US3915832A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electroplating apparatus for forming a nonuniform coating on workpieces
Assignee: AT&T Inc
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Filing: 1974-03-27
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Granted: 1975-10-28
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Expires: 1994-03-27
Abstract
Abstract In making transistors using lead frames, improved bonds and savings in gold result from plating gold more heavily and in controlled amounts at the ends of the lead frames where wire and semiconductive chip bonds are to be made. To accomplish such nonuniform plating, the lead frames are arranged in a spaced, radial, fan-like manner about an axis to form a cylindrical configuration of the frames. The ends of the frames where bonds are to be made are on the outer periphery of the configuration. The carrier strips, which are located opposite such ends and which are eventually trimmed away, are on the internal portion of the configuration and may be partially masked to reduce gold plating on such strips. A cathode is connected to the lead frames, which are then immersed in a plating bath and revolved about the axis of the frames and within a hollow cylindrical anode spaced midway between two flat anodes. A sparger pumps the bath in a direction substantially perpendicular to the axis of the frames. The frames and cylindrical anode are positioned midway between the top surface of the bath and the bottom of a tank holding the bath. With this arrangement the frames are nonuniformly plated, with more gold being plated on the ends where bonds are to be made than on the carrier strips. Also, each group of three leads of each frame for a single transistor is plated substantially alike. This arrangement of the frames and rotation of them in the bath also results in the plating of a large number of frames using a minimum volume of a tank holding the bath. An increase in plating rates is also achieved.
Inventors
- 👤 John Joseph Rackus
- 👤 John Paul Skilbeck
- 👤 Alfons Henryk Szkudlapski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:13
CPC Classifications
C; C25; C25D; C25D17/00; C25D17/06; C25D17/02; H; H10; H10W; H10W70/00; H10W70/01; H10W70/04; H10W72/00; H10W72/01; H10W72/0198; H10W72/50; H10W72/551; H10W72/552; H10W72/5522; H10W90/00; H10W90/701; H10W90/751; H10W90/756; Y; Y10; Y10S; Y10S204/00; Y10S204/07
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
178 words
In an apparatus for plating a nonuniform layer of a metal on a plurality of conductive planar articles, wherein the articles and an anode of a plating source are immersed into a metal plating bath and a cathode of such source is connected to the articles to thereby plate the articles, the improvement which comprises: means for loosely receiving the planar articles with outer side portions of the articles being free and inner side portions being partially masked and for arranging the articles in a spaced, radial, fan-like manner to form a cylindrical configuration of the articles about an axis with the planes of the articles passing through the axis so that the outer side portions of the articles on which the greatest thickness of the metal layer is to be formed are on the outer periphery of the cylindrical configuration and so that the articles are spaced one from the other; and means for moving the articles during the plating to form the greatest thickness of the metal layer on the outer side portions of the articles.
Claim 2
Dependent Claim
178 words
In an apparatus for plating a nonuniform layer of a metal on a plurality of conductive planar articles, wherein the articles and an anode of a plating source are immersed into a metal plating bath and a cathode of such source is connected to the articles to thereby plate the articles, the improvement which comprises: means for loosely receiving the planar articles with outer side portions of the articles being free and inner side portions being partially masked and for arranging the articles in a spaced, radial, fan-like manner to form a cylindrical configuration of the articles about an axis with the planes of the articles passing through the axis so that the outer side portions of the articles on which the greatest thickness of the metal layer is to be formed are on the outer periphery of the cylindrical configuration and so that the articles are spaced one from the other; and means for moving the articles during the plating to form the greatest thickness of the metal layer on the outer side portions of the articles.
Claim 3
Dependent Claim
23 words
The apparatus of claim 1, wherein the moving means includes a means for revolving the articles about the axis of the cylindrical configuration.
Claim 4
Dependent Claim
83 words
The apparatus of claim 1, wherein the anode has a hollow cylindrical configuration with a diameter adapted to exceed that of the cylindrical configuration of the articles, the moving means includes a means for revolving the articles within the cylindrical anode and about the axis of their cylindrical configuration, and the apparatus further comprises: a sparger adapted to be immersed in the plating bath; and means for pumping continuously the plating bath through the sparger in a direction suBstantially perpendicular to such axis.
Claim 5
Dependent Claim
46 words
The apparatus of claim 3, further comprising a tank for holding the plating bath, said tank having spaced, parallel, flat anodes on two of its opposite walls, and the means for receiving the articles and the cylindrical anode are positioned substantially midway between the flat anodes.
Claim 6
Dependent Claim
238 words
IN AN APPARTUS FOR PLATING A NONUNIFORM LAYER OF GOLD ON A PLURALITY OF NICKEL LEAD FRAMES HAVING OPPOSED INNER AND OUTER SIDE PORTIONS AND OPPOSED FIRST AND SECOND END PORTIONS, WHEREIN ONE LEAD FRANES ARE IMMERSED IN A GOLD PLATING BATH, THE IMPROVEMENT WHICH COMPRISES: A HOLLOW TUBULAR MEMBER HAVING A PLURALITY OF SPACED SLOTS PARALLEL TO EACH OTHER AND TO THE AXIS OF THE TUBULAR MEMBER, THE SLOTS BEING FORMED ON THE OUTER SURFACE OF THE MEMBER TO RECEIVE THE INNER SIDE PORTION OF THE LEAD FRAMES AND TO ARRANGE THEM IN A HOLLOW CYLINDRICAL CONFIGURATION SO THAT THE OUTER SIDE PORTION OF THE FRAMES EXTEND FROM THE SLOTS AND ARE ON THE OUTER PERIPHERY OF THE CYLINDRICAL CONFIGURATION AND SO THAT THE FRAMES ARE SPACED ONE FROM THE OTHER, A CONDUCTIVE BASE MOUNTED TO ONE END OF THE TUBULAR MEMBER AND HAVING AN ANNULAR CHANNEL FOR RETAINING THE FIRST END PORTION OF THE LEAD FRAMES IN ITS SLOT, AN INSULATIVE CAPPING MEMBER HAVING A CENTRAL APERTURE THEREIN AND REMOVABLE MOUNTED TO THE OTHER END OF THE TUBULAR MEMBER AND HAVING ANOTHER ANNULAR CHANNEL FOR RETAINING THE SECOND END PORTION OF EACH FRAME IN ITS SLOT, A CONDUCTIVE SHAFT EXTENDING THROUGH THE APERTURE IN THE CAPPING MEMBER AND FIXED TO THE BASE, THE ASSEMBLY OF THE SHAFT, THE CAPPING MEMBER, THE BASE AND THE TUBULAR MEMBER BEING IMMERSED WITH THE LEAD FRAMES IN THE PLATING BATH,
Claim 7
Dependent Claim
238 words
IN AN APPARTUS FOR PLATING A NONUNIFORM LAYER OF GOLD ON A PLURALITY OF NICKEL LEAD FRAMES HAVING OPPOSED INNER AND OUTER SIDE PORTIONS AND OPPOSED FIRST AND SECOND END PORTIONS, WHEREIN ONE LEAD FRANES ARE IMMERSED IN A GOLD PLATING BATH, THE IMPROVEMENT WHICH COMPRISES: A HOLLOW TUBULAR MEMBER HAVING A PLURALITY OF SPACED SLOTS PARALLEL TO EACH OTHER AND TO THE AXIS OF THE TUBULAR MEMBER, THE SLOTS BEING FORMED ON THE OUTER SURFACE OF THE MEMBER TO RECEIVE THE INNER SIDE PORTION OF THE LEAD FRAMES AND TO ARRANGE THEM IN A HOLLOW CYLINDRICAL CONFIGURATION SO THAT THE OUTER SIDE PORTION OF THE FRAMES EXTEND FROM THE SLOTS AND ARE ON THE OUTER PERIPHERY OF THE CYLINDRICAL CONFIGURATION AND SO THAT THE FRAMES ARE SPACED ONE FROM THE OTHER, A CONDUCTIVE BASE MOUNTED TO ONE END OF THE TUBULAR MEMBER AND HAVING AN ANNULAR CHANNEL FOR RETAINING THE FIRST END PORTION OF THE LEAD FRAMES IN ITS SLOT, AN INSULATIVE CAPPING MEMBER HAVING A CENTRAL APERTURE THEREIN AND REMOVABLE MOUNTED TO THE OTHER END OF THE TUBULAR MEMBER AND HAVING ANOTHER ANNULAR CHANNEL FOR RETAINING THE SECOND END PORTION OF EACH FRAME IN ITS SLOT, A CONDUCTIVE SHAFT EXTENDING THROUGH THE APERTURE IN THE CAPPING MEMBER AND FIXED TO THE BASE, THE ASSEMBLY OF THE SHAFT, THE CAPPING MEMBER, THE BASE AND THE TUBULAR MEMBER BEING IMMERSED WITH THE LEAD FRAMES IN THE PLATING BATH,
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |