Overmolded circuit board and method

• US 8,230,575 B2
• Filed: 12/12/2008
• Issued: 07/31/2012
• Est. Priority Date: 12/12/2007
• Status: Active Grant

• Current Assignee: Fujitsu Limited, Innotec, Corp.
• Original Assignee: Innotec, Corp.
• Inventors: Veenstra, Thomas J., Mulder, Jason R., Fleischmann, Eric L.
• Primary Examiner(s): HAUGHTON, ANTHONY MICHAEL
• Application Number:
  US12/333,397
• Publication Number:
  US 20090154182A1
• Time in Patent Office: 1,327 Days
• Field of Search: 174/377, 174/378, 361/751, 361/752, 361/737, 295/921
• US Class Current: 29/592.1
• CPC Class Codes: B60Q 1/2696 Mounting of devices using LEDs
• CPC Class Codes: B60Q 3/217 Doors, e.g. door sills; Steps
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21V 19/001 the light sources being semiconductors devices, e.g. LEDs
• CPC Class Codes: H05K 1/142 Arrangements of planar printed circuit boards in the same plane, e.g. auxiliary printed circuit insert mounted in a main printed circuit
• CPC Class Codes: H05K 1/148 Arrangements of two or more hingeably connected rigid printed circuit boards, i.e. connected by flexible means
• CPC Class Codes: H05K 1/185 Components encapsulated in the insulating substrate of the printed circuit or incorporated in internal layers of a multilayer circuit semiconductor chips encapsulated by interconnect and support structures H01L23/5389, H01L24/00
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2201/0108 Transparent
• CPC Class Codes: H05K 2201/0129 Thermoplastic polymer, e.g. auto-adhesive layer; Shaping of thermoplastic polymer
• CPC Class Codes: H05K 2201/09118 Moulded substrate
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 2201/10151 Sensor
• CPC Class Codes: H05K 2201/1034 Edge terminals, i.e. separate pieces of metal attached to the edge of the printed circuit board [PCB]
• CPC Class Codes: H05K 2201/10689 Leaded Integrated Circuit [IC] package, e.g. dual-in-line [DIL]
• CPC Class Codes: H05K 2203/1316 Moulded encapsulation of mounted components
• CPC Class Codes: H05K 2203/1476 Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning
• CPC Class Codes: H05K 3/202 using self-supporting metal foil pattern
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence
• CPC Class Codes: H05K 3/3405 Edge mounted components, e.g. terminals
• CPC Class Codes: H05K 5/064 : sealed by potting, e.g. waterproof resin poured in a rigid casing
• CPC Class Codes: Y10T 29/49002 : Electrical device making
• CPC Class Codes: Y10T 29/49146 : with encapsulating, e.g., potting, etc.

Abstract

An electrical device includes a circuit board having one or more electrical components mounted to the circuit board. At least a portion of the circuit board is encapsulated in a thermoplastic polymer material to encapsulate the electrical components. The device may be fabricated by at least partially shielding the electrical components with polymer material, followed by overmolding the polymer material with thermoplastic polymer material. The shielding material may comprise a pre-formed component, or it may comprise thermoplastic polymer material that is molded around the electrical components in a first molding step or “shot”.

Claims

1. A method of fabricating an electrical assembly, comprising:

providing a plurality of electrically conductive circuit elements;

providing at least one circuit element comprising a board having a side surface and a plurality of conductive tracks disposed on the side surface of the board;

securing at least one electrical component to at least a selected one of the conductive tracks;

positioning at least a portion of the circuit element and the electrical component in a first mold cavity having a first shape;

molding thermoplastic polymer material around the electrical component while it is in the first mold cavity to encapsulate the electrical component in a protective capsule of thermoplastic polymer material, the protective capsule having a first portion in contact with the conductive tracks and the board, the protective capsule having peripheral edge portions extending around at least a portion of the electrical component;

positioning at least a portion of the circuit element and the electrical component in a second mold cavity having a second shape that is substantially different than the first shape;

molding thermoplastic polymer material over at least a portion of the protective capsule.

2. The method of claim 1, wherein:

the side surface of the board defines a generally flat surface portion;

the peripheral edge portions of the protective capsule extend to the flat first surface portion and define a peripheral edge surface that is transverse to the flat surface portion.

3. The method of claim 2, wherein:

an exposed portion of the flat surface portion of the board is not covered by the protective capsule of polymer prior to positioning the circuit element and the electrical component in the second mold cavity; and

including;

molding thermoplastic polymer material over the exposed portion.

4. The method of claim 3, wherein:

the first mold cavity is shaped to mold thermoplastic polymer material over at least a substantial portion of the conductive circuit elements.

5. The method of claim 4, wherein:

the first mold cavity forms a groove around the electrical component that is generally C-shaped in plan view, and wherein the first mold cavity is shaped such that a bridge of thermoplastic polymer material extending from the additional polymer material to the protective capsule is formed in the first mold cavity.

6. The method of claim 5, wherein:

the groove defines a base surface, and at least a portion of the base surface comprises portions of the conductive tracks.

7. The method of claim 1, wherein:

the step of securing at least one electrical component includes soldering the electrical component to the conductive tracks.

8. The method of claim 1, wherein:

the one electrical component comprises an LED.

9. The method of claim 8, wherein:

at least one additional electrical component in addition to the LED is secured to the circuit element; and

a protective capsule of thermoplastic polymer material is molded over the additional electrical component in the first mold cavity.

10. The method of claim 1, wherein:

the one electrical component comprises an integrated circuit having a generally quadrilateral perimeter;

the peripheral edge of the protective capsule has a generally quadrilateral shape.

11. A method of fabricating an electrical device, comprising;

providing a printed circuit board;

mounting at least two electrical components on the printed circuit board;

molding, in a first mold cavity, a barrier of thermoplastic polymer material around the two electrical components such that the thermoplastic polymer material at least partially covers the two electrical components;

molding, in the first mold cavity, a bridge of thermoplastic polymer material linking the barriers;

removing the printed circuit board and the two electrical components from the first mold cavity;

positioning the printed circuit board and the two electrical components in a second mold cavity;

injecting molten thermoplastic polymer material into the second mold cavity such that the molten thermoplastic polymer material encapsulates the barriers and the bridge.

12. The method of claim 11, wherein:

the barrier comprises thermoplastic polymer material that is molded around the one electrical component after the one electrical component is mounted to the printed circuit board.

13. A method of fabricating an electrical device, comprising;

providing a printed circuit board;

mounting at least one electrical component on the printed circuit board;

molding a barrier of thermoplastic polymer material around the one electrical component after the one electrical component is mounted to the printed circuit board;

positioning the printed circuit board and the one electrical component in a mold cavity;

injecting molten thermoplastic polymer material into the mold cavity such that the molten thermoplastic polymer material comes into contact with the barrier;

the mold cavity comprises a second mold cavity defining a second shape;

the thermoplastic polymer material is molded around the electrical component in a first mold cavity having a first shape that is substantially different than the second shape.

14. The method of fabricating an electrical device of claim 13, wherein:

the barrier includes a generally dome-shaped portion.

15. The method of fabricating an electrical device of claim 14, including:

forming a layer of thermoplastic polymer material on the printed circuit board in the mold cavity; and

forming a groove around the dome-shaped portion of the barrier.