US-12621930-B2 - Printed circuit board dielectric molding or machining and electrolytic metallization

Abstract

A printed circuit board (PCB) has a tridimensional (3D) dielectric substrate having opposite sides and made of fiber-reinforced polymer. Each side comprises channels and pockets formed by molding or machining a dielectric laminate, and the channels and pockets define a layout for conductive traces and pads of the PCB. The channels and pockets in a same side of the 3D dielectric substrate have a uniform depth. Side walls of the channels and pockets have a draft angle in a range of at least about 5 degrees to at least about 15 degrees.

Inventors

• Edward C. Carignan
• Paulo Guedes-Pinto

Assignees

• Infinitum Electric Inc.

Dates

Publication Date

20260505

Application Date

20240326

Claims (18)

1. 1 . A printed circuit board (PCB) stator for an axial field rotary energy device, the PCB stator comprising: PCB panels, each comprising a tridimensional (3D) dielectric substrate with opposite sides and made of fiber-reinforced polymer; each side comprises channels and pockets comprising machined dielectric laminate, the channels and pockets in each side have a uniform depth, and the channels and pockets comprise a layout of conductive traces and pads that are plated therein and the outer surface of those conductive traces and pads are flush with the sides of the 3D dielectric substrate; and side walls of the channels and pockets have a draft angle in a range of at least about 5 degrees to at least about 15 degrees.
2. 2 . The PCB stator of claim 1 , wherein the channels and pockets of a first side of the sides of the PCB panels have a first depth, the channels and pockets of a second side of the sides of the PCB panels have a second depth.
3. 3 . The PCB stator of claim 2 , wherein the first and second depths are the same or within 25 μm of each other.
4. 4 . The PCB stator of claim 3 , wherein the sides of each PCB panel have a same layout.
5. 5 . The PCB stator of claim 3 , wherein the sides of each PCB panel have a different layout.
6. 6 . The PCB stator of claim 2 , wherein the first depth differs from the second depth.
7. 7 . The PCB stator of claim 6 , wherein the sides of each PCB panel have a same layout.
8. 8 . The PCB stator of claim 6 , wherein the sides of each PCB panel have a different layout.
9. 9 . The PCB stator of claim 1 , wherein the uniform depth of the channels and pockets is equal to or greater than 140 μm.
10. 10 . A printed circuit board (PCB) stator for an axial field rotary energy device, the PCB stator comprising: PCB panels, each comprising a tridimensional (3D) dielectric substrate with opposite sides and made of fiber-reinforced polymer; each side comprises channels and pockets comprising molded dielectric laminate, the channels and pockets in each side have a uniform depth, and the channels and pockets comprise a layout of conductive traces and pads that are plated therein and the outer surface of those conductive traces and pads are flush with the sides of the 3D dielectric substrate; and side walls of the channels and pockets have a draft angle in a range of at least about 5 degrees to at least about 15 degrees.
11. 11 . The PCB stator of claim 10 , wherein the channels and pockets of a first side of the sides of the PCB panels have a first depth, the channels and pockets of a second side of the sides of the PCB panels have a second depth.
12. 12 . The PCB stator of claim 11 , wherein the first and second depths are the same or within 25 μm of each other.
13. 13 . The PCB stator of claim 12 , wherein the sides of each PCB panel have a same layout.
14. 14 . The PCB stator of claim 12 , wherein the sides of each PCB panel have a different layout.
15. 15 . The PCB stator of claim 11 , wherein the first depth differs from the second depth.
16. 16 . The PCB stator of claim 15 , wherein the sides of each PCB panel have a same layout.
17. 17 . The PCB stator of claim 15 , wherein the sides of each PCB panel have a different layout.
18. 18 . The PCB stator of claim 10 , wherein the uniform depth of the channels and pockets is equal to or greater than 140 μm.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of and claims priority to and the benefit of U.S. patent application Ser. No. 18/382,921, filed Oct. 23, 2023, which is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 18/127,453, filed Mar. 28, 2023, each of which is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION Field of the Disclosure The present disclosure relates in general to an additive system, method and apparatus for printed circuit board (PCB) construction, in particular, where PCB traces are designed to carry large electrical currents, and further relates to PCB structures designed to operate as stators in electric motors. Description of the Prior Art A PCB typically can comprise one or more layers of a foil made of copper or other electrically conductive material, such as aluminum laminated onto a sheet of a dielectric material made of a fiber-reinforced polymer, such as a NEMA FR-4 woven fiberglass cloth with epoxy resin binder laminate. The electrically conductive layer can be laminated on one or both sides of the dielectric (e.g., FR-4) sheet. The most common conductive material used in PCB construction is copper foil, which can have electrical conductivity of 58 mS/m at 20° C., and its thickness is expressed in ounces of copper per square foot, being 1 oz/ft2 copper the most common copper foil employed in PCB construction. The 1 oz/ft2 copper foil has a thickness of about 35 μm. The PCB can have a plurality of conductive pads that are interconnected by a plurality of traces. Both pads and traces can be formed by etching the conductive material through a conventional photo-lithography process 100 depicted in FIG. 1, which includes steps 101-129. In some embodiments, portions of a circuit formed in the PCB can carry high electric currents (e.g., several to tens of amperes). In those cases, the PCB can be made of thicker conductive foil. The commonly commercially available copper foils for PCBs are 2, 3 and 4 oz/ft2, which have thicknesses of 70, 105 and 140 μm, respectively. In other embodiments, in addition to employing thicker foil, the PCB can have multiple layers configured to receive high electric currents that can flow in parallel layers and/or parallel traces. Examples of PCB structures that require high electric current carrying capability are PCB stators employed in axial field rotary energy devices similar to the devices described in U.S. Pat. Nos. 10,141,803, 10,135,310, 10,340,760, 10,141,804, 10,186,922, and 11,502,583, each of which is incorporated herein by reference in its entirety. Some of these PCB stator embodiments can have a plurality of conductive layers and conductive traces configured to carry high electric currents, as shown in FIG. 2, which shows a partial sectional view of a PCB structure 200 with a plurality of traces 201. The conventional PCB manufacturing process depicted in FIG. 1 presents some disadvantages. First, the etching step 105 of the process 100 does not produce traces with a uniform cross section. FIG. 3 shows a magnified view of two conventional, adjacent traces 201 after the etching step 105 (FIG. 1). In FIG. 3, it can be seen that the width A of the base of the trace is wider than the width B at the top of the trace. The distance between adjacent traces C has a minimum value, called space, based on the voltage applied to the PCB. While the distance C can meet the minimum space requirement, it can be seen that the distance D at the top of the trace exceeds the minimum clearance value. The tapered profile at the side walls of the trace can be controlled to some extent by adjusting etching parameters, however it may be difficult to eliminate in its entirety. In PCB manufacturing, an “etch factor” is defined as the ratio W/T where W=(A−B)/2 and T is the thickness of the conductive trace. This etch factor is typically between 0.3 and 0.5. The result of the etching process is that the volume 202, which is the difference between a maximum theoretical rectangular trace shown as a dotted line and the actual trace cross section, is lost resulting in a smaller cross section available to current carrying, which can lead to higher resistance and a less efficient electrical circuit. A second disadvantage of the conventional PCB manufacturing process 100 depicted in FIG. 1 is that, in some steps of the process, such as step 101 (pre-clean), step 108 (oxide coat), and step 111 (through hole metallization) for example, some conductive material can be removed, resulting in further reduction of the sectional area of traces 201. A third disadvantage of the conventional PCB manufacturing process 100 depicted in FIG. 1 is that conductive material is removed from the PCB conductive layers. Although most of the conductive material can be recovered, the chemical processes required to recover conductive material employ hazardous chemicals and are energy intensive. Final