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Researchers Submit Patent Application, "Method for Detaching a Semiconductor Chip from a Foil", for Approval

August 6, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Barmettler, Ernst (Emmenbrucke, CH); Rodriguez, Irving (Hermetschwil, CH), filed on November 20, 2013, was made available online on July 24, 2014.

The patent's assignee is Besi Switzerland AG.

News editors obtained the following quote from the background information supplied by the inventors: "The semiconductor chips are typically provided on a foil held by a frame, which is also known in the field as a tape, for processing on a semiconductor mounting apparatus, a so called die bonder. The semiconductor chips adhere to the foil. The frame with the foil is accommodated by a displaceable wafer table. The wafer table is displaced in order to supply one semiconductor chip after the other at a location and the supplied semiconductor chip is taken up by a chip gripper and placed on a substrate in cycles. The removal of the supplied semiconductor chip from the foil is supported by a chip ejector (known in the field as a die ejector) arranged beneath the foil.

"The detachment of a semiconductor chip typically occurs in two phases, namely a first phase in which the semiconductor chip is detached at least partly from the foil by the die ejector without assistance by the chip gripper, and a second phase in which the chip gripper grips the semiconductor chip and detaches the same completely from the foil. The first phase is known by experts as 'prepeeling' phase. The die ejector comprises mechanically movable means such as needles or a displaceable carriage or several plates that can be lifted and lowered, and several parameters which determine how the mechanical means are moved need to be determined and set in a setup phase. The parameters need to be set in such a way that the prepeeling process occurs within the shortest possible period of time on the one hand and the semiconductor chip is not damaged on the other hand. If the prepeeling process is performed too rapidly, there is a likelihood that the semiconductor chip will break apart."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "It is the object of the present invention to improve the detachment of a semiconductor chip from the foil during the prepeeling phase.

"The invention generally relates to methods for detaching a semiconductor chip from the foil during the prepeeling phase. The prepeeling phase is the phase during which the chip gripper is not involved in the detachment. In accordance with a first aspect, the invention relates to such a method comprising a setup phase for determining and setting time periods which each defines a duration of a prepeeling step of the detachment process, wherein during each prepeeling step firstly at least one area of the semiconductor chip remains sticked to the foil and is bent and afterwards detaches from the foil. The setup phase comprises the following steps:

"illuminating a semiconductor chip to be removed with light which impinges substantially perpendicularly onto the surface of the semiconductor chip;

"carrying out the following steps for each prepeeling step whose duration is to be determined: initiating the prepeeling step; repeating the two steps: recording of an image of the semiconductor chip and assigning a time period to the image which has passed since the initiation of the prepeeling step, and checking whether in the image a peripheral region of the semiconductor chip is darker than a predetermined brightness value; until the check leads to the result that no peripheral region of the semiconductor chip is darker than the predetermined brightness value; and assigning to the prepeeling step the time period associated with the last recorded image or a time period derived therefrom.

"In accordance with a second aspect, the invention relates to a method in which the detachment of the foil is monitored in realtime during the prepeeling phase. The method comprises the following steps:

"illuminating a semiconductor chip to be removed with light which impinges substantially perpendicularly onto the surface of the semiconductor chip;

"carrying out at least one prepeeling step, in which firstly at least one region of the semiconductor chip remains sticked to the foil and is bent and afterwards detaches from the foil, wherein each of the at least one prepeeling steps comprises the following steps: initiating the prepeeling step; repeating the two steps: recording of an image of the semiconductor chip, and checking whether in the image a peripheral region of the semiconductor chip is darker than a predetermined brightness value; until the check leads to the result that no peripheral region of the semiconductor chip is darker than the predetermined brightness value; and at the end of the last prepeeling step grasping the semiconductor chip by a chip gripper and completing the detachment of the semiconductor chip from the foil.

"The detachment of the semiconductor chip from the foil in the prepeeling phase occurs for example by means of a die ejector with liftable and lowerable plates. In this case, the aforementioned initiation in the prepeeling step contains the lowering of the outermost plates that have not yet been lowered.

"The detachment of the semiconductor chip from the foil in the prepeeling phase can also be performed by means of a carriage that is displaceable parallel to the surface of the foil. In this case, the aforementioned initiation in the prepeeling step comprises the displacement of the carriage by a predetermined distance.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

"The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present invention and, together with the detailed description, serve to explain the principles and implementations of the invention. The figures are not to scale. In the drawings:

"FIG. 1 schematically shows by way of example the mutual arrangement of the components of a semiconductor mounting device which are required for performing the processes in accordance with the invention;

"FIG. 2 shows a top view of an arrangement of liftable and lowerable plates, and

"FIGS. 3-13 show images recorded by a camera."

For additional information on this patent application, see: Barmettler, Ernst; Rodriguez, Irving. Method for Detaching a Semiconductor Chip from a Foil. Filed November 20, 2013 and posted July 24, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5024&p=101&f=G&l=50&d=PG01&S1=20140717.PD.&OS=PD/20140717&RS=PD/20140717

Keywords for this news article include: Electronics, Semiconductor, Besi Switzerland AG.

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Source: Electronics Newsweekly


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