapered extensions 74 to facilitate positioning of the package on the board with conventional automatic pick and place equipment. However, the hole diameter is smaller than the base of tapered extensions 74, such that when tapered extensions 74 are forced into the holes, friction will retain the gull-wing leads in a compressed state and the package itself in a stable upright position on circuit board 72 until a solder reflow can be effected. The rectangular-cross section shank 76 of anchoring pin 73 limits the insertion depth of tapered extensions 74 into circuit board 72.

Although only certain embodiments of the invention have been described herein, it will be apparent to one skilled in the art that changes and modifications may be made thereto without departing from the spirit and the scope of the invention as claimed.

Claims

1. A vertically-oriented semiconductor package designed for surface mounting on one of a pair of planar surfaces of a printed circuit board, said package comprising:

a body having a pair of substantially parallel, vertical planar sides, lower and upper horizontal edges and a substantially vertical edge at each end of the package;

a semiconductor die having a face on which integrated circuitry is constructed, said die being encapsulated within said body such that said face is positioned between and substantially parallel to the vertical planar sides of said body;

a plurality of gull-wing, zig-zag inline leads, each of which is electrically connected, within said body, to a portion of the circuitry on said die, and each of which extends in a downward direction through the lower edge of said body, below which it is bent such that it is resiliently biased against the planar surface of the circuit board when the package is in a mounted position thereupon;

at least one downward-facing anchoring pin integral with said body at each end thereof; and

means for securely attaching each anchoring pin to the circuit board in order to maintain a mounted position thereupon during solder reflow operations.

2. The semiconductor package of claim 1, wherein said means for securely attaching comprises a barb on the end of each anchoring pin which, when said anchoring pins are inserted from said one surface through properly sized and aligned holes in said circuit board, hooks on the other surface of said circuit board.

3. The semiconductor package of claim 2, wherein each of said anchoring pins has a shoulder that is larger than the diameter of the holes in said circuit board which seats against said one planar surface of said circuit board.

4. The semiconductor package of claim 3, wherein said anchoring pins are molded with an outwardlyfacing outwardly-facing bevel and with inwardly-facing barbs.

5. The semiconductor package of claim 3, wherein said anchoring pins are molded with an inwardlyfacing inwardly-facing bevel and with outwardly-facing barbs.

6. The semiconductor package of claim 1, wherein said means for securely attaching comprises a nub on the end of each anchoring pin which is anchored to a recess in said board with quick-setting adhesive.

7. The semiconductor package of claim 6, wherein each of said anchoring pins has a shoulder that is larger than the diameter of the recesses in said circuit board which seats against said one planar surface of said circuit board.

8. The semiconductor package of claim 1 wherein said means for securely attaching consists of bonding the end of each anchoring pin directly to the planar surface of said board with quick-setting adhesive.

9. The semiconductor package of claim 1, wherein said means for securely attaching comprises a tapered extension on the end of each anchoring pin which, when said anchoring pins are inserted from said one surface through holes in said circuit board that are properly aligned and properly sized for a forcedinsertion fit, said tapered extensions are frictionally locked in said holes.

10. The semiconductor package of claim 9, wherein each of said anchoring pins has a shoulder that is larger than the diameter of its corresponding hole in said circuit board, said shoulder seating against said one planar surface of said circuit board.

11. The semiconductor package of claim 10, wherein said tapered anchoring pin extensions are longer that the thickness of said circuit board.

12. A circuit board/semiconductor package assembly comprising a circuit board, a first gull-wing ZIP zig-zag inline lead semiconductor package having a pair of anchoring pins molded with an inwardly-facing bevel and with outwardly-facing barbs, and a second gull-wing ZIP zig-zag inline lead semiconductor package having a pair of anchoring pins molded with an outwardly-facing bevel and with inwardly-facing barbs, one anchoring pin of each of said first and second packages sharing a first anchoring hole in said board and the remaining pin of each of said first and second packages sharing a second anchoring hole in said board.

13. A semiconductor package, designed for surface mounting on one of a pair of planar surfaces of a printed circuit board, said package comprising:

a body having a pair of substantially parallel, vertical planar faces, lower and upper horizontal edges, and a substantially vertical edge at both ends thereof;

a semiconductor die having a face on which integrated circuitry is constructed, said die being encapsulated within said body such that said face is positioned between and substantially parallel to the vertical planar faces of said body; and

a plurality of inline leads, each of which is electrically connected, within said body, to a portion of the circuitry on said die, and each of which extends in a downward direction through the lower edge of said body such that when said package is mounted on said circuit board, said leads are in compressive contact with said planar surface; and

at least one downward-facing anchoring pin integral with said body at each end thereof;

said anchoring pin having a barb on the end thereof which, when said anchoring pin is inserted from said one surface through properly sized and aligned holes in said circuit board, hooks on the other surface of said circuit board. 14. The semiconductor package of claim 13, wherein each said anchoring pin has a shoulder that is larger than the diameter of the holes in said circuit board which seats against said one

planar surface of said circuit board. 15. The semiconductor package of claim 14, wherein said anchoring pins are molded with an outwardly-facing bevel and with inwardly-facing barbs. 16. The semiconductor package of claim 14, wherein said anchoring pins are molded with an inwardly-facing bevel and with outwardly-facing barbs. 17. A semiconductor package, designed for surface mounting on one of a pair of planar surfaces of a printed circuit board, said package comprising:

a body having a pair of substantially parallel, vertical planar faces, lower and upper horizontal edges, and a substantially vertical edge at both ends thereof;

a semiconductor die having a face on which integrated circuitry is constructed, said die being encapsulated within said body such that said face is positioned between and substantially parallel to the vertical planar faces of said body; and

a plurality of inline leads, each of which is electrically connected, within said body, to a portion of the circuitry on said die, and each of which extends in a downward direction through the lower edge of said body such that when said package is mounted on said circuit board, said leads are in compressive contact with said planar surface; and

at least one downward-facing anchoring pin integral with said body at each end thereof;

said anchoring pin having a nub on the end thereof which is non-frictionally anchored within an alignment recess in said board with

quick-setting adhesive. 18. A semiconductor package, designed for surface mounting on one of a pair of planar surfaces of a printed circuit board, said package comprising:

a body having a pair of substantially parallel, vertical planar faces, lower and upper horizontal edges, and a substantially vertical edge at both ends thereof;

a semiconductor die having a face on which integrated circuitry is constructed, said die being encapsulated within said body such that said face is positioned between and substantially parallel to the vertical planar faces of said body; and

a plurality of inline leads, each of which is electrically connected, within said body, to a portion of the circuitry on said die, and each of which extends in a downward direction through the lower edge of said body such that when said package is mounted on said circuit board, said leads are in compressive contact with said planar surface; and

at least one downward-facing anchoring pin integral with said body at each end thereof;

the end of said anchoring pin having a planar surface which is bondable directly to the planar surface of said board with quick-setting adhesive.