JP6322492B2 - Printed wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a printed wiring board having a thick conductor wiring pattern corresponding to a large current and a printed wiring board that is excellent in miniaturization and insulation and a manufacturing method thereof.

  In recent years, in the automobile field, computerization has rapidly progressed, and with this, the number of printed wiring boards mounted is also increasing. In particular, in hybrid vehicles and electric vehicles that are remarkably widespread, many electric parts are used not only for control systems but also for drive systems such as motors. Since a large current flows through the electrical parts used in such a drive system, characteristics corresponding to this are required.

  In the printed wiring board, since the current capacity of the wiring pattern depends on the cross-sectional area, it can be dealt with by increasing the current capacity. In this case, if an attempt is made to form a large current-corresponding wiring pattern with a commonly used conductor thickness (for example, 18 μm), it is necessary to increase the pattern width, and the printed wiring board becomes large.

  Thus, it has been proposed to reduce the size of a printed wiring board having a wiring pattern corresponding to a large current by increasing the conductor thickness of the wiring pattern as in Patent Document 1. This manufacturing method will be described with reference to FIGS.

  First, an insulating base material 15 on which a thick conductor wiring pattern 16 is formed is prepared, and a plurality of insulating adhesive sheets 17 such as prepregs and a metal foil 18 are sequentially disposed thereon, and a release material 19 is provided above and below them. (See FIG. 16A). The insulating adhesive sheet 17 used here is a so-called prepreg in which an insulating resin 17b such as an inexpensive and highly insulating epoxy resin is impregnated with a reinforcing base material 17a such as a glass woven fabric (particularly for in-vehicle use). This is an essential material structure because it requires high rigidity and high reliability.

  Next, this is sandwiched between hot plates HP and laminated and pressed to be integrated (see FIGS. 16B and 16C). Thereafter, by producing the thin conductor wiring pattern 21 by circuit formation, a printed wiring board Q1 including the thick conductor wiring pattern 16 corresponding to a large current in the inner layer is obtained (see FIG. 17D).

Since the insulating resin layer 20 of the printed wiring board Q1 uses only the release material 19 at the time of lamination, the surface is smooth and the inside is filled with the insulating resin 17b between the thick conductor wiring patterns, and is reinforced on this. The base material 17a is present.

  In order to form this state, it is necessary to flow a large amount of the insulating resin 17b constituting the insulating adhesive sheet 17 at the time of the lamination press processing. For this reason, it is necessary to set a plurality of insulating adhesive sheets 17 and to set the processing conditions strictly so that the resin can easily flow (for the processing conditions, the temperature rise rate is increased to lower the resin viscosity, Set the pressure higher and push the insulating resin between the patterns).

  As a result, the thickness of the printed wiring board Q1 is increased (in order to overlap a plurality of insulating adhesive sheets). Under such processing conditions, the reinforcing base material 17a included in the insulating resin layer 20 is thick conductor wiring. A case of contacting the corner portion PC of the pattern 16 occurs (see FIG. 18A).

  When the reinforcing base (for example, glass woven fabric) comes into contact with the wiring pattern in this way, ion migration such as CAF 22 is likely to occur along the reinforcing base, and the insulating property is lowered. In particular, the thick conductor wiring pattern 16 through which a large current flows is more likely to occur.

  Further, in the insulating resin layer 20 on the thick conductor wiring pattern, a large part of the resin flows between the thick conductor wiring patterns 16, so that the thin conductor wiring pattern 21 formed thereon and the reinforcing base material 17a. Will be in close contact. For this reason, ion migration of CAF22 or the like is likely to occur here, and the insulating property is lowered. As a result, it is difficult to arrange the wiring patterns at a high density (see FIG. 18B).

  Further, when the thickness of the wiring pattern is increased, so-called undercut, which is side-etched during circuit formation, is likely to occur. In particular, in the case of a thick wiring pattern exceeding 200 μm, the pattern width corresponding to the middle layer position is smaller than the pattern upper layer position, and the corner portion tends to be in a sharper state.

  For this reason, even if a plurality of insulating adhesive sheets are stacked on the wiring pattern via a release material and laminated press processing is performed, the insulating resin hardly penetrates between the wiring patterns and voids are likely to occur. In addition, in the acute corner portion, it becomes difficult for the insulating resin to intervene between the reinforcing base material and the reinforcing base material is more likely to come into contact with the wiring pattern.

  Therefore, as a method for solving the above problems, the manufacturing method shown in FIG. 19 has been proposed. This is a method of laminating an insulating adhesive sheet 23 previously punched along the shape of the thick conductor wiring pattern 16. According to this method, the wiring pattern can be filled with the insulating resin without using many insulating adhesive sheets, and the plate thickness can be reduced. In addition, voids during stacking are less likely to occur.

  However, in this method, it is necessary to process the insulating adhesive sheet 23 in advance, and there are design restrictions in order to form the sheet. Furthermore, since alignment is required at the time of laminating press processing, pin lamination is essential, and workability is reduced. If processing is performed in a state where even a slight misalignment occurs during the laminating press processing, since the reinforcing base material 23a is exposed at the end surface of the punched insulating adhesive sheet, this becomes the thick conductor wiring pattern 16. In contact with each other, the insulating property tends to decrease (see FIG. 20).

JP 2002-33568 A Japanese Patent Laid-Open No. 9-5582

  The present invention has been made in view of the conventional problems as described above, and it is an object of the present invention to provide a printed wiring board having a thick conductor wiring pattern and having excellent miniaturization and insulation and a method for manufacturing the same. .

  The present invention provides at least a thick conductor wiring pattern formed on an insulating base material and an insulating base material positioned in a non-formed portion of the thick conductor wiring pattern so as to cover a side surface of the thick conductor wiring pattern. In a printed wiring board comprising an insulating resin layer having a reinforcing base material formed therein, the surface layer surface of the thick conductor wiring pattern, the exposed surface of the insulating resin layer, and the thick conductor wiring pattern recently The above-mentioned problem is solved by a printed wiring board characterized in that a groove is formed between the reinforcing substrate in contact with the substrate.

  The printed wiring board of the present invention has excellent insulating properties because the reinforcing base in the insulating resin layer does not contact the thick conductor wiring pattern.

  The present invention also relates to a method for producing a printed wiring board having a thick conductor wiring pattern, comprising at least a step of preparing an insulating substrate having a metal plate on one side, and forming an etching resist pattern on the metal plate Etching the metal plate on which the etching resist pattern is formed, forming a thick conductor wiring pattern, removing the etching resist pattern, and an insulating substrate on which the thick conductor wiring pattern is formed On top of this, at least an insulating adhesive sheet including a reinforcing base and a cushioning material are sequentially arranged, and in this arrangement state, the upper portion of the thick conductor wiring pattern and its surroundings are raised by heat and pressure treatment. Forming the insulating resin layer, a step of exposing the surface of the thick conductor wiring pattern by polishing, and the thick conductor wiring A step of chamfering the corners of the turn, the manufacturing method of the printed wiring board and having a is obtained by solving the above problems.

  In this way, by using a cushioning material at the time of lamination, the insulating adhesive sheet including the reinforcing base material is insulated without voids between the thick conductor wiring patterns without being processed in advance or requiring many sheets. A resin layer can be formed. In addition, since the insulating resin layer between the wiring patterns includes a reinforcing base material, the strength does not decrease even if it is thinned.

  Further, by etching so as to chamfer the corner portion of the thick conductor wiring pattern exposed by the polishing process, a groove is formed between the surface layer surface of the thick conductor wiring pattern and the polishing surface of the insulating resin layer. For this reason, the contact distance between the reinforcing base exposed on the polished surface of the insulating resin layer and the thick conductor wiring pattern is increased, and the occurrence of ion migration such as CAF can be reduced.

  As described above, a printed wiring board having a thick conductor wiring pattern corresponding to a large current and having excellent miniaturization and insulation can be obtained.

  According to the present invention, an insulating resin layer without a void can be formed by laminating an insulating adhesive sheet containing a reinforcing base material on a thick conductor wiring pattern using a cushioning material. In addition, the insulating resin layer raised by the lamination is removed by polishing to expose the surface layer surface of the thick conductor wiring pattern, and then etched so as to chamfer the corner portion of the thick conductor wiring pattern. Since a groove can be formed between the surface layer surface of the conductor wiring pattern and the polished surface of the insulating resin layer on the same surface, the insulation can be improved. Therefore, despite having the thick conductor wiring pattern, a printed wiring board excellent in insulation can be obtained without being thickened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 2 is a schematic cross-sectional process explanatory diagram (with a partial enlarged view) continued from FIG. 1. FIG. 3 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 2 (with a partially enlarged view). FIG. 4 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 3. The principal part expanded sectional explanatory drawing of the printed wiring board of FIG. The schematic sectional drawing (with a partial enlarged view) after the printed wiring board lamination | stacking which has the bump for interlayer connection. Schematic cross-sectional process explanatory drawing at the time of the etching at the time of using a negative type and a positive type photosensitive dry film for a chamfering resist. The schematic cross-sectional process explanatory drawing of the improved type of the printed wiring board which concerns on 1st embodiment. The schematic cross-sectional process explanatory drawing which shows the manufacturing method of the printed wiring board which concerns on 2nd embodiment of this invention. FIG. 10 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 9. The principal part expanded sectional explanatory drawing of the printed wiring board of FIG. The schematic sectional drawing of the printed wiring board which concerns on 3rd embodiment of this invention. The schematic cross-sectional process explanatory drawing which shows the manufacturing method of the printed wiring board which concerns on 4th embodiment of this invention. FIG. 14 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 13 (with a partially enlarged view). The schematic cross-sectional process explanatory drawing which shows the manufacturing method of the printed wiring board which concerns on 5th embodiment of this invention. Schematic cross-sectional process explanatory drawing which shows the manufacturing method of the conventional 1st printed wiring board. FIG. 17 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 16. The principal part expanded sectional explanatory drawing of the printed wiring board of FIG. Schematic cross-sectional process explanatory drawing which shows the manufacturing method of the conventional 2nd printed wiring board. The principal part expanded sectional explanatory drawing of the printed wiring board of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 to 3 show schematic cross-sectional process diagrams of a method for manufacturing a printed wiring board according to the first embodiment of the present invention.

  First, as shown to Fig.1 (a), the metal plate 2 is bonded together by the thermocompression bonding to the at least single side | surface of the insulating base material 1 used as a core.

  The insulating substrate 1 is not particularly limited as long as it is an insulating resin, but it is preferable to use an epoxy resin excellent in heat resistance and electrical characteristics. In addition, the presence or absence of a reinforcing substrate such as a glass woven fabric or a glass nonwoven fabric may be used. However, in order to stably form a thick conductor wiring pattern through which a large current flows, it is electrically and mechanically improved. It can be said that it is preferable to be included.

  The metal plate 2 is not particularly limited as long as it can form a circuit by etching, but it is preferable to use a copper plate in consideration of conductivity, thermal conductivity, and cost merit. Moreover, as a kind of copper plate, either an electrolytic copper plate or a rolled copper plate may be sufficient, and what can give a cost merit by thickness should just be used. Incidentally, if the thickness is 200 μm or more, the rolled copper sheet tends to be advantageous in terms of cost from the viewpoint of manufacturing.

  Although there is no restriction | limiting in particular about the thickness of the metal plate 2, When considering that a heavy current flows, it is preferable that it is 70 micrometers or more. The upper limit is not particularly limited, but is preferably 2000 μm or less in consideration of etching properties.

  Therefore, when a copper plate is used as the metal plate, it is preferable to use an electrolytic copper plate if it is 70 μm or more and less than 200 μm, and use a rolled copper plate if it is 200 μm or more and 2000 μm or less, respectively because productivity and cost merit can be obtained. I can say that.

  Next, as shown in FIG. 1B, a thick conductor wiring pattern forming resist R <b> 1 (hereinafter referred to as a resist R <b> 1) is formed on the metal plate 2. There is no restriction | limiting in particular as resist R1, What is necessary is just to use the photosensitive dry film used by circuit formation.

  Next, the thick conductor wiring pattern 3 is formed by etching this (see FIGS. 1C and 1D).

  For etching, a normal etching apparatus may be used, but when the metal plate is relatively thick as in the configuration of the present invention, the undercut of the thick conductor wiring pattern is suppressed by using a vacuum etching apparatus or the like. Since a wiring pattern can be formed, it is more preferable.

  Next, as shown in FIG.1 (e), the insulating adhesive sheet 4 and the cushion material 5 are arrange | positioned one by one on the insulating base material 1 in which the thick conductor wiring pattern 3 was formed.

  The insulating adhesive sheet 4 used here comprises a reinforcing base 4a and an insulating resin 4b. Although there is no restriction | limiting in particular as the reinforcement base material 4a, If it is a glass woven fabric, since it is cheap and also shows the outstanding intensity | strength, it is preferable. In addition to this, it is more preferable to include a silica-based filler, alumina and the like because not only mechanical characteristics and electrical characteristics are improved, but also heat generated from a large current can be efficiently radiated. The insulating resin 4b is not particularly limited as long as it is an insulating resin, but it is preferable to use an epoxy resin excellent in workability, heat resistance, and electrical characteristics.

  The cushion material 5 is not particularly limited as long as the insulating resin can be embedded between the wiring patterns without voids, and there is no particular limitation on the single layer structure or the multi-layer structure. In the case of the mold material 5a + cushion member 5b + release material 5a), the cushion member 5b can be adjusted (for example, the thickness is changed) according to the thickness of the wiring pattern to easily cope with it.

  At this time, the release material 5a is not particularly limited as long as it can be peeled off without being attached to the product after use. However, if a resin-based material is selected, the followability to the wiring pattern and the shape itself are also deformed. This is preferable because it is advantageous for embedding. If the thickness is too thin, it will be torn, and if it is too thick, it will be difficult to follow, so 20 to 100 μm is preferable.

  The cushion member 5b is not particularly limited as long as it can melt and follow the wiring pattern at the time of laminating press processing. However, if an inexpensive polyethylene resin is selected, it is preferable because cost merit can be obtained.

  Regarding the thickness, in order to embed the insulating resin between the wiring patterns without voids, it is necessary that the thickness is equal to or greater than the thickness obtained by subtracting the thickness of the insulating adhesive sheet 4 from the thickness of the inner thick conductive wiring pattern 3. It is more preferable to select one that is 30 μm thicker than this. This is because if the thick conductor wiring pattern and the step difference of the insulating adhesive sheet are selected or less than that, even if the cushion member 5b is melted at the time of lamination, the inner layer pattern cannot be followed and voids are likely to occur. It is to become. For this reason, it is necessary to avoid the risk of void generation by selecting a thicker one than these thickness differences.

  However, if the cushion member 5b is too thick, the amount of resin flow to the outside of the product becomes excessive, which adheres to a laminated member such as a hot plate and adversely affects workability. Furthermore, if the next product is laminated with these attached, it may cause defects such as dents. Therefore, the upper limit of the thickness of the cushion member is preferably selected to be 100 μm or less than the thickness difference between the thick conductor wiring pattern and the insulating adhesive sheet.

  From the above, for example, when the thickness of the thick conductor wiring pattern is 200 μm and the insulating adhesive sheet is 180 μm, the thickness of the cushion member 5b may be selected from 50 μm to 120 μm.

  Further, the surface of the thick conductor wiring pattern 3 may be roughened in order to improve the adhesion with the insulating adhesive sheet 4.

  The roughening treatment includes physical etching such as blasting and polishing. However, in a three-dimensional wiring pattern, chemical etching using acid or alkali is more preferable because it can be processed efficiently.

  Among these, in the case where an electrolytic copper plate is used for the thick conductor wiring pattern 3, the chemical etching may be performed by soft etching or the like mainly containing formic acid or an amine complexing agent.

  However, in the case formed with a rolled copper plate, since it is harder to roughen than an electrolytic copper plate, the above-mentioned soft etching is not sufficiently roughened, and there is a possibility that adhesion cannot be ensured. For this reason, in the case where a rolled copper plate is used, it is preferable to perform blackening etc. as a pretreatment. Of course, the electrolytic copper plate may be roughened by blackening or the like.

  Next, the cushioning material 5 is deformed by sandwiching the constituent material shown in FIG. 1 (e) between the hot plates HP and performing lamination press processing while heating, so that the insulating adhesive sheet 4 is placed between the thick conductor wiring patterns. Therefore, the insulating resin layer 6 can be formed without voids. At this time, the insulating resin layer is raised on the thick conductor wiring pattern 3 (the raised portion 6a) (see FIGS. 2F and 2G).

  At this time, it is possible to obtain a more preferable shape in the present invention by paying attention to the following two points and laminating and pressing. That is, use of the cushion member 5b having a softening point lower than that of the insulating adhesive sheet 4 and advance the pressurization timing from the general conditions.

  Usually, in order to laminate the insulating adhesive sheet 4 made of a general epoxy resin, it is recommended to apply pressure between 100 ° C. and 130 ° C. at which the resin becomes soft. This is because the resin is easily filled between the wiring patterns by applying pressure at the timing when the viscosity of the insulating adhesive sheet is lowered. In this case, since a large amount of resin flows simultaneously with pressurization, the raised portion 6a of the insulating resin layer has a gentle inclination. However, after that, the raised portion 6a is removed in the polishing step. However, if the slope of the raised portion is gentle, the roll surface of the polishing roll hits so that it takes a long time to remove. . Therefore, by processing based on the above two points, it is possible to make the slope of the raised portion 6a steep and to efficiently remove the raised portion. The mechanism is as follows.

First, regarding the cushion member, at the temperature at which the cushion member 5b becomes soft, the insulating resin 4b of the insulating adhesive sheet 4 has not yet reached the softening point, so it is still difficult to flow. When the pressure is applied at this timing, the cushion member 5b is deformed in accordance with the shape of the thick conductor wiring pattern 3 in the inner layer, but the insulating adhesive sheet 4 is formed so as to follow the thick conductor wiring pattern 3 without being deformed. The Then, even if it heats to the softening point of an insulation adhesive sheet in this state, the flow amount of the insulation adhesive sheet 4 (actually insulating resin 4b) is suppressed by the cushion member 5 rather than when processing with the recommended conditions of an insulation adhesive sheet. The As a result, the slope of the raised portion 6a of the insulating resin layer can be made steeper.
Specifically, when an epoxy resin generally used as an insulating adhesive sheet is applied, it is recommended to pressurize between 110 ° C. and 130 ° C. Therefore, for example, when a polyethylene-based thermoplastic resin having a softening point of 80 ° C. to 100 ° C. is used for the cushion member, a more preferable configuration can be obtained in the present invention by pressurizing at a timing in this temperature range. It will be.

  The internal state of the insulating resin layer 6 processed in this way is such that at least a part of the reinforcing substrate 4a is present at a position lower than the height of the thick conductor wiring pattern 3 in the thick conductor wiring pattern non-forming portion. It is formed. Therefore, even if the thickness of the insulating resin layer is relatively thin, since the reinforcing base 4a is included, the insulating resin layer 6 having high strength can be formed.

  In the internal state around the raised portion 6a on the thick conductor wiring pattern 3, the flow amount of the insulating resin 4b is relatively suppressed by the above processing conditions. However, the flow amount cannot be completely suppressed. This is because the thick conductor wiring pattern for flowing a large current has a larger thickness and width than a general wiring pattern. The thick conductor wiring pattern in the present invention refers to one having a thickness of 70 μm or more and a width of 400 μm or more, but this wiring pattern surface layer area is considerably larger than a general wiring pattern. Lamination is performed on such a wiring pattern in consideration of the points described above. However, since the pressure applied to the wiring pattern is large, the insulating resin 4b slightly flows away from the pressing of the cushion material. In addition, since more pressure is applied between the corner portion PC of the wiring pattern and the cushion material 5 than at other portions, the insulating resin 4b flows more easily than on the wiring pattern. As a result, in the vicinity of the side surface of the thick conductor wiring pattern 3, the reinforcing base material is present along the side surface through the insulating resin, but on the wiring pattern, the reinforcing base material 4a is close to the corner portion PC. Then, it will be in the state which contacted (refer FIG.2 (g) enlarged view).

  Incidentally, if this is a lamination process for the interlayer connection bump BP having a thickness of about 50 μm and a diameter of about 100 μm as shown in FIG. 6, the cushion material can suppress the flow of the insulating resin. The insulating adhesive layer 6 can be formed with a large amount of insulating resin 4b interposed between the reinforcing base 4a.

  When there is a slight contact with the reinforcing substrate 4a in this way, a current of several A or more flows through the thick conductor wiring pattern 3, so that ion migration such as CAF is more likely to occur than a general printed wiring board. As a result, the insulating property decreases in a short time.

  Therefore, in the present invention, the reinforcing substrate 4a that is close to or in contact with these thick conductor wiring patterns is removed by polishing the raised portions 6a of the insulating resin layer (FIG. 2). (See (h)). Thereby, not only the reinforcing substrate 4a on the thick conductor wiring pattern included in the raised portion 6a of the insulating resin layer but also the surrounding reinforcing substrate 4a can be removed at the same time.

  The level of the polishing treatment may be such that the surface layer surface 3a of the thick conductor wiring pattern is completely exposed, but a more preferable state is obtained by further removing the surface layer of the wiring pattern by 1 μm or more. This is because the distance between the thick conductor wiring pattern and the reinforcing base material 4a in the vicinity of the surface of the insulating resin layer around the thick conductor wiring pattern can be ensured, so that the risk of occurrence of ion migration such as CAF can be reduced.

  Although there is no restriction | limiting in particular as a grinding | polishing processing method, It is preferable to carry out by physical grinding | polishing, such as buff grinding | polishing and belt grinding | polishing which can grind | polish a reinforcement base material, a metal, and resin substantially the same.

  Among these, in buffing, it is preferable to use a multi-axis polishing machine. This is because both surfaces can be processed at the same time, and the polishing is performed by a plurality of polishing wheels, so that the processing can be efficiently performed in a short time. At this time, it is preferable to use a ceramic wheel and a non-woven buff wheel in combination, instead of using the same polishing wheel. This is because the reinforcing base 4a contained in the insulating resin is first removed with a ceramic wheel, and then fine irregularities generated on the surface from which the reinforcing base is removed are removed with a non-woven buff wheel. Thereby, a smoother polished surface can be formed in a short time.

  However, by physically polishing the surface layer portion of the wiring pattern, the metal forming this wiring pattern is flush with the surface layer surface 3a of the thick conductor wiring pattern (in this case, indicates a difference within 0 to 3 μm). A so-called polishing sag portion 3b is generated by being stretched onto the polishing surface 6b of a certain insulating resin layer. In particular, when the wiring pattern is made of copper, the polishing sag portion 3b is remarkably generated.

  At this time, if the polishing sag portion 3b covers the reinforcing substrate 4a exposed from the polishing surface 6b of the insulating resin layer, ion migration such as CAF is likely to occur from this point (FIG. 2 ( h) See enlarged view). Therefore, the polishing sag portion 3b is removed next.

  As this method, a method of soft etching the entire surface is conceivable. However, as in the configuration of the present invention, the reinforcing base material 4a is exposed at a continuous position on the same surface as the surface layer surface 3a of the wiring pattern through which a large current flows. When there is a polished surface 6b of the insulating resin layer, even a slight metal residue is not preferable because it tends to cause a decrease in insulation. Therefore, it is conceivable to provide a step between the surface layer 3a of the thick conductor wiring pattern and the polished surface 6b of the insulating resin layer by increasing the amount of soft etching. However, with this method, the cross-sectional area of the thick conductor wiring pattern 3 becomes small, and there is a possibility that it becomes a disadvantageous shape for handling a large current. Therefore, the polishing sag is removed by the following method.

  First, a chamfering resist R2 is provided on the surface layer surface 3a of the thick conductor wiring pattern exposed by polishing with a resist width RW that fits in the pattern top width TW (see FIG. 3I).

  The resist width RW is only required to be narrower than the top width TW of the thick conductor wiring pattern 3, but if it is too narrow, the cross-sectional area of the wiring pattern becomes small due to excessive etching. Further, if the thickness is approximately equal to the top width TW of the thick conductor wiring pattern, there is a case in which the polishing sag portion 3b cannot be removed when the position is shifted to the outside from the pattern corner portion PC due to the alignment. Therefore, the resist width RW is preferably set to be 50 μm to 300 μm smaller than the top width TW of the thick conductor wiring pattern.

As the chamfering resist R2 used here, a photosensitive dry film resist may be applied, but in the present invention, it is more preferable to use a positive photosensitive dry film resist.
The reason is that, for example, when a negative photosensitive dry film NR that is often used in the subtractive method is used, an undercut occurs during exposure, resulting in an inversely tapered shape (see FIG. 7 (a) -1). . For this reason, the flow of the etching solution ET in the subsequent chamfer etching is such that it flows inside the thick conductor wiring pattern (see FIG. 7A-2). As a result, the cross-sectional area of the thick conductor wiring pattern 3 tends to be small, which is disadvantageous for dealing with a large current. On the other hand, the positive photosensitive dry film PR has a forward tapered shape (see FIG. 7B-1). As a result, the flow of the etching solution ET is opposite to that of the negative type photosensitive dry film, and it is possible to reduce the etching amount of the thick conductor wiring pattern 3 and to remove the polishing sag 3b (see FIG. 7 (b) -2). From the above, it is desirable to use the positive photosensitive resist PR as the chamfering resist R2.

  Thereafter, as shown in FIG. 3J, by etching this, the corner portion PC of the thick conductor wiring pattern is chamfered to form a chamfered portion PM. Thereby, the polishing sag portion 3b on the polishing surface 6b of the insulating resin layer is removed. At the same time, a groove D1 is formed between the surface layer surface 3a of the thick conductor wiring pattern and the polished surface 6b of the insulating resin layer. Since the groove D1 is formed, the possibility of contact between the thick conductor wiring pattern 3a and the reinforcing substrate 4a exposed on the polished surface can be further reduced, so that ion migration such as CAF can occur. Is more reduced.

  The etching solution ET at this time is not particularly limited as long as it can etch a metal. However, when copper is used as the metal, diffusion-controlled etching such as ferric chloride solution or cupric chloride solution is used. If the liquid is used, the groove D1 is unlikely to become excessively deep in combination with the shape of the chamfering resist R2 having the forward taper shape by the positive photosensitive resist PR described above, that is, the thick conductor wiring pattern 3 It is more preferable because it can be formed with a large cross-sectional area.

  Finally, by removing the chamfering resist R2, a printed wiring board having the thick conductor wiring pattern 3 and the reinforcing substrate 4a in the insulating resin layer is not in contact with the thick conductor wiring pattern 3 Pb1 is obtained (see FIG. 3 (k)). The point of the present invention is between the surface layer surface 3 a of the thick conductor wiring pattern 3 and the reinforcing substrate 4 a that is exposed from the polished surface 6 b of the insulating resin layer 6 and is closest to the thick conductor wiring pattern 3. In addition, the groove D1 is formed so as to cut off these.

  If the printed wiring board Pb1 is used as a base and the same configuration as that of the conventional example is formed, the insulating adhesive sheet 7, the metal foil 8, and the release material 9 are sequentially arranged thereon and laminated and integrated (FIG. 4 ( 1) (see (m)), and then through each step, the printed wiring board Pb2 in which the thin conductor wiring pattern 11 is formed on the thick conductor wiring pattern 3 is obtained (see FIG. 4 (n)).

  In this printed wiring board Pb2, the thick conductor wiring pattern 3 of the inner layer already has a characteristic excellent in insulating properties, and has become a substantially smooth surface by the polishing process. For this reason, since it is not necessary to fill the space between the thick conductor wiring patterns 3 as the insulating adhesive sheet 7 provided thereon, a thin one can be applied, a cushioning material is unnecessary, and processing can be performed only with a release material.

  That is, since it is not necessary to increase the amount of resin flow, the processing can be performed in a state where the insulating resin 7 b is sufficiently present between the reinforcing base 7 a included in the insulating adhesive sheet 7 and the metal foil 8.

  From the above, since the thickness of the insulating resin layer 10 to be formed is suppressed, an increase in the overall plate thickness is suppressed. Moreover, since the surface of the metal foil 8 has high smoothness, the thin conductor wiring pattern 11 can be thinned.

  And since the insulating resin 7b formed on the groove D1 provided between the surface layer surface 3a of the thick conductor wiring pattern and the polished surface 6b of the insulating resin layer is filled, the insulation is improved. To do. Furthermore, the adhesion between the insulating resin layers can be improved by increasing the contact area by the amount of the groove D1 (see FIG. 5).

  In the above configuration, the printed wiring board Pb2 is formed by directly laminating the insulating adhesive sheet 7 and the like on the printed wiring board Pb1, but as shown in FIG. 8, flash etching is performed before the lamination. The sharp part of the chamfered portion PM of the wiring pattern can be formed into a curved shape 3c.

  Thus, by making the chamfered portion of the wiring pattern into the curved shape 3c, for example, even if it is used in an environment where the thermal cycle is repeated, the stress applied to the corner portion of the wiring pattern is dispersed. The possibility of cracks occurring in the layer 10 (actually the insulating resin 7b) can be reduced.

  Next, a second embodiment of the printed wiring board of the present invention will be described with reference to FIGS.

  The point of this configuration is that a thick conductor wiring pattern in which a large current flows and a thin conductor wiring pattern in which a control signal flows are mixed in the same layer.

  In the first embodiment, when a thin conductor wiring pattern is formed, the insulating adhesive sheet and a metal foil are newly laminated on the thick conductor wiring pattern, and this metal foil is formed by forming a circuit. . That is, in order to form a thick conductor wiring pattern and a thin conductor wiring pattern, at least two or more conductor layers on which the respective wiring patterns are formed are provided.

  On the other hand, in the second embodiment, the thick conductor wiring pattern and the thin conductor wiring pattern can be formed in the same layer. As a result, the manufacturing process can be shortened, the printed wiring board can be made thinner, and the wiring density can be increased.

  In this manufacturing method, as shown in the first embodiment, the metal film 12 is formed on the entire surface by conducting a conductive process on the surface layer 3a of the thick conductor wiring pattern exposed by the polishing process. (See FIGS. 9A and 9B).

  There is no particular limitation on the conductive treatment method, as long as a metal film can be formed, either a dry method or a wet method. However, a plating method is preferable because the metal film can be easily formed on the entire surface. However, since it is necessary to form a metal film on the surface of the insulating resin layer, it is preferable to ensure the conductor thickness by forming a thin metal film by chemical plating and then performing electroplating.

  At this time, in order to improve the adhesion of chemical plating, it is desirable to improve the adhesion by the anchor effect by roughening the surface of the insulating resin layer. There are no particular limitations on the roughening treatment method, either physical treatment or chemical treatment, but wet treatment with an alkaline permanganate solution is preferable because it can be uniformly treated in a short time.

  The metal film is not particularly limited as long as it can form a circuit by etching, but it is preferable to select copper in view of conductivity, thermal conductivity, and cost merit.

  Next, a chamfering resist R2 is formed on the metal film 12 on the thick conductor wiring pattern 3 as in the first embodiment. At the same time, a thin conductor wiring pattern forming resist R3 (hereinafter referred to as resist R3) is formed on the metal film 12 on the insulating resin layer 6 in the thick conductor wiring pattern non-forming portion (see FIG. 9C). ).

  By etching this and peeling off the respective resists, the thick conductor wiring pattern 3 having the metal film 12a on the surface layer whose corners are chamfered and etched, and the insulating resin layer 6 are removed as in the first embodiment. In addition, a thin conductor wiring pattern 11a made of the metal film 12b can be simultaneously formed, and a printed wiring board Pb3 in which these are mixed in the same layer is obtained (see FIGS. 10D and 10E).

  In this printed wiring board, not only the insulation of the thick conductor wiring pattern is high, but also the groove D2 is formed between the thick conductor wiring pattern and the thin conductor wiring pattern. high. Further, by forming a solder resist SR layer having an opening W on the metal film 12a of the thick conductor wiring pattern 3 on this, the groove D2 is filled with the solder resist SR. And insulation improves (refer to Drawing 10 (f) Drawing 11).

  Furthermore, since the metal film 12a is formed on the thick conductor wiring pattern 3 in this configuration, the cross-sectional area can be increased, and a more advantageous structure can be obtained for flowing a large current.

  Next, a third embodiment will be described. The structure of the second embodiment described above is a structure in which a metal film is directly formed on the insulating resin layer by conducting treatment. In this case, the insulating resin layer is roughened to improve adhesion. A process is required. Therefore, when the insulating adhesive sheet is laminated, the printed wiring board Pb4 that ensures the adhesion to the insulating resin layer 6 by simultaneously laminating the metal foil 13 may be used. In this case, the thin conductor wiring pattern 11b is composed of the metal foil 13 and the metal film 12b (see FIG. 12). Incidentally, the metal foil on the thick conductor wiring pattern 3 is removed together with the insulating resin at the time of polishing.

  Next, a fourth embodiment of the printed wiring board of the present invention will be described with reference to FIGS. In the first, second, and third embodiments shown so far, a groove is formed between the surface of the thick conductor wiring pattern and the polished surface of the insulating resin layer. A chamfering resist was formed on the surface and etched. In this case, the alignment accuracy on the thick conductor wiring pattern is required, but it is necessary to set the chamfering resist in consideration of the amount of deviation at this time. Therefore, the cross-sectional area of the large current pattern becomes smaller than in the initial state. Therefore, in the fourth embodiment, a groove is formed between the surface layer surface of the thick conductor wiring pattern and the polished surface of the insulating resin layer without newly providing this chamfering resist.

  First, the insulating adhesive sheet 4 and the cushion material 5 are sequentially disposed without peeling off the thick conductor wiring pattern forming resist R4 (hereinafter referred to as resist R4) used when forming the thick conductor wiring pattern. Stacked and integrated with the hot plate HP (see FIGS. 13A and 13B). Thereby, the thick conductor wiring pattern surface layer surface 3a, the pattern corner portion PC, and the periphery thereof are covered with the resist R4 (see FIG. 14C). The presence of the resist R4 can prevent the corner portion PC of the thick conductor wiring pattern and the reinforcing base 4a included in the insulating resin layer from coming into direct contact (actual resist thickness is reduced by lamination, (In order to make the configuration easier to understand, it is shown thicker). Therefore, the structure which reduced the generation | occurrence | production risk of CAF at this time is obtained.

  However, when the resist R4 used here is a general photosensitive resist used in circuit formation, since the resin is not designed in consideration of the insulation, the insulation may be further deteriorated. It is done. Moreover, since the surface layer surface is also in the state 6c in which the insulating resin layer is raised, problems are likely to occur when the layers are further multilayered. Then, next, this resist R4 and the protruding portion 6c of the insulating resin layer are removed.

  First, the raised portion 6c of the insulating resin layer is removed by polishing in the same manner as in the first embodiment so far. By this polishing, the resist R4 existing between the surface layer 3a of the thick conductor wiring pattern and the polishing surface 6b of the insulating resin layer is exposed (see FIG. 14D). Therefore, next, the process of removing the resist R4 is performed, but before that, flash etching for removing the polishing sag portion generated by the polishing is performed. This etching is for removing polishing sag on the resist R4. Therefore, even if it is not completely removed, it is removed together with the resist R4 in a later step, and therefore, it may be performed by a short time processing flash etching.

  It is considered that the resist R4 can be removed by a normal dry film peeling process depending on the type of the resist. However, when a general photosensitive resist is used, the insulating process is performed by a heat treatment during the lamination press. In many cases, it is in close contact with the resin layer 6 and cannot be completely removed only by peeling treatment. Therefore, it is preferable to remove this by wet treatment with an alkaline permanganic acid solution because it can be easily removed in a shorter time (see FIG. 14E).

  Accordingly, the groove D3 between the surface layer surface 3a of the thick conductor wiring pattern and the polishing surface 6b of the insulating resin layer can be easily formed without forming a chamfering resist.

  Further, by performing the flash etching process after forming the groove D3, the corner portion PC of the thick conductor wiring pattern 3 can be formed into a curved shape 3d, which has a configuration in which an insulating resin layer is formed thereon. In this case, the occurrence of cracks in the insulating resin layer starting from the corner portion can be prevented.

  In the above, a photosensitive dry film for circuit formation is applied as the resist R4. However, by adopting a resist such as a solder resist for a flexible substrate, it may be configured not to be peeled off. it can.

  Next, a fifth embodiment of the printed wiring board of the present invention will be described with reference to FIG.

  The point of this configuration is that the insulating resin layer that fills the thick conductor wiring pattern is formed with varnish-like insulating ink in addition to the insulating adhesive sheet.

  In the first to fourth embodiments shown so far, the insulating resin layer is formed only by the insulating adhesive sheet, but this becomes more difficult as the thick conductor wiring pattern becomes thicker. In addition, if this is forcibly embedded with the cushion material, the cushion material may be torn and the cushion member may adhere to the product.

  Therefore, the above-described problems can be solved by appropriately embedding and raising the thick conductor wiring pattern in advance with insulating ink before laminating the insulating adhesive sheets.

  In this manufacturing method, the insulating ink 14 is applied to the entire surface or the thick conductor wiring pattern non-formed portion on the thick conductor wiring pattern 3 formed on the insulating base material 1 (see FIG. 15A).

  The coating amount is formed so that the surface layer surface is at a position lower than the height of the thick conductor wiring pattern at least in the portion where the thick conductor wiring pattern is not formed. This is for the purpose of ensuring that the reinforcing base material contained in the insulating adhesive sheet laminated thereon is included in the insulating resin layer even after the subsequent polishing process.

  For example, when the thick conductor wiring pattern is 200 μm thick, it is embedded in the insulating ink up to a height of about 100 μm and then laminated with an insulating adhesive sheet of about 100 μm thickness, the reinforcing resin layer is formed on the insulating resin layer to be formed. A configuration including the material can be formed.

  In other words, the thickness of the insulating adhesive sheet laminated thereon and the thickness formed with the insulating ink may be applied with reference to the thickness of the thick conductor wiring pattern. There is no restriction | limiting in particular as the frequency | count of application | coating, It may be 1 time or multiple times.

  By the way, although not shown this time, when applied to the entire surface, most of the insulating ink on the thick conductor wiring pattern flows to the thick conductor wiring pattern non-forming portion, and on the thick conductor wiring pattern, it is several μm. An insulating resin film (2 to 5 μm thick) is formed. Since this can further improve the insulation of the thick conductor wiring pattern, it is a more preferable structure.

  The insulation ink is not particularly limited as long as the insulation between the wiring patterns can be ensured. However, considering that heat is generated when a large current flows in this configuration, an epoxy resin or a polyimide resin having excellent heat resistance. Is preferably used. More preferably, the adhesiveness between insulating resins can be improved by using a resin of the same system as the insulating adhesive sheet provided thereon.

  In addition, it is more preferable that the insulating ink contains a silica-based filler, alumina, and the like because not only mechanical characteristics and electrical characteristics are improved, but also heat dissipation is improved.

  As a forming method, it can be performed by a screen printing method, a curtain coating method, a roll coater method, or the like, but if the object to be applied is both sides, the roll coater method is more preferable because both sides can be efficiently applied.

  The cured state of the insulating ink may be a completely cured state, but the semi-cured state (resin reaction rate is about 30 to 50%), the so-called B stage state, is an insulating layer formed thereon. In order to improve the adhesiveness with the adhesive sheet, it is preferable to cure in this state.

  Next, the insulating adhesive sheet 4 and the cushioning material 5 are sequentially arranged on the surface to which the insulating ink 14 is applied, and are sandwiched between the hot plates HP and laminated and pressed, so that the thick conductor wiring pattern is formed. The insulating resin layer 6 is formed to be the raised portion 6d (see FIGS. 15B and 15C).

  As described above, the thickness of the insulating adhesive sheet 4 used here can be selected based on the remaining thickness of the thick conductor wiring pattern embedded with the insulating ink 14. Therefore, since the thickness of the insulating adhesive sheet disposed thereon can be reduced by increasing the amount of embedding, a cost merit can be achieved. In addition, since the level difference from the wiring pattern is also reduced, the risk of void generation during the lamination press processing can be further reduced.

  In the description of the present invention, the description has mainly been given of the printed wiring board having a single-sided configuration as an example. However, other configurations can be used as long as they do not depart from the configuration of the present invention.

1: Insulating base material 2: Metal plate R1: Thick conductor wiring pattern forming resist 3: Thick conductor wiring pattern 4: Insulating adhesive sheet 4a: Reinforcing base material 4b: Insulating resin 5: Cushion material 5a: Release material 5b: Cushion member HP: hot plate 6: insulating resin layer 6a: raised portion of insulating resin layer PC: corner portion 3a of thick conductor wiring pattern: surface layer surface 6b of thick conductor wiring board pattern: polished surface 3b of insulating resin layer: on insulating resin layer Thick conductor wiring pattern polishing sagging portion R2: chamfering resist TW: wiring pattern top width BW: wiring pattern bottom width RW: resist width PM: thick conductor wiring pattern chamfered portion D1: groove Pb1: printed circuit board 7: insulating adhesive sheet 7a : Reinforcing substrate 7b: Insulating resin 8: Metal foil 9: Release material 10: Insulating resin layer 11: Thin conductor wiring pattern Pb2: Printed wiring board BP: Bump for interlayer connection PC: Corner portion NR of interlayer connection bump NR: Negative photosensitive resist PR: Positive photosensitive resist ET: Etching solution 3c: Thick conductor wiring pattern curved corner portion 12: Metal film R3: Thin conductor wiring pattern forming resist 12a: metal film 12b: metal film D2: groove 11a: thin conductor wiring pattern Pb3: printed wiring board W: opening SR: solder resist Pb4: printed wiring board 13: metal foil 11b: thin conductor wiring pattern R4: thick conductor wiring Pattern forming resist 6c: raised portion D3 of insulating resin layer: groove 3d: thick conductor wiring pattern curved corner portion 14: insulating ink 6d: raised portion 15 of insulating resin layer: insulating substrate 16: thick conductor wiring pattern 17: Insulating adhesive sheet 17a: Reinforcing substrate 17b: Insulating resin 18: Metal foil 19: Release material 20: Insulating resin layer 21: Thin conductor arrangement Pattern Q1: conventional method according to the printed wiring board 22: CAF
23: Insulating adhesive sheet 23a subjected to window removal processing: Reinforcing base material 23b: Insulating resin 24: Insulating resin layer Q2: Printed wiring boards S1, S2, S3 by a conventional method: enlarged view

Claims (10)

  At least the thick conductor wiring pattern formed on the insulating base material and the insulating base material positioned on the non-forming portion of the thick conductor wiring pattern, and formed so as to cover the side surface of the thick conductor wiring pattern. In a printed wiring board provided with an insulating resin layer having a reinforcing substrate inside, the surface layer surface of the thick conductor wiring pattern, and a position exposed from the insulating resin layer and closest to the thick conductor wiring pattern A printed wiring board, wherein a groove is formed between the reinforcing substrate.   An insulating resin layer having a reinforcing substrate and a thin conductor wiring pattern are formed on the printed wiring board according to claim 1, and an insulating resin of the insulating resin layer is filled in a groove of the printed wiring board. Printed wiring board characterized by being made. A thin conductor wiring pattern is formed on the insulating resin layer in the same layer as the thick conductor wiring pattern of the printed wiring board according to claim 1, and a solder resist layer is formed on the thin conductor wiring pattern and the insulating resin layer. The printed wiring board is characterized in that the groove of the printed wiring board is filled with a solder resist of the solder resist layer.   A metal film is formed on the surface layer of the thick conductor wiring pattern, and a thin conductor wiring pattern made of a metal film formed simultaneously with the metal film on the surface layer of the thick conductor wiring pattern is formed on the insulating resin layer. The printed wiring board according to claim 3, wherein the printed wiring board is formed.   5. The printed wiring board according to claim 4, wherein the thin conductor wiring pattern comprises a metal foil and a metal film.   The printed wiring board according to claim 1, wherein the insulating resin layer is made of an insulating ink and an insulating adhesive sheet. A method of manufacturing a printed wiring board having a thick conductor wiring pattern,
At least a step of preparing an insulating substrate having a metal plate on one side;
Forming an etching resist pattern on the metal plate;
Etching the metal plate on which the etching resist pattern is formed to form a thick conductor wiring pattern;
Removing the etching resist pattern;
On the insulating base material on which the thick conductor wiring pattern is formed, at least an insulating adhesive sheet including a reinforcing base material, and a step of sequentially arranging a cushion material,
In this arrangement state, a process of forming an insulating resin layer in which the upper portion of the thick conductor wiring pattern and the periphery thereof are raised by heat and pressure treatment,
A step of exposing a surface layer of the thick conductor wiring pattern by a polishing process;
Chamfering the corner of the thick conductor wiring pattern;
A method for producing a printed wiring board, comprising: A method of manufacturing a printed wiring board having a thick conductor wiring pattern,
At least a step of preparing an insulating substrate having a metal plate on one side;
Forming an etching resist pattern on the metal plate;
Etching the metal plate on which the etching resist pattern is formed to form a thick conductor wiring pattern;
Removing the etching resist pattern;
On the insulating base material on which the thick conductor wiring pattern is formed, at least an insulating adhesive sheet including a reinforcing base material, and a step of sequentially arranging a cushion material,
In this arrangement state, a process of forming an insulating resin layer in which the upper portion of the thick conductor wiring pattern and the periphery thereof are raised by heat and pressure treatment,
A step of exposing a surface layer of the thick conductor wiring pattern by a polishing process;
A step of forming a metal film on the surface layer surface of the thick conductor wiring pattern and the insulating resin layer by a conductive treatment;
Etching the metal film, chamfering the surface of the thick conductor wiring pattern, and simultaneously forming a thin conductor wiring pattern on the insulating resin;
A method for producing a printed wiring board, comprising: A method of manufacturing a printed wiring board having a thick conductor wiring pattern,
At least a step of preparing an insulating substrate having a metal plate on one side;
Forming an etching resist pattern on the metal plate;
Etching the metal plate on which the etching resist pattern is formed to form a thick conductor wiring pattern;
On the insulating base material on which the thick conductor wiring pattern is formed, at least an insulating adhesive sheet including a reinforcing base material, and a step of sequentially arranging a cushion material,
In this arrangement state, a process of forming an insulating resin layer in which the upper portion of the thick conductor wiring pattern and the periphery thereof are raised by heat and pressure treatment,
By the polishing process, the surface layer surface of the thick conductor wiring pattern, the step of exposing the etching resist pattern,
Removing the etching resist pattern;
A method for producing a printed wiring board, comprising:   The method for manufacturing a printed wiring board according to any one of claims 7 to 9, wherein the insulating resin layer is formed of an insulating adhesive sheet including a reinforcing base and an insulating ink.