Encapsulation means and method
US5904955A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 5, 1997 |
| Grant date | May 18, 1999 |
| Priority date | — |
| Expiry date | Sep 5, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/181
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An electronic device in a cavity in a mold is encapsulated by a composite plastic having two materials placed, respectively, in sequential locations in a reservoir in the mold. The first material has desirable properties when in contact with the surface of the device, e.g., better adhesion. The second and different material has other desirable properties, e.g., mechanical strength, low moisture permeability, etc. The first location is first in line in a direction through the mold chambers to the cavity. The two-part encapsulant is injected into the cavity without significant turbulence so as to avoid much mixing of the two materials. This creates a boundary layer of the first material which preferentially applies a coating to the device while the second material substantially fills the bulk of the space in the mold cavity. A composite encapsulation is formed having overall superior properties.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.