Method and apparatus using colored foils for placing conductive preforms

• US 6,230,963 B1
• Filed: 04/03/1997
• Issued: 05/15/2001
• Est. Priority Date: 01/28/1997
• Status: Expired due to Term

• Current Assignee: Galahad, Co.
• Original Assignee: Galahad, Co.
• Inventors: Hertz, Eric L.
• Primary Examiner(s): Ryan, Patrick
• Assistant Examiner(s): Knapp, Jeffrey T.
• Application Number:
  US08/832,288
• Time in Patent Office: 1,503 Days
• Field of Search: 228/41, 228/246, 298/42, 298/84, 297/47
• US Class Current: 228/246
• CPC Class Codes: B23K 3/0623 for shaped solder piece feeding, e.g. preforms, bumps, balls, pellets, droplets
• CPC Class Codes: H05K 2203/0338 Transferring metal or conductive material other than a circuit pattern, e.g. bump, solder, printed component affixing a prefabricated conductor pattern H05K3/20
• CPC Class Codes: H05K 2203/041 Solder preforms in the shape of solder balls soldering leadless components having an array of bottom contacts H05K3/3436
• CPC Class Codes: H05K 2203/082 Suction, e.g. for holding solder balls or components
• CPC Class Codes: H05K 3/3478 Applying solder preforms; Transferring prefabricated solder patterns

Abstract

A method and apparatus are disclosed for placing solder balls on electronic pads on a component or substrate, such as for a ball grid array (BGA) applicator. The BGA applicator utilizes a foil(s) that is treated to provide color to the surface; the color is used to assist in inspection of the solder spheres. The solder balls can transferred to the electronic pads by holding them to openings in the foil by applying a holding force such as a vacuum applied to the solder balls through the openings in a foil. Optionally, a second material can be placed against the foil where the secondary material holds solder spheres to the apertures. After locating the solder balls to the electronic pads of a component or substrate, the solder balls are released and placed on the electronic pads by removing the holding force such as by deactivating the vacuum.

Claims

1. A method for placing a plurality of conductive preforms on a plurality of electronic pads, the method comprising the steps of:

placing a plurality of conductive preforms with relation to a plurality of openings in at least one foil whereby the surface of the foil is treated to differ in color from the conductive preforms,

holding a plurality of conductive preforms to a plurality of openings in the at least one foil by providing at least one holding force to the plurality of conductive preforms against a secondary material which covers at least a portion of the openings of the foil;

applying a tacky media to at least one of the plurality of conductive preforms and the plurality of electronic pads;

inspecting the plurality of conductive preforms whereby the inspection step is assisted by the color of the foil;

locating the plurality of conductive preforms at a plurality of electronic pads; and

placing the plurality of conductive preforms on the plurality of electronic pads.

2. The method of claim 1, wherein the placing step comprises the steps of:

applying placing force to the plurality of conductive preforms in the direction of the plurality of electronic pads.

3. An apparatus for placing a plurality of conductive preforms on a plurality of electronic pads, the apparatus comprising:

at least one foil including a plurality of openings, whereby the surface of at least one foil is treated to provide color to assist in the inspection of the plurality of conductive preforms;

a secondary material located proximate the at least one foil, whereby the second material covers at least a portion of the opeings of the foil therein for holding a plurality of conductive preforms to the plurality of openings against the secondary material by a holding force; and

a means for placing the plurality of conductive preforms on a plurality of electronic pads.

4. The apparatus of claim 3, wherein the foil is manufactured from one of the following materials:

(a) Stainless Steel;

(b) Brass;

(c) Nickel;

(d) Polyimide; and

(e) a thin strong polyester film.

5. The apparatus of claim 3, wherein the plurality of openings in the foil are constructed using at least one of the following production processes:

(a) chemically etching the foil utilizing predefined artwork masking for the pattern of the plurality of openings;

(b) laser drilling the foil utilizing a predefined pattern for drilling the plurality of openings; and

(c) mechanically drilling the foil utilizing a predefined pattern for drilling the plurality of openings.

6. The apparatus of claim 3, wherein the secondary material consists of one of the following materials:

(a) Woven fabric;

(b) Polyester mesh;

(c) Silk screen;

(d) Metal screening; and

(e) A sponge material.

7. The apparatus of claim 3, wherein the secondary material is at least partially adhered to the foil.

8. The apparatus of claim 3, wherein the secondary material is contained between two foils.

9. The apparatus of claim 3, wherein the secondary material is a second foil wherein,

the apertures are smaller in size compared to the apertures of the first foil.

10. The apparatus of claim 3 where the dimensions of the aperture on one side of the foil differ from the dimensions of the aperture on the opposing side of the aperture.

21. The apparatus of claim 3, whereby the means for placing the conductive preforms on the plurality of electronic pads is a plurality of pins.

22. The apparatus of claim 9, whereby the second foil is manufactured from one of the following materials:

(a) Stainless Steel

(b) Brass

(c) Nickel

(d) Polyimide

(e) Mylar.

11. An apparatus for placing a plurality of conductive preforms on a plurality of electronic pads, the apparatus comprising:

at least one foil including a plurality of openings, whereby the surface of at least one foil is treated to provide color to the surface to assist in the inspection of the plurality of conductive preforms;

a secondary material which covers at least a portion of the openings of the foil therein for holding a plurality of conductive preforms to the plurality of openings against the secondary material by a vacuum holding force applied to the plurality of conductive preforms through the plurality of openings and for placing the plurality of conductive preforms on a plurality of electronic pads; and

a block structure including a chamber for applying at least one vacuum force to the foil.

12. The apparatus of claim 11, wherein the apparatus further includes:

at least one aligning pins located on a workplate; and

at least one aligning hole in at least one of the block structure and the at least one foil corresponding to the at least one aligning pin for alignment.

13. The apparatus of claim 12, the apparatus further comprising an aligning plate wherein the alignment plate comprises at least one aligning hole and at least one of at least one aperture and at least one cavity for a component.

14. The apparatus of claim 11, wherein the plurality of openings in the foil are constructed using at least one of the following production processes:

(a) chemically etching the foil utilizing predefined artwork masking for pattern of the plurality of openings;

(b) laser drilling the foil utilizing a predefined pattern for drilling the plurality of openings; and

(c) mechanically drilling the foil utilizing a predefined pattern for drilling the plurality of openings.

15. The apparatus of claim 11, wherein the secondary material consists of one of the following materials:

(a) Woven fabric;

(b) Polyester mesh;

(c) Silk screen;

(d) Metal screening; and

(e) Mylar.

16. The apparatus of claim 11, wherein the secondary material is contained between two foils.

17. The apparatus of claim 11, wherein the secondary material is a second foil wherein, the apertures are smaller in diameter compared to the apertures of the first foil.

18. The apparatus of claim 11 where the dimensions of the aperture on one side of the foil differ from the dimensions of the aperture on the opposing side of the aperture.

19. An apparatus for placing a plurality of conductive preforms on a plurality of electronic pads, the apparatus comprising:

a foil including a plurality of openings therein for placing a plurality of conductive performs on a plurality of electronic pads whereby the surface of the foil is treated to provide color to the surface of the foil for assisting in inspection of the plurality of conductive preforms.

20. The apparatus of claim 19, wherein the apparatus further comprises:

a means for applying a removable holding force to the plurality of conductive preforms.