EP0520679A2
Expired / Lapsed
EP
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Method of forming a premolded package assembly
Assignee: AT&T Inc
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Filing: 1992-06-18
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Granted: —
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Expires: 2012-06-18
Abstract
Abstract In a pre-molded package assembly, a thermoplastic ring molded onto a leadframe (30) must maintain lead coplanarity. In this invention a plastic member of liquid crystal polmar is molded onto the leads (32) of a metal leadframe (30). The plastic member is a thermoplastic anisotropic material which, when formed, has a flow direction which is in the long dimension of the plastic member and a transverse direction which is in the short dimension of the plastic member. Dam members (38,40) on the leadframe (30) help contain the plastic molding compound within the mold cavity during the molding process. A puddle gate prevents the formation of a weld line in the plastic member. Upon completion of the molding process, the dam members (38,40) are excised from the leadframe (30) to provide discrete leads (32).
Inventors
- 👤 Ranjit Biswas
- 👤 Michael A. Zimmerman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 15:33
CPC Classifications
H; H10; H10W; H10W70/00; H10W70/40; H10W70/464; H10W70/468; H10W74/00; H10W74/01; H10W76/00; H10W76/10; H10W76/12; H10W76/15; H10W76/157; H10W72/00; H10W72/50; H10W72/551; H10W72/552; H10W72/5522; H10W72/5524
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
120 words
A method of forming a plastic member on a lead frame having a plurality of leads located side by side where each has an outer end and an inner end. comprising the steps of locating a first dam member between said leads located side by side and positioned between the outer ends and the inner ends of said leads, locating a second dam member between said leads located side by side and positioned between said first dam member and the inner ends of said leads, said first and second dam members dividing said leads into an outer section, an inner section and intermediate section, and encapsulating in plastic molding compound the intermediate section of the leads of the lead frame.
Claim 2
Dependent Claim
34 words
A method of forming a plastic member on a lead frame as defined in claim 1 wherein said plastic molding compound encapsulating the the intermediate section of the leads comprises a liquid crystal polmar.
Claim 3
Dependent Claim
26 words
A method of forming a plastic member on a lead frame as defined in claim 2 wherein said liquid crystal polmer is an anisotropic thermoplastic material.
Claim 4
Dependent Claim
52 words
A method of forming a plastic member on a lead frame as defined in claim 2 further comprises the step of causing said molding compound to flow between said first and second dam members progressively from a first end lead to a last end lead of said side by side located leads.
Claim 5
Dependent Claim
88 words
A method of forming a plastic member on a lead frame as defined in claim 4 wherein said molding compound has a coefficient of thermal expansion in the direction of flow which is substantially similar to the coefficient of thermal expansion of a ceramic member adapted to be coupled to said leads, and said molding compound has a coefficient of thermal expansion in the transverse direction which is not substantially similar to the coefficient of thermal expansion of the ceramic member adapted to be coupled to said leads.
Claim 6
Dependent Claim
47 words
A method of forming a plastic member on a lead frame as defined in claim 4 further comprising the step of causing the leading end of the molding compound to flow past the last end lead of the side by side located leads to a puddle gate.
Claim 7
Dependent Claim
49 words
A method of forming a plastic member as a lead frame as defined in claim 6 further comprising the step of excising said first dam member from between said leads and said second dam members from between said leads thereby providing leads which are electrically isolated from each other.
Claim 8
Independent Claim
208 words
A method of forming a plastic member on a lead frame having first, second, third and fourth plurality of leads located side by side, where each lead has an outer end and an inner end, said first, second, third and fourth plurality of leads being arranged to form a square. comprising the steps of locating a first dam member between the outer ends and the inner ends of said first, second, third and fourth plurality of leads. locating a second dam member between said first dam member and the inner ends of said first, second, third and fourth plurality of leads, said first and second dam members dividing the leads of said first, second, third and fourth plurality of leads into an outer section, an inner section and an intermediate section, causing molding compound to flow from along two paths from one corner of said square to the opposite corner of said square to encapsulate in the plastic molding compound the intermediate section of said leads of said first, second, third and fourth plurality of leads, and causing the leading ends of the molding compound from the two paths which merge at the opposite corner of the square to flow past the opposite corner to a puddle gate.
Claim 9
Dependent Claim
23 words
A method of forming a plastic member on a lead frame as defined in claim 8 wherein said molding compound is anisotropic thermoplastic.
Claim 10
Dependent Claim
46 words
A method of forming a plastic member on a lead frame as defined in claim 9 further comprising the step of removing said first and second dam members from between said leads to provide a lead frame having leads which are electrically isolated from each other.
References Cited (Backward Citations)
No citation records indexed.
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