JP2012199380A - Formation method of electrical insulation resin rough surface - Google Patents

Abstract

In a method for forming a roughened insulating resin surface of a multilayer printed wiring board in which conductor layers and insulating resin layers are alternately laminated, a low roughness and uniform roughened surface required for the insulating resin can be easily obtained by an imprint method. The purpose is to form.
At least (a) a step of sandwiching the insulating resin layer from above and below by a planar mold having a fine shape, (b) a step of pressing and curing the insulating resin layer, and (c) the above And a step of peeling off the mold and the insulating resin layer.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a multilayer printed wiring board in which insulating layers and conductor layers are alternately laminated. For example, the present invention relates to a method for roughening an insulating resin, which is used for manufacturing a printed wiring board or a semiconductor package substrate to improve adhesion between a conductor layer and an insulating layer.

  In recent years, with the increase in functionality, miniaturization and thinning of electronic devices, high-density mounting of electronic components is rapidly progressing. In response to these, in printed wiring boards and semiconductor package substrates, demands for higher wiring density due to finer wiring are increasing year by year.

  There are mainly two methods of manufacturing a printed wiring board and a semiconductor package substrate: a subtractive method and a semi-additive method, and the semi-additive method is generally advantageous for forming fine wiring.

  A part of the wiring forming method by the semi-additive method will be described as an example. A base material called a prepreg made of an epoxy resin and a glass cloth is sandwiched between copper plates, and an insulating resin is laminated thereon to form an insulating layer. After the formed insulating resin laser processing is performed to form fine vias, the surface of the insulating resin is roughened, and then a thin power supply layer having a thickness of about 0.3 to 3 μm is formed on the resin substrate by electroless plating. After forming a photoresist layer on the power supply layer, the portion of the power supply layer where the wiring circuit is to be formed is exposed by exposing it to ultraviolet rays through a mask on which a desired circuit pattern is drawn. A resist pattern covered with a resist film is formed. Subsequently, a current is applied to the power feeding layer, and a photoresist pattern is used as a mold, thereby forming a wiring circuit by electrolytic plating. Subsequently, the photoresist pattern is removed with an alkaline stripping solution, and the power feeding layer is removed by etching to form a wiring circuit.

  The roughening step of the insulating resin applied by the semi-additive method is a step in which the insulating resin is dissolved by first performing a conditioner treatment for swelling the resin and then treating with an alkaline permanganate. The liquid to be roughened is alkaline permanganate: 40-80 g / l, and temperature: 50-80 ° C., but this liquid has been self-adjusted. Is different. The roughening treatment on the surface of the insulating resin varies depending on the concentration of the swelling liquid and permanganate solution, the temperature, and the treatment time. Moreover, it is difficult to keep the roughening solution uniform, and it is necessary to thoroughly examine the roughening conditions in order to uniformly roughen the insulating resin. The surface of the insulating resin is required to have low roughness and flatness due to demands for finer wiring and higher density of wiring.

  In order to form a roughened surface on an insulating resin, a method using an oxidizing agent such as permanganate is common. However, this method has problems that the roughened surface changes greatly depending on the temperature of the roughening liquid, the processing time, etc., and that the liquid is difficult to manage. Therefore, a new method for forming a uniform roughened surface on the insulating resin has been desired.

  Since the roughness of the insulating resin affects signal transmission, the surface of the insulating resin has a small roughness and is required to be flat.

  It is known that there is an imprint apparatus capable of forming a fine shape with high throughput. A part of the imprint transfer method is to apply a photo-curing resin to a film substrate, press a mold with a fine shape of submicron unit, irradiate light, and then peel off the mold. The pattern is transferred to a film to form a fine shape on the resin surface. Since imprinting is suitable for large area transfer, it can be said that it is useful for forming a fine shape in an insulating resin.

  The roughening method of the insulating resin is generally performed using an oxidizing agent such as permanganic acid as seen in Patent Documents 1 to 4. Various treatments for improving the adhesion to the conductor layer have been studied, but it is difficult to manage the liquid and it is difficult to form a uniform roughened surface. Japanese Patent Application Laid-Open No. 2004-228561 uses a method of imprinting to produce a printed wiring board simply and at a low cost. However, forming a fine circuit pattern by imprinting has many problems to be solved such as contamination.

JP 2007-254709 PR Japanese Laid-Open Patent Publication No. 2007-273616 Japanese Laid-Open Patent Publication No. 2007-73989 JP 2007-73991 A JP 2006-100463 PR

  The present invention is to solve the problem of a method for forming a roughened insulating resin surface, which is important in forming a fine circuit pattern in a multilayer printed wiring board. Insulating resin roughened surface formation is generally performed using an oxidizing agent such as permanganate, liquid management is difficult, and uniform roughened surface formation is difficult.

  In view of such a problem, an object of the present invention is to solve the problem by simply forming a low roughness and uniform roughened surface required for an insulating resin by an imprint method.

In order to solve the above-mentioned problems, the invention of claim 1 is directed to a method for forming an insulating resin roughened surface of a multilayer printed wiring board in which conductor layers and insulating resin layers are alternately laminated. A step of sandwiching the insulating resin layer from above and below by a planar mold that is made
(B) pressurizing and curing the insulating resin layer;
(C) a step of peeling off the mold and the insulating resin layer;
The method for forming a roughened insulating resin surface is characterized by comprising:

  In the invention of claim 2, the mold has protrusions having a diameter of 0.01 to 2 μm and a height of 0.01 to 0.5 μm uniformly on the surface in a pitch range of 0.01 to 2 μm. The method for forming a roughened insulating resin surface according to claim 1.

  In the invention of claim 3 of the present application, the roughened surface of the insulating resin produced using the mold has a surface roughness Ra measured in accordance with JIS B 0633: 2001 in the range of 10 nm to 200 nm. The method for forming a roughened insulating resin surface according to claim 1 or 2.

  The invention of claim 4 of the present application is characterized in that a mold release agent is uniformly applied on the surface of the mold before the step of sandwiching the insulating resin layer from above and below. 2. A method for forming a roughened insulating resin surface according to item 1.

In the present invention, as described above, in forming the roughened insulating resin surface, the resin is vacuum laminated on the substrate in order to take interlayer insulation, and then thermally cured to have a diameter of 0.01 to 2 μm and a height of 0.01 to The shape of the surface of the mold is transferred to the resin by pressing a mold having protrusions of 0.5 μm uniformly in a pitch range of 0.01 to 2 μm from above and under pressure and heat treatment.
In addition, the present invention employs a method in which a metal mold uniformly coated with a release agent is pressed from above and below, the resin is cured under pressure, and then the metal mold is peeled off from the resin.

  Further, the present invention provides a roughened insulating resin surface that can be controlled in a range of 20 nm to 200 nm in surface roughness Ra of the roughened insulating resin surface measured according to JIS B 0633: 2001 by transferring the surface shape of the mold. The forming method is adopted.

  According to the first aspect of the present invention, in forming a multilayer printed wiring board, a roughened surface can be formed on an insulating resin at a low cost and a high throughput with a simple apparatus. Since the roughened surface is formed by the imprint method, a uniform roughened surface can be formed. Since no roughening liquid is used, there is no need for liquid management, and no waste liquid is produced. In addition, it is possible to gradually reduce the warpage by sandwiching the substrate from above and below with a mold.

  Further, according to the invention of claim 2 of the present application, since the insulating resin roughened surface formation that has been achieved by changing the insulating resin can be achieved by a process of pressing a mold in which fine protrusions are uniformly present, Regardless of this, low roughness can be achieved.

According to the third aspect of the present invention, since the roughness can be changed by a pattern, such as a fine portion where the fine circuit exists on the insulating roughened surface and a rough portion where the circuit does not exist, the fine metal wiring and It becomes possible to improve the adhesiveness of the insulating resin as a base.
According to the invention of claim 4 of the present application, the mold can be easily peeled off by applying the release agent on the mold surface, and the mold can be used for many times of transfer.

It is a figure showing one Embodiment of this invention. It is a top view of the roughened surface roughened by this invention. It is sectional drawing of the multilayer printed wiring board which has the roughening surface roughened by this invention.

  An embodiment of a method for forming a roughened insulating resin surface according to the present invention will be described with reference to the drawings. Insulating resin roughened surface formation according to the present invention is performed during resin lamination.

  After the circuit-formed substrate is dried, a dry film insulating resin is temporarily stretched on both sides. Next, the substrate on which the insulating resin is temporarily stretched is evacuated and laminated. Thereafter, flat pressing is performed to flatten the surface. Thereafter, the PET film stuck on the dry film is peeled off.

  In FIG. 1A, this state is illustrated by a case where the conductor layer 7 is laminated on the prepreg 6 and the insulating resin layer 5 is laminated thereon.

  Next, the planar mold 1 having fine projections uniformly applied is pressed from above and below to the insulating resin 5 from which the PET film has been peeled off, and the insulating resin layer 5 is kept in close contact therewith. Pressing and heat treatment are performed to transfer a fine uneven pattern on the mold surface by imprinting. After pressing and heat treatment to harden the resin, the mold 1 is peeled off to form a roughened surface on the insulating resin layer 5. (FIG. 1 (b)). At this time, alignment between the mold and the substrate is performed using an alignment pattern provided at the end of the mold 1. In the figure, as a fine uneven pattern, a needle-shaped mold surface 2 with a submicron pitch (needle diameter, pitch 0.01 to 1.0 μm), a pitch needle diameter coarser than this needle-shaped mold surface 2, pitch 0. The needle-shaped mold surface 3 of 1 to 2.0 μm) is exemplified.

  The release agent layer on the prepared insulating resin roughened surface is immersed in a liquid such as water, methanol, isopropyl alcohol, or removed by UV ozone cleaning or the like. After laser processing is performed on the manufactured insulating resin to form fine vias, the resin residue at the bottom of the vias is removed by dipping in a sulfuric acid-hydrogen peroxide mixture. Thereafter, the conductive layer is formed by electroless copper plating or electrolytic copper plating to produce a fine wiring pattern.

  According to the method for forming a roughened insulating resin surface according to the present invention, the shape of the mold surface on which the fine-shaped protrusions are uniformly present can be obtained by using the method shown in FIG. The inverted pattern as shown in FIG. 2 is transferred to the resin surface. The cross-sectional shape as shown in FIG. In the present invention, a multilayer printed wiring board is formed by repeatedly performing processes such as electrolytic copper plating layer preparation, resist pattern preparation, pattern copper plating formation, resist peeling, and flash etching on a substrate having a cross-sectional shape as shown in FIG. To do.

  According to the method for forming a roughened insulating resin surface according to the present invention, when the insulating resin is thermally cured as shown in FIG. . As a result, the wiring pattern becomes fine, and the demand for flattening the roughened resin surface can be solved.

  Examples of the insulating resin layer include thermosetting resin epoxy resin, bismaleimide triazine resin, imide resin, allylated phenylene ether resin, thermoplastic resin liquid crystal polymer, PEEK resin, PTFE resin, etc., among which silica filler When an epoxy resin having a high content is used, insulation, dielectric properties, heat resistance, dimensional stability, flatness, thermal expansion, and flexibility are good, and this is preferable for making a printed wiring board.

  Silicone release agents and fluorine release agents are used as release agents, but if fluorine release agents are used, thin film coatability (about several tens of nanometers), release properties (contact angle of 100 ° or more) ) And the like, it is preferable as a release agent used for forming a roughened insulating resin surface.

  There are innumerable holes in which the mold surface shape is inverted by a mold having protrusions having a diameter of 0.01 to 2.0 μm and a height of 0.01 to 0.5 μm in a pitch range of 0.01 to 2.0 μm. An insulating resin surface can be produced. If it is said range, an insulating resin layer and the layer of electroless copper plating can fully be stuck. This is close to the rough surface with low roughness required for the next-generation printed wiring board, and is preferable as the rough shape of the insulating resin rough surface.

  Quartz, silicon (Si), silicon carbide (SiC), glassy carbon (GC), nickel (Ni), tantalum (Ta), and the like are listed as mold materials. High rigidity, chemical resistance, and fine workability are preferable as an insulating roughened surface forming mold.

  An example of the manufacturing method of the metal mold | die for insulating resin roughening surface formation by this invention is shown. An electron beam resist is applied onto a quartz substrate, and the electron beam is exposed and developed to produce an electron beam resist pattern layer having a fine shape. Next, by dry etching, a quartz mold having submicron pitch protrusions uniformly present on the surface is produced. Thereafter, the resist layer is removed. By using electron beam lithography, a mold pattern can be produced with high accuracy, and the mold can be freely controlled.

  In forming a multilayer printed wiring board according to the present invention, if a UV laser is used as a laser, a via having a small diameter can be formed because it has a shorter wavelength than the current mainstream CO2 laser. Moreover, since UV laser is easy to absorb with respect to insulating resin and copper, processing with little heat influence is attained.

  In the formation of the multilayer printed wiring board in the present invention, if soft etching is performed with a sulfuric acid-hydrogen peroxide mixture after forming vias with a UV laser, it is not necessary to perform desmearing treatment to remove the resin residue on the bottom of the vias. Since an oxidizing agent such as permanganic acid is not used for the roughening of the resin surface, there is an advantage that in the formation of the multilayer printed wiring board, management of the desmear liquid is not necessary and no waste liquid is generated.

  According to the method for forming a roughened insulating resin surface according to the present invention, the roughness can be controlled by the wiring pattern by designing the mold. As a result, when there is a printed wiring board wiring pattern on the insulating resin, a mold having protrusions with a pitch of 0.01 μm to 1.0 μm uniformly is transferred to increase the roughness (provide fine irregularities). The adhesion with the underlying copper is improved by the anchor effect. For areas where there is no pattern on the insulating resin, electroless transfer is performed by transferring a mold in which protrusions with a pitch of 0.1 to 2.0 μm are uniformly present, and reducing the roughness (roughly uneven). Make it easier to remove the copper plating layer. As described above, it can be expected that the adhesion of the wiring pattern in the multilayer printed wiring board and the insulation reliability between the lines are improved.

  The method for forming a roughened insulating resin surface according to the present invention includes a step of laminating a dry film in a vacuum state on both sides of a circuit-formed substrate, which is a conventional resin laminating step, and thermally curing in an oven to form an insulating layer. Applied. The detail of the process of this invention is shown. The multilayer printed wiring board was dried, and an epoxy resin having a property of being cured by heat as an interlayer insulating film was temporarily attached. Next, resin was embedded between the wirings by vacuum lamination. Next, flat pressing was performed to flatten the insulating resin layer, and the PET film was peeled off. Next, press the mold so that the fine protrusions uniformly coated with the fluorine-based mold release agent are sandwiched between them, create a roughened surface on the resin surface, and then keep the mold in close contact with the resin. Was hardened (180 ° C./30 min), and after solidifying, the mold was peeled off.

  The release agent layer on the produced insulating resin roughened surface was removed by UV ozone cleaning. Thereafter, via holes were formed by UV laser processing and immersed in a sulfuric acid-hydrogen peroxide mixture to remove the resin residue on the bottom of the via. Then, circuit formation was performed by electroless copper plating, dry film pattern formation, and electrolytic copper plating.

  As described above, according to the method for forming a roughened insulating resin surface of the present invention in the production of a multilayer printed wiring board, the surface of the insulating resin can be roughened with a mold without using a roughening solution. That is, the insulating resin can be appropriately roughened by controlling the mold. In addition, it is possible to achieve the flattened rough surface and low roughness required for the next generation insulating resin. Since the roughening process is not required, the process for forming a multilayer printed board wiring by the semi-additive method can be shortened, and it can be said that the printed wiring board can be manufactured at a low cost.

  Furthermore, the present invention can reduce the chemical solution cost and the waste liquid processing cost by transferring a mold having a fine shape to the roughening, which has been conventionally performed by an oxidizing agent such as permanganate, and is also effective for the environment. Good. In addition, by changing the roughened shape according to the circuit pattern, it is possible to improve the adhesion with the base substrate only at a place where the metal wiring pattern is present, and thus it is possible to improve the insulation reliability between the wirings. Further, since only the surface of the insulating resin can be roughened, an improvement in interlayer insulation can be expected. Further, since the roughening is performed by the imprint method, the warping of the printed circuit board can be suppressed. This technique leads to an improvement in the performance of the multilayer printed wiring board, and can be widely applied to all device manufacturing processes that require resin adhesion.

1 Mold 2 Needle-shaped mold surface with submicron pitch (needle diameter, pitch 0.01 to 1.0 μm) 32 Needle-shaped mold surface with coarser pitch (needle diameter, pitch 0.1 to 2.0 μm) 4 Alignment Pattern 5 Insulating Resin Layer 6 Prepreg 7 Conductor Layer 8 Insulating Resin Roughening Mold Top View 9 Printed Wiring Board Cross Section Example After Roughening Surface Fabrication by Imprint Method 10 Through Hole 11 Metal Wiring Pattern

Claims (4)

In a method for forming a roughened insulating resin surface of a multilayer printed wiring board in which conductor layers and insulating resin layers are alternately laminated, at least (a) the insulating resin layer is sandwiched from above and below by a planar mold having a fine shape. Process,
(B) pressurizing and curing the insulating resin layer;
(C) a step of peeling off the mold and the insulating resin layer;
An insulating resin roughened surface forming method comprising:   The mold is characterized in that protrusions having a diameter of 0.01 to 2.0 μm and a height of 0.01 to 0.5 μm are uniformly present on the surface within a pitch range of 0.01 to 2.0 μm. Item 2. The method for forming a roughened insulating resin surface according to Item 1.   3. The insulating resin according to claim 1, wherein the roughened surface of the insulating resin produced using the mold has a surface roughness Ra measured in accordance with JIS B 0633: 2001 in a range of 10 nm to 200 nm. Roughened surface forming method.   The insulating resin roughening according to any one of claims 1 to 3, wherein a release agent is uniformly applied on the surface of the mold before the step of sandwiching the insulating resin layer from above and below. Surface forming method.