Method and system of drying materials and method of manufacturing circuit boards using the same

• US 6,893,530 B2
• Filed: 02/08/2002
• Issued: 05/17/2005
• Est. Priority Date: 06/08/2000
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Nakamura, Shinji, Takenaka, Toshiaki, Nishii, Toshihiro, Kishimoto, Kunio, Miura, Akihiro
• Primary Examiner(s): Haran, John T.
• Application Number:
  US10/068,025
• Publication Number:
  US 20020173109A1
• Time in Patent Office: 1,194 Days
• Field of Search: 156/285, 156/286, 156/312, 156/381, 156/382, 34/92, 342/42
• US Class Current: 156/285
• CPC Class Codes: F26B 5/04 by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum F26B11/049 and F26B17/128 take precedence
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 2203/0191 Using tape or non-metallic foil in a process, e.g. during filling of a hole with conductive paste
• CPC Class Codes: H05K 2203/081 Blowing of gas, e.g. for cooling or for providing heat during solder reflowing
• CPC Class Codes: H05K 2203/085 Using vacuum or low pressure
• CPC Class Codes: H05K 2203/1461 Applying or finishing the circuit pattern after another process, e.g. after filling of vias with conductive paste, after making printed resistors
• CPC Class Codes: H05K 3/0032 of organic insulating material
• CPC Class Codes: H05K 3/0055 After-treatment, e.g. cleaning or desmearing of holes
• CPC Class Codes: H05K 3/227 Drying of printed circuits
• CPC Class Codes: H05K 3/4069 for via connections in organic insulating substrates

Abstract

A method and system of cleaning to remove cutting dust and the like generated and adhering to a board material (1a) during drilling for electrical connection, and drying the board material, in a process of manufacturing a circuit board for small electronic equipment and the like. A large amount of board materials can be treated without receiving thermal damage by performing the steps of: placing sheets of the board material that have absorbed moisture resulting from cleaning, like a stack in a vacuum chamber (11); and drying the board material by repeating evacuation and pressurization under predetermined conditions while heating the board material.

Claims

1. A method of drying a circuit board material comprising the steps of:

evacuating air in a vacuum chamber containing said material under an atmospheric pressure to a predefined pressure; and

supplying air to said vacuum chamber to return the pressure in said chamber to the atmospheric pressure,

wherein said evacuating and supplying steps are performed more than once, and

the predefined pressure of a subsequent evacuating step is lower than the predefined pressure of the previous evacuating step.

2. The method of drying a circuit board material according to claim 1 further comprising the steps of:

supplying hot air into said chamber when said chamber is returned to the atmospheric pressure; and

evacuating said chamber while said hot air is supplied to said vacuum chamber;

stopping the supply of said hot air after a predetermined time duration; and

evacuating said chamber to said predefined pressure.

3. The method of drying a circuit board material according to claim 2, wherein said predetermined time duration is at least one second.

4. The method of drying a circuit board material according to claim 2, wherein the air pressure of said hot air of a subsequent evacuating step is lower than the air pressure of said hot air of the previous evacuating step.

5. The method of drying a circuit board material according to claim 2, wherein a temperature of said hot air is at least 35°

C.

6. The method of drying a circuit board material according to claim 1, wherein said steps are performed while heating said material in said vacuum chamber.

7. The method of drying a circuit board material according to claim 6, wherein said material is heated by one of radiation heat from a heater and a heating by microwave.

8. The method of drying a circuit board material according to claim 6, wherein said material is heated using dielectric heating by microwaves.

9. The method of drying a circuit board material according to claim 1, wherein said supplying of air to said vacuum chamber is performed from a plurality of points.

10. The method of drying a circuit board material according to claim 1, wherein said evacuating of said vacuum chamber is performed from a plurality of points.

11. The method of drying a circuit board material according to claim 1, wherein said air to be supplied is dry air.

12. The method of drying a circuit board material according to claim 11, wherein said dry air is passed through at least one of an air cleaner and a dehumidifier.

13. The method of drying a circuit board material according to claim 1, wherein said predefined pressure is at most 200 Pa.

14. A method of manufacturing a circuit board comprising the steps of:

bonding a film shape material to at least one surface of a substrate material to form a board material with a film;

forming one of a through hole and a blind hole by irradiating said board material with a film with a laser;

cleaning said board material to remove at least one of altered parts and altered substances formed on an inner wall of one of said through hole and said blind hole, and to remove foreign substance adhering to a surface of said board material with a film;

blowing gas onto the surface of said board material with a film to remove water drops adhering to said surface;

drying moisture adhering to and absorbed in said board material with a film, using a method of drying; and

forming an electrical connection means in one of said through hole and said blind hole,

said method of drying comprising the steps of;

evacuating air in a vacuum chamber containing said board material under an atmospheric pressure to a predefined pressure; and

supplying air to said vacuum chamber to return the pressure in said chamber to the atmospheric pressure,

wherein said evacuating and supplying steps are performed more than once, and

the predefined pressure of a subsequent evacuating step is lower than the predefined pressure of the previous evacuating step.

15. The method of manufacturing a circuit board according to claim 14, wherein said substrate material comprises a prepregnated material, said prepregnated material being made by impregnating a reinforcing material with a thermosetting resin and making the resin into B stage.

16. The method of manufacturing a circuit board according to claim 15, wherein said reinforcing material is one of a glass fiber fabric and a glass fiber non-woven fabric.

17. The method of manufacturing a circuit board according to claim 15, wherein said reinforcing material is one of an aromatic polyamide fiber fabric and an aromatic polyamide fiber non-woven fabric.

18. The method of manufacturing a circuit board according to claim 14, wherein said forming an electrical connection means is a method of filling said hole with paste containing conductive particles.

19. The method of manufacturing a circuit board according to claim 14, wherein forming an electrical connection means is a method of forming a plating layer on an inner wall of said hole.

20. The method of manufacturing a circuit board according to claim 14, wherein one of said board material and said circuit board is dried under a state of stacking sheets of one of said board material and said circuit board one on top of another.

21. The method of manufacturing a circuit board according to claim 14, wherein said film-shape material is coated with a thermosetting epoxy resin on a surface thereof.

22. A method of manufacturing a circuit board comprising the steps of:

bonding a film-shape material to at least one surface of a substrate material to form a board material with a film;

forming one of a through hole and a blind hole by irradiating said board material with a film with a laser;

filling one of said through hole and said blind hole with conductive paste;

drying a double-sided circuit board having circuit patterns on both surfaces thereof, using a method of drying; and

laminating said double-sided circuit board and said board material to form a multi-layer circuit board, said board material being filled with said conductive paste and said film-shape materials on the both sides of said board material being peeled off,

said method of drying comprising the steps of;

evacuating air in a vacuum chamber containing said circuit board under an atmospheric pressure to a predefined pressure; and

supplying air to said vacuum chamber to return the pressure in said chamber to the atmospheric pressure,

wherein said evacuating and supplying steps are performed more than once, and

the predefined pressure of a subsequent evacuating step is lower than the predefined pressure of the previous evacuating step.

23. A method of manufacturing a circuit board comprising the steps of:

removing moisture from a circuit board having a circuit pattern on at least one surface thereof;

bonding a board material to at least one surface of said circuit board;

laminating said circuit board and said board material by further bonding a metal foil on said board material, and heating and pressing said circuit board and said board material at the same time; and

forming a means for electrically connecting said circuit board and said metal foil,

wherein moisture contained in said circuit board is removed using a method of drying,

said method of drying comprising the steps of;

evacuating air in a vacuum chamber containing said circuit board under an atmospheric pressure to a predefined pressure; and

supplying air to said vacuum chamber to return the pressure in said chamber to the atmospheric pressure,

wherein said evacuating and supplying steps are performed more than once, and

the predefined pressure of a subsequent evacuating step is lower than the predefined pressure of the previous evacuating step.