Reflow furnace and soldering method

Patent metadata

Field	Value
Publication number	US-11148217-B2
Application number	US-201916275218-A
Country	US
Kind code	B2
Filing date	Feb 13, 2019
Priority date	Jun 27, 2018
Publication date	Oct 19, 2021
Grant date	Oct 19, 2021

Abstract

A reflow furnace that can reduce both the flux clinging defect in a circuit board, and the thermal cracking defect in an electronic component has a heat zone in which a circuit board with a mounted electronic component is heated, and a cooling zone in which the heated circuit board is cooled, and includes: a shield disposed between the heat zone and the cooling zone and having an opening for passage of the circuit board; and a tunnel-like cover physically coupled to the opening and extending along a transport direction of the circuit board.

First claim

What is claimed is:

1. A reflow furnace that has a heat zone in which a circuit board with a mounted electronic component is heated, and a cooling zone in which the heated circuit board is cooled,
the reflow furnace comprising:
a shield disposed between the heat zone and the cooling zone and having an opening for passage of the circuit board;
a tunnel-like cover coupled to the opening and extending along a transport direction of the circuit board; and
an electrostatic-precipitation flux collection apparatus that includes a drawing unit that draws an atmosphere gas out of the reflow furnace in the heat zone, and a flux collection unit that collects a flux contained in the atmosphere gas,
wherein the flux collection apparatus returns the gas to the cooling zone after collecting the flux.

2. The reflow furnace according to claim 1 , wherein the drawing unit has a slit-like suction nozzle disposed over a width direction perpendicular to the transport direction of the circuit board in the reflow furnace.

3. The reflow furnace according to claim 1 , which satisfies TP1>TP2>TP3>TP4, where TP1 is an ambient temperature of the heat zone, TP2 is a temperature inside the tunnel-like cover on the heat zone side of the shield, TP3 is a temperature inside the tunnel-like cover on the cooling zone side of the shield, and TP4 is an ambient temperature of the cooling zone.

4. The reflow furnace according to claim 1 , which satisfies PA 1 <PA 2 , where PA 1 is a pressure in the heat zone, and PA 2 is a pressure in the cooling zone.

5. The reflow furnace according to claim 2 , which satisfies PA 1 <PA 2 over the width direction perpendicular to the transport direction of the circuit board in the reflow furnace, where PA 1 is a pressure in the heat zone, and PA 2 is a pressure in the cooling zone.

6. A soldering method comprising:
heating an electronic component-mounted circuit board in a heat zone; and
cooling the heated circuit board in a cooling zone;
drawing an atmosphere gas from the heat zone;
collecting a flux contained in the atmosphere gas by means of electrostatic precipitation; and
returning the atmosphere gas to the cooling zone after the collection of the flux,
wherein the heat zone and the cooling zone are spatially separated from each other by a shield having an opening, and
wherein the heated circuit board is carried into the cooling zone from the heat zone through a tunnel-like cover physically coupled to the opening.

7. The method according to claim 6 , wherein, the drawing further includes drawing the atmosphere gas over a width direction perpendicular to a transport direction of the circuit board.

8. The method according to claim 6 , which satisfies TP1>TP2>TP3>TP4, where TP1 is an ambient temperature of the heat zone, TP2 is a temperature inside the tunnel-like cover on the heat zone side of the shield, TP3 is a temperature inside the tunnel-like cover on the cooling zone side of the shield, and TP4 is an ambient temperature of the cooling zone.

9. The method according to claim 6 , which satisfies PA 1 <PA 2 , where PA 1 is a pressure in the heat zone, and PA 2 is a pressure in the cooling zone.

10. The method according to claim 7 , which satisfies PA 1 <PA 2 over the width direction perpendicular to the transport direction of the circuit board in the furnace, where PA 1 is a pressure in the heat zone, and PA 2 is a pressure in the cooling zone.

11. The reflow furnace according to claim 1 , wherein the tunnel-like cover is solid and has a shape of a hollow rectangular column.

12. The reflow furnace according to claim 1 , wherein the tunnel-like cover is solid, and has a shape of a hollow rectangular, circular, or arc-shaped cover with an open bottom.

13. The method according to claim 6 , wherein the tunnel-like cover is solid and has a shape of a hollow rectangular column.

14. The method according to claim 6 , wherein the tunnel-like cover is solid, and has a shape of a hollow rectangular, circular, or arc-shaped cover with an open bottom.

15. The reflow furnace according to claim 1 , wherein the tunnel-like cover is physically coupled to the opening.

16. The reflow furnace according to claim 1 , wherein the tunnel-like cover extends to the cooling zone.

17. The method according to claim 6 , wherein the tunnel-like cover extends to the cooling zone.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Yamaguchi Naoshi
• Kanda Toshiro
• Takano Yasuyuki
• Nagai Koichi

Classifications

• B23K1/0016 Primary

  Soldering of electronic components · CPC title

• B23K3/0478

  comprising means for controlling or selecting the temperature or power · CPC title

• B23K1/008

  Soldering within a furnace (B23K1/012 takes precedence) · CPC title

• B23K3/082

  Flux dispensers; Apparatus for applying flux · CPC title

• B23K2101/42

  Printed circuits · CPC title