Methods of and apparatus for aligning and bonding workpieces

Abstract

Bonding machines have transparent elements on their bonding axes. Magnified optical means are positioned to view bonding tips and integrated-circuit chips simultaneously through the transparent elements thereby facilitating alignment of the chips to the tips. In one embodiment a bonding tip is transparent and a transparent compliant bonding member is utilized in conjunction with the tip to produce compliant bonds. Another embodiment utilizes a transparent tip in a "hard tip" type of bonding operation. A third embodiment utilizes a transparent tray closely positionable to the bonding tip. After alignment of the tip to one of the chips is achieved the tray is removed and bonding proceeds on an accurately positioned substrate.

What is claimed is: 
     
       1. In a method of compliant bonding wherein metal-to-metal bonding of a first workpiece to a second workpiece is accomplished by the steps of clamping said workpieces together around the desired bond region between a support and a deformable compliant member, said member being capable of deformation around one of said workpieces, and applying sufficient thermal and/or mechanical bonding energy to said bond region to deform said member around said one workpiece and bond said workpiece, the improvement which comprises the steps of: providing that said compliant member is transparent, and   viewing the workpieces through said transparent compliant member while aligning said workpieces to each other whereby said alignment is facilitated.   
     
     
       2. A method for compliantly bonding a first workpiece to a second workpiece, which comprises: aligning the first workpiece to a predetermined portion of a transparent compliant bonding member said member being capable of deformation around one of said workpieces while viewing the workpiece through the member;   engaging the aligned first workpiece with the member;   aligning the engaged first workpiece with a predetermined portion of the second workpiece while viewing said workpieces through the member; and   compressively engaging, for a predetermined period, a bonding tip against the said portion of said second workpiece with the first workpiece and the compliant member therebetween to effect compliant bonding between the workpieces while viewing said workpieces through the member.   
     
     
       3. A method for thermocompression bonding a beam-lead integrated circuit chip to a substrate, which comprises: aligning the chip to a predetermined portion of a transparent tip while viewing the chip through the tip;   engaging the aligned chip with the tip; aligning the leads of the engaged chip with a predtermined portion of the substrate while viewing the chip and substrate through the tip; and   compressively engaging for a predetermined period the tip against said portion of said substrate with the leads of the chip therebetween to effect bonding between the leads and the substrate while viewing said leads through the tip.   
     
     
       4. A method of bonding first workpieces to second workpieces, which comprises the steps of: supporting a plurality of the first workpieces on a transparent tray;   moving the tray into intersecting relationship with a bonding axis of a bonding machine;   viewing along the bonding axis with a magnifying optical system through the transparent tray to simultaneously visualize a bonding tip and any of the first workpieces or portions thereof which are on or near the bonding axis;   manipulating the supporting tray in response to the visualization to align one of the first workpieces with the tip;   moving the tip along the bonding axis to engage the tip with the aligned first workpiece;   moving the tip to a retracted position;   moving the tray out of intersecting relationship with the bonding axis;   placing a second workpiece into a pre-positionable location so that a desired portion of the second workpiece is aligned with the bonding axis; and   moving the tip and the engaged first workpiece into compressive relationship with the second workpiece to effect bonding between the first workpiece and the desired portions of the second workpiece.   
     
     
       5. The method of bonding of claim 4 wherein the first workpieces are beam-lead integrated-circuit chips, the second workpieces are substrates and bonding is effected between the leads of the chips and conductive elements formed on the surface of the substrates. 
     
     
       6. In a bonding apparatus, a system for aligning a workpiece with a bonding tip which comprises: a transparent tray for supporting the workpiece;   optical magnification means having a predetermined depth of field for viewing the workpiece and the bonding tip through the transparent tray;   means for supporting the transparent tray close enough to the bonding tip so that the tip and the workpiece are simultaneously within the depth of field of the optical magnification means; and   means for manipulating the transparent tray to align the workpieces with the bonding tip.   
     
     
       7. An apparatus for bonding beam-lead integrated circuit chips to conductive elements on substrates which comprises: a bonding tip;   a transparent tray for supporting a plurality of the chips;   means for moving the tray into and out of intersecting relationship with the bonding axis;   magnifying optical means for viewing simultaneously the bonding tip and the chips or portions thereof which are on or near the bonding axis when the transparent tray intersects the bonding axis;   means for manipulating the tray in response to an image of the tip and the chips as seen through the magnifying optical means to align one of the chips with the tip;   means for moving the bonding tip along the bonding axis to engage the tip with the aligned chip and returning the tip to a retracted position;   a removable support block having two intersecting reference surfaces thereon and having a clamp assembly thereon for maintaining a desired portion of the conductive elements of the substrate at a desired location with respect to the reference surfaces of the block;   at least two stop members against which the reference surfaces of the block can be placed, the stop members being adjustable positionable with respect to the bonding axis, in a plane intersecting the axis, such that the desired portion of substrate can be aligned with the bonding axis when the support block is located against the stop members; and   means for moving the bonding tip and the engaged chip into compressive engagement with the conductive elements of one of the substrates held in the desired location on the block against the stop members to effect bonding between the leads of the chip and the conductive elements of the substrate.   
     
     
       8. Apparatus for thermocompression bonding a first workpiece to a second workpiece, which comprises: a bonding head capable of transmitting light through at least a tip portion thereof;   means for aligning said first workpiece to a predetermined portion of the tip;   means for engaging said aligned first workpieces to said tip;   means for aligning the engaged first workpiece with a predetermined portion of the second workpiece;   means for compressively engaging for a predetermined period the tip against the said portion of said second workpiece with the first workpiece therebetween to effect bonding between the workpieces; and   means for viewing the first workpiece and said predetermined portion of the second workpiece through the light transmitting portion of the tip whereby said alignment of the first workpiece to the tip, the alignment of the first workpiece to the second workpiece and the compressive engagement between the workpieces is performable in response to visual information transmitted through said viewing means.   
     
     
       9. The apparatus of claim 8, which further comprises: means for engaging a transparent compliant member with the tip whereby the apparatus can be made capable of producing compliant bonds.   
     
     
       10. The apparatus of claim 9 wherein the head comprises: a hollow chamber internal of said head, the chamber being formed and located so that bonding axis passes two sides thereof;   being closed on one of its sides through which the bonding axis passes by the transparent engagement portion being in communication with the aperture in the engagement portion;   being closed at the opposite one of the sides through which the bonding axis passes by a transparent member; and   having an aperture in one of the sides other than those through which the bonding axis passes which aperture is connectable to the vacuum source whereby the connection to the vacuum source is remote from the bonding axis and visibility along the axis is not impaired by such connection.   
     
     
       11. The apparatus of claim 8 wherein the bonding head includes a transparent engagement portion and the means for engaging the first workpiece with the head includes an aperture in said engagement portion connectable to a source of vacuum whereby said first workpiece can be held against said head by the forces of the vacuum source. 
     
     
       12. The apparatus of claim 11 wherein the aperture in the engagement portion is shaped to accommodate a body portion of a beam-lead integrated-circuit chip while leads of the chip bear against the engagement portion. 
     
     
       13. The apparatus of claim 8 wherein the bonding head includes a transparent engagement portion which is quartz. 
     
     
       14. The apparatus of claim 8 wherein the bonding head includes a transparent engagement portion which is glass. 
     
     
       15. In an apparatus for compliant bonding wherein metal-to-metal bonding of a first workpiece to a second workpiece including means for clamping said workpieces together around the desired bond region between a support and a deformable compliant member, said member being capable of deformation around one of said workpieces and means for applying sufficient thermal and/or mechanical bonding energy to said bond region to deform said member around said one workpiece and bond said workpiece, the improvement which comprises: the compliant member being transparent; and   the apparatus having means for viewing the workpieces through the transparent compliant member whereby alignment of the workpieces with each other and with the compliant member is facilitated.   
     
     
       16. The apparatus of claim 15 wherein the compliant member is formed of a film of polyimide film. 
     
     
       17. In a bonding head wherein a first workpiece to be bonded to a second workpiece is held in engagement with the head on a bonding axis prior to engagement with the second workpiece, the improvement which comprises: the bonding head being transparent along the bonding axis whereby the engaged first workpiece is visible through the head, the second workpiece is visible through the head when the engaged first workpiece overlies the second workpiece and alignment between the workpieces is facilitated because of such visibility.   
     
     
       18. The bonding head of claim 17 which comprises: a transparent engagement portion against which the first workpiece bears, and   an aperture in said engagement portion connectable to a source of vacuum whereby said first workpiece can be held against said head by the forces of the vacuum source.   
     
     
       19. The bonding head of claim 18 which comprises: a hollow chamber internal of said head, the chamber being formed and located so that bonding axis passes two sides thereof;   being closed on one of its sides through which the bonding axis passes by the transparent engagement portion being in communication with the aperture in the engagement portion;   being closed at the opposite one of the sides through which the bonding axis passes by a transparent member; and   having an aperture in one of the sides other than those through which the bonding axis passes which aperture is connectable to the vacuum source whereby the connection to the vacuum source is remote from the bonding axis and visibility along the axis is not impaired by such connection.   
     
     
       20. The bonding head of claim 18 wherein the aperture in the engagement portion is shaped to accommodate a body portion of a beam-lead integrated-circuit chip while leads of the chip bear against the engagement portion. .Iadd. 21. A bonding tool for attaching a plurality of preformed electrical connectors on a semiconductor device to a plurality of electrical conductors on a substrate or carrier, said bonding tool comprising: an elongated body, means on the body for mounting the bonding tool on a bonding machine, a central observation opening through the body which is larger than the semiconductor device to be bonded, said central observation opening in said elongated body having a transparent and non diffused field of view therethrough encompassing the area defined by the preformed electrical connectors on the semiconductor device, and a transparent bonding wedge having a substantially flat working face thereon mounted on the lower end of the body in the central observation opening for pressing said preformed electrical connectors into engagement with said electrical conductors to effect bonding attachment thereto while observing and aligning the connectors with the conductors through the central observation opening. .Iaddend..Iadd. 22. A bonding tool as set forth in claim 21 wherein said transparent bonding wedge is provided with a central aperture therein and said working face extends outwardly therefrom. .Iaddend..Iadd. 23. A bonding tool as set forth in claim 22 wherein said working face on said bonding wedge projects downwardly away from said bonding wedge to permit the tip of the bonding tool to pick up a device out of an array of a plurality of devices. .Iaddend. .Iadd. 24. A bonding tool as set forth in claim 21 which further includes vacuum means attached to the upper part of body. .Iaddend..Iadd. 25. A bonding tool as set forth in claim 24 wherein said vacuum means provides the means for mounting the bonding tool on a bonding machine. .Iaddend..Iadd. 26. A bonding tool as set forth in claim 25 wherein said central observation opening is closed at the top with a transparent cap. .Iaddend..Iadd. 27. A bonding tool as set forth in claim 22 which further includes a heating coil on the outside of said body near the transparent bonding wedge. .Iaddend. .Iadd. 28. A bonding tool for picking up and attaching a beam lead semiconductor device to a conductive pattern on a substrate or carrier, said tool comprising, an elongated body, a central observation opening through the length of the elongated body, said opening being substantially larger than the beam lead device to be picked up and bonded to the substrate, a transparent bonding wedge on the lower end of the elongated body, an aperture in said bonding wedge smaller than the device to be picked up and bonded to the substrate, a working face on said bonding wedge extending outwardly and downwardly from said aperture for engaging only the leads of the beam lead device, and means for connecting a negative pressure source to said bonding tool whereby a beam lead device is observed and aligned with the bonding wedge during pickup and the leads of the beam lead device are observed and aligned with the conductive pattern on the substrate during attachment. .Iaddend.