Moisture getting composition for hermetic microelectronic devices

• US 5,591,379 A
• Filed: 08/02/1993
• Issued: 01/07/1997
• Est. Priority Date: 07/06/1990
• Status: Expired due to Term

• Current Assignee: Alpha Fry Limited (Element Solutions Inc)
• Original Assignee: Alpha Fry Limited (Element Solutions Inc)
• Inventors: Shores, A. Andrew
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): Sample, David
• Application Number:
  US08/100,181
• Time in Patent Office: 1,254 Days
• Field of Search: 252/194, 106/122, 501/32, 501/39, 501/80, 523/466, 524/444
• US Class Current: 252/194
• CPC Class Codes: C09K 2200/0243 Silica-rich compounds, e.g. silicates, cement, glass
• CPC Class Codes: C09K 2200/06 Macromolecular organic compounds, e.g. prepolymers
• CPC Class Codes: C09K 3/1018 Macromolecular compounds having one or more carbon-to-silicon linkages
• CPC Class Codes: H05K 5/0212 Condensation eliminators
• CPC Class Codes: H05K 5/0213 Venting apertures; Constructional details thereof
• CPC Class Codes: H10K 50/844 Encapsulations
• CPC Class Codes: H10K 50/846 comprising getter material or desiccants
• CPC Class Codes: Y10S 95/902 Molecular sieve
• CPC Class Codes: Y10T 428/28 Web or sheet containing structurally defined element or component and having an adhesive outermost layer
• CPC Class Codes: Y10T 428/2835 including moisture or waterproof component
• CPC Class Codes: Y10T 428/2852 Adhesive compositions
• CPC Class Codes: Y10T 428/2891 including addition polymer from alpha-beta unsaturated carboxylic acid [e.g., acrylic acid, methacrylic acid, etc.] Or derivative thereof
• CPC Class Codes: Y10T 428/2896 including nitrogen containing condensation polymer [e.g., polyurethane, polyisocyanate, etc.]

Abstract

This invention describes a composition of matter having moisture gettering properties and applicable as coating or adhesive in a hermetic microelectronic device. The composition is applied to the interior surface of the packaging at a thickness of 0.1-25 mil and comprises a desiccant finely dispersed in a binder which is a water vapor permeable solid material. This may be a polymer, porous ceramic or glass. The desiccant is a particulate solid with 0.2-100 micrometer average particle size. It ought to be able to absorb from a one atmosphere pressure gas containing one volume percent water vapor at least four parts by weight of water vapor per 100 parts by weight of desiccant at 25° C., and for high reliability devices, it should also be able to absorb at least two parts by weight of water vapor per 100 parts by weight of desiccant at 100° C. The desiccant to binder volume ratio ought to be between 0.002 and 2. Molecular sieves are especially useful as the desiccant component of the composition of this invention.

Claims

1. A composition of matter useful as a desiccant in a hermetic electronic device, comprising a powder dispersed in a binder, wherein

said powder is selected from the group consisting of zeolite molecular sieves, activated alumina, silica gel, alkaline earth oxide, and alkali metal carbonate;

said binder is a continuous matrix of porous glass or porous ceramic; and

said powder to binder volume ratio is 0.001-2.

2. A composition as in claim 1, wherein said powder is a zeolite molecular sieve.

3. A composition as in claim 2, wherein said binder is a continuous matrix of porous glass.

4. A composition as in claim 2, wherein said binder is a continuous matrix of porous ceramic.

said powder to binder volume ratio is 0.001-2.

5. A composition of matter useful as a desiccant and particle getter in a hermetic electronic device, comprising a powder dispersed in a binder, wherein

said powder is selected from the group consisting of zeolite molecular sieves, activated alumina, silica gel, alkaline earth oxide, and alkali metal carbonate;

said binder is a polysiloxane or polyurethane gel which is effective as a particle getter, and

said powder to binder volume is 0.001-2.

6. A composition as in claim 5, wherein said powder is a zeolite molecular sieve.

7. A composition as in claim 6, wherein said binder is a polysiloxane gel.