Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With contact or lead
Reexamination Certificate
1997-08-27
2001-08-07
Williams, Alexander O. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With contact or lead
C257S797000, C257S694000, C257S666000, C257S668000, C257S207000, C257S773000, C257S723000, C257S701000, C174S050510, C206S323000, C206S701000, C206S725000, C206S722000
Reexamination Certificate
active
06271584
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns an arrangement in the mounting of semiconductor components on a bearer strip, whereby the components are placed on the bearer strip in at least two parallel rows in the longitudinal direction and are provided with a covering or sheath made of plastic, which can be manufactured in a corresponding mold by means of the usually lateral supplying of free-flowing plastic molding material.
The manufacturing of semiconductor modules containing electronic components preferably ensues by mounting the electronic components on a bearer strip. There are a predetermined number of electronic components on this strip. With this bearer strip, the components are transported through the various processes for manufacturing the semiconductor modules. Meanwhile, due to increased demands on the packing density of the components on this bearer strip, i.e. for the increasing of the packing density, not only one component is assembled, electrically connected and extrusion-coated with plastic. Rather, several components are deposited one after the other in series on a bearer strip and are each correspondingly processed to form a semiconductor module. The next step in the increasing of the packing density is to arrange several such rows next to one another and to arrange them in parallel in the longitudinal direction on a bearer strip. Thus, in the first view corresponding to the multiplication of the components, a corresponding multiplication of the capacity on a bearer strip (e.g. a lead frame) could be manufactured. However, this presupposes a spacing between the individual components that remains the same. However, as a result of the method this encounters problems in the sheathing with a plastic (pressing compound) that is for example duroplastic. This step of the process provides the covering or sheathing of the arrangement of the individual components with the plastic, whereby this takes place in a corresponding mold, a cavity. As a rule, the free-flowing plastic is thereby guided from an outer edge of the bearer strip (lead frame) to the individual components. Since in the arrangement of the components with an increased packing density and several parallel rows of components are however to be reserved for the free-flowing plastic [sic], a faultless covering with plastic is no longer guaranteed for such arrangements.
The previous tendency in the manufacturing of semiconductor modules was to minimize the consumption of raw material in the lead frame and in the quantity of plastic. The currently existing consumption data are a general standard. In addition, the capacity of the molds in a production line is first of all limited in a production line without the production of new molds. In these regards, the minimization of the spacing between the components on a bearer strip has also been the declared aim of an economical production.
However, extraordinary advantages can be gained by a parallel arrangement of several rows of components.
SUMMARY OF THE INVENTION
The underlying aim of the invention is to provide an arrangement of electronic components on a bearer strip by means of which semiconductor modules as described above can be manufactured with good quality in a manufacturing process that essentially remains the same.
In an embodiment, the invention provides a device comprising a bearer strip having a predetermined number of electronic components arranged thereon in at least two parallel rows, wherein the components are separated by minimum spacing in a longitudinal direction of the bearer strip, the components being sufficiently separated to allow for the supply of a free flowing plastic molding compound onto a corresponding mold between adjacent components.
The invention is based on the knowledge that a qualitatively good covering or sheathing with plastic can be produced with the parallel arrangement of electronic components on a bearer strip, if an expansion of the spacing of the components, regarded in the longitudinal direction (pitch) is carried out. The enlargement of the spacing of the components is not uniform, but rather leads to different spacing, according to the placement of the components during the covering or, respectively, sheathing with a free-flowing plastic molding material. Since, as a rule, the plastic molding material is supplied laterally from an outer edge of a lead frame, for this supplying of molding compound a corresponding space requirement for the plastic has to be provided between the rows arranged in parallel and between the components themselves. In general, it can be said that the space requirement necessary for the supply of molding compound corresponds to the expansion or enlargement of the pitch.
These and other features of the invention are discussed in greater detail below in the following detailed description of the presently preferred embodiments with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The sole FIGURE illustrates a segment of a bearer strip that can be employed in the invention.
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Barchmann Bernd
Fischer Siegfried
Gruber Otto
Juri Walter
Petz Martin
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
Williams Alexander O.
LandOfFree
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