JP2016100390A - Peelable metal foil and manufacturing method of the same, and printed circuit board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a peelable metal foil from being peeled due to stress in a manufacturing process of a printed circuit board to improve manufacturing yield of the printed circuit board.SOLUTION: A manufacturing method of a printed circuit board comprises the steps of: manufacturing a multilayer substrate by layering an insulating resin layers and a peelable metal foil in which a plurality of through holes are formed on an outer periphery of the peelable metal foil and a plurality of metal layers are layered with peelable intermediate layers being sandwiched among the metal layers one by one for making the plurality of metal layers be peelable by the intermediate layers and a plurality of through holes are formed adjacent to each other on an outer periphery of the peelable metal foil; cutting off a peripheral part of the multilayer substrate by machine work; and subsequently peeing the peelable metal foils to manufacture the printed circuit board.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a peelable metal foil used for manufacturing a printed wiring board, a manufacturing method thereof, and a manufacturing method of a printed wiring board manufactured using the same.

  In recent years, electronic devices have been further reduced in size, weight, and functionality, and along with this, higher integration and miniaturization of wiring are rapidly progressing, and miniaturization of wiring is progressing. In addition, there is an increasing demand for a downsized package such as a so-called chip size package (CSP; Chip Size / Scale Package) that is almost the same size as a semiconductor chip. On the other hand, the wiring that can be formed with high yield by the subtractive method of forming the wiring by etching is wiring width (L) / wiring gap (S) = about 50 μm / 50 μm.

  If an attempt is made to form a wiring pattern with a finer wiring width / wiring gap by etching a copper foil having a conventional thickness by a subtractive method, the verticality of the side wall of the wiring pattern formed by etching is deteriorated. Further, if the wiring width is narrow, the wiring is likely to be disconnected by etching.

  In order to form a fine wiring pattern with a wiring width / wiring gap of about 35 μm / 35 μm with a good yield by the subtractive method, it is necessary to use a thin copper foil having a thickness of 10 μm or less.

  In addition, in order to produce a wiring having a fine wiring width / wiring gap = 35 μm / 35 μm, a relatively thin electroless metal plating layer is formed on the surface of the substrate, and a plating resist is formed thereon, It is also possible to use a semi-additive method in which a conductor is formed to a required thickness by electrolytic metal plating, and then the thin metal plating layer is removed by soft etching after resist stripping.

  In any method, it is necessary to use a thin copper foil having a thickness of 10 μm or less for the production of a printed wiring board having a fine wiring pattern, and therefore, a peelable metal foil is used.

  In Patent Document 1, a core substrate is manufactured by stacking and curing two detachable peelable metal foils with a prepreg sandwiched between them, and an interlayer insulating resin layer and a wiring pattern are formed on both surfaces of the core substrate. Build up sequentially to form a multilayer structure. And the technique which manufactures the printed wiring board which has fine wiring by peeling and separating the peelable metal foil from the multilayer structure formed on both surfaces of the core substrate is disclosed.

JP 2005-101137 A

  In the technique of Patent Document 1, a prepreg and a peelable metal foil are laminated on the outer side of the core substrate, and the prepreg is cured by heating and pressurizing to produce a laminated substrate in which the peelable metal foil is bonded to the core substrate. However, the peelable metal foil has a peeling boundary line that is exposed on the end face of the laminated substrate, so the peeling interface easily peels off during the manufacturing process due to the stress of manufacturing the printed wiring board. There was a problem that caused.

The purpose of the present invention is to prevent peeling of the peelable metal foil during the production due to stress in the production process of the printed wiring board produced using the peelable metal foil, and to improve the production yield of the printed wiring board. To do.

  In order to solve the above-described problems, the present invention provides a peelable metal foil in which a plurality of metal layers are laminated with a peelable intermediate layer interposed therebetween, and the plurality of metal layers can be peeled by the intermediate layer. The peelable metal foil is characterized in that a plurality of mutually adjacent through holes are formed in the outer peripheral portion of the peelable metal foil.

  The present invention uses this peelable metal foil to produce a printed wiring board, thereby preventing peeling of the peelable metal foil during the production due to stress in the production process of the printed wiring board, and the production yield of the printed wiring board. There is an effect that can be improved.

  Moreover, this invention is said peelable metal foil, Comprising: The welding part which connects these metal layers to the wall surface of the said through-hole is formed, It is a peelable metal foil characterized by the above-mentioned.

  Further, the present invention is the above-described peelable metal foil, wherein the through holes are arranged in a staggered pattern on an outer peripheral portion of the peelable metal foil, and the through holes are adjacent to at least four through holes. It is a peelable metal foil.

  Further, the present invention is a peelable metal foil which is laminated with a peelable intermediate layer sandwiched between a plurality of metal layers, and the plurality of metal layers can be peeled by the intermediate layer, wherein the peelable metal foil A peelable metal foil having a plurality of non-through holes adjacent to each other on the outer peripheral portion and a non-through hole formed with a welded portion connecting the plurality of metal layers.

  Further, the present invention is a method for producing a peelable metal foil, wherein a plurality of metal layers are laminated with a peelable intermediate layer interposed therebetween, and the plurality of metal layers are peelable by the intermediate layer, A method for producing a peelable metal foil, wherein a plurality of mutually adjacent through holes or non-through holes are formed in a peripheral portion of the peelable metal foil by drilling with a laser drilling apparatus.

  The present invention also relates to a method for producing a printed wiring board using the peelable metal foil, the step of producing a laminated substrate by laminating the peelable metal foil and an insulating resin layer, and the through hole of the laminated substrate. Or having a step of exposing a cross section of the peelable metal foil to a cut surface by cutting a peripheral portion including a non-through hole by machining, and then a step of peeling the peelable metal foil with the intermediate layer. It is the manufacturing method of the printed wiring board characterized.

  The present invention manufactures a printed wiring board using a peelable metal foil in which a plurality of mutually adjacent through holes or non-through holes are formed on the outer peripheral portion, and is manufactured due to stress in the manufacturing process of the printed wiring board. There is an effect that the peelable metal foil is prevented from being peeled off in the middle and the production yield of the printed wiring board can be improved.

  That is, the peeling of the peelable metal foil during the production of the printed wiring board can be prevented by suppressing the peeling of the metal layer with the through hole or the non-through hole formed in the peelable metal foil. Moreover, the periphery of the peelable metal foil including the through hole or the non-through hole is cut off by machining so that the cross section of the peelable metal foil is exposed so that the peelable metal foil can be peeled off. Thus, this invention has the effect which can provide the selectivity of the peelability of peelable metal foil.

It is the top view and sectional drawing which show the peelable metal foil of the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the peelable metal foil of the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the printed wiring board of the 1st Embodiment of this invention (the 1). It is sectional drawing which shows the manufacturing method of the printed wiring board of the 1st Embodiment of this invention (the 2). It is sectional drawing which shows the manufacturing method of the printed wiring board of the 1st Embodiment of this invention (the 3). It is sectional drawing which shows the manufacturing method of the printed wiring board of the 1st Embodiment of this invention (the 4). It is sectional drawing which shows the manufacturing method of the printed wiring board of the 1st Embodiment of this invention (the 5). It is sectional drawing which shows the manufacturing method of the printed wiring board of the 1st Embodiment of this invention (the 6). It is sectional drawing which shows the laminated substrate structure of the modification 2 of the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the peelable metal foil of the 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the printed wiring board of the 3rd Embodiment of this invention (the 1). It is sectional drawing which shows the manufacturing method of the printed wiring board of the 3rd Embodiment of this invention (the 2).

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The plan view of FIG. 1A shows the structure of the peelable metal foil 13 according to the first embodiment, and FIG. 1B shows a side sectional view of the end portion. 2 shows a manufacturing method of the peelable metal foil 13 in the order of steps, and FIGS. 3 to 9 show a manufacturing method of a multilayer printed wiring board using the peelable metal foil 13. It shows in order of process.

  Using the peelable metal foil 13 as shown in the plan view of FIG. 1A and the partial cross-sectional view of FIG. 1B, the peelable metal foil 13 attached to the core substrate as shown in FIG. The laminated substrate 100 exposed to the substrate is manufactured.

(Peelable metal foil)
A plurality of mutually adjacent through holes H are formed in the outer periphery of the peelable metal foil 13 in the peelable metal foil 13 as shown in the plan view of FIG. 1A and the side sectional view of FIG. In the plan view of FIG. 1A, a plurality of through holes H are arranged in a staggered pattern so that one through hole H is adjacent to at least four through holes in four directions.

  These through holes H are formed by penetrating the thick copper foil layer 13a and the thin copper foil layer 13b by making holes in the peelable metal foil 13 with a laser drilling apparatus. A welded portion 15 formed by laser welding the thick copper foil layer 13a and the thin copper foil layer 13b is formed on the hole wall of the through hole H.

  In the present embodiment, the welded portion in which the thick copper foil layer 13a and the thin copper foil layer 13b are welded to the hole wall of the through hole H by forming the through hole H in the peelable metal foil 13 with the laser drilling apparatus in this way. 15 is formed. By using this peelable metal foil 13, peeling of the thin copper foil layer 13b of the peelable metal foil 13 from the thick copper foil layer 13a in the substrate manufacturing process can be effectively prevented.

(Manufacturing method of peelable metal foil)
The thin copper foil layer 13b having a thickness of 10 μm or less in the peelable metal foil 13 is a main material used for the production of the printed wiring board. However, the thin copper foil layer 13b alone has no rigidity, so that it has rigidity. A printed wiring board is manufactured using the peelable metal foil 13 combined with the thick copper foil layer 13a. Thereby, the thin copper foil layer 13b can be easily handled.

  The original plate of the peelable metal foil 13 may be manufactured by bonding the thin copper foil layer 13b to the thick copper foil layer 13a via an intermediate layer (peeling layer 13d and diffusion preventing layer 13c). It is not limited. For example, the original plate of the peelable metal foil 13 can be manufactured as follows in the order of steps in the side sectional view of FIG.

(Process 1)
First, as shown in FIG. 2A, a thick copper foil layer 13a such as a copper metal plate is prepared. The thick copper foil layer 13a is thicker than the thin copper foil layer 13b. There is no restriction | limiting in particular in thickness, Arbitrary thickness according to a use can be used. The thickness of the thick copper foil layer 13a is often 12 μm or more and 35 μm or less (for example, 18 μm).

(Process 2)
Next, as shown in FIG. 2B, a diffusion preventing layer 13c is formed on the upper surface of the thick copper foil layer 13a. The diffusion preventing layer 13c has a property of preventing the copper component of the thick copper foil layer 13a from diffusing into the thin copper foil layer 13b.

  The diffusion prevention layer 13c is formed by plating a metal alloy such as Ni, Co, Fe, Cr, Mo, Ta, Cu, Al, P alone or an alloy of Ni with Co or the like, or by sputtering. Of the diffusion preventing layer 13c having a thickness of 0.01 μm or more and 0.3 μm or less.

  For example, electrolytic nickel / phosphorus plating is performed on the upper surface of the thick copper foil layer 13a to form the diffusion preventing layer 13c.

(Process 3)
Next, a release layer 13d is formed on the upper surface of the diffusion prevention layer 13c. The release layer 13d has a property of easily peeling the thin copper foil layer 13b formed on the release layer 13d from the thick copper foil layer 13a.

  The peeling layer 13d is formed by forming a single metal such as Cr, Ni, Fe or the like, an alloy layer thereof, or a layer of these hydrated oxides by electrolytic plating or the like.

  For example, the peeling layer 13d is formed by forming a chromium metal, a chromium alloy, and a chromium metal layer, and forming a chromium hydrated oxide layer thereon.

When the release layer 13d is formed of chromium metal, it is formed to a thickness of 0.01 mg / dm ² or more and 4.5 mg / dm ² or less. For example, a chromium metal peeling layer 13d having a thickness of about 0.005 μm is formed by chromium plating.

  These diffusion prevention layer 13c and peeling layer 13d constitute an intermediate layer formed between the thick copper foil layer 13a and the thin copper foil layer 13b.

(Process 4)
Next, as shown in FIG. 2C, the upper surface of the release layer 13d, the thick copper foil layer 13a which is a layer other than the release layer 13d, and the exposed cross section of the side edge of the intermediate layer are thickened by electrolytic copper plating. A thin copper foil layer 13b having a thickness of 10 μm or less and a thickness of 1 μm to 9 μm (for example, 5 μm) is formed to produce an original plate of the peelable metal foil 13.

(Process 5)
Next, as shown in FIG. 2D, the peelable metal foil 13 is manufactured by cutting the original sheet of the peelable metal foil 13 into a predetermined dimension.

  As a result, the cross section of the intermediate layer is exposed at the end of the outer peripheral edge of the peelable metal foil 13, and the peelable metal foil 13 is peeled off at the portion of the peel layer 13d in the cross section of the intermediate layer so that the thick copper foil layer 13a and the thin copper foil The layer 13b can be easily separated.

(Step 6)
Next, as shown in FIG. 2 (e), a laser drilling device is used at the end of the peelable metal foil 13 having a predetermined dimension, and for example, the laser light is irradiated from the thick copper foil layer 13a side, thereby allowing the through hole H is formed. Thereby, a plurality of mutually adjacent through holes H are formed as shown in the plan view of FIG. 1A and the side sectional view of FIG.

  At that time, a welded portion 15 of the thick copper foil layer 13a and the thin copper foil layer 13b is formed on the wall surface of the through hole H. The welded portion 15 firmly connects the thick copper foil layer 13a and the thin copper foil layer 13b of the peelable metal foil 13, and the peelable metal foil 13 peels off from the end of the peeling layer 13d even when there is an impact in the manufacturing process. This has the effect of avoiding defects.

  The peelable metal foil 13 can use a metal layer other than the copper layer for the thick copper foil layer 13a and the thin copper foil layer 13b. For example, the thick copper foil layer 13a can also be configured by a combination of different metal layers, such as a combination of copper and aluminum for the thick copper foil layer 13a and the thin copper foil layer 13b.

  Thus, the peelable metal foil 13 is formed by laminating a peelable intermediate layer between a plurality of metal layers of the thick copper foil layer 13a and the thin copper foil layer 13b, and the peelable metal foil 13 is formed. The welded portion 15 that connects the plurality of metal layers is formed on the outer peripheral portion.

  The peelable metal foil 13 is affixed to the core substrate 10 and the multilayer wiring structure 30 is formed thereon, and then the outer peripheral portion where the through holes H of the peelable metal foil 13 are formed is cut off by machining. By doing so, the cross section of the peelable metal foil 13 from which the through hole H has been removed is exposed and can be peeled off. As such, the peelable metal foil is given the selectivity of whether or not it can be peeled depending on whether or not there is a through hole H.

(Manufacture of laminated substrates)
3 to 8, the laminated substrate 100 in which the peelable metal foil 13 having a cross-sectional structure in which the intermediate layer is sealed by the welded portion 15 is attached to the core substrate 10 and the multilayer wiring structure 30 is formed thereon is formed. To manufacture. And after cutting the edge part, the peelable metal foil 13 is peeled and a printed wiring board is manufactured. First, the manufacturing method which manufactures the multilayer substrate 100 using this peelable metal foil 13 is demonstrated.

(Core substrate)
First, as shown in FIG. 3A, the core substrate 10 is a substrate having a thickness of 0.04 mm to 0.8 mm, and has a copper foil 11 having a thickness of 18 μm on both sides, and an organic resin is made of glass, polyimide, liquid crystal, or the like. A double-sided copper-clad laminate (for example, a size of 610 × 510 mm) made of a material impregnated with reinforcing fibers is used.

The organic resin material constituting the core substrate 10 is epoxy, acrylic, urethane,
Organic resins mainly composed of epoxy acrylate, phenol epoxy, polyimide, polyamide, cyanate, and liquid crystal can be used. Alternatively, a substrate in which a filler made of silica, butyl organic material, calcium carbonate, or the like is included in the organic resin can be used.

(Core board copper foil roughening process)
First, the surface of the copper foil 11 of the double-sided copper clad laminate used for the core substrate 10 is roughened by a soft etching process using an etchant such as perhydrosulfuric acid.

(Modification 1)
As a first modification, the core substrate 10 is made of glass (blue plate, non-alkali glass, quartz) or metal (mainly stainless steel, iron, copper, titanium, tungsten, magnesium, aluminum, chromium, molybdenum, etc.). Can also be used.

(Peelable metal foil lamination process)
Next, as shown in FIG. 3B, the core substrate 10 having a size of, for example, 610 × 510 mm is centered, and outside the core substrate 10, the size of the same size as the core substrate 10 in a plan view is 610 × 510 mm. A semi-cured insulating resin sheet 12a made of a prepreg or a resin film is stacked, and a peelable metal foil 13 having a size smaller than that of the semi-cured insulating resin sheet 12a is 600 × 500 mm and a welded portion 15 is formed at the end. Repeat.

  And the release film 20 is piled up on the outer side of the peelable metal foil 13, and the semi-cured insulating resin sheet 12a on the outer side of the core substrate 10 is cured by a laminating process in which heating and pressing are performed by a vacuum laminating press apparatus. Set to 12.

  As a result, the peelable metal foil 13 is laminated on the outside of the core substrate 10 via the insulating resin layer 12 formed by curing the semi-cured insulating resin sheet 12a, and the peelable metal foil 13 becomes the insulating resin layer 12 and the core substrate 10. The laminated substrate 100 integrated with is manufactured.

  That is, using the peelable metal foil 13 smaller than the entire size of the multilayer substrate 100, the multilayer substrate 100 is manufactured in which the frame portion 14 made of the insulating resin layer 12 is formed outside the peelable metal foil 13.

(Semi-cured insulating resin sheet)
As the semi-cured insulating resin sheet 12a used here, a prepreg having a thickness of 0.04 mm to 0.4 mm (for example, a thickness of 0.07 mm) and impregnated with an organic resin is used as a semi-cured insulating resin. Used as a sheet 12a. The prepreg is preferably adjusted to be resin-rich. If necessary handling properties can be ensured, a semi-cured insulating resin sheet 12a made of a resin film not containing reinforcing fibers may be used.

  As the organic resin material of the semi-cured insulating resin sheet 12a, epoxy resin, bismaleimide-triazine resin (hereinafter referred to as BT resin), polyimide resin, PPE resin, phenol resin, PTFE resin, silicon resin, polybutadiene resin, polyester Organic resins such as resins, melamine resins, urea resins, PPS resins, PPO resins, cyanate resins, and cyanate ester resins can be used.

  As the reinforcing fiber, glass fiber, aramid nonwoven fabric, aramid fiber, polyester fiber, polyamide fiber, liquid crystal fiber, or the like can be used. In addition, the organic resin of the semi-cured insulating resin sheet 12a can include a filler made of silica, butyl organic material, calcium carbonate, or the like.

  As shown in FIG. 3B, the peelable metal foil 13 with the welded portion 15 formed on the outer side of the semi-cured insulating resin sheet 12a is stacked with the thick copper foil layer 13a on the inside and heated by a vacuum lamination press. By pressing, the peelable metal foil 13 is laminated on the outside of the core substrate 10 via the semi-cured insulating resin sheet 12a. The conditions of the vacuum lamination press are carried out by adjusting the heating rate, pressure, and pressurization timing according to the material of the semi-cured insulating resin sheet 12a to be applied. In the case of using a material having high fluidity, adjustment may be made to slow the temperature increase rate or pressurization timing.

  Then, after the semi-cured insulating resin sheet 12a is solidified to form the insulating resin layer 12, the release film 20 is peeled off, and the outer peripheral portion of the peelable metal foil 13 having a size of 600 × 500 mm is formed as shown in FIG. The laminated substrate 100 in which the frame portion 14 having a width of 5 mm surrounded by the insulating resin layer 12 is manufactured.

(Modification 2)
As a modified example 2, as shown in FIG. 9, a laminated substrate is obtained by laminating by a vacuum laminating press with a semi-cured insulating resin sheet 12 a having a size larger than that of the peelable metal foil 13 between the two peelable metal foils 13. 100 can also be manufactured. As shown in FIG. 9, the laminated substrate 100 is cured by lamination to form an insulating resin layer 12 having sufficient thickness between two peelable metal foils 13 smaller than the size of the laminated substrate 100. .

(Release film)
In the step of FIG. 3 (b), as the release film 20 sandwiched between the stainless steel press plate of the vacuum lamination press apparatus in the vacuum lamination press, a resin material such as polyphenylene sulfide and polyimide, stainless steel, brass, etc. A film having a thickness of 10 to 200 μm made of a composite material combined with the above metal material is used.

  3B, the resin-rich semi-cured insulating resin sheet 12a is overlaid on the outside of the core substrate 10, the peelable metal foil 13 is overlaid on the outside, and the release film 20 is overlaid on the outside. The laminated substrate 100 is manufactured by stacking using a vacuum lamination press apparatus that is sandwiched between press plates and heated and pressed by the press plates.

  Thus, as shown in FIG. 3 (c), the laminated substrate 100 is formed using the peelable metal foil 13 that is welded and fixed to the thick copper foil layer 13a at the peripheral weld portion 15 of the thin copper foil layer 13b. To manufacture. Here, the semi-cured insulating resin sheet 12 a is heated and pressed by a press plate to melt and flow out, and is filled in the through hole H in the peelable metal foil 13.

  A part of the resin filled in the through hole H flows to the surface of the peelable metal foil 13 and is connected to the resin of the through hole H adjacent to the through hole H on the surface of the peelable metal foil 13. The resin bridge connecting adjacent through holes H is cured, and the resin bridge on the surface of the peelable metal foil 13 between the through holes H presses the peelable metal foil 13 to prevent the peeling.

  When the through-holes H are arranged in a staggered pattern as shown in the plan view of FIG. 1A and one through-hole H is adjacent to the other four through-holes H, Since four resin bridges are formed between them, the effect of the resin bridges suppressing the peelable metal foil 13 is increased.

By using this peelable metal foil 13, the peelable metal foil 13 is pressed by a cured resin bridge from the surface side, and the thick copper foil layer 13 a and the thin copper foil layer 13 b are welded. The peeling of the boundary surface of the foil 13 between the thick copper foil layer 13a and the thin copper foil layer 13b can be prevented. Therefore, due to the stress of the subsequent manufacturing process,
It is possible to prevent the peeling interface between the thick copper foil layer 13a and the thin copper foil layer 13b from peeling off and to prevent manufacturing defects due to peeling at the interface.

(Method for manufacturing printed wiring board)
Using this multilayer substrate 100, a printed wiring board is manufactured as follows.

(Forming a plating base conductive layer on the multilayer substrate)
First, as shown in FIG. 4D, the entire surface of the thin copper foil layer 13 b of the peelable metal foil 13 and the surface of the insulating resin layer 12 of the frame portion 14 by electroless copper plating on both surfaces of the multilayer substrate 100. Then, a plating base conductive layer 1 having a thickness of 0.5 μm to 3 μm is formed.

  In this electroless copper plating process, a conductive layer underlying the electrolytic copper plating layer that forms the wiring pattern 4 is formed next. However, this electroless copper plating process is omitted and the conductive metal foil 13 is directly applied. The wiring pattern 4 may be formed by bringing an electrode for electrolytic copper plating into contact with the copper foil and directly electrolytic copper plating on the peelable metal foil 13.

(Wiring pattern formation process)
Next, as shown in FIG. 4E, a photosensitive resist, for example, a dry film plating resist is attached to both surfaces of the laminated substrate 100 by roll lamination, and the pattern of the pattern exposure film is exposed and developed on the photosensitive resist. Then, a pattern 2 of a reverse plating resist of the wiring pattern 4 is formed on both surfaces of the multilayer substrate 100. That is, the plating resist pattern 2 is formed into a pattern having an opening in which the plating base conductive layer 1 is exposed at the wiring pattern 4 portion.

  Next, as shown in FIG. 4 (f), a copper plating layer having a thickness of 15 μm is formed on the surface of the plating base conductive layer 1 exposed at the wiring pattern portion by conducting electrical copper plating from the peelable metal foil 13 side. The wiring pattern 4 by the copper plating layer is formed by performing pattern plating for thickening. Here, the frame metal pattern 3 may be formed on the welded portion 15 of the peelable metal foil 13 by pattern plating of copper plating.

  Next, as shown in FIG. 5G, the plating resist is peeled off to expose the wiring pattern 4 by the copper plating layer on the peelable metal foil 13 of the multilayer substrate 100.

(Interlayer insulating resin layer formation process)
Next, as a pretreatment for forming the interlayer insulating resin layer 5, the surface of the wiring pattern 4 is roughened by an etching process of intergranular corrosion, a blackening process by an oxidation-reduction process, or a perhydrosulfuric acid system. Roughening is performed by soft etching.

  Next, as shown in FIG. 5H, the interlayer insulating resin layer 5 is thermocompression-bonded on the wiring pattern 4 by roll lamination or lamination press. For example, an epoxy resin having a thickness of 45 μm is roll laminated. When glass epoxy resin is used, copper foil of any thickness is stacked and thermocompression bonded with a lamination press.

As a resin material of the interlayer insulating resin layer 5, epoxy resin, bismaleimide-triazine resin (hereinafter referred to as BT resin), polyimide resin, PPE resin, phenol resin, PTFE resin, silicon resin, polybutadiene resin, polyester resin, melamine resin Organic resins such as urea resin, PPS resin, PPO resin, cyanate resin, and cyanate ester resin can be used. In addition, these resins can be used alone, or a combination of resins such as mixing a plurality of resins or preparing a compound can be used. Further, an interlayer insulating resin layer 5 in which a glass fiber reinforcing material is mixed with these materials can be used. As the reinforcing material, an aramid nonwoven fabric, an aramid fiber, or a polyester fiber can be used.

(Via hole and wiring pattern formation process)
Next, as shown in FIG. 5I, via hole prepared holes 6 for interlayer connection are formed by a laser method or a photo etching method. When copper foil is used for thermocompression bonding of the interlayer insulating resin layer 5, as a pretreatment for forming the via hole prepared hole 6, the entire copper foil is etched or an opening for the via hole prepared hole 6 is formed in the copper foil. The via hole prepared hole 6 is formed by the laser beam by performing the etching process to be formed or by performing the surface treatment of the copper foil to improve the laser beam absorbability of the copper foil in the via hole prepared hole 6 part.

  Next, electroless plating is performed on the wall surface of the via hole prepared hole 6 and the surface of the interlayer insulating resin layer 5. Next, a photosensitive plating resist film is formed on the surface of the interlayer insulating resin layer 5 subjected to electroless plating on the surface, and is exposed and developed, whereby the via hole pilot hole 6 portion and the second wiring pattern 19 are formed. The pattern 2 of the 2nd plating resist which opened this part is formed. Next, the copper plating is thickened by performing electrolytic copper plating with a thickness of 15 μm on the opening of the second plating resist pattern.

  Next, the second plating resist is peeled off, and the electroless plating remaining on the interlayer insulating layer is removed by perhydrosulfuric acid-based flash etching or the like, as shown in FIG. A filled via hole 7 and a second wiring pattern are formed. Then, the interlayer insulating resin layer forming step and the via hole and wiring pattern forming step are repeated to build up a plurality of layers of the interlayer insulating resin layer 5, the via hole 7 and the second wiring pattern on the multilayer substrate 100. Structure 30 is formed.

  Next, the surface of the multilayer wiring structure 30 is roughened with a microetching agent, and then a thick coating of an azole compound is formed to improve the solder resist adhesion. Next, a film of the photosensitive solder resist 8 is formed, exposed and developed, and the pad portion is opened as shown in FIG. 6 (k), followed by heat curing to form the solder resist 8 pattern. When the adhesion between the multilayer wiring structure 30 and the solder resist 8 can be ensured after the roughening treatment, the treatment with the azole compound may not be performed.

  Next, an etching resist R having a desired size is pasted on the surface of the multilayer wiring structure 30, and the peripheral portion of the integrated body of the multilayer wiring structure 30 and the laminated substrate 100 is diced by a cutting line 16, router processing, shearing processing, or the like. Cut and cut by machining. By the machining, the frame portion 14 and the welded portion 15 of the peelable metal foil 13 are cut off, and the cross section of the intermediate layer is exposed at the cut portion, so that the boundary line of the peelable metal foil 13 is exposed.

  Then, as shown in FIG. 7 (l), the thin copper foil layer 13b is peeled from the thick copper foil layer 13a of the peelable metal foil 13 from the exposed peeling boundary line, whereby the multilayer substrate 100 having a thickness of 0.4 mm is obtained. The multilayer wiring structure 30 is separated from the wiring.

  Next, using sulfuric acid-hydrogen peroxide soft etching, the thin copper foil layer 13b and the plating base conductive layer 1 which are exposed without being covered with the etching resist R are removed, and then the etching resist R is removed. As a result, a multilayer wiring structure 30 in which the wiring pattern 4 embedded in the interlayer insulating resin layer 5 is exposed as shown in FIG.

(Land plating)
Next, as shown in FIG. 8, a solder resist 9 having a pattern having an opening in the land portion of the wiring pattern 4 is printed on the exposed wiring pattern 4. Although FIG. 8 shows an example in which the solder resist is provided on both surfaces, the solder resist 8 may be formed on only one surface of FIG.

  Next, 3 μm or more of electroless Ni plating is formed on the land portions of the openings of the solder resists 9 and 8, and 0.03 μm or more of electroless Au plating is formed thereon. The electroless Au plating may be formed with a thickness of 1 μm or more. Furthermore, it is also possible to pre-coat solder thereon. Alternatively, electrolytic Ni plating may be formed at 3 μm or more in the solder resist opening, and electrolytic Au plating may be formed thereon at 0.5 μm or more.

  Alternatively, a surface treatment layer can be formed in the solder resist opening by nickel-palladium-gold, electroless tin plating or the like. Furthermore, you may form an organic rust preventive film in this soldering resist opening part other than metal plating.

(Outline processing)
Next, the outer shape of the multilayer wiring structure 30 is processed with a dicer or the like and separated into individual printed wiring boards.

<Second Embodiment>
The manufacturing method of the peelable metal foil 13 of 2nd Embodiment is shown to the side sectional drawing of FIG. 10 in order of a process.

(Step 1 to Step 5)
The peelable metal foil 13 is manufactured according to steps 1 to 5 of the first embodiment, as shown in FIG.

(Step 6)
Next, as shown in FIG. 10 (b), a laser drilling device is used at the end of the peelable metal foil 13 having the predetermined dimensions, and laser light is irradiated from the thick copper foil layer 13a side, thereby FIG. As shown in the side sectional view of c), a plurality of adjacent non-through holes V are formed.

  As the non-through hole V, a non-through hole V having an opening on the thick copper foil layer 13a side and stopping in the middle of the thin copper foil layer 13b is formed. This non-through hole V forms a non-through hole V having an appropriate depth by adjusting the laser processing output by the laser drilling apparatus and the number of shots (irradiation number) of laser light.

  This non-through hole V has an opening on the thick copper foil layer 13a side, and the hole stops halfway through the thin copper foil layer 13b. When the non-through hole V is formed by irradiating the laser beam, the thick copper foil layer 13a is melted by the laser beam to form a welded portion 15 connected to the thin copper foil layer 13b at the bottom of the hole. Since the welded portion 15 firmly connects the thick copper foil layer 13 a and the thin copper foil layer 13 b of the peelable metal foil 13, the peelable metal foil 13 is peeled off even if there is an impact during the manufacturing process of the laminated substrate 100. This has the effect of preventing unwanted peeling from the end of 13d.

  Using this peelable metal foil 13, the laminated substrate 100 with the peelable metal foil 13 exposed on the surface is manufactured in the same manner as in FIG. 3C of the first embodiment, and as in FIG. A multilayer wiring structure 30 of a multilayer printed wiring board is manufactured outside the multilayer substrate 100. And after cutting the edge part of the multilayer substrate 100, the peelable metal foil 13 is peeled and a printed wiring board is manufactured.

<Third Embodiment>
In the present invention, the peelable metal foil 13 is laminated on the core substrate 10 to form the laminated substrate 100 as in the above embodiment, and then the peelable metal foil 13 is peeled off to form the multilayer wiring structure 30 from the core substrate 10. It is not limited to the use which manufactures a printed wiring board by isolate | separating. That is, as in the following third embodiment, the peelable metal foil 13 can be used to form the thin copper foil layer 13b on the surface of the core substrate of the printed wiring board. Hereinafter, the third embodiment will be described with reference to FIGS. 11 and 12.

(Method for manufacturing printed wiring board)
First, as shown in FIG. 11A, the wiring board 40 in which the wiring patterns 17 are formed by etching the copper foils on both sides of the core board having a thickness of 0.04 mm to 0.8 mm is manufactured.

(Peelable metal foil lamination process)
Next, as shown in FIG. 11B, a semi-cured insulating resin sheet 12a made of a prepreg or resin film having the same size as the wiring substrate 40 is stacked on the outer side of the wiring substrate 40, and the outer side of the semi-cured insulating resin sheet 12a. The peelable metal foil 13 having a size smaller than the cured insulating resin sheet 12a and having the welded portion 15 formed at the end is overlapped with the thin copper foil 13b inside.

  And the release film 20 is piled up on the outer side of the peelable metal foil 13, and the peelable metal foil 13 is laminated | stacked on the outer side of the wiring board 40 via the semi-hardened insulating resin sheet 12a with a vacuum lamination press.

  The semi-cured insulating resin sheet 12a outside the wiring substrate 40 is cured to form the insulating resin layer 12 by a laminating process that is heated and pressurized by a vacuum laminating press.

  As a result, the peelable metal foil 13 is laminated on the outside of the wiring substrate 40 via the insulating resin layer 12 formed by curing the semi-cured insulating resin sheet 12 a, and the peelable metal foil 13 becomes the insulating resin layer 12 and the wiring substrate 40. The laminated substrate 200 integrated with is manufactured.

  That is, as shown in FIG. 11C, a laminated substrate 200 is manufactured in which the peelable metal foil 13 having the welds 15 formed on the outside of the insulating resin layer 12 is disposed with the thin copper foil 13b on the inside.

  In this laminated substrate 200, as shown in FIG. 11C, the outer peripheral portion of the peelable metal foil 13 is surrounded by a frame portion 14 having a width of 5 mm by the insulating resin layer 12.

  Thus, as shown in FIG. 11 (c), the laminated substrate 200 having the peelable metal foil 13 on the surface, which is welded and fixed to the thick copper foil layer 13a at the welded portion 15 at the peripheral edge of the thin copper foil layer 13b and protected. Manufacturing. By using this peelable metal foil 13, it is possible to prevent the peeling interface between the thick copper foil layer 13 a and the thin copper foil layer 13 b of the peelable metal foil 13 from being peeled off due to stress in the subsequent manufacturing process. It is possible to prevent manufacturing defects due to peeling.

  Next, as shown in FIG. 12 (d), the frame portion 14 and the peelable metal foil 13 are cut by cutting the peripheral edge portion of the multilayer substrate 200 with a cutting line 16 by mechanical processing such as dicing processing, router processing, or shearing processing. As shown in FIG. 12E, the cross section of the intermediate layer of the peelable metal foil 13 is exposed in the cut cross section, and the boundary line of the peeling is exposed.

  Then, as shown in FIG. 12 (f), the laminated substrate 200 with the thin copper foil layer 13 b exposed on the surface is peeled off by peeling the thick copper foil layer 13 a of the peelable metal foil 13 from the exposed peeling boundary line. To manufacture.

  Next, the printed wiring board in which the thin copper foil layer 13b on the surface of the multilayer substrate 200 is etched to form a fine wiring pattern is manufactured.

  Furthermore, a multilayer build-up printed wiring board can be manufactured by sequentially building up an interlayer insulating resin layer and a wiring pattern on the outside of the printed wiring board.

DESCRIPTION OF SYMBOLS 1 ... Plating base conductive layer 2 ... Plating resist pattern 3 ... Frame metal pattern 4 ... Wiring pattern 5 ... Interlayer insulating resin layer 6 ... Via hole pilot hole 7 ... Via hole 8 , 9 ... Solder resist 10 ... Core substrate 11 ... Copper foil 12 ... Insulating resin layer 12a ... Semi-cured insulating resin sheet 13 ... Peelable metal foil 13a ... Thick copper foil layer 13b ... Thin copper foil layer 13c ... Diffusion prevention layer 13d ... Release layer 14 ... Frame portion 15 ... Welded portion 16 ... Cutting line 17 ... Wiring pattern 20 ... Separation Mold film 30 ... Multilayer wiring structure 40 ... Wiring substrate 100 ... Laminated substrate 200 ... Laminated substrate H ... Through hole R ... Etching resist V ... Non-through hole

Claims (6)

  A peelable metal foil laminated with a peelable intermediate layer sandwiched between a plurality of metal layers, and the plurality of metal layers being peelable by the intermediate layer, wherein a plurality of peelable metal foils are disposed on an outer periphery of the peelable metal foil. A peelable metal foil in which through holes adjacent to each other are formed.   2. The peelable metal foil according to claim 1, wherein a welded portion connecting the plurality of metal layers is formed on a wall surface of the through hole.   3. The peelable metal foil according to claim 1, wherein the through holes are arranged in a staggered pattern on an outer peripheral portion of the peelable metal foil, and the through holes are adjacent to at least four through holes. Peelable metal foil.   A peelable metal foil laminated with a peelable intermediate layer sandwiched between a plurality of metal layers, and the plurality of metal layers being peelable by the intermediate layer, wherein a plurality of peelable metal foils are disposed on an outer periphery of the peelable metal foil. A peelable metal foil having non-through holes in which welds connecting the plurality of metal layers are formed by non-through holes adjacent to each other.   A method for producing a peelable metal foil, wherein a plurality of metal layers are sandwiched between layers, and the plurality of metal layers are peelable by the intermediate layer. A plurality of through holes or non-through holes adjacent to each other are formed by drilling with a laser drilling apparatus.   A method for producing a printed wiring board using the peelable metal foil according to any one of claims 1 to 4, wherein the peelable metal foil and an insulating resin layer are laminated to produce a laminated substrate, and the lamination A step of exposing a cross section of the peelable metal foil to a cut surface by cutting a peripheral portion including the through hole or the non-through hole of the substrate by machining, and then peeling the peelable metal foil with the intermediate layer A method for producing a printed wiring board, comprising a step.

Images