The present invention relates in general to semiconductor bridges and, in particular, to a surface mountable, semiconductor bridge die having rectangular, plated-through “half-holes” which facilitate the solderable connection of the semiconductor bridge die to a header.
A semiconductor bridge (“SCB”) die device has typically been configured to include a pair of conductive lands connected together by a narrower conductive bridge segment. The bridge segment may be formed from doped or undoped silicon, either alone or having an upper layer of a metal such as tungsten or titanium disposed thereover. The lands may also comprise silicon, oftentimes covered with a layer of, e.g., aluminum. Other configurations of the die exist in the art. The conductive lands are commonly connected to a source of electrical energy (e.g., an active power source or a stored charge device such as a capacitor). For use as an explosive initiator or igniter, the bridge segment is typically placed in close physical contact with an explosive charge (e.g., a pyrotechnic material charge). In various embodiments of these devices, an electrical current passing through the bridge causes plasma to form from the electrically activated bridge material, wherein the plasma subsequently initiates or ignites the explosive charge. The explosive charge may be connected by, e.g., a shock tube, to a detonator device that detonates upon initiation or ignition of the explosive charge by the SCB device.
In addition, the SCB die is typically connected to a header device. The header may comprise ceramic, glass, metal or other suitable material. The bottom surface of the SCB die may connect to the top surface of the header by, e.g., a soldered connection or epoxy. Besides this physical connection of the SCB die to the header, an electrical connection from the electrically conductive SCB die to pins (typically two pins) on the header also exists. The header pins are then connected to the electrical power source.
Prior art SCB devices typically utilize bondwires (e.g., 5 mils in diameter) to make an electrical connection from the top surface of the die (i.e., from the metallized conductive lands on the die) to the pins or other suitable contact areas on the header. However, issues regarding the use of bondwires may include bondwire cutoff smearing aluminum across the glass seal which surrounds the pin to be wirebonded, sub-optimal bondwire configuration for relatively small geometry applications, minimum powder load requirements to assure the bondwires do not touch the output cup, added header cost due to the unique features required for wirebonding, electrostatic discharge issues, and with respect to high volume applications the cost of capital equipment required for wirebonding at high speed.
For these and other reasons, it is known to eliminate the bondwires and use some type of electrically conductive surface connection between the bottom surface of the SCB die and the top surface of the header. Such a surface mounted SCB die enables igniters with relatively smaller charges to be readily manufactured since the header can be made with a smaller diameter and the minimum powder bed above the die can be reduced, as there are no bondwires that might contact the output cup. However, these and other common known approaches for connecting the SCB die to the header without bondwires (e.g., submounts and wraparound metallization) are relatively limited in their applicability, for example, in that they require relatively tightly controlled header dimensions. Also, these methods are of relatively high cost and not easily manufacturable.
Vertical holes have been manufactured but fabricating die with metal on the insides of the holes has proven problematic. What is needed is a tapered or “slope-sided” SCB die and method for making such a die wherein the resulting die is relatively more easily solderable to the header through use of a surface mounting technique without the use of bondwires, the connection between the die and the header being relatively more reliable, the dimensional requirements of the header are relaxed to a certain degree, and the manufacture of the SCB die and header, along with the soldering of the die to the header, are all of relatively lower cost.
According to an embodiment of the invention, a semiconductor bridge die has an “H-design” configuration in which a center bridge segment is flanked by three angled or sloped walls on each side of the bridge segment. Each wall is plated with a conductive material, thereby providing a continuous conductive path across the top surface of the die. A bottom surface of the die may be connected to a top surface of a header by epoxy in various configurations. The plated angled walls facilitate the solderable connection of the walls to a plated top surface of each of several pins on a top surface of the header, thereby providing a continuous electrical connection between the pins and the die.
According to another embodiment of the invention, a semiconductor bridge die has a “trapezoidal” design configuration in which a center bridge segment is flanked by a single angled or sloped wall on each side of the bridge segment. Each wall is plated with a conductive material, thereby providing a continuous conductive path across the top surface of the die. A bottom surface of the die may be connected to a top surface of a header by epoxy in various configurations. The plated angled walls facilitate the solderable connection of the walls to a plated top surface of each of several pins on a top surface of the header, thereby providing a continuous electrical connection between the pins and the die.
According to another aspect of the invention, a method is provided for manufacturing a semiconductor bridge die in accordance with the various embodiments of the die. For example, a difference between the “H-design” and the “trapezoidal” design configurations of the corresponding dies lies in a dicing step in which more of the “trapezoidal” die is removed by dicing than in the “H-design” die configuration.
The various embodiments of the present invention can be understood with reference to the following drawings. The components are not necessarily to scale. Also, in the drawings, like reference numerals designate corresponding parts throughout the several views.
The present invention is more particularly described in the following description and examples that are intended to be illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. As used in the specification and in the claims, the singular form “a,” “an,” and “the” may include plural referents unless the context clearly dictates otherwise. Also, as used in the specification and in the claims, the term “comprising” may include the embodiments “consisting of” and “consisting essentially of.” Furthermore, all ranges disclosed herein are inclusive of the endpoints and are independently combinable.
As used herein, approximating language may be applied to modify any quantitative representation that may vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially,” may not to be limited to the precise value specified, in some cases. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value.
In an embodiment of the invention, a semiconductor bridge die has an “H-design” configuration in which a center bridge segment is flanked by three angled or sloped walls on each side of the bridge segment. Each wall is plated with a conductive material, thereby providing a continuous conductive path across the top surface of the die. A bottom surface of the die may be connected to a top surface of a header by epoxy in various configurations. The plated angled walls facilitate the solderable connection of the walls to a plated top surface of each of several pins on a top surface of the header, thereby providing a continuous electrical connection between the pins and the die.
In another embodiment of the invention, a semiconductor bridge die has a “trapezoidal” design configuration in which a center bridge segment is flanked by a single angled or sloped wall on each side of the bridge segment. Each wall is plated with a conductive material, thereby providing a continuous conductive path across the top surface of the die. A bottom surface of the die may be connected to a top surface of a header by epoxy in various configurations. The plated angled walls facilitate the solderable connection of the walls to a plated top surface of each of several pins on a top surface of the header, thereby providing a continuous electrical connection between the pins and the die.
According to another aspect of the invention, a method is provided for manufacturing a semiconductor bridge die in accordance with the various embodiments of the die. For example, a difference between the “H-design” and the “trapezoidal” design configurations of the corresponding dies lies in a dicing step in which more of the “trapezoidal” die is removed by dicing than in the “H-design” die configuration.
The foregoing and other features of various disclosed embodiments of the invention will be more readily apparent from the following detailed description and drawings of the illustrative embodiments of the invention wherein like reference numbers refer to similar elements.
Referring to
Referring to
In the embodiment of
The surface of each of the angled or sloped walls 216 may be plated with a conductive material, for example, gold, to facilitate the soldered connection of the die 200 to the header 100, as described in detail hereinafter. A relatively thin layer of nickel (e.g., 2.54 um-5.08 um) may be disposed underneath the gold plating. In an embodiment, the solderable plating is present on the walls 216 of the half-holes 208, and the plating is not on the top portion of the die 200, for example, where the bridge segment 204 is located. Also, the plating may be solderable using eutectic or non-eutectic tin/lead solder or using tin/gold solder. The bridge 204 of the die 200 is also in electrical connection with each of the plated half-hole walls 216. Thus, a continuous electrical connection exists across the die 200 from one side to the other (i.e., between the two half-holes 208). Also, in an embodiment, the width of the opening 212 of each of the half-holes 208 is substantially equal to the diameter of the pins 108 at the top surface 112 of the header, as illustrated in more detail in
Referring to
As noted hereinabove, the die 200 and header 100 device combination may be utilized as a bridge igniter device in which the bridge 204 of the die 200 is in contact with a reactive or explosive material such as a pyrotechnic charge. The pins 108 of the header may have an electrical power source connected across the pins 108 such that when an electrical current is applied through the bridge 204 an initiation or ignition of the reactive or explosive material occurs, which effect may then be used to trigger a detonator device connected further downstream of the reactive or explosive material by, e.g., a shock tube.
Referring to
Thus, as seen from
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Referring to
As an alternative to the use of a small “dot” of epoxy, a stamped epoxy die or an epoxy perform may be utilized. In this embodiment, the die 400 is stamped into a stripe 700 of epoxy 500, as shown in
In any of the embodiments of the epoxy 500, a relatively high temperature epoxy that is compatible with the soldering process may be utilized. That is, the epoxy 500 preferably does not contaminate the solder joints and the epoxy cures within the reflow process prior to solder paste reflow.
Referring to
Embodiments of the invention provide for the elimination of bondwires or epoxy to electrically connect the SCB die to the header. Embodiments of the invention also provide for a relatively more reliable and easier solderable connection of the SCB die to the header. Also due to the design of the SCB die, its dimensional requirements are relaxed and, thus, the cost of the header is less.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. All citations referred herein are expressly incorporated herein by reference.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/168,650, entitled “Surface Mountable Semiconductor Bridge Die”, filed Apr. 13, 2009, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61168650 | Apr 2009 | US |