Eco-friendly printed circuit board for high temperature and low temperature applications

Patent metadata

Field	Value
Publication number	US-12402249-B2
Application number	US-202318501619-A
Country	US
Kind code	B2
Filing date	Nov 3, 2023
Priority date	Nov 3, 2023
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A multi-layer printed circuit board (PCB) is fabricated using basalt fibers instead of glass fibers. Using basalt fibers in lieu of glass fibers makes the PCB more environmentally friendly without sacrificing mechanical and electrical properties. The multi-layer PCB includes a basalt fiber core comprised of a basalt fiber prepreg provided between two copper layers. A first copper layer and a second copper are coupled to different sides of the basalt fiber core. A first basalt fiber prepreg is coupled to the first copper layer and a second basalt fiber prepreg is coupled to the second copper layer.

First claim

What is claimed is:

1. A printed circuit board (PCB), comprising:
a basalt fiber core comprising:
a first prepreg comprising basalt fibers and epoxy resin;
a first copper layer coupled to a first surface of the first prepreg; and
a second copper layer coupled to a second surface of the first prepreg;

a third copper layer coupled to the first copper layer;
a fourth copper layer coupled to the second copper layer;
a second prepreg coupled to the third copper layer, the second prepreg comprising basalt fibers and epoxy resin; and
a third prepreg coupled to the fourth copper layer, the third prepreg comprising basalt fibers and epoxy resin.

2. The PCB of claim 1 , further comprising a fifth copper layer coupled to the second prepreg and a sixth copper layer coupled to the third prepreg.

3. The PCB of claim 1 , wherein the first copper layer is coupled to the first surface of the first prepreg and the second copper layer is coupled to the second surface of the first prepreg during a compression curing process.

4. The PCB of claim 1 , wherein the PCB has a modulus of elasticity between 6.0 gigapascals (GPa) to 9.0 GPa.

5. The PCB of claim 1 , wherein the PCB has a coefficient of thermal expansion (CTE) between 12 parts per million per degree Celsius (ppm/° C.) and 18 ppm/° C. in a first axis and a CTE between 15 ppm/° C. and 19 ppm/° C. in a second axis.

6. The PCB of claim 1 , wherein the PCB has a density between 1.9 grams per cubic centimeter (g/cm 3 ) and 2.3 g/cm 3 and wherein the PCB has a thermal conductivity between 2.5 watts per meter per Kelvin (W/m·K) and 3.2 W/m·K.

7. The PCB of claim 1 , wherein the PCB has a dielectric constant at 1 GHz between 4.7 and 5.8.

8. A printed circuit board (PCB), comprising:
a core comprising a first prepreg consisting of basalt fibers and epoxy resin positioned between two copper layers;
a first copper layer coupled to a first surface of the core;

a second copper layer coupled to a second surface of the core;
a second prepreg coupled to the first copper layer, the second prepreg consisting of basalt fibers and epoxy resin; and
a third prepreg coupled to the second copper layer, the third prepreg consisting of basalt fibers and epoxy resin.

9. The PCB of claim 8 , further comprising a third copper layer coupled to the second prepreg and a fourth copper layer coupled to the third prepreg.

10. The PCB of claim 8 , wherein the PCB has a modulus of elasticity between 6.0 gigapascals (GPa) to 9.0 GPa.

11. The PCB of claim 8 , wherein the PCB has a coefficient of thermal expansion (CTE) between 12 parts per million per degree Celsius (ppm/° C.) and 18 ppm/° C. in a first axis and a CTE between 15 ppm/° C. and 19 ppm/° C. in a second axis.

Assignees

• Sandisk Technologies Inc

Inventors

• Kumaresan Vigneshwarram
• Janakiraman Vishnu Chandar
• Devarajan Mutharasu

Classifications

• H05K1/0298 Primary

  Multilayer circuits · CPC title

• H05K3/4644

  by building the multilayer layer by layer, i.e. build-up multilayer circuits (making via holes in the insulating layers H05K3/0011; special circuit boards as base or core whereon the multilayer is built H05K3/4602) · CPC title

• H05K1/0373

  containing additives, e.g. fillers (H05K1/036 takes precedence) · CPC title

• H05K1/0366 Primary

  reinforced, e.g. by fibres, fabrics (H05K1/036 takes precedence) · CPC title