EP0248566A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Process for controlling solder joint geometry when surface mounting a leadless integrated circuit package on a substrate
Assignee: AT&T Inc
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Filing: 1987-05-21
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Granted: —
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Expires: 2007-05-21
Abstract
Abstract A solder joint assembly technique applies controlled volumes of solder to pads of both package and substrate (31, 32). The two units are positioned adjacent each other with the pads and solder deposits mechanically maintained in registration with each other (34, 35). The assembly is reflowed and the final separation between package and substrate at which the resulting solder joint solidifies is mechanically controlled in order to control a geometry of the resultant solidified joint (36, 37). The solder volume deposits may assume various forms including spherical bumps and solder paste deposits.
Inventors
- 👤 Francis Lovasco
- 👤 Michael Ackman Oien
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 08:52
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/20; H05; H05K; H05K3/00; H05K3/30; H05K3/303; H05K3/32; H05K3/34; H05K3/341; H05K3/3431; H05K3/3436; H05K2201/00; H05K2201/03; H05K2201/0332; H05K2201/0335; H05K2201/035; H05K2201/0364; H05K2201/0379; H05K2201/09; H05K2201/09818; H05K2201/09909; H05K2201/10; H05K2201/10431; H05K2201/10568; H05K2201/10613; H05K2201/10621; H05K2201/10734; H05K2201/20; H05K2201/2036; H05K2203/00; H05K2203/04; H05K2203/043; H05K2203/0465; H05K2203/16; H05K2203/167; H05K3/3465; H05K3/3485; H10W72/071; H10W72/072; H10W72/07211; H10W72/07221; H10W72/07227; H10W72/07231; H10W72/07236; H10W72/241; H10W72/251; H10W72/252; Y; Y02; Y02P; Y02P70/00; Y02P70/50
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
213 words
A method of forming solder joints for joining a package and a substrate, CHARACTERIZED BY depositing substantial, predetermined and controlled volumes of solder on individual pads of a package, each of these pads having a predetermined and controlled size and shape, depositing substantial, predetermined and controlled volumes of solder on individual pads of a substrate, each of these pads having a predetermined and controlled size and shape, laterally positioning the substrate and package adjacent to each other with individual pads of the package in registration with associated individual pads of the substrate, establishing an initial vertical separation between the package and the substrate which is small enough to allow the predetermined and controlled volumes of solder on each associated pair of pads to touch and coalesce when molten, applying sufficient heat to an assembly of the package and substrate to achieve a predetermined reflow temperature, such that the first and second volume of solder on each associated pair of pads become molten and coalesce to form a solder joint between a pad on the package and an associated pad on the substrate, and maintaining a predetermined and a controlled final separation between package and substrate after molten solder joints form in order to control a solidified shape of each of the solder joints.
Claim 2
Independent Claim
213 words
A method of forming solder joints for joining a package and a substrate, CHARACTERIZED BY depositing substantial, predetermined and controlled volumes of solder on individual pads of a package, each of these pads having a predetermined and controlled size and shape, depositing substantial, predetermined and controlled volumes of solder on individual pads of a substrate, each of these pads having a predetermined and controlled size and shape, laterally positioning the substrate and package adjacent to each other with individual pads of the package in registration with associated individual pads of the substrate, establishing an initial vertical separation between the package and the substrate which is small enough to allow the predetermined and controlled volumes of solder on each associated pair of pads to touch and coalesce when molten, applying sufficient heat to an assembly of the package and substrate to achieve a predetermined reflow temperature, such that the first and second volume of solder on each associated pair of pads become molten and coalesce to form a solder joint between a pad on the package and an associated pad on the substrate, and maintaining a predetermined and a controlled final separation between package and substrate after molten solder joints form in order to control a solidified shape of each of the solder joints.
Claim 3
Dependent Claim
56 words
A method of forming solder joints as defined in claim 1 CHARACTERIZED IN THAT the step of depositing a substantial, predetermined and controlled volume of solder on individual pads of a package, the substantial predetermined and controlled volumes of solder are deposited on individual pads of the package as solder bumps having a substantially spherical shape.
Claim 4
Dependent Claim
56 words
A method of forming solder joints as defined in claim 1 CHARACTERIZED IN THAT the step of depositing a substantial, predetermined and controlled volume] of solder on individual pads of a substrate, the substantial, predetermined and controlled volumes of solder are deposited on individual pads of the substrate as solder bumps having a substantially spherical shape.
Claim 5
Dependent Claim
55 words
A method of forming solder joints as defined in claim 1 CHARACTERIZED IN THAT the step of establishing an initial vertical separation between the package and substrate includes selecting a first vertical separation prior to application of heat this is greater than the controlled final separation between the substrate and the package after solder reflow.
Claim 6
Dependent Claim
37 words
A method of forming solder joints as defined in claim 4 CHARACTERIZED IN THAT the step of laterally positioning the substrate and package includes a step of using mechanical apparatus to positively maintain a desired lateral positioning.
Claim 7
Dependent Claim
26 words
A method of forming solder joints as defined in claim 1 CHARACTERIZED IN THAT the step of establishing an initial separation includes utilizing a mechanical means.
Claim 8
Dependent Claim
51 words
A method of forming solder joints as defined in claim 5 CHARACTERIZED IN THAT the step of laterally positioning the substrate and package includes a step of utilizing pins attached to the package and having the pins pass through holes in the substrate in order to maintain a desired lateral positioning.
Claim 9
Dependent Claim
45 words
A method of forming solder joints as defined in claim 7 CHARACTERIZED IN THAT in the step of maintaining a predetermined and controlled final separation includes adding a shoulder to the pins which rest on the substrate after solder reflow to control the final separation.
Claim 10
Dependent Claim
49 words
A method of forming solder joints as defined in claim 1 CHARACTERIZED IN THAT the step of establishing an initial vertical separation between the substrate and the package involves utilizing a physical contact of certain of first controlled volumes of solder with their associated second controlled volumes of solder.
Claim 11
Dependent Claim
45 words
A method of forming solder joints as defined in claim 9 CHARACTERIZED IN THAT the step of using mechanical apparatus to maintain lateral positioning includes a step of utilizing an auxiliary fixture which is removed from a resulting assembly after the solder joints have solidified.
References Cited (Backward Citations)
No citation records indexed.
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