Printed circuit board for integrated LED driver
A multi-layer metal core printed circuit board (MCPCB) has mounted on it at least one or more heat-generating LEDs and one or more devices configured to provide current to the one or more LEDs. The one or more devices may include a device that carries a steep slope voltage waveform. Since there is typically a very thin dielectric between the patterned copper layer and the metal substrate, the steep slope voltage waveform may produce a current in the metal substrate due to AC coupling via parasitic capacitance. This AC-coupled current may produce electromagnetic interference (EMI). To reduce the EMI, a local shielding area may be formed between the metal substrate and the device carrying the steep slope voltage waveform. The local shielding area may be conductive and may be electrically connected, to a DC voltage node adjacent to the one or more devices.
1. A light emitting diode (LED) module comprising:
a first dielectric layer on a base metal substrate;
a first patterned metal layer on the first dielectric layer;
a local shielding area within the first patterned metal layer, the local shielding area comprising a substantially continuous area of conductive material;
a second dielectric layer on the first patterned metal layer;
a second patterned metal layer on the second dielectric layer;
one or more LEDs on the second patterned metal layer, wherein the one or more LEDs are thermally coupled to the base metal substrate;
one or more devices on the second patterned metal layer configured to provide a target current to the one or more LEDs, wherein a device of the one or more devices carries a steep slope voltage waveform and is located above at least a portion of the local shielding area; and
a DC voltage node on the second patterned metal layer, wherein the DC voltage node is electrically connected to the local shielding area.
2. The module of claim 1 , wherein the DC voltage node and the local shielding area are electrically connected by a conductive via extending through a portion of the first patterned metal layer, the second dielectric layer, and the second patterned metal layer.
3. The module of claim 1 , wherein an outer edge of the local shielding area extends laterally beyond an outer edge of the device carrying the steep slope voltage waveform.
4. The module of claim 1 , wherein the DC voltage node is located above at least a portion of the local shielding area.
5. The module of claim 1 , wherein a portion of the first patterned metal layer below the one or more LEDs does not contain the local shielding area.
6. The module of claim 1 , wherein the device carrying the steep slope voltage waveform comprises a switching transistor that generates a square wave voltage waveform from an AC voltage input.
7. The module of claim 1 , wherein the DC voltage node is electrically coupled to a ground.
8. The module of claim 1 , wherein the DC voltage node is electrically coupled to a positive DC voltage source.
9. The module of claim 1 , wherein an outer edge of the local shielding area extends laterally beyond an outer edge of the DC voltage node.
10. The module of claim 1 , further comprising:
a heat sink thermally coupled to the base metal substrate.
11. A method of forming a light emitting diode (LED) module, the method comprising:
forming a first dielectric layer on a base metal substrate;
forming a first patterned metal layer on the first dielectric layer;
forming a local shielding area within the first patterned metal layer, the local shielding area comprising a substantially continuous area of conductive material;
forming a second dielectric layer on the first patterned metal layer;
forming a second patterned metal layer on the second dielectric layer;
forming one or more LEDs on the second patterned metal layer, wherein the one or more LEDs are thermally coupled to the base metal substrate;
forming one or more devices on the second patterned metal layer configured to provide a target current to the one or more LEDs, wherein a device of the one or more devices carries a steep slope voltage waveform and is located above at least a portion of the local shielding area; and
forming a DC voltage node on the second patterned metal layer, wherein the DC voltage node is electrically connected to the local shielding area.
12. The method of claim 11 , further comprising:
forming a conductive via between the DC voltage node and the local shielding area, wherein the conductive via extends through a portion of the first patterned metal layer, the second dielectric layer, and the second patterned metal layer.
13. The method of claim 11 , wherein an outer edge of the local shielding area extends laterally beyond an outer edge of the device carrying the steep slope voltage waveform.
14. The method of claim 11 , wherein the DC voltage node is located above at least a portion of the local shielding area.
15. The method of claim 11 , wherein a portion of the first patterned metal layer below the one or more LEDs does not contain the local shielding area.
16. The method of claim 11 , wherein the device carrying the steep slope voltage waveform comprises a switching transistor that generates a square wave voltage waveform from an AC voltage input.
17. The method of claim 11 , wherein the DC voltage node is electrically coupled to a ground.
18. The method of claim 11 , wherein the DC voltage node is electrically coupled to a positive DC voltage source.
19. The method of claim 11 , wherein an outer edge of the local shielding area extends laterally beyond an outer edge of the DC voltage node.
20. The method of claim 11 , wherein the base metal substrate is thermally coupled to a heat sink.