Mold for injection molding encapsulation over small device on substrate

• US 6,139,304 A
• Filed: 07/17/1998
• Issued: 10/31/2000
• Est. Priority Date: 12/10/1996
• Status: Expired due to Term

• Current Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Centofante, Charles A.
• Primary Examiner(s): Davis, Robert
• Application Number:
  US09/118,670
• Time in Patent Office: 837 Days
• Field of Search: 425/116, 425/117, 425/121, 425/125, 425/127, 425/129.1, 425/588
• US Class Current: 425/121
• CPC Class Codes: B29C 45/14311 using means for bonding the coating to the articles B29C45/14795 takes precedence
• CPC Class Codes: B29C 45/14655 connected to or mounted on a carrier, e.g. lead frame
• CPC Class Codes: B29C 45/2708 Gates B29C45/2703 takes precedence
• CPC Class Codes: B29C 70/74 Moulding material on a relatively small portion of the preformed part, e.g. outsert moulding B29C70/845 takes precedence
• CPC Class Codes: G09F 9/3023 Segmented electronic displays
• CPC Class Codes: G09F 9/33 being semiconductor devices, e.g. diodes
• CPC Class Codes: H01L 21/565 Moulds
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/52 Encapsulations
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence

Abstract

A method and apparatus for encapsulating one or more small electronic devices, including for example light-emitting diodes, mounted directly on a substrate by providing a three-dimensional formation on the substrate adjacent to the device and injection molding a thermoplastic encapsulating material to cover the device and extend over the three-dimensional formation on the substrate and wherein the encapsulating material mechanically bonds to the three-dimensional formation. A gate plate for use in injection molding a thermoplastic encapsulating material over a small electronic device mounted directly on a substrate including a cavity formed to enclose the device, and a short gate formed entirely within the gate plate having an input for receiving an encapsulating material and an output communicating with the cavity. One or more encapsulated electrical devices mounted directly on a substrate, including, for example, an LED or an array of LEDs, wherein the device is fully and individually encapsulated by an encapsulating material which is injection molded onto and mechanically bonded to the substrate.

Claims

1. A mold for injection molding a thermoplastic encapsulating material over a small electronic device mounted directly on a substrate comprising;

a base member,

a top member including an inlet, and

a gate plate, the gate plate including a short gate having an input communicating with the inlet and an output communicating with a cavity shaped to form a package of encapsulating material capable of focusing and reflecting light wherein the gate and the cavity are formed entirely within the gate plate.

2. The mold of claim 1, wherein the gate is substantially conical in shape.

3. The mold of claim 1, wherein the cross sectional area of the gate is reduced from the input to the output to form a region of relatively reduced strength in hardened encapsulating material, whereby the material is caused to break off near to the output of the gate when the mold is opened.

4. The mold of claim 3, wherein the sidewalls of the gate are inclined about 15 degrees over the length of the gate from the input to the output.

5. A gate plate for use in injection molding a thermoplastic encapsulating material over a small electronic device mounted directly on a substrate, the gate plate comprising:

a cavity formed to enclose the device and shaved to form a package of encapsulating, material capable of focusing and reflecting light, and

a short gate having an input for receiving an encapsulating material and an output communicating with the cavity, wherein the gate and the cavity are formed entirely within the gate plate.

6. The gate plate of claim 5, wherein the gate is substantially conical in shape.

7. The gate plate of claim 5, wherein the cross sectional area of the gate is reduced from the input to the output to form a region of relatively reduced strength in hardened encapsulating material, whereby the encapsulating material is caused to break off near to the output of the gate when the mold is opened.

8. The gate plate of claim 7, wherein the sidewalls of the gate are inclined about 15 degrees over the length of the gate from the input to the output.

9. The gate plate of claim 5, wherein the gate plate is about 0.250 inches thick.

10. The gate plate of claim 5, wherein the gate plate further includes a distribution runner connected to the gate.

11. The gate plate of claim 5, wherein the length of the gate is about 0.065 inches.

12. A gate plate for use in injection molding a light-transmissive thermoplastic encapsulating material over a set of light emitting diodes mounted directly on a substrate having a hole through the substrate adjacent to each light emitting diode, the gate plate comprising:

a set of cavities arranged in the form of an alphanumeric display and formed entirely within the gate plate, each cavity shaped to form a package of encapsulating material capable of focusing and reflecting light and to enclose one light emitting diode and extend over its adjacent hole; and

a set of short conical gates formed entirely within the gate plate, each gate having an input for receiving an encapsulating material and an output communicating with a cavity.

13. The gate plate of claim 12, wherein the cavities are arranged to form a seven-segment display.

14. The gate plate of claim 12, wherein each cavity has a base opposite from the output, which base is substantially triangular with rounded corners, each cavity is substantially rounded above its base, and wherein each output is substantially round.

15. A gate plate for use in injection molding an encapsulating a thermoplastic material over a plurality of small electronic devices mounted directly on a substrate, two or more of the devices being in close proximity to one another, the gate plate comprising:

a plurality of cavities, each cavity formed entirely within the gate plate and designed to form a package of encapsulating material capable of focusing and reflecting light and to enclose a single device and

a plurality of short gates, each formed entirely within the gate plate and having an input for receiving an encapsulating material and an output communicating with one of the cavities.

16. The gate plate of claim 15, wherein the gate plate includes a distribution runner connected to all of the gates.