Circuit encapsulation process

• US 5,728,600 A
• Filed: 11/15/1994
• Issued: 03/17/1998
• Est. Priority Date: 11/15/1994
• Status: Expired due to Term

• Current Assignee: VLT Incorporated (Vicor Corporation)
• Original Assignee: VLT Incorporated (Vicor Corporation)
• Inventors: Hedlund, Walter R. III, Saxelby, John R. Jr.
• Primary Examiner(s): GRAYBILL, DAVID E
• Application Number:
  US08/340,162
• Time in Patent Office: 1,218 Days
• Field of Search: 437/205, 437/207, 437/211, 437/212, 437/214, 437/216, 437/219, 264/272.17, 264/276, 425/116, 425/117, 425/125, 425/127, 249/84, 249/85, 249/95, 249/96, 29/841, 29/856, 29/858
• US Class Current: 264/272.11
• CPC Class Codes: H01L 21/565 Moulds
• CPC Class Codes: H01L 2224/48091 Arched
• 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: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence
• CPC Class Codes: Y10T 29/49146 with encapsulating, e.g., potting, etc.

Abstract

A method for encapsulating portions of a circuit formed on a substrate. The substrate has two faces and perimeter sides. Encapsulating surrounds, in molding compound, a portion of one of the faces of the substrate and a portion of the sides of the substrate, and during encapsulation a portion of the one face of the substrate that bears conductive pads is left unencapsulated.

An encapsulated circuit including a substrate having two faces and perimeter sides around the faces and a circuit formed on the substrate. The substrate also includes conductive pads that are formed on a portion of one of the faces near one of the sides and are connected to the circuit. An integrally formed encapsulating mass encapsulates all of the one face except in the region of the pads, all of the other face except in a region opposite to the region of the pads, and all of the sides.

Claims

1. A method for encapsulating portions of a circuit formed on a substrate having two faces and perimeter sides, comprising

inserting the substrate into a mold,

closing a top of the mold and a bottom of the mold against the substrate,

pushing molding compound from a conduit having a top defined by the substrate into a chamber in the mold, and

encapsulating, in the molding compound, a first portion of one of the faces of the substrate and a portion of the sides of the substrate, and, during encapsulation, leaving a second portion of the one face of the substrate unencapsulated, the second portion of the one face bearing conductive pads.

2. The method of claim 1, further comprising encapsulating a portion of the other of the faces of the substrate.

3. The method of claim 2, further comprising

leaving a second portion of the other of the faces of the substrate unencapsulated.

4. The method of claim 3, wherein the second portion of the other of the faces bears conductive pads.

5. The method of claim 1, wherein the conductive pads are electrically connected to electronic components, the electronic components being mounted on the substrate and encapsulated in the molding compound.

13. The method of claim 1, wherein the top of the mold and the bottom of the mold are separated by the substrate.

14. The method of claim 1, wherein the mold is connected to a compliance mechanism of a press, the press provides an even pressure distribution across the substrate through the compliance mechanism.

15. The method of claim 14, wherein the press includes molds and a compliance mechanism for attachment to each of the molds to enable the press to provide an even pressure distribution across substrates inserted in the molds.

16. The method of claim 14, wherein the compliance mechanism comprises a spring.

17. The method of claim 14, wherein the compliance mechanism comprises a pneumatic cylinder.

18. The method of claim 14, wherein the compliance mechanism comprises a hydraulic cylinder.

19. The method of claim 1, further comprising

curing the molding compound,

removing the substrate with exposed conductive pads from the mold, and

cutting away the waste portion and waste molding compound.

20. The method of claim 1, wherein the conduit includes a pot and a runner.

21. The method of claim 20, wherein the pot and the runner are in the bottom of the mold.

6. A method for encapsulating portions of a circuit formed on a substrate having two faces and perimeter sides, comprising

inserting the substrate into a mold, the substrate including an active portion on which the conductive pads and electronic components electrically connected to the conductive pads, are mounted, and a waste portion connected to the active portion by a segment in the area of the conductive pads,

closing a top of the mold and a bottom of the mold against the waste portion and against the segment of the active portion in the area of the conductive pads,

pushing molding compound from a conduit, having a top defined by the waste portion into a chamber in the mold, and

encapsulating, in the molding compound, a first portion of one of the faces of the substrate and a portion of the sides of the substrate, and, during encapsulation, leaving a second portion of the one face of the substrate unencapsulated, the second portion of the one face bearing conductive pads.

7. The method of claim 6, wherein the segment includes segments.

8. The method of claim 6, wherein closing the mold comprises

causing a ridge on the top of the mold to extend down against the waste portion and the segment of the active portion in the area of the conductive pads, and

causing a first ridge on the bottom of the mold to press up against the waste portion and the segment including the conductive pads.

9. The method of claim 8, further comprising

defining an end of the conduit with a second ridge on the bottom of the mold.

10. The method of claim 8, further comprising

causing the top of the mold to extend down against a second segment of the active portion, and

causing the bottom of the mold to press up against the second segment.

11. The method of claim 10, wherein the second segment includes segments.

12. The method of claim 10, further comprising

defining an end of the conduit with a second ridge on the bottom of the mold.

22. A method for encapsulating a circuit, comprising

inserting a substrate into a mold, wherein the substrate includes an active portion bearing electronic components and conductive pads for connecting to the components and a waste portion connected to the active portion by a segment in the area of the conductive pads,

closing the mold causing a ridge on a top of the mold to extend down against the waste portion and the segment including the conductive pads and causing a first ridge on a bottom of the mold to press up against the waste portion and the segment including the conductive pads,

pushing molding compound from a conduit having a top defined by the waste portion and an end defined by a second ridge on the bottom of the mold, into a mold cavity to encapsulate a portion of the active area, leaving the conductive pads exposed.

23. A method for encapsulating circuits, comprising

inserting a substrate into a mold, wherein the substrate includes active portions bearing electronic components and conductive pads for connecting to the components and waste portions connected to the active portions by segments in the areas of the conductive pads,

closing the mold causing ridges on a top of the mold to extend down against the waste portions and the segments including the conductive pads and causing first ridges on a bottom of the mold to press up against the waste portions and the segments including the conductive pads,

pushing molding compound from conduits having tops defined by the waste portions and ends defined by second ridges on the bottom of the mold, into mold cavities to encapsulate portions of the active areas, leaving the conductive pads exposed.

24. The method of claim 23, wherein the mold is connected to a compliance mechanism of a press, the press provides an even pressure distribution across the substrate through the compliance mechanism.

25. A method for encapsulating portions of a circuit formed on a substrate, comprising

inserting the substrate into a mold, the substrate including an active portion on which conductive pads and electronic components electrically connected to the conductive pads are mounted and a waste portion connected to the active portion by a segment in the vicinity of the conductive pads,

closing a top of the mold and a bottom of the mold against the waste portion and against the segment of the active portion in the vicinity of the conductive pads, and

pushing molding compound from a conduit, having a top defined by the waste portion, into a chamber in the mold.