Semiconductor device manufacturing: process – Formation of electrically isolated lateral semiconductive... – Having substrate registration feature
Reexamination Certificate
1999-07-01
2001-02-20
Trinh, Michael (Department: 2822)
Semiconductor device manufacturing: process
Formation of electrically isolated lateral semiconductive...
Having substrate registration feature
C438S106000, C438S800000, C029S830000, C029S759000, C029S240000, C029S241000, C269S042000, C269S071000, C269S160000, C269S903000
Reexamination Certificate
active
06190997
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for mechanically aligning a carrier substrate for electronic circuits.
BACKGROUND INFORMATION
In the processing of carrier substrates for electronic circuits, such as printed-circuit boards or ceramic substrates, the carrier substrates are aligned in the individual processing stations with respect to a predetermined position. To affix, for example, printed circuit traces or components to the carrier substrates at the positions intended for this, the carrier substrates are mechanically aligned in the fixture of a screen-printing station for imprinting circuit traces or in the fixture of an inserter (automatic component-insertion machine) for affixing electrical and/or electronic components. To this end, it is generally known to use devices for aligning a carrier substrate, which have several centering elements which engage on the peripheral surface of the carrier substrate, shifting the carrier substrate into the desired processing position. The centering elements can be adjusted in the device relative to the carrier substrate by an adjusting device and can be made to engage on the peripheral area of the carrier substrate in a spring-biased manner. By pressing the centering elements against the peripheral surface of the carrier substrate using elastic tensional force, the carrier substrates, whose size varies within a certain range of tolerance, are prevented from being damaged already at the time of engagement of the centering elements.
It must be regarded as disadvantageous in these known devices that when working with relatively brittle carrier substrates, such as ceramic multilayer substrates and, in particular, LTCC substrates, the substrate edges often break off in a muscle-shell shape at places where the centering elements engage, and that sometimes the carrier substrates break into pieces. This is due to the fact that the friction between the stop faces of the centering elements and the peripheral surface of the carrier substrate is quite substantial, and that the centering elements are not movable along the peripheral surface of the carrier substrate, but are only able to be moved towards and away from the peripheral surface. Therefore, a jamming of the carrier substrate between the centering elements cannot be ruled out. As a result, during processing, a short jerky movement produced, for example, by negative pressure applied to the bottom side of the carrier substrate or by the compressive force of an SMD inserter (component-insertion machine) can lead to breakage of the brittle carrier substrate. A further disadvantage is that the rubbing of the carrier substrate at the stop faces of the centering elements leads to premature wear and tear of the centering elements, which can result, in turn, in an imprecise alignment of the carrier substrates, as well as in break edges at the peripheral surface of the carrier substrates.
SUMMARY OF THE INVENTION
The device according to the present invention, which is used to align a carrier substrate for electronic circuits, avoids the disadvantages encountered in the related art. The device according to the present invention advantageously prevents the stop face of the centering elements from rubbing along the peripheral surface of the carrier substrate, for example, when the centering elements shift the carrier substrate into the predetermined position, or when the carrier substrate moves perpendicularly to the horizontal fixture. This advantageously prevents brittle carrier substrates from breaking off in muscle-shell shapes or in pieces. Since in the stations where carrier substrates are processed, forces are generally applied orthogonally to the main surfaces of the carrier substrate, it is a significant advantage that the special arrangement of the centering elements allows all centering elements engaging on the peripheral surface of the carrier substrate to perform a compensating movement by rotating or shifting in this direction, without any mechanical stresses being produced in the carrier substrate. A further benefit is that the mobility of the centering elements engaging on the carrier substrate prevents the centering elements from being subject to any premature wear caused by friction, thereby prolonging the service life of the device.
It is advantageous if the at least two further centering elements are supported on at least two second shafts (spindles) in a manner allowing rotation and axial displacement, the shafts running parallel to each other and perpendicularly to the horizontal fixture. This not only permits the stop faces of these centering elements to move orthogonally to the horizontal fixture of the carrier substrates, but also permits the centering elements to engage optimally on the opposing sections of the peripheral surface of the carrier substrate by executing a rotary motion about the second shafts, even if these sections are not completely plane, which is often true of ceramic LTCC substrates.
It is beneficial for the first shafts to be mounted on their respective adjusting device in a plane beneath a plane defined by the horizontal fixture, for at least one stop element to be arranged on each adjusting device, and for the centering element to be pressed against a stop face of the stop element by the centering element supported on the respective first shaft engaging on the peripheral surface of the carrier substrate. In this manner, the centering elements, movably supported on the first shafts, are not able to rotate upon making contact with the peripheral surface of the carrier substrate; however, the centering elements are still able to rotate in the opposite direction, in the case that the carrier substrate moves toward the fixture. Friction between the centering element in question and the stop face of the stop element in response to a displacement of the centering element on the first shaft can be advantageously avoided by having the stop face of the at least one stop element be movably supported in the second direction. This is easily achieved by forming at least one stop element as a cylindrical roller that is mounted on the respective adjusting device so as to permit rotation about a shaft running perpendicularly to the fixture, the stop face being formed by the lateral surface of the cylindrical roller.
It is also beneficial that the centering elements, which engage on the peripheral surface of a carrier substrate, be mounted on the respective shaft in a manner allowing rotation against the tensional force of a spring element and displacement against the tensional force of a spring element. The advantageous result is that when the carrier substrate is removed from the fixture of the device, the tensional force of the springs moves the centering elements into a defined original position or neutral position, where the centering elements are ready to receive a new carrier substrate.
A further benefit is derived when the centering elements have a plane stop face which engages on the peripheral surface of the carrier substrate. Since ceramic substrates used for electronic circuits generally have the form of a thin rectangular board, the centering elements having the plane stop faces are able to engage securely on the end faces of the ceramic substrates forming the peripheral surface.
It is advantageous for a ball bearing to be used to mount the centering elements on shafts in each case, so as to allow rotation and displacement, and thereby prolong the service life of the device.
Furthermore, it is advantageous if the centering elements of the device are forced to engage successively with the peripheral surface of a carrier substrate in such a way that one of the at least two other centering elements, whose stop faces are movably supported substantially perpendicularly to the horizontal fixture, last engages on the peripheral surface. This ensures that the carrier substrate is not jammed in between the other centering elements which are not able to move in the horizontal direction prior to the engagement of the centering elements whic
Armbruster Eugen
Becker Klaus
Kenyon & Kenyon
Robert & Bosch GmbH
Trinh Michael
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