JP4582277B2 - Method for forming columnar metal body and method for manufacturing multilayer wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of forming a columnar metal body that can be used for conductive connection between wiring layers of a multilayer wiring board, and a method of manufacturing a multilayer wiring board using the same.
[0002]
[Prior art]
In recent years, along with miniaturization and weight reduction of electronic devices and the like, electronic components have been miniaturized, and a demand for higher density is increasing for wiring boards for mounting electronic components. In order to increase the density of the wiring board, a method of increasing the wiring density of the wiring layer itself or a method of forming a multilayer structure by stacking a plurality of wiring layers is employed.
[0003]
A method for manufacturing a multilayer wiring board includes a bonding method in which a wiring layer is formed on each of a plurality of substrates, and an insulating sheet is interposed between the substrates to perform bonding, etc., and a substrate on which a wiring pattern is formed There is a build-up method in which an insulating layer is formed on a material, a wiring pattern is formed on the insulating layer, and the laminated structure is formed by sequentially repeating the formation of the insulating layer and the wiring pattern. To do.
[0004]
On the other hand, in a multilayer wiring board, it is necessary to perform conductive connection according to circuit design between the respective wiring layers. For this reason, in order to conductively connect the upper and lower wiring layers, there are those in which a copper plating layer is formed on the inner wall surface of the via hole and multilayer wiring boards in which a columnar conductor is formed in the via hole.
[0005]
As a method for manufacturing a multilayer wiring board having the latter structure, Japanese Patent Laid-Open No. 6-314878 discloses that a columnar metal body is formed in a lower wiring layer and then an upper wiring layer is formed so that the wiring layer is electrically conductive. A method of connecting is disclosed. This will be described with reference to FIG.
[0006]
First, the conductive thin film layer 42 is formed on the surface of the base material 41 by sputtering or the like (see FIG. 1A), and a pattern is formed thereon by electrolytic copper plating using a plating resist or the like (FIG. 2)). Next, a plating resist is uniformly applied, exposed and developed to form a resist pattern 44 opposite to the via hole (see FIG. 3 (3)), and then conductive from the conductive thin film layer 42 side. Then, metallic copper is deposited in the recess 45 of the resist pattern 44 by electrolytic copper plating to form a copper columnar body 46 corresponding to a via hole (see FIG. 4 (4)). Subsequently, the resist pattern 44 is peeled and removed, and the exposed conductive thin film layer 42 is removed by etching (see FIG. 5). Next, an insulating resin 47 is applied to the entire surface (see (6) in the same figure), and is flattened by heating and pressing with a press device or the like so as to be flush with the height of the copper columnar body 46 (see FIG. 7)).
[0007]
[Problems to be solved by the invention]
However, in this method, when a plurality of copper columnar bodies are formed by electrolytic plating in accordance with actual circuit design requirements, the height of the copper columnar bodies is likely to be uneven, especially for increasing the density. It has been found that when forming a small-diameter copper columnar body, the height disproportionation is remarkable and it is difficult to make the height uniform by post-processing. That is, when the copper columnar body is formed at a non-biased position (for example, at equal intervals), the movement of metal ions or the like (that is, current density) is uniform, but in actual circuit design, the copper columnar body is at a deviated position. Therefore, the current density at the time of plating becomes non-uniform, and the height of the copper columnar body becomes non-uniform (for example, the maximum height / minimum height = 2 to 4 times, or the current density increases. It was found that a portion in which a copper columnar body is not formed is generated).
[0008]
And if the height of the copper columnar body is non-uniform, the upper layer forming process becomes difficult, and post-processing is required to make the height uniform. Problems are also likely to arise. Another problem is that the current density non-uniformity during plating differs depending on the circuit design of the wiring board. Therefore, the plating current should be set so that the current density does not become excessive on a certain wiring board. However, there is a problem in that it is necessary to change the setting for wiring boards of other circuit designs, and the conditions must be set again.
[0009]
On the other hand, WO00 / 52977 discloses that a protective metal layer is formed by covering another surface of a lower wiring layer including a non-patterned portion with another metal having resistance during etching of a metal constituting a columnar metal body. After the metal plating layer constituting the columnar metal body is formed on the entire surface of the protective metal layer by electrolytic plating, a mask layer is formed on the surface portion of the plating layer on which the columnar metal body is formed, and the plating layer is etched. A method of manufacturing a multilayer wiring board is disclosed in which after the etching is performed, etching capable of eroding the protective metal layer is performed to remove the protective metal layer covering the non-patterned portion. According to this manufacturing method, manufacturing can be performed with a combination of simple equipment and conventional processes, a wiring layer can be thinned, and a multilayer wiring board with high wiring board reliability can be obtained.
[0010]
However, since the columnar metal body obtained by this method is formed by etching, it tends to be a shape with an expanded lower side or a reduced diameter at an intermediate height compared to the ideal cylindrical shape, and a higher density. For this reason, there is a disadvantageous side face when the diameter of the columnar metal body is reduced.
[0011]
Therefore, the object of the present invention is to further reduce the diameter by controlling the shape of the columnar metal body, to make the height uniform, and to reconfigure the plating current for each circuit design. It is an object of the present invention to provide a method for forming a columnar metal body and a method for manufacturing a multilayer wiring board using the same.
[0012]
[Means for Solving the Problems]
As a result of intensive research to achieve the above object, the present inventors have found that the above object can be achieved by providing an annular resist that forms a columnar metal body inside during plating in the invention of the above international publication. The invention has been completed.
[0013]
That is, the columnar metal body forming method of the present invention is a columnar metal body forming method in which a columnar metal body is formed on a metal layer having no wiring layer or wiring pattern.
(A) A step of forming a first protective metal layer by coating another metal exhibiting resistance during etching of the metal constituting the columnar metal body over substantially the entire surface of the wiring layer or the metal layer,
(B) A step of forming a plurality of annular resists having openings for forming the columnar metal bodies in the first protective metal layer at positions where the columnar metal bodies are formed and resisting plating around the openings. ,
(C) A metal plating layer constituting the columnar metal body is applied to the first protective metal layer exposed from the annular resist by electrolytic plating so that the height thereof is substantially the same as or lower than that of the annular resist. Forming step,
(D) removing the annular resist to form an annular recess;
(E) forming an opening resist layer in which an opening edge is located near the outer edge of the annular recess;
(F) a step of forming a second protective metal layer by covering another portion exposed from the opening resist layer with another metal exhibiting resistance during etching of the metal constituting the columnar metal body;
(G) removing the opening resist layer;
(H) etching an exposed portion of the plating layer; and
(I) etching the second protective metal layer and the first protective metal layer sequentially or simultaneously.
[0014]
In the above, in the step (b), after the photosensitive resin layer is applied or formed on the first protective metal layer, the annular resist is formed by performing exposure to a predetermined position and development. Is preferred.
[0015]
In the step (a), after electroless plating is performed on substantially the entire surface including the non-patterned portion of the wiring layer that has been previously patterned to form a base conductive layer, electrolytic plating is further performed on the entire surface. It is preferable to form the first protective metal layer.
[0016]
In that case, it is preferable that the said (f) process forms the said 2nd protective metal layer by performing electrolytic plating of the same metal as the said 1st protective metal layer.
[0017]
Further, the metal constituting the columnar metal body is copper, and another metal constituting the first protective metal layer and the second protective metal layer is gold, silver, zinc, palladium, ruthenium, nickel, rhodium, A lead-tin solder alloy or a nickel-gold alloy is preferable.
[0018]
On the other hand, the method for producing a multilayer wiring board of the present invention includes a step of forming a columnar metal body for conductively connecting between wiring layers by any of the above-described columnar metal body forming methods.
[0019]
[Function and effect]
According to the method for forming a columnar metal body of the present invention, an annular resist having an opening for forming the columnar metal body and resisting plating around the opening is formed. The height of the columnar metal body can be made uniform as compared with the case where the plating resist (the opening is present) is formed on the entire surface as in the prior art. The reason is presumed that plating also occurs in a wide region outside the annular resist, so that even when the formation position of the columnar metal body is biased, it is difficult to affect the entire current density. For this reason, even if the circuit design is different, if the area of the wiring board is the same, it is not necessary to change the entire current, and the setting of the plating current becomes extremely easy as compared with the prior art. Further, compared to the case where the columnar metal body is formed by etching without forming the annular resist, the shape of the columnar metal body can be easily controlled, so that the diameter can be further reduced. Furthermore, since the accuracy of the opening position of the opening resist layer is not required with high accuracy, it becomes easy to cope with the reduction in diameter and density of the columnar metal body. In addition, since the entire columnar metal body is covered with the protective metal layer when the plating layer is etched, it is easier to form the columnar metal body having a desired shape. As a result, the diameter of the columnar metal body can be reduced by controlling the shape of the columnar metal body, the height thereof can be made uniform, and there is almost no need to reset the plating current for each circuit design. A forming method can be provided.
[0020]
In the case where the step (b) includes forming or laminating the photosensitive resin layer on the first protective metal layer, and then performing exposure to a predetermined position and development to form the annular resist, the process is relatively small. An annular resist can be formed with high positional accuracy and shape accuracy by an apparatus. In particular, when a so-called dry film is used, the process can be further simplified.
[0021]
In addition, after the base conductive layer is formed in the step (a), when the first protective metal layer is further formed by electrolytic plating on substantially the entire surface, the base conductive layer is previously formed by electroless plating. Since it is formed, it can be used as an electrode for plating, and a protective metal layer can be suitably formed by electrolytic plating. It is preferable to perform such electrolytic plating because, in electroless plating, it may be difficult to etch the protective metal layer later due to the mixing of components other than metal. Note that the underlying conductive layer remaining in the non-patterned portion is preferably removed by soft etching or the like in a later step, thereby reliably preventing a short circuit between the patterned portions and further improving the reliability of the wiring board. be able to.
[0022]
In the step (f), when the second protective metal layer is formed by performing electrolytic plating of the same metal as the first protective metal layer, the adhesion and integrity of the first protective metal layer and the second protective metal layer Therefore, the protective effect of the columnar metal body is increased during etching, and both protective metal layers can be removed simultaneously, so that the process can be simplified.
[0023]
Further, when the metal constituting the columnar metal body is copper and the other metal constituting the first protective metal layer and the second protective metal layer is the metal, by a widely used etching method, The columnar metal body can be made of copper with good conductivity at low cost, and the metal constituting the protective metal layer exhibits good resistance to the etching, so the reliability of the wiring layer and the like is improved. Can be kept high. Among them, the metal constituting the columnar metal body is copper, and the other metal constituting the protective metal layer is nickel. This means that adhesion between metal layers, ease of peeling of the protective metal layer, This is most preferable for ensuring insulation, inter-layer conductivity, manufacturing cost, and the like.
[0024]
On the other hand, according to the method for manufacturing a multilayer wiring board of the present invention, the method for forming a columnar metal body of the present invention includes a step of forming a columnar metal body for conductive connection between wiring layers. Can be controlled to further reduce the diameter, and the height can be made uniform. As a result, a multilayer wiring board capable of further higher density can be manufactured more efficiently.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, an example is shown in which, when wiring layers are laminated on both sides of a core substrate, a columnar metal body is formed on both sides of the substrate to manufacture a multilayer wiring substrate in which wiring layers are conductively connected.
[0026]
First, as shown in FIG. 1A, a core substrate is prepared in which a wiring layer 22 is formed on both surfaces of a base material 21. At that time, any pattern forming method may be used. For example, a method using an etching resist or a method using a pattern plating resist may be used. As the base material 21, a base material made of glass fiber or a polymer nonwoven fabric and various reaction curable resins such as polyimide resin can be used, and as the metal constituting the wiring layer 22, copper, nickel are usually used. , Tin etc. are used.
[0027]
Next, as shown in FIG. 1B, the base conductive layer 10 is formed by performing electroless plating on the entire surface including the non-patterned portion of the wiring layer 22 patterned in advance. For electroless plating, a plating solution such as copper, nickel, and tin is usually used, but these metals may be the same as or different from the metal constituting the wiring layer 22. Electroless plating solutions are well known for various metals, and various types are commercially available. In general, the liquid composition contains a metal ion source, an alkali source, a reducing agent, a chelating agent, a stabilizer, and the like. A plating catalyst such as palladium may be deposited prior to electroless plating.
[0028]
Next, as shown in FIG. 1C, electrolytic plating is performed on the entire surface of the underlying conductive layer 10 so as to cover the substantially entire surface including the non-patterned portion of the lower wiring layer 22 with the first protective metal layer 11. Thus, the first protective metal layer 11 is formed. At that time, as the metal constituting the first protective metal layer 11, another metal having resistance at the time of etching the metal constituting the columnar metal body is used. Specifically, when the metal composing the columnar metal body is copper, as another metal composing the first protective metal layer, gold, silver, zinc, palladium, ruthenium, nickel, rhodium, lead-tin system A solder alloy or a nickel-gold alloy is used. However, the present invention is not limited to the combination of these metals, and any combination of a metal that can be electroplated and another metal that exhibits resistance during etching can be used.
[0029]
The above-described electrolytic plating can be performed by a known method. In general, while the substrate of FIG. 1 (2) is immersed in a plating bath, the base conductive layer 10 is used as a cathode and the metal metal to be plated. The ion supply source is used as an anode, and metal is deposited on the cathode side by an electrolysis reaction.
[0030]
That is, in the step (a) of the present invention, the metal layer constituting the columnar metal body is coated with another metal exhibiting resistance at the time of etching on the substantially entire surface of the wiring layer 22 or the metal layer having no wiring pattern. Although the protective metal layer 11 is formed, it may be coated with the first protective metal layer 11 with the underlying conductive layer 10 or the like interposed as described above, or the underlying conductive layer 10 or the like is interposed. Instead, the first protective metal layer 11 may be directly coated.
[0031]
In the step (b) of the present invention, as shown in FIGS. 2 (4) to 2 (5), an opening 15b for the formation of the columnar metal body of the first protective metal layer 11 is formed around the position where the columnar metal body is formed. And a plurality of annular resists 15a for resisting plating around the openings. In the present embodiment, the step (b) is an example in which the photosensitive resin layer 15 is applied or formed on the first protective metal layer 11 and then exposed to a predetermined position and developed to form the annular resist 15a. Indicates.
[0032]
The shape of the opening 15b of the annular resist 15a is preferably a columnar shape or a prismatic shape, and may be a cylindrical shape having a diameter of 10 to 200 μm, for example. Further, the outer edge shape of the annular resist 15a may be any, but a cylindrical shape or a prismatic shape is preferable. Its diameter or width is preferably 2 to 4 times that of the opening 15b, specifically about 30 to 600 μm. In the case where the annular resists 15a approach or overlap each other, a composite annular resist (for example, figure 8) may be used. However, the current density is made uniform by notching the approaching portions so that they do not contact each other. Preferred above.
[0033]
The photosensitive resin layer 15 refers to a resin composition containing a low molecular weight and / or high molecular weight component that causes photodecomposition, photocrosslinking, or photopolymerization by light. For coating, a method of laminating a dry film, a method of applying and curing a photosensitive resin composition, or the like can be used. The dry film (photoresist) includes an organic solvent development type and an alkaline aqueous solution development type, and thermocompression bonding (laminate) is performed using a dry film laminator having a thermocompression bonding roll or the like. Application of the photosensitive resin composition can be performed using various coaters.
[0034]
Next, a portion where the opening 15b is formed and a portion where the annular resist 15a is not formed, or a reverse portion thereof is exposed and developed to remove the former portion. Such exposure is usually performed with ultraviolet rays or the like using an exposure machine, with a photomask film interposed, or by direct exposure using a photoplotter or the like. For the development, a developer or the like corresponding to the type of dry film is used. For example, trichloroethane is used for the organic solvent development type, and sodium carbonate is used for the alkaline aqueous solution development type.
[0035]
In the step (c) of the present invention, as shown in FIG. 3 (6), a metal plating layer 24 constituting a columnar metal body is formed on the first protective metal layer 11 exposed from the annular resist 15a. It is formed by electrolytic plating so as to be substantially the same as or lower than the annular resist 15a. However, as shown in FIG. 3 (6), the height of the plating layer 24 is preferably substantially the same as that of the annular resist 15a.
[0036]
Usually, copper, nickel, or the like is used as the metal, but the metal constituting the wiring layer 22 may be the same or different. Electrolytic plating is performed by the same method as described above, but the first protective metal layer 11 is used as a cathode. Specific examples of the thickness of the plating layer 24 include 20 to 200 μm or more. Through the step (c), the columnar metal body 24a having a substantially uniform height is formed in the opening 15b of the annular resist 15a, and the plating layer 24b to be removed later is formed on the outer portion of the annular resist 15a. It is formed.
[0037]
In the step (d) of the present invention, as shown in FIG. 3 (7), the annular resist 15a is removed to form the annular recess 16. The removal method of the annular resist 15a may be appropriately selected according to the type of the annular resist 15a, such as removal of chemicals and peeling removal. For example, in the case of a dry film resist, it can be peeled off with, for example, methylene chloride for an organic solvent development type, and sodium hydroxide for an alkaline aqueous solution development type.
[0038]
In the step (e) of the present invention, as shown in FIG. 3 (8), an opening resist layer 17 in which the opening edge 17 a is located in the vicinity of the outer edge 16 a of the annular recess 16 is formed. The opening edge 17a and the outer edge 16a of the annular recess 16 may be located at the same position, but need not be completely coincident, open larger than the columnar metal body 24a, and the exposed portion of the plating layer 24b is excessively large (for example, The length is not more than 100 μm).
[0039]
As the method for forming the opening resist layer 17, the same method as in the case of the annular resist 15a can be used. Among them, a portion to be opened after thermocompression bonding (laminating) a dry film (photoresist), Alternatively, it is preferable to expose and develop the inverted portion to remove the opening. Further, when the opening edge 17a is larger than the outer edge 16a of the annular recess 16, it can be formed by a printing method such as screen printing. In addition, the thickness of the opening resist layer 17 should just be a thickness with which a resist function is obtained, for example, is 1-100 micrometers.
[0040]
In the step (f) of the present invention, as shown in FIG. 3 (9), the portion exposed from the opening resist layer 17 is coated with another metal having resistance during etching of the metal constituting the columnar metal body 24a. The second protective metal layer 18 is formed. This step (f) may be performed using a metal different from the first protective metal layer 11, or may be performed by electroless plating or the like, but electrolytic plating of the same metal as the first protective metal layer 11 is performed. It is preferred to do so.
[0041]
Although the shape of the second protective metal layer 18 is slightly different depending on the size of the opening edge 17a of the opening resist layer 17, the columnar metal body 24a is formed into the first protective metal layer 11 and the second protective metal by the step (f). Completely covered with layer 18. The method of electrolytic plating, the type of metal, and the like are the same as in the case of the first protective metal layer 11.
[0042]
Step (g) of the present invention is to remove the opening resist layer 17 as shown in FIG. The removal method can be the same as in the case of the annular resist 15a, but the method of peeling and removing is preferable because the process becomes simple. Moreover, in the case of the photosensitive ink formed by screen printing, it can be removed with chemicals such as alkali.
[0043]
In the step (h) of the present invention, as shown in FIG. 4 (11), the exposed portion 24b of the plating layer 24 is etched. After the etching, the second protective metal layer 18 having a shape corresponding to the annular resist 15a remains. At this time, since the portion of the columnar metal body 24a is completely protected, it is possible to prevent the diameter of the columnar metal body 24a (increase in undercut) due to excessive etching erosion.
[0044]
Examples of the etching method include etching methods using various etching solutions according to the types of metals constituting the plating layer 24 and the first protective metal layer 11. For example, when the plating layer 24 (that is, the columnar metal body 24a) is copper and the first protective metal layer 11 is the aforementioned metal (including a metal resist), a commercially available alkaline etching solution, ammonium persulfate, hydrogen peroxide / Sulfuric acid or the like is used.
[0045]
In the step (i) of the present invention, as shown in FIG. 4 (12), the second protective metal layer 18 and the first protective metal layer 11 are etched sequentially or simultaneously. In this embodiment, since the second protective metal layer 18 and the first protective metal layer 11 are the same metal, they can be etched at the same time, but even in the case of different metals, an appropriate etchant is selected, Both may be etched simultaneously.
[0046]
As an etching method, an etching method using an etching solution different from the step (h) can be mentioned. However, when a chloride etching solution is used, both the metal-based resist and copper are eroded. It is preferable to use it. Specifically, in the case where the columnar metal body 24a and the lower wiring layer 22 are copper and the first protective metal layer 11 is the above-mentioned metal, nitric acid-based, sulfuric acid-based, cyanogen commercially available for solder peeling. It is preferable to use an acid-based etching solution or the like. Thereby, as shown in FIG. 4 (12), only the first protective metal layer 11 interposed between the columnar metal body 24 a and the wiring layer 22 (pattern part) can be left. Further, only the base conductive layer 10 remains in the non-patterned portion.
[0047]
Next, as shown in FIG. 4 (13), the underlying conductive layer 10 remaining in the non-patterned portion is removed by soft etching. The soft etching is performed by the columnar metal body 24a and the exposed wiring layer 22 ( This is to prevent the pattern portion) from being excessively eroded. Examples of the soft etching method include a method of using an etching solution for the metal constituting the underlying conductive layer 10 at a low concentration or using a mild etching process condition.
[0048]
That is, in this embodiment, at least the first protective metal layer 11 is etched so that the first protective metal layer 11 can be eroded, and at least the first protective metal layer 11 covering the non-patterned portion is removed. In this case, the first protective metal layer 11 and the underlying conductive layer 10 are sequentially etched to remove the first protective metal layer 11 and the underlying conductive layer 10 in the non-patterned portion. Thereby, the fall between pattern parts can be prevented reliably.
[0049]
Next, as shown in FIG. 5 (14), an insulating material 26a for forming the insulating layer 26 is applied. As the insulating material 26a, for example, a reactive curable resin such as a liquid polyimide resin that has good insulation and is inexpensive can be used, and after this is applied by various methods so as to be slightly thicker than the height of the columnar metal body 24a. It can be cured by heating, light irradiation or the like. As a coating method, a hot press and various coaters are used.
[0050]
Next, as shown in FIG. 5 (15), the insulating layer 26 having a thickness substantially equal to the height of the columnar metal body 24a is formed by grinding and polishing the hardened insulating material 26a. Examples of the grinding method include a method using a grinding apparatus having a hard rotary blade in which a plurality of hard blades made of diamond or the like are arranged in the radial direction of the rotary plate, and the hard rotary blade is fixedly supported while rotating. By moving along the upper surface of the wiring board, the upper surface can be planarized. Moreover, as a grinding | polishing method, the method of lightly grind | polishing by a belt sander, buff grinding | polishing, etc. is mentioned.
[0051]
Next, as shown in FIG. 5 (16), an upper wiring layer 27 partially conductively connected to the columnar metal body 24 a is formed. The wiring layer 27 can be formed by the same method as that for forming the lower wiring layer 22. For example, the wiring layer 27 having a predetermined pattern can be formed by forming a predetermined mask using a photolithography technique and performing an etching process.
[0052]
According to the above steps, a multilayer wiring board 30 as shown in FIG. 6, for example, can be manufactured by forming a wiring layer as an upper layer. The multilayer wiring board 30 is a six-layer board having a six-layer circuit configuration of wiring layers 31 to 36 in the board. Inside this, interlayer connection structures 37, 38, 39 corresponding to via holes are formed by columnar metal bodies 24a. The interlayer connection structure 37 connects the first layer and the second layer when the wiring layers are formed on both surfaces of the substrate, and the interlayer connection structure 38 connects the second layer and the third layer. The interlayer connection structure 39 connects the first layer and the third layer. In the present invention, when the first layer and the third layer are connected, a columnar metal body 24a that connects the second layer and the third layer is further provided above the columnar metal body 24a that connects the first layer and the second layer. What is necessary is just to form.
[0053]
Another embodiment
Hereinafter, another embodiment of the present invention will be described.
[0054]
(1) In the above embodiment, the columnar metal body is formed on both sides of the substrate. However, the columnar metal body is formed only on one side of the substrate, that is, the wiring layers are laminated only on one side. There may be.
[0055]
(2) In the above-described embodiment, after the step (a) includes forming a base conductive layer by performing electroless plating on the entire surface including the non-patterned portion of the lower wiring layer that has been previously patterned, electrolysis is further performed on the entire surface. Although the example in which the first protective metal layer is formed by plating is shown, the electroless plating is performed on the entire surface of the insulating layer, and then the underlying conductive layer is formed on the entire surface. The first protective metal layer may be formed by plating. In that case, since the underlying conductive layer already exists, it is possible to form the pattern of the lower wiring layer by pattern plating using electrolytic plating. In any of the above methods, the base conductive layer is formed by electroless plating, but it can also be formed by sputtering or the like.
[0056]
(3) In the above-described embodiment, an example in which an insulating layer having substantially the same thickness as the height of the columnar metal body is formed by grinding / polishing the insulating material, but a resin sheet that is an insulating material, etc. By stacking by heating and pressing, an insulating layer having a thickness substantially the same as the height of the columnar metal body may be formed. In that case, the insulating resin remaining thinly on the columnar metal body can be easily removed by plasma treatment or the like, and can be polished and flattened after heating.
[0057]
(4) In the above-described embodiment, the step (b) is an example in which a photosensitive resin layer is applied or laminated on the first protective metal layer, and then an annular resist is formed by exposing and developing at a predetermined position. However, the cyclic resist may be directly formed by a printing method such as screen printing. In that case, an ink material other than the photosensitive resin can be used. It is also possible to form an adhesive by a method of transferring an annular resist separately formed in a predetermined shape and position.
[0058]
(5) In the above-described embodiment, the example in which the first protective metal layer is coated on the lower wiring layer having the base conductive layer is shown. However, the first protective metal layer is directly covered without forming the base conductive layer. May be. In that case, the first protective metal layer may be coated on the lower wiring layer by electroless plating or the like, and the first protective metal that covers the non-patterned portion only by etching capable of eroding the first protective metal layer. The layer can be removed to prevent a fall between the pattern portions.
[0059]
(6) In the above-described embodiment, an example of a method for manufacturing a multilayer wiring board including a step of forming a columnar metal body for conductive connection between wiring layers by the method for forming a columnar metal body of the present invention has been shown. The method for forming a columnar metal body of the present invention can also be used for other applications. For example, it can be used for bump formation for mounting components on a wiring board, bump formation on an electrode of a chip component, bump formation on an inspection probe of a wiring board, and the like.
[0060]
(7) In the above embodiment, the columnar metal body is formed on the wiring layer. However, the columnar metal body forming method of the present invention forms the columnar metal body on the metal layer having no wiring pattern. It may be a thing. In that case, as shown in FIG. 7 (3 '), another metal exhibiting resistance when etching the metal constituting the columnar metal body is applied to the metal layer (panel metal layer) 22a having no wiring pattern. The process of forming the 1st protective metal layer 11 by covering is performed. As a coating method, in addition to the method of the above-described embodiment, a first layer which is a metal layer before patterning a lower wiring layer and a second layer of metal constituting the first protective metal layer are rolled. A method of laminating with the above is also possible. Subsequently, by performing the steps (b) to (e) of the present invention, the columnar metal body 24a can be formed as shown in FIG. 7 (13 ′).
[0061]
Next, an insulating material (thermosetting resin or the like) is applied to the side on which the columnar metal body 24a is formed, and then subjected to heat pressing on the other patterned wiring layer, so that the columnar metal body 24a and the other The wiring layer is electrically connected. Thereafter, the wiring pattern is formed by etching the panel metal layer 22a and the first protective metal layer 11 is removed if not removed. In this way, a multilayer wiring board by a bonding method can be manufactured.
[0062]
【Example】
Examples and the like specifically showing the configuration and effects of the present invention will be described below.
[0063]
[Example 1]
What formed the wiring pattern with copper on both surfaces of the base material made from a polyimide resin reinforced with glass fiber was prepared (pattern line width 75 μm, pattern interval 75 μm, thickness 15 μm). Electroless plating is performed on the entire surface using a commercially available copper plating solution to form a base conductive layer (thickness 0.3 μm), and electroplating is performed on the entire surface by a conventional method to form a first protective metal layer made of nickel. (Thickness 4 μm) was formed. Further, a dry film (thickness 50 μm) is laminated on the entire surface with a laminator, exposed and developed, and an annular resist having an outer diameter of 90 μm and an inner diameter of 30 μm is randomly formed on the pattern (the shortest distance between the centers is 200 μm, the longest distance is 30 mm). ). A copper plating layer (thickness: about 50 μm) was formed thereon by electrolytic plating.
[0064]
About this thing, all the height of the columnar metal body from the base-material surface was measured about the columnar metal body, and the maximum value and the minimum value were calculated | required. As a result, the maximum value was 54 μm and the minimum value was 44 μm, and the difference between them was 10 μm.
[0065]
[Comparative Example 1]
Instead of providing an annular resist in Example 1, the steps up to the formation of the plating layer were performed in the same manner as in Example 1 except that a full-surface resist having openings having the same dimensions was provided at the same position. About this thing, all the height of the columnar metal body from the base-material surface was measured about the columnar metal body, and the maximum value and the minimum value were calculated | required. As a result, the maximum value was 60 μm and the minimum value was 10 μm, and the difference between them was 50 μm. In addition, depending on the position of the opening, the current density becomes too high, and a so-called plating burn phenomenon has occurred in which the columnar metal body cannot be formed.
[0066]
[Comparative Example 2]
In Comparative Example 1, the steps up to the formation of the plating layer were performed in the same manner as in Comparative Example 1, except that the plating current was reduced to such an extent that the phenomenon of plating burn did not occur. About this thing, all the height of the columnar metal body from the base-material surface was measured about the columnar metal body, and the maximum value and the minimum value were calculated | required. As a result, depending on the position of the opening, the current density was too low, and there was a portion where the formation of the columnar metal body was not recognized.
[Brief description of the drawings]
FIG. 1 is a process diagram (1) to (3) showing an example of a method for producing a multilayer wiring board according to the present invention.
FIG. 2 is a process diagram (4) to (6) showing an example of a method for producing a multilayer wiring board according to the present invention.
FIG. 3 is a process diagram (7) to (10) showing an example of a method for producing a multilayer wiring board according to the present invention.
FIG. 4 is a process diagram (11) to (13) showing an example of a method for producing a multilayer wiring board according to the present invention.
FIG. 5 is a process diagram (14) to (16) showing an example of a method for producing a multilayer wiring board according to the present invention.
FIG. 6 is a schematic cross-sectional view showing an example of a multilayer wiring board that can be formed according to the present invention.
FIGS. 7A and 7B are process diagrams (3 ′) and (13 ′) illustrating another example of the method for manufacturing a multilayer wiring board according to the present invention.
FIG. 8 is a process diagram (1) to (7) showing an example of a conventional method for manufacturing a multilayer wiring board.
[Explanation of symbols]
10 Ground conductive layer
11 First protective metal layer
15 Photosensitive resin layer
15a Circular resist
15b opening
16 annular recess
16a Outer edge of annular recess
17 Opening resist layer
17a Open edge
18 Second protective metal layer
21 Base material
22 Lower wiring layer
24 plating layer
24a Columnar metal body
27 Upper wiring layer

Claims (6)

In the method for forming a columnar metal body, the columnar metal body is formed on a metal layer having no wiring layer or wiring pattern.
(A) A step of forming a first protective metal layer by coating another metal exhibiting resistance during etching of the metal constituting the columnar metal body over substantially the entire surface of the wiring layer or the metal layer,
(B) A step of forming a plurality of annular resists having openings for forming the columnar metal bodies in the first protective metal layer at positions where the columnar metal bodies are formed and resisting plating around the openings. ,
(C) A metal plating layer constituting the columnar metal body is applied to the first protective metal layer exposed from the annular resist by electrolytic plating so that the height thereof is substantially the same as or lower than that of the annular resist. Forming step,
(D) removing the annular resist to form an annular recess;
(E) forming an opening resist layer in which an opening edge is located near the outer edge of the annular recess;
(F) a step of forming a second protective metal layer by covering another portion exposed from the opening resist layer with another metal exhibiting resistance during etching of the metal constituting the columnar metal body;
(G) removing the opening resist layer;
(H) a step of etching an exposed portion of the plating layer; and (i) a step of sequentially or simultaneously etching the second protective metal layer and the first protective metal layer. Method for forming a metal body. 2. The step (b) is to form the annular resist by performing exposure to a predetermined position and development after applying or forming a photosensitive resin layer on the first protective metal layer. Of forming a columnar metal body. In the step (a), an electroless plating is performed on substantially the entire surface including the non-patterned portion of the wiring layer that has been patterned in advance to form a base conductive layer, and then the electroplating is further performed on the substantially entire surface. The method for forming a columnar metal body according to claim 1 or 2, wherein a protective metal layer is formed. The method for forming a columnar metal body according to claim 3, wherein the step (f) includes performing electrolytic plating of the same metal as the first protective metal layer to form the second protective metal layer. The metal constituting the columnar metal body is copper, and another metal constituting the first protective metal layer and the second protective metal layer is gold, silver, zinc, palladium, ruthenium, nickel, rhodium, lead- It is a tin-type solder alloy or a nickel-gold alloy, The formation method of the columnar metal body in any one of Claims 1-4. A method for manufacturing a multilayer wiring board, comprising a step of forming a columnar metal body for electrically connecting wiring layers by the method for forming a columnar metal body according to any one of claims 1 to 5.

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