Magnetic pre-alignment of semiconductor device chips for bonding

• US 3,868,759 A
• Filed: 11/09/1973
• Issued: 03/04/1975
• Est. Priority Date: 11/09/1973
• Status: Expired due to Term

• Current Assignee: James P. Grabowski, Ronald J. Hartleroad
• Original Assignee: James P. Grabowski, Ronald J. Hartleroad
• Inventors: Hartleroad, Ronald J., Grabowski, James P.
• Primary Examiner(s): Smith, Al Lawrence
• Assistant Examiner(s): Ramsey, K. J.
• Application Number:
  US05/414,272
• Time in Patent Office: 480 Days
• Field of Search: 29/23P,23J,23V,23MM,464,589,576S,626,628,471.1 228/4-6 214/1R,152 198/254
• US Class Current: 29/464
• CPC Class Codes: H01L 21/67144 Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates
• CPC Class Codes: Y10T 29/49895 Associating parts by use of aligning means [e.g., use of a drift pin or a "fixture"]
• CPC Class Codes: Y10T 29/53196 Means to apply magnetic force directly to position or hold work part

Abstract

Apparatus and a method for generally aligning semiconductor device chips having soft ferromagnetic leads with conductive lead frame structures prior to bonding thereto. The chips are prealigned in a temporary chip carrier and transported to a bonding station without losing their prealigned position. A vibratory force applied to the carrier and a magnetic plate below the carrier are used to bring the integral chip leads into close proximity with their corresponding lead frame fingers to promote subsequent consistent precisely aligned engagement therebetween.

Claims

1. Apparatus for prealigning semiconductor device chips having soft ferromagnetic integral leads thereon with corresponding fingers of a lead frame structure to promote subsequent consistent prEcision engagement therebetween for bonding, said apparatus comprising:

a template having two major parallel surfaces and a plurality of recesses in one of said surfaces;

a conductive lead frame structure having sets of soft ferromagnetic fingers said sets being located in said lead frame so as to correspond to said template recesses, said lead frame fingers having free end portions which correspond to the integral lead pattern on a semiconductor device chip;

a first means for holding the lead frame substantially against said one template surface;

a magnetic plate coextensive and contiguous the opposite surface of the template, said plate having two major faces serving as opposing poles of a magnet;

a second means for concentrating the magnetic force from the plate in the areas of the template recesses;

means for temporarily securing said first means, said lead frame, said template, and said magnetic plate together in mutual registration wherein said sets of lead frame fingers overlie said template recesses; and

means for vibrating said template so that all of the semiconductor device chips in the template recesses are automatically prealigned, with the integral chip leads being brought into close proximity with their corresponding lead frame finger-free ends thereby promoting subsequent consistent precision engagement therebetween for bonding.

2. Apparatus for prealigning semiconductor device chips having soft ferromagnetic integral leads thereon with conductive lead frame structures to promote subsequent consistent precision engagement therebetween for bonding, said apparatus comprising:

a template having two major parallel surfaces, a plurality of recesses in one of said surfaces, said recesses being located in spaced rows and columns, said recesses having an opening extending to the opposite surface of said template;

a conductive lead frame structure having sets of soft ferromagnetic fingers, said sets being located in spaced rows and columns corresponding to said template recesses, said lead frame fingers having free ends corresponding to the integral lead pattern on the semiconductor chips to be located in the template recesses;

a first means for holding said lead frame substantially against said one template surface;

a rubbery strip coextensive and contiguous the opposite surface of the template, said strip having two major faces serving as opposite poles of a permanent magnet, soft ferromagnetic pins extending from one face of said rubbery strip, said pins being located in spaced rows and columns corresponding to said openings in said template, said pins being inserted in said openings so that said pins extend partially therethrough;

means for temporarily securing said first means, said lead frame, said template, and said rubbery strip together in mutual registration wherein said sets of lead frame fingers overlie said template recesses and said pins remain inserted in the template openings; and

means for vibrating said template so that all of the semiconductor chips located in the template recesses can be automatically prealigned, with the integral chip leads being brought into close proximity with their overlying corresponding lead frame finger-free ends thereby promoting subsequent consistent precision engagement therebetween for bonding.

3. A method of prealigning integrally leaded semiconductor device chips with conductive lead frame structures to promote a consistent precise subsequent engagement therebetween for bonding, said method comprising the steps of:

placing a semiconductor device chip having a plurality of soft ferromagnetic integral leads on one face thereof into each of a plurality of recesses in one surface of a template, with said chip face oriented upwardly;

positioning a conductive lead frame structure having sets of soft ferromagnetic fingers corresponding to the integral chip leads on said one template surface so that a set of lead frame fingers overlie each of the template recesses;

placing a magnetic plate contiguous and coextensive with the backside of said template, said plate being a permanent magnet with the major faces of the plate serving as opposite poles of the magnet;

holding said template, said lead frame, and said magnetic plate together in mutual registration to form a subassembly;

vibrating said subassembly for a short period of time so that all of said chips are automatically prealigned, with the integral chip leads being in close proximity with their corresponding lead frame fingers; and

transporting said subassembly to a bonding station without disturbing said prealignment, said prealignment promoting a consistent precision engagement after the chips have been magnetically transferred and oriented into engagement with the lead frame fingers for bonding thereto.