Semiconductor chip assembly system with a suction nipple for...

Semiconductor device manufacturing: process – Semiconductor substrate dicing – With attachment to temporary support or carrier

Reexamination Certificate

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Reexamination Certificate

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06727162

ABSTRACT:

BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a semiconductor chip assembly system with a suction nipple for removing a semiconductor chip from a carrier film and for positioning and setting down the semiconductor chip in a component position of a lead frame for electronic components.
With increasing miniaturization of semiconductor chips, in particular with increasing reduction of the volume of the semiconductor chips by reducing the thickness of the semiconductor chips by etching or grinding them thin, to a thickness of only a few tenths of micrometers, the handling of semiconductor chips in a semiconductor chip assembly system is becoming increasingly more difficult. At present, the failure rate when using standard handling tools in a semiconductor chip assembly system is already approximately 20%. With such a high proportion of damaged miniaturized semiconductor chips, in particular in the case of semiconductor chips intended for radio-frequency applications, it is necessary to reduce the failure rate. Particularly high failure rates occur in semiconductor chip assembly systems that are used for “die bonding”. In this case, the semiconductor chip is removed from a carrier film that is adhesive on one side and brought into a position in which the semiconductor chip is fixed on a chip island of a lead frame in a component position for producing an electronic component.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a semiconductor chip assembly system with a suction nipple for removing a semiconductor chip that overcomes the above-mentioned disadvantages of the prior art devices of this general type, with which the failure rate in the handling and transporting of the semiconductor chip within the semiconductor chip assembly system is reduced.
With the foregoing and other objects in view there is provided, in accordance with the invention, a semiconductor chip assembly system. The system contains a suction nipple for removing a semiconductor chip from a carrier film and for positioning and setting down the semiconductor chip in a component position of a lead frame for electronic components. The suction nipple includes a dimensionally stable cylindrical mouthpiece with a suction bore formed therein, a rubber-elastic region adjoining the cylindrical mouthpiece, and a dimensionally stable suction tube attachment extending from the rubber-elastic region.
According to the invention, a semiconductor chip assembly system is provided, which system is equipped with a suction nipple for picking up a semiconductor chip from a carrier film and at the same time holds the semiconductor chip for positioning it and setting it down in a component position of a lead frame for electronic components. For this purpose, the suction nipple has a dimensionally stable cylindrical mouthpiece with a suction bore, which is adjoined by a rubber-elastic region of the suction nipple which goes over into a dimensionally stable suction tube attachment.
When a suction nipple is used in a semiconductor chip assembly system, it is under vacuum as soon as a surface of the semiconductor chip closes its suction opening. The dimensionally stable configuration of a cylindrical mouthpiece has the effect of ensuring that the mouthpiece does not collapse, deform or in some other way damage or lose the semiconductor chip during the manipulation within the semiconductor chip assembly system. What is more, the dimensionally stable cylindrical mouthpiece has the effect of ensuring that the surface of the semiconductor chip can support itself on a dimensionally stable surface of the cylindrical mouthpiece.
The rubber-elastic region of the suction nipple adjoining the mouthpiece allows the nipple to adapt itself to the position of the upper side of the semiconductor chip without exerting damaging pressure on the semiconductor chip. Rather, the mouthpiece is rubber-elastically cushioned and can consequently be set down gently on the surface of the semiconductor chip. The adjoining dimensionally stable suction tube attachment of the suction nipple ensures that the suction tube attachment of the suction nipple can be connected in a gastight manner to a corresponding vacuum tube or a vacuum line. In this case, the dimensionally stable suction tube attachment supplies the rubber-elastic region and the dimensionally stable cylindrical mouthpiece of the suction nipple with a vacuum during operation, without itself collapsing and consequently putting at risk the secure holding of the semiconductor chip.
The inside diameter of the suction tube attachment is many times greater than the suction bore of the cylindrical mouthpiece. The rubber-elastic region consequently forms the transition from the suction bore to the many times greater diameter of the suction tube attachment. For this purpose, the rubber-elastic region has an inner cone and an outer cone, which between them has a thin rubber-elastic wall. The configuration of the inner cone and outer cone allows the elasticity of the rubber-elastic region to be varied and set to the requirements of the semiconductor chip assembly system for miniaturized semiconductor chips. The choice of the same slope of the inner cone and outer cone allows a constant wall thickness of a rubber-elastic material from the suction tube attachment to the mouthpiece to be realized. The wall thickness itself may in this case be made to match very precisely the loading capability of the semiconductor chips to be held.
To achieve decreasing elasticity of the rubber-elastic region with increasing deformation of the rubber-elastic region, this region may have between the inner cone and the outer cone a wall thickness of a rubber-elastic material that becomes thinner toward the mouthpiece. If there is slight deflection of the cylindrical mouthpiece in the axial direction, consequently a high rubber-elasticity is initially provided, decreasing as the degree of deformation of the rubber-elastic region increases. With such a configuration of the suction nipple, the deformation resistance becomes greater as the deformation of the rubber-elastic region of the suction nipple increases.
The size of the rubber-elastic region is substantially determined by the area ratio between the cross section of the suction bore of the mouthpiece and the inner cross section of the suction tube attachment. To achieve effective cushioning by the rubber-elastic region of the cylindrical mouthpiece, this area ratio lies between 1:9 and 1:16.
Apart from the area ratio, the length of the rubber-elastic region in the axial direction is decisive for the elasticity of the region. The greater the length, the more rigid the rubber-elastic region becomes in the axial direction. A preferred ratio between the length of the rubber-elastic region in the axial direction in relation to the inside diameter of the suction tube attachment lies between 1:2 and 1:4. The smaller the ratio becomes, the softer and more elastic the rubber-elastic region will act. However, if the ratio goes below 1:4, the risk increases of the vacuum within the suction tube attachment alone causing the dimensionally stable mouthpiece to be inverted into the interior space of the suction tube attachment and the suction nipple consequently no longer being serviceable.
The ratio of the length of the rubber-elastic region in the axial direction to the diameter of the suction bore of the mouthpiece should also not exceed a range from 1:1 to 3:1. Here, too, outside this range there is, on the one hand, a risk of the rubber-elastic region becoming rigid and, in the opposite direction, the risk of the mouthpiece being inverted into the interior space of the suction tube attachment.
To ensure the dimensional stability of the cylindrical mouthpiece and of the suction tube attachment in comparison with the rubber-elastic region, the wall thickness of the rubber-elastic region may be less than or equal to the wall thickness of the cylindrical mouthpiece and, in any event, less than the wall thickness of the suction tube attac

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