Circuit board configurations facilitating operation of heat sensitive sensor components

Patent metadata

Field	Value
Publication number	US-2016334279-A1
Application number	US-201514714005-A
Country	US
Kind code	A1
Filing date	May 15, 2015
Priority date	May 15, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

A multilayered circuit board having a metal-free region vertically extending through at least a portion of a conductive layer, which lies generally parallel to a horizontal plane, vertically spaced from an outer surface. Heat-emitting and heat-sensitive components are mounted on the outer surface. The heat-emitting component is vertically and laterally spaced from the metal-free region, whereas the heat-sensitive component is vertically spaced and laterally aligned within the metal-free region such that the metal-free region is a thermal barrier that shields heat-sensitive component from radial heat flowing from the heat-emitting component.

First claim

What is claimed is:

1 . A thermal-isolation assembly, comprising:
a multilayer circuit board, including:
first and second outer surfaces being spaced along a vertical axis, each of the first and second outer surfaces lying generally parallel to a horizontal plane, the first outer surface facing a first direction generally parallel to the vertical axis, the second outer surface facing a second, opposite direction;
first and second outer conductive layers being spaced along the vertical axis between the first and second outer surfaces, each of the first and second outer conductive layers lying generally parallel to the horizontal plane;
first and second dielectric layers being spaced along the vertical axis between the first and second outer conductive layers, each of the first and second dielectric layers lying generally parallel to the horizontal plane;
first and second inner conductive layers being spaced along the vertical axis between the first and second dielectric layers, each of the first and second inner conductive layers lying generally parallel to the horizontal plane;
a middle dielectric layer being located along the vertical axis between the first and second inner conductive layers, the middle dielectric layer lying generally parallel to the horizontal plane;
a metal-free region extending along the vertical axis through at least a portion of the first outer conductive layer, the metal-free region having an outer periphery along the horizontal plane;
a heat-emitting component being mounted at a first mounting location on the first outer surface, the heat-emitting component and the metal-free region being spaced along the vertical axis and the horizontal plane, the heat-emitting component being electrically coupled to the first outer and the first inner conductive layers; and a heat-sensitive component being mounted at a second mounting location on the first outer surface, the heat-sensitive component and the metal-free region being spaced along the vertical axis and generally aligned along the horizontal plane, the heat-sensitive component being electrically coupled to the second outer and the second inner conductive layers; wherein the middle dielectric layer thermally isolates the heat-sensitive component by resisting heat flow from the first to the second inner and outer conductive layers, thereby limiting return heat flow to the heat-sensitive component, wherein the metal-free region thermally isolates the heat-sensitive component by resisting heat flow generally parallel to the horizontal plane towards the heat-sensitive component.

2 . The thermal-isolation assembly of claim 1 , further comprising:
a plurality of through holes extending along the vertical axis through the metal-free region and being spaced around the heat-sensitive component, wherein the through holes resist heat flow generally parallel to the horizontal plane towards the heat-sensitive component.

3 . The thermal-isolation assembly of claim 1 , further comprising:
a plurality of metal-plated vias extending along the vertical axis and being located along the horizontal plane outside the metal-free region, wherein the metal-plated vias provide thermal paths away from the heat-sensitive component.

4 . The thermal-isolation assembly of claim 1 , further comprising:
a silicon rubber sleeve fitted around a portion of the heat-sensitive component that projects away from the first outer surface, the silicon rubber sleeve thermally isolates the heat-sensitive component by resisting heat transfer by radiation to the heat-sensitive component.

5 . The multilayer circuit board of claim 14 , wherein the heat-emitting component is an LED and the heat-sensitive component is a PIR sensor, both installed in a combined smoke detector and carbon monoxide device.

6 . The thermal-isolation assembly of claim 1 , wherein the metal-free region is free of metal ground planes but includes metal ground, power, or signal traces.

7 . A multilayered circuit board, comprising:
a first conductive layer lying generally parallel to a horizontal plane; a metal-free region extending along a vertical axis through at least a portion of the first conductive layer; and a first outer surface being located along the vertical axis above the first conductive layer, lying generally parallel to the horizontal plane, and supporting a heat-emitting component and a heat-sensitive component, the heat-emitting component and the metal-free region being spaced along the vertical axis and the horizontal plane, the heat-sensitive component and the metal-free region being spaced along the vertical axis and generally aligned along the horizontal plane, wherein the metal-free region thermally isolates the heat-sensitive component by resisting heat flowing generally parallel to the horizontal plane towards the heat-sensitive component.

8 . The multilayered circuit board of claim 7 , wherein the metal-free region includes inner and outer peripheries, and the heat-sensitive component is aligned along the horizontal plane inside the inner periphery such that the metal-free region provides a thermal-isolation barrier along the horizontal plane between the heat-sensitive and heat-emitting components.

9 . The multilayered circuit board of claim 7 , wherein the metal-free region is free of metal ground planes but includes metal ground, power, or signal traces.

10 . The multilayered circuit board of claim 9 , further comprising:
a second conductive layer being located along the vertical axis below the first conductive layer and lying generally parallel to the horizontal plane; a second metal-free region extending along the vertical axis through at least a portion of the second conductive layer, the first and second metal-free regions being spaced along the vertical axis and the horizontal plane, the first and second metal-free regions being spaced along the vertical axis and generally aligned along the horizontal plane,

11 . The multilayer circuit board of claim 7 , further comprising:
a first connector extending generally parallel to the vertical axis and electrically coupling the heat-emitting component to the first conductive layer; a second connector extending generally parallel to the vertical axis and electrically coupling the heat-sensitive component to the second conductive layer; and a middle dielectric layer being located along the vertical axis between the first and second conductive layers and thermally resisting heat flow from the first conductive layer to the second conductive layer, thereby limiting return heat flow through the second connector to the heat-sensitive component.

12 . The multilayer circuit board of claim 7 , further comprising:
a plurality of through holes extending along the vertical axis through the metal-free region and being spaced around the heat-sensitive component, wherein the through holes resist heat flow generally parallel to the horizontal plane towards the heat-sensitive component; and a plurality of metal-plated vias extending along the vertical axis and being located outside the metal-free region, wherein the metal-plated vias provide thermal paths away from the heat-sensitive component.

13 . The multilayer circuit board of claim 7 , further comprising:
a silicon rubber sleeve fitted around a portion of the heat-sensitive component that projects away from the first outer surface, the silicon rubber sleeve thermally isolates the heat-sensitive component by resisting heat transfer by radiation to the heat-sensitive component.

14 . The multilayer circuit board of claim 7 , wherein the heat-emitting component is an LED and th

Assignees

• Google Inc

Inventors

• Mittleman Adam
• Smith Ian Charles
• Warren Daniel Adam
• Dong William Raeming
• Wheeler Jeff

Classifications

• G01J5/10

  using electric radiation detectors · CPC title

• G01J5/06 Primary

  Arrangements for eliminating effects of disturbing radiation; Arrangements for compensating changes in sensitivity (for adjusting of solid angle of collected radiation G01J5/07; means for wavelength selection G01J5/0801) · CPC title

• H05K1/0298

  Multilayer circuits · CPC title

• G01J5/0014

  for sensing the radiation from gases, flames · CPC title

• H05K1/0201

  Thermal arrangements, e.g. for cooling, heating or preventing overheating · CPC title