Method and apparatus for molding a synthetic resin lens for a light emitting diode

• US 4,486,364 A
• Filed: 06/29/1982
• Issued: 12/04/1984
• Est. Priority Date: 12/04/1981
• Status: Expired due to Term

• Current Assignee: Stanley Electric Company Limited
• Original Assignee: Stanley Electric Company Limited
• Inventors: Takahashi, Kaoru
• Primary Examiner(s): Lowe, James
• Application Number:
  US06/393,466
• Time in Patent Office: 889 Days
• Field of Search: 264/272.15, 264/272.16, 264/272.17, 264/1.5, 264/1.7, 264/275, 357/72, 29/569 L, 29/588, 425/808, 425/121, 249/85, 249/96
• US Class Current: 264/1.7
• CPC Class Codes: B29C 70/72 Encapsulating inserts having non-encapsulated projections, e.g. extremities or terminal portions of electrical components B29C70/742 takes precedence
• CPC Class Codes: B29L 2031/3406 Components, e.g. resistors
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 25/13 the devices being of a type provided for in group H01L33/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/483 Containers
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: Y10S 425/808 Lens mold

Abstract

A lens for a light emitting diode is formed by inserting a pair of lead frames into a mold having grooves for snugly receiving the outer free ends of the lead frames. The outer-most edge of the lead frame free ends engage the base of the mold, thereby precisely locating the light emitting element, mounted on the lead frames, relative to the top surface of the lens. The snug fit for the outer free ends assures that the outer free ends are free of the resin to facilitate alignment of the finished product in an electro-optical circuit and to provide improved radiation of heat to the atmosphere.

Claims

1. A method for molding a synthetic resin lens for a light emitting diode, the method comprising the steps of:

providing a mold with a mold cavity having a bottom wall and a plurality of side walls defining a lens for the light emitting diode;

forming a pair of grooves in the mold which are arranged on opposite sides of and communicate with the mold cavity, fitting the first ends of a pair of lead frames having a light emitting element mounted at a fixed position on one of said lead frames into said mold, so that a first portion of the first ends of each lead frame inserted into said mold extends into and is closely fitted within an associated one of said grooves, and so that the remaining portion of the first ends of each lead frame extends into said mold cavity, the first ends of said lead frames being inserted into the mold, so that the free ends thereof engage a bottom wall of the mold, and filling said mold with synthetic resin, the tight fit between said first portions of said lead frame and said grooves preventing the synthetic resin from entering into said grooves to completely expose the surfaces of the first portions when the molded product is removed from the mold.

5. The molding apparatus of claim 1 wherein the lead frames are provided with tapering portions adjacent said free edges to facilitate insertion of the lead frames onto the cooperating recesses.

2. Apparatus for molding a synthetic resin lens for a light emitting diode structure comprised of a pair of conductive lead frames joined by removable reinforcing means to maintain the lead frames in a predetermined spaced-apart arrangement;

the free ends of said conductive lead frames having free end edges lying in a common imaginary plane and having opposing sides projecting away from one another;

a mounting surface on one side of said lead frames extending toward the other lead frame and arranged a predetermined distance from the free end edge thereof;

a light emitting element mounted upon said mounting surface to provide an electrical connection therebetween;

means for electrically connecting said light emitting element to the remaining one of said lead frames;

a mold having a mold cavity with a shape conforming to the lens to be molded and a pair of aligned recesses communicating with and on opposite sides of the cavity of said mold forming said lens, each receiving one of said opposing sides of said conductive lead frames;

said lead frames having at least the inner portions thereof arranged within said mold cavity;

at least a portion of the base of said mold cavity being arranged to engage said free edges and being flat to be engaged by both of said free edges to thereby precisely locate the light emitting element relative to the base of said mold cavity to assure precise positioning of the light emitting element relative to the surface of the lens formed by the base of said mold;

the grooves each forming a tight fit with the opposing surfaces of an associated lead frame to prevent the synthetic resin, used to fill the mold and form the lens, from entering said grooves, whereby the surfaces of said opposing sides are exposed and not covered by the synthetic resin when the molded lens is removed from the mold after being formed to provide for radiation of heat generated by said diode structure through the outer portions of said conductive lead frames.

3. The apparatus of claim 2 wherein the width of said recesses are substantially equal to the thickness of the opposing sides of said lead frames to keep the opposing sides of the lead frames received by said recesses free of synthetic resin poured into the mold, the opposing sides of said finished product extending sidewise from the molded lens serving as a heat radiating means.

4. The molding apparatus of claim 2 wherein the lead frames are provided with openings near the free ends thereof to receive resin and thereby strengthen the bonding of the resin to the lead frames.