Epoxy molding compounds with resistance to UV light and heat

• US 7,125,917 B2
• Filed: 09/22/2003
• Issued: 10/24/2006
• Est. Priority Date: 06/06/2001
• Status: Expired due to Fees

• Current Assignee: Henkel Corporation (Henkel AG & Co KGaA)
• Original Assignee: Henkel Corporation (Henkel AG & Co KGaA)
• Inventors: Starkey, Dale
• Primary Examiner(s): SELLERS, ROBERT E
• Application Number:
  US10/667,706
• Publication Number:
  US 20040063840A1
• Time in Patent Office: 1,128 Days
• Field of Search: None
• US Class Current: 523/458
• CPC Class Codes: C08G 59/3245 containing only nitrogen as a heteroatom
• CPC Class Codes: C08G 59/4215 cycloaliphatic
• CPC Class Codes: C09K 11/02 Use of particular materials as binders, particle coatings or suspension media therefor
• CPC Class Codes: C09K 11/08 containing inorganic luminescent materials
• 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 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 33/501 characterised by the materials, e.g. binder

Abstract

A molding compound is provided for use in encapsulating electronic packages which include an optoelectronic component, such as an LED. The molding compound includes a partially cured epoxy composition, an antioxidant, and, optionally, a phosphor material substantially uniformly distributed throughout the epoxy composition. The optional phosphor material may be suspended within the epoxy composition by pre-reacting a portion of the epoxy composition prior to B-staging of the molding compound. As such, the optional phosphor material is suspended within the epoxy composition, thereby preventing settling of the phosphor material during B-staging, as well as during curing of the molding compound in the encapsulation process.

Claims

1. A method of preparing a molding compound comprising:

(a) mixing an epoxy composition comprising an epoxy resin and a cyclic anhydride with an antioxidant and a visible light-emitting phosphor material to provide a homogeneous mixture with said phosphor material suspended within said epoxy composition;

(b) increasing the viscosity of said homogeneous mixture by initiating reaction of the cyclic anhydride with the epoxy resin while maintaining said phosphor material suspended within said epoxy composition to form a pre-reacted intermediate; and

(c) partially curing said epoxy composition of said pre-reacted intermediate, thereby forming said molding compound.

2. The method according to claim 1, wherein step (b) comprises adding to the homogeneous mixture an anhydride ring opening agent to initiate reaction of the cyclic anhydride.

3. The method according to claim 1, wherein step (b) comprises:

cooling the homogeneous mixture to a temperature of about 45°

C. to about 85°

C. and adding a polyol; and

heating to a temperature of about 70°

C. to about 80°

C. for from about 10 minutes to 30 minutes to increase the viscosity to form the pre-reacted intermediate.

4. The method according to claim 1, wherein step (c) comprises heating the pre-reacted intermediate to a temperature of about 50°

C. to about 100°

C. for a period of about 30 minutes to about 24 hours.

5. The method according to claim 1, wherein step (c) comprises reacting about 40% to about 60% of the epoxy moieties of the epoxy resin.