JP2005347429A - Manufacturing method of printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of a printed circuit board capable of plasma desmear processing without producing poor appearance of a solder resist and capable of performing good nickel/gold plating processing. <P>SOLUTION: This manufacturing method of the printed circuit board has at least the steps of laser via processing for exposing a circuit pattern in an electronic device component mounting location of the printed circuit board comprising an interlayer insulating film consisting of an organic material, the circuit pattern comprising a conductive material on the interlayer insulating film, and the solder resist formed on the interlayer insulating film and the circuit pattern; and finishing for electrically connecting the circuit pattern exposed by the laser via processing and the electronic device component. The steps of cover film sticking for sticking a cover film all over the surface of the solder resist, plasma desmear processing for performing desmear processing by plasma after the cover film sticking step, and removing the cover film are provided between above-mentioned laser via processing step and the finishing step. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a printed circuit board on which electronic components are mounted.

  On the printed board, a solder resist is applied to the final layer as a polymer film in order to prevent solder defects when mounting components such as electronic devices and to protect the surface circuit of the printed board from the external environment. Since this layer is made of an insulating material, vias are formed at the positions where electronic device components are to be mounted to expose the circuit pattern, and electroless nickel / gold plating is used as a finishing process to retain that portion. It was given.

  In recent years, electronic devices to be mounted have been highly integrated, and fine processing of patterns has been required for printed circuit boards. Conventionally, solder resist pipe turning has been performed by screen printing. Patterning by a photo solder resist using a printing technique has been frequently used. However, the demand for higher accuracy and higher resolution of solder resists has further increased, and a technique for drilling a solder resist with a laser and performing nickel / gold plating has been studied. However, when laser processing is performed, a molten resin residue called smear is generated, which adheres to the bottom of the hole and the side of the hole. Therefore, if smear removal called desmear treatment is not performed, nickel / gold plating will run around. The problem of getting worse occurs.

  For this reason, the smear removing method for the multilayer substrate disclosed in Patent Document 1 is a plasma containing oxygen gas in order to remove smear remaining in the inner via hole formed by laser processing on the insulating resin layer of the multilayer substrate. The inner via hole of the multilayer substrate is plasma treated with the generated gas to make the surface of the insulating resin layer hydrophilic, and then the smear is removed by wet treatment using a desmear aqueous solution containing an oxidizing agent. is there.

In addition, the desmear treatment method disclosed in Patent Document 2 heats the build-up substrate at a predetermined temperature prior to plasma etching for removing the resin residue remaining in the via by etching such as plasma etching, and the like in the via. The resin residue distribution is made uniform to shorten the processing time.
JP 2000-49463 A JP 2002-50603 A

  In the wet (wet process) desmear treatment as disclosed in Patent Document 1, since a desmear aqueous solution containing an oxidizing agent is used, a problem such as a rough surface may occur depending on the substrate of the printed circuit board. There are also problems with environmental issues. On the other hand, in the dry method disclosed in Patent Document 2, there is a problem that the solder resist is shaved during the desmearing process of the laser-processed hole (laser via), resulting in a defective appearance such as generation of filler in the solder resist. .

  For this reason, this invention provides the manufacturing method of the printed circuit board which can perform a plasma desmear process and does nickel / gold plating processing satisfactorily, without producing the external appearance defect of a soldering resist.

  Accordingly, the present invention provides an electronic device component for a printed circuit board comprising an interlayer insulating film made of an organic material, a circuit pattern made of a conductor material on the interlayer insulating film, and a solder resist formed on the interlayer insulating film and the circuit pattern. In the method of manufacturing a printed circuit board, the laser via processing step of exposing a circuit pattern at a mounting position of the circuit board and a finishing processing step of electrically connecting the circuit pattern exposed by the laser via processing and the electronic device component are provided. Between the processing step and the finishing treatment step, a cover film attaching step for attaching a cover film to the entire surface of the solder resist, a plasma desmear treatment step for performing a desmear treatment with plasma after the cover film attaching step, Removal to remove cover film Lies in the fact that provided a degree.

  Before the plasma desmear process, the solder resist surface can be protected from the plasma by applying the cover film to the entire solder resist surface, and the cover film on the via is more scraped than the cover film on the solder resist. Since the speed at which the cover is formed is very high, smear in the via is removed after the cover film on the via is removed.

  Moreover, it is desirable that the removing step includes a step of peeling the cover film and an ozone treatment step of removing the adhesive remaining after the cover film is peeled off. Thus, when the adhesive remains on the solder resist surface, the adhesive can be removed without damaging the solder resist surface by the ozone treatment apparatus.

  Furthermore, the cover film is preferably a resin film having an adhesive means on one side. In particular, the resin film is preferably a polyimide resin film, an epoxy resin film, a PET film, or the like.

  Furthermore, the finishing process is an electroless nickel / gold plating process.

  As described above, the surface of the solder resist can be protected at the time of the desmear process only by sticking a cover film on the entire surface of the solder resist before the plasma desmear process, so that the quality of the printed circuit board can be kept good. Electroless nickel. Gold plating can also be performed in good condition.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 2A, the printed board 10 is basically composed of an interlayer insulating film 1 made of an organic material such as a prepreg and a copper foil layer or a copper plating layer formed on the interlayer insulating film 1. The printed wiring layer 2 and a solder resist 3 made of a polymer film formed to protect the printed wiring layer 2 from the external environment.

  In order to mount the electronic device component on the printed board 10, it is necessary to expose the copper surface of the printed wiring layer 2, and laser via processing is performed in the laser via processing step shown in Step 100 of FIG. In this laser via processing, as shown in FIG. 2 (b), a predetermined position of the solder resist 3 is irradiated with a laser 4, and the solder resist 3 within the irradiation range is removed by evaporation to form a via 5. Thus, although there is an effect that the high-precision via 5 can be formed, as shown in FIG. 2C, the smear 6 made of a resin having a very small thickness remains on the bottom and side surfaces of the via 5. If plating for forming a new conductor layer is performed with the smear 6 remaining, plating failure or conduction failure may occur. Therefore, it is necessary to perform a desmear process for removing the smear 6.

  In the desmear treatment process according to the present invention, first, in step 200, on the solder resist 3 of the printed circuit board 10 in which the plurality of vias 5 are formed in the laser via processing process 100, as shown in FIG. A cover film 7 made of a resin film, an epoxy resin film, a PET film or the like is attached (laminated).

  In step 300, a plasma desmear process is performed. In the conventional plasma desmear process, when the smear 6 in the via 5 is removed by evaporation, the surface of the solder resist 3 is also shaved, so that a problem such as generation of filler in the solder resist 3 has occurred. The solder resist 3 can be protected by attaching the cover film 7. Further, the cover film 7 located on the via 5 and the cover film 7 located on the solder resist 3 are greatly different in scraping speed, and therefore the cover film 7 on the via 5 is removed at the initial stage of the plasma desmear process. Therefore, even if the cover film is affixed as a whole, the desmear treatment can be performed without any particular problem. In addition, after this plasma desmear process, as shown in FIG.3 (b), since the cover film 7 is scraped off by plasma, thickness is thin.

  In step 400, the cover film 7 is peeled off. In this step, as shown in FIG. 3C, when the adhesive 8 used when the cover film 7 is pasted remains, in step 500, surface treatment is performed by an ozone treatment device (not shown), and adhesion is performed. The agent 8 is removed.

  After the peeling process of the cover film 7 in the step 400 or after the ozone surface treatment in the step 500, the surface of the solder resist 3 remains clean as shown in FIG. 6 can be obtained, and the nickel / gold plating process in step 600 can be performed in a good state.

It is the flowchart figure which showed the printed circuit board manufacturing method of this invention. It is explanatory drawing which showed the state of laser via processing. It is explanatory drawing which showed the process of the desmear process in the printed circuit board manufacturing method of this invention.

Explanation of symbols

1 Interlayer insulating film 2 Printed wiring layer 3 Solder resist 4 Laser 5 Via 6 Smear 7 Cover film 8 Adhesive 10 Printed circuit board

Claims (4)

An interlayer insulating film made of an organic material, a circuit pattern made of a conductor material on the interlayer insulating film, and a circuit pattern at a mounting position of an electronic device component on a printed circuit board made of a solder resist formed on the interlayer insulating film and the circuit pattern In a method for manufacturing a printed circuit board, the method includes at least a laser via processing step that exposes a circuit pattern, and a finish processing step that electrically connects the circuit pattern exposed by the laser via processing and the electronic device component,
Between the laser via processing step and the finishing step,
A cover film attaching step of attaching a cover film to the entire solder resist surface;
A plasma desmear treatment step of performing a desmear treatment with plasma after the cover film attaching step;
A method for producing a printed circuit board, comprising: a removing step for removing the cover film.   The method for manufacturing a printed circuit board according to claim 1, wherein the removing step includes a step of peeling the cover film and an ozone treatment step of removing the adhesive remaining after the cover film is peeled off.   3. The method of manufacturing a printed circuit board according to claim 1, wherein the cover film is a resin film having an adhesive means on one side.   4. The method of manufacturing a printed circuit board according to claim 1, wherein the finishing process is an electroless nickel / gold plating process.

Images