US4983804A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Localized soldering by inductive heating
Assignee: Nokia Bell Labs
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Filing: 1989-12-21
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Granted: 1991-01-08
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Expires: 2009-12-21
Abstract
Abstract Disclosed is a method for selective soldering of components by inductive heating. A ferromagnetic material is provided as part of the components so that an applied electromagnetic field will create sufficient heat to melt the solder. The Curie temperature of the material is chosen to be just above the melting temperature of the solder to regulate the amount of heating.
Inventors
- 👤 Hinghung A. Chan
- 👤 Michael A. Oien
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:41
CPC Classifications
H; H05; H05K; H05K1/00; H05K1/02; H05K1/0201; H05K1/0212; B; B23; B23K; B23K1/00; B23K1/002; H05K13/00; H05K13/04; H05K13/046; H05K13/0465; H05K3/00; H05K3/30; H05K3/32; H05K3/34; H05K3/341; H05K3/3431; H05K3/3436; H05K1/0203; H05K1/0204; H05K1/0206; H05K2201/00; H05K2201/02; H05K2201/0203; H05K2201/0206; H05K2201/0215; H05K2201/08; H05K2201/083; H05K2201/10; H05K2201/10227; H05K2201/10234; H05K2201/10613; H05K2201/10621; H05K2201/10666; H05K2201/10719; H05K2201/10734; H05K2203/00; H05K2203/10; H05K2203/101; H05K2203/104; H05K3/3447; H05K3/3494; H05K3/36; H05K3/361; H05K3/363; H10; H10W; H10W72/00; H10W72/01; H10W72/012; H10W72/01221; H10W72/01225; Y; Y02; Y02P; Y02P70/00; Y02P70/50
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
126 words
A method of selectively soldering conductive elements on an electronic component to conductive elements on a substrate having two major surfaces comprising the steps of: providing solder to the elements to be soldered; providing a ferromagnetic material within 0.5 mm of the elements to be soldered, the ferromagnetic material having a Curie temperature in the range 200-400 degrees C and having a saturation field of at least 1 Tesla; and applying an electromagnetic field with a frequency in the range 5×10 3 to 2×10 5 Hz to the ferromagnetic material by means of a pair of coils detached from the material with a coil opposite each major surface of the substrate so as to inductively heat said material to a temperature sufficient to melt the solder.
Claim 2
Independent Claim
126 words
A method of selectively soldering conductive elements on an electronic component to conductive elements on a substrate having two major surfaces comprising the steps of: providing solder to the elements to be soldered; providing a ferromagnetic material within 0.5 mm of the elements to be soldered, the ferromagnetic material having a Curie temperature in the range 200-400 degrees C and having a saturation field of at least 1 Tesla; and applying an electromagnetic field with a frequency in the range 5×10 3 to 2×10 5 Hz to the ferromagnetic material by means of a pair of coils detached from the material with a coil opposite each major surface of the substrate so as to inductively heat said material to a temperature sufficient to melt the solder.
Claim 3
Dependent Claim
15 words
The method according to claim 1 wherein the ferromagnetic material is provided within the solder.
Claim 4
Dependent Claim
28 words
The method according to claim 2 wherein the component comprises a package for a semiconductor chip and the elements to be soldered comprise conductive pads on said package.
Claim 5
Dependent Claim
32 words
The method according to claim 3 wherein the ferromagnetic material is a sphere embedded within a solder mound provided between each pad on the package and pad on a printed circuit board.
Claim 6
Dependent Claim
27 words
The method according to claim 4 wherein the volume of the sphere is at least one quarter of the total volume of the ferromagnetic material and solder.
Claim 7
Dependent Claim
19 words
The method according to claim 1 wherein the ferromagnetic material is a layer placed in contact with the component.
Claim 8
Dependent Claim
15 words
The method according to claim 1 wherein the ferromagnetic material is embedded within the substrate.
Claim 9
Independent Claim
23 words
The method according to claims 6 or 7 wherein the component is a flexible circuit and the substrate is a printed circuit board.
Claim 10
Independent Claim
24 words
The method according to claims 6 or 7 wherein the electromagnetic field has a frequency within the range 10 4 to 10 5 Hz.
Claim 11
Dependent Claim
18 words
The method according to claim 1 wherein the ferromagnetic material comprises an alloy of iron, cobalt, and nickel.
Claim 12
Dependent Claim
26 words
The method according to claim 10 wherein the alloy comprises 50 to 75 percent iron, 2 to 20 percent cobalt, and 20 to 35 percent nickel.
Claim 13
Independent Claim
106 words
A method of selectively soldering conductive elements on an electronic component to conductive elements on a substrate comprising the steps of: providing a ferromagnetic material within solder mounds and providing said mounds to the said conductive elements, the ferromagnetic material having a Curie temperature within the range 200-400 degrees C and a saturation field of at least 1 Tesla; and applying an electromagnetic field with a frequency in the range 5×10 3 to 2×10 5 Hz to the ferromagnetic material by means of a pair of coils detached from the material so as to inductively heat said material to a temperature sufficient to melt the solder.
Claim 14
Independent Claim
106 words
A method of selectively soldering conductive elements on an electronic component to conductive elements on a substrate comprising the steps of: providing a ferromagnetic material within solder mounds and providing said mounds to the said conductive elements, the ferromagnetic material having a Curie temperature within the range 200-400 degrees C and a saturation field of at least 1 Tesla; and applying an electromagnetic field with a frequency in the range 5×10 3 to 2×10 5 Hz to the ferromagnetic material by means of a pair of coils detached from the material so as to inductively heat said material to a temperature sufficient to melt the solder.
Claim 15
Independent Claim
113 words
A method of selectively soldering conductive elements on an electronic component to conductive elements on a substrate comprising the steps of: providing a planar sheet of ferromagnetic material in contact with one of said component or substrate, and providing solder to said conductive elements, the ferromagnetic material having a Curie temperature within the range 200-400 degrees C and a saturation field of at least 1 Tesla; and applying an electromagnetic field with a frequency in the range 10 4 to 10 5 Hz to the ferromagnetic material by means of a pair of coils detached from the material so as to inductively heat said material to a temperature sufficient to melt the solder.
Claim 16
Independent Claim
113 words
A method of selectively soldering conductive elements on an electronic component to conductive elements on a substrate comprising the steps of: providing a planar sheet of ferromagnetic material in contact with one of said component or substrate, and providing solder to said conductive elements, the ferromagnetic material having a Curie temperature within the range 200-400 degrees C and a saturation field of at least 1 Tesla; and applying an electromagnetic field with a frequency in the range 10 4 to 10 5 Hz to the ferromagnetic material by means of a pair of coils detached from the material so as to inductively heat said material to a temperature sufficient to melt the solder.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-01-07 | 1994-07-09 | 1995-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-07 | 1998-07-09 | 1999-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-07 | 2002-07-09 | 2003-01-08 | $7700.00 | Window Closed / Lapsed |