The increasing complexity and compactness of present day electronic manufacturing provides increased packing density of various elements on semiconductor substrates and other electronic assemblies, such that a need exists for apparatus for holding and aligning preforms and especially preforms in the form of elongated elements, such as columns, or pins or the like, to facilitate appropriate mounting of these elements on similarly arrayed sites of an electronic component such as a substrate or package.
In the prior art, various devices for positioning discrete elements, such as solder balls, on electronic substrates have been provided. Typical of such arrangements, are devices which employ a vacuum for securing solder balls in a predetermined array in apertures of a principal face of a fixture for subsequent engagement of the solder balls with conductive pads, or other sites, on an electronic assembly.
In these prior art arrangements, the apparatus applies a vacuum to the fixture to provide a suction to secure a plurality of solder balls within apertures on a principal face of the fixture in an array that is complementary to select sites on an electronic substrate. Then, the fixture is appropriately positioned over the substrate with its arrayed solder balls essentially touching the selected sites of the electronic assembly, and subsequently upon termination of the vacuum, the solder balls are released from the fixture to their respective sites.
While the above noted arrangements are well utilized in the construction of electronic devices, they still suffer from various disadvantageous. That is, as electronic assemblies continue to increase in complexity, additional needs such as more compact substrates and board designs are also required. With these requirements, users also simultaneously demand ever smaller and more portable devices that not only retain the capacity of larger devices but also provide increased capabilities. Hence, to meet these needs and demands, the packing density of electronic assemblies continues to rapidly increase. And as to be expected, with both increased capacity requirements and miniaturization, still ever greater burdens are placed upon the density and compactness of sites such as conductive pads on electronic substrates.
In order to satisfy this ever increasing density of sites on electronic substrates, an ever higher degree of precision is required in the placement of discrete elements, and especially elongated elements such as columns or pins on the substrate sites. In the prior art, solder balls are often rigidly held by the applied vacuum within conical or stepped apertures in the fixture's principal face. However, the discontinuities resulting from these conical or stepped apertures often result in offsetting, and in many cases, jamming of the preforms in their receiving apertures.
Moreover, such discontinuities often trap debris which, in turn, will contribute to offsetting or jamming of the solder in their receiving apertures. These problems not only effect the precise positioning of the preforms in the fixture's array but, in addition to termination of the vacuum, often also require application of other mechanical forces to drive the tightly held solder balls from the fixture.
In turn, the difficulties of the above noted devices are further complicated where columns, including rods, pins, or other elongated preforms, rather than ball shaped preforms are utilized for mounting on electronic assemblies. For example, debris trapped in a conical, or stepped end of a column receiving hole can not only result in tipping and possible jamming of the column, but also can provide considerable variation in the relative position of their exterior ends.