Making an aluminum nitride heater

Patent metadata

Field	Value
Publication number	US-11676746-B2
Application number	US-202016782287-A
Country	US
Kind code	B2
Filing date	Feb 5, 2020
Priority date	Feb 8, 2019
Publication date	Jun 13, 2023
Grant date	Jun 13, 2023

Abstract

A method of making a heater includes an aluminum nitride base having equal to or less than 1% impurities, particularly one embodiment having none of polybrominated biphenyl, polybrominated diphenyl ether, hexabromocyclododecane, polyvinyl chloride, chlorinated paraffin, phthalate, cadmium, hexavalent chromium, lead, and mercury. The base is fired in a heating unit before any layering. Thereafter, on a topside and backside of the base a conductor layer is layered and allowed to settle and dry before firing. Next, a resistive layer is layered on the base from a resistor paste such that the resistive layer connects to the conductor layer on the topside. The resistor paste is allowed to settle and dry and then the base with the conductor and resistor layers is fired. At least four layers of glass are layered next over the resistive layer, each instance thereof including layering a glass, drying the glass and firing.

First claim

The invention claimed is:

1. A method of making a heater, comprising:
on an aluminum nitride base having equal to or less than 1% impurities, positioning the aluminum nitride base in a heating unit and firing the heating unit at a temperature of about 850° C. for at least 5 minutes;
removing from the heating unit the aluminum nitride base;
providing a first mesh stencil over the aluminum nitride base;
leveling through the first mesh stencil a conductive paste of silver and platinum or palladium, the conductive paste forming a conductor layer on the aluminum nitride base;
letting settle the conductor paste for about 5 to about 10 minutes;
drying the conductor layer in a drying unit;
firing the aluminum nitride base having said conductor layer in a same or different said heating unit at 850° C. for at least 5 minutes;
removing from said same or different said heating unit the aluminum nitride base having said conductor layer;
providing a second mesh stencil over the aluminum nitride base having said conductor layer;
leveling through the second mesh stencil a resistor paste of silver and palladium, the resistor paste forming a resistive layer on the aluminum nitride base and connecting to the conductor layer;
letting settle the resistor paste for about 5 to about 10 minutes;
drying the resistive layer in a same or different said drying unit;
firing the aluminum nitride base having said conductor and resistive layers in said same or different said heating unit at 850° C. for at least five minutes; and
overlying at least four layers of glass over the resistive layer and a portion of the conductor layer, wherein the drying unit and the heating unit are a same or different unit.

2. The method of claim 1 , further including providing the aluminum nitride base wherein the impurities do not include any of polybrominated biphenyl, polybrominated diphenyl ether, hexabromocyclododecane, polyvinyl chloride, chlorinated paraffin, phthalate, cadmium, hexavalent chromium, lead, and mercury.

3. The method of claim 1 , wherein the overlying said at least four layers of glass further includes overlying a first two consecutive layers of glass with a same glass.

4. The method of claim 3 , wherein the overlying the first two consecutive layers of glass further includes for each layer of the first two consecutive layers of glass overlying a glass having a solid content of about 70% or more and a viscosity of about 65 Pa·s or less.

5. The method of claim 3 , wherein the overlying said at least four layers of glass further includes overlying a second two consecutive layers of glass over the first two consecutive layer, wherein each of the second two consecutive layers of glass are a same glass different than the first two consecutive layers of glass.

6. The method of claim 1 , further including overlying a fifth layer of glass over the at least four layers of glass.

7. The method of claim 1 , further including
providing a third mesh stencil over the aluminum nitride base on a side opposite a side of the aluminum nitride base having said conductor layer,
leveling through the third mesh stencil a same or different said conductive paste of silver and platinum or palladium, said same or different said conductive paste forming a second conductor layer on said side opposite of the aluminum nitride base,
letting settle the same or different said second conductive paste, and
drying the second conductor layer in said same or different said heating unit before said firing the aluminum nitride base having said conductor layer in said same or different said heating unit.

8. The method of claim 1 , wherein the overlying said at least four layers of glass further includes for each layer of said at least four layers of glass the following:
providing a third mesh stencil over the aluminum nitride base having said conductor and resistive layers,
leveling through the third mesh stencil a glass,
letting settle the glass,
drying the glass in said same or different said drying unit, and
firing the glass.

9. The method of claim 8 , wherein said firing the glass further includes firing the glass at a peak temperature of 830° C. for at least 5 minutes.

10. The method of claim 8 , wherein said letting settle the glass for about 5 to about 10 minutes.

11. The method of claim 1 , wherein each instance of said drying further includes drying for a period of time of about 30 total minutes at a temperature profile of the drying unit beginning at about 25° C. and ramping up to about 80° C. for about 10 minutes, ramping up again to about 160° C. for about 10 minutes and cooling down to below 50° C.

12. The method of claim 1 , wherein each instance of said firing further includes firing the heating unit at a heating profile for at least 40 total minutes starting at about 25° C. and ramping up to 850° C. by 20 minutes and maintaining 850° C. for at least 10 minutes and decreasing the temperature for at least 10 minutes.

Assignees

• Lexmark Int Inc

Inventors

• Aoki Makoto
• Smith Jerry Wayne

Classifications

• H05B2203/02

  Heaters using heating elements having a positive temperature coefficient · CPC title

• H05K3/1216

  by screen printing or stencil printing · CPC title

• H05B3/12

  characterised by the composition or nature of the conductive material · CPC title

• H05K1/167

  incorporating printed resistors · CPC title

• H05B2203/017

  Manufacturing methods or apparatus for heaters · CPC title