Multiple Component Assembly Alignment Tool

This invention relates to semiconductor devices, and more particularly to an alignment tool for alignment of integrated circuit package lids for the package.

As the degree of integration of semiconductor integrated circuits increases, greater demands are placed on integrated circuit packaging and assembly. Common among these demands is a need for miniaturization of integrated circuit packages. This miniaturization forces critical consideration of package design criteria. For hermetic packaging, package and lid dimensions are squeezed from both sides, i.e. higher levels of integration resulting in larger semiconductor die sizes which must be accommodated by the package cavity, while integrated circuit users demand the greatest possible density of circuit functions per square inch of circuit board space, driving external package dimensions smaller. Given these demanding package design considerations, lid-to-package alignment accuracy plays a key role in package integrity.

Common techniques for locating integrated circuit package elements during encapsulation consist of two pieces of tooling: a boat that carries and locates the package or substrate, and an alignment cover that locates the other package element or lid during thermal processing, including encapsulation. This technique introduces several sources of variation in package/lid alignment, such as variation in package or substrate dimension which must be accommodated by the boat. This necessary clearance reduces the locational accuracy of the lid relative to the package. Similarly, the alignment cover's positional accuracy is determined by the clearance between its cavity dimension and the lid being located. Also, the relative position of the cover's cavity or lid alignment features to those alignment features of the boat affect package die alignment.

The invention is an integrated circuit package lid alignment tool that minimizes variance of the lid-to-package alignment. An alignment boat has a recessed area in which the package is placed. An alignment cover is positioned over the boat and positioned by alignment tabs that are inserted into openings in the boat, and prevent the alignment cover from moving. Lid tabs on the alignment cover have a chamfer or beveled shape locating the semiconductor package beneath the cover. The lid is placed over the package through an opening in the alignment cover that has been accurately located over the semiconductor package by the alignment tabs.

The lid alignment assembly includes a boat for holding at least one semiconductor package, an alignment cover, mountable to said boat and having at least one opening therein for positioning a lid over the semiconductor package in said boat, and a plurality of tapered tabs extending from said cover, in contact with said semiconductor package, for centering said semiconductor package under said at least one opening in said cover.

The objects of the present invention will become apparent from the following description of a preferred embodiment of the invention when considered in conjunction with the accompanying drawings and the novel features set forth in the appended claims.

FIG. 1 is a top view of the top guide cover of the alignment assembly of the present invention;

FIG. 2 is an end view of the top guide cover of FIG. 1;

FIG. 3 is a top view of a package carrier/boat;

FIG. 4 is a cross-sectional view of the alignment assembly; and

FIG. 5 is an enlarged view of the alignment surfaces.

The invention is an integrated circuit package lid alignment tool that minimizes variance of the lid-to-package alignment. A top view of the alignment tool is illustrated in FIG. 1. Cover 10 may have one or more alignment stations. Each station has an opening 11a into which a device package lid 11 is placed. On each side of opening 11a are tapered alignment tabs 12, 13, 14, 15, 16, 17, 18 and 19. Cover 10 may be a single piece of rigid material with tabs 12-19 die cut out of cover 10 and bent to extend downward from the surface of cover 10. Tabs 12-19 align the semiconductor package with the cover as described below.

FIG. 2 is an end view of cover 10 showing tapered tabs 13, 14, 15 and 16. Tabs 14 and 15 are shown from an end view. Tabs 13 and 15 are shown from a side view, showing the tapered or beveled sides. Legs 20 and 21 are used in conjunction with boat 40 (FIG. 3) to position lid cover 10 over boat 40, and to align cover 10 over boat 40.

FIG. 3 is a top view of the package carrier/boat 40 that is used in conjunction with the cover 10 to align lid 11 to semiconductor package 36 (FIG. 4). A semiconductor package 36 is placed in boat 40 and resides on support surfaces 34 and 35. Openings 20a and 21a receive tapered legs or pins 20 and 21 to align cover 10 over boat 40.

FIG. 4 is a combination cross-sectional view taken through section 4B--4B of FIG. 3, and a cross-section of the cover 10 taken through section A--A of FIG. 1.

Boat 40 has a recessed area which includes bottom supports 34 and 35 on which semiconductor package 36 is placed. The semiconductor package support surfaces 34 and 35 can be provided with a plurality of planar surfaces or facets 37a-e which are dimensioned and configured to cooperate with complementary configured surfaces of the semiconductor package 36 and projecting alignment tabs, such as tabs 12 and 17 depicted in FIG. 4. More particularly, facets 37a and 37b are formed along upwardly-extending flanges 38 and 39 which cooperate with alignment tabs 12 and 17, respectively, to facilitate proper alignment between the tapered surfaces of the cover 10 and the boat 40, as well as any lid 11 and package 36 respectively received therein. With cover 10 in place, tapered tabs 12 and 17 abut against the edges of package 36. The alignment tabs, 12-19 (FIG. 1) will abut against package 36 centering it beneath opening 11a over package 36. Package lid 11, placed in opening 11a, will then also be centered over package 36. Since tabs 12-19 are tapered, variances in package dimensions are taken into consideration, and lid 11 is centered over package 36.

FIG. 5 is an enlarged view of the right side portion of FIG. 4 illustrating the tapered tabs of cover 30 and semiconductor package 36 and the sliding and centering action between semiconductor package 36 and cover 10. While details of the left side portion are not similarly illustrated in an enlarged view, it is to be understood that cooperation between the tapered surfaces of tab 17 and edges of the semiconductor package 36 are the same as that described below regarding the tab 12 and semiconductor package 36. As cover 10 is lowered, angularly inclined tapered face 12b of tab 12 engages edge 36c of package, whereas angularly inclined tapered face 12a engages angularly inclined facet surface 37b of the boat 40 36. Since cover 10 places two tapered tabs (12 and 17) on each side of package 36 (tabs 12-19) for the quadrilateral package depicted in the drawings, package 36 is centered in relation to cover opening 11a. Opening 11a in cover 10 is simultaneously centered over package 36. When package lid 11 is placed in opening 11a over package 36, then lid 11 is centered over package 36. The tapered shapes of tabs 12-19 compensate for variances in package sizes, while still centering lid 11 over package 36.

Although the present invention and its advantages have been described in connection with the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the accompanying claims.