JP2006012870A - Manufacturing method of stack via structure multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for improving adhesion with a lower layer conductor circuit in an interlayer connection post formed on the lower layer conductor circuit by electrolytic plating and uniforming plating height, and to provide the manufacturing method of a multilayer wiring board using the method. <P>SOLUTION: A feeding conductive thin film layer is installed on a whole face including the lower layer conductor circuit on an insulating substrate where the lower layer conductor circuit is arranged. A plating resist layer is formed on the whole face. The substrate is anode-connected in electrolyte, and voltage is applied in a state where an opening for plating-forming the post on the connected lower layer conductor circuit is formed in the resist layer. Thus, the whole feeding conductive thin film layer and a part of the lower layer conductor circuit of a part with the post formed thereon are dissolved and removed. The post is formed in metal plating liquid by depositing electrolytic plating in the opening. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for manufacturing a multilayer via substrate having a stacked via structure, and performs electrical connection of different circuit layers of a multilayer interconnection substrate having a plurality of layers of wiring circuits by using posts formed by electrolytic metal plating. The present invention relates to a method for manufacturing a multilayer wiring board and the multilayer wiring board.

As electronic devices are becoming smaller, lighter and thinner, the wiring board has adopted a build-up structure, but in order to meet today's demand for higher density, the stack via structure has been changed from the conventional staggered via structure. It has been demanded.

Various methods for realizing this stacked via structure have been proposed. For example, an insulating layer 203 is formed on an insulating base material 201 provided with a conductor circuit layer 202 as shown in FIG. 2, and a connection hole (via hole) 204 is formed in the insulating layer 203. There is a method of filling the hole with a conductive paste 205 or a method of filling with a plating as shown in FIG. 3 (filled plating method).
There are hole processing methods at this time, one that processes photosensitive insulating material by exposure and development, and one that laser-processes after forming a thermosetting resin, but the former material is still difficult to process and difficult to miniaturize. However, the latter has to be processed one hole at a time, and as the number of processed holes increases and the number of processed holes increases, the processing time increases and an expensive laser processing machine is required. Has occurred.
Furthermore, the electrical connection reliability remains in paste filling and the plating solution stability remains in plating filling, and the mass production method has not yet been established.

On the other hand, many methods have been proposed in which a conductive conductive protrusion for connection is formed before the insulating layer is formed, and the insulating layer is formed so as to be embedded.
For example, a conductive paste 403 is formed in a protruding shape by printing on a lower conductor circuit 402 or a lower conductor circuit forming conductor layer as shown in FIG. 4, and an insulating layer 404 with an upper circuit forming conductor layer 405 is processed thereon. As shown in FIG. 5, the conductive protrusions 506 are plated with metal 504 on the lower conductor circuit 502 or the upper conductor circuit forming conductive layer 504, and then the etching resist 505 is exposed and developed thereon. Some of them form connection protrusions, but the former is difficult to miniaturize because it is formed by screen printing, and the latter is an etching barrier layer to protect the lower circuit or upper circuit forming conductive layer from the etching solution. A metal thin film layer different from the projection forming metal is formed in advance as 503, and the projection is etched and then removed by selective etching. Step there is adhesion problems when the diameter of the man-hours and cost of protrusions at that challenges remain and further miniaturization request at a point is reduced for taking.

In addition to the above-described method, a method of conducting conductive protrusions directly by metal electrolytic plating (hereinafter, conductive protrusions formed by electrolytic plating are referred to as posts) is disclosed in JP-A-6-314878. The method is a combination of existing techniques, simple and advantageous in terms of cost, and excellent in that a small-diameter post can be formed. Post height uniformity is low due to non-uniform current density due to randomly and densely arranged resist openings, and it is difficult to expose all the tops of the post at a uniform height by grinding and polishing after forming the insulating layer. I found that there was a problem

This construction method will be described below with reference to FIG.
After the conductive thin film layer 602 for feeding is formed on the entire surface of the substrate 601 (FIG. 6A), the plating resist is processed into a circuit shape, and then pattern electroplating is performed to form the lower conductor circuit 602 (FIG. 6B). A plating resist 604 having a post forming opening 605 is formed thereon (FIG. 6C), and the opening 606 is filled with electrolytic copper plating by using the conductive thin film layer 602 for feeding. Form (FIG. 6-d). Thereafter, the resist pattern and the conductive thin film layer for power feeding are removed (FIG. 6E), and the insulating layer 607 is formed so as to embed the post (FIG. 6F), and is ground and polished so as to have the same height as the post (FIG. 6). -G). Thereafter, a power feeding film is provided on the insulating layer to form an upper conductor circuit as in FIG. 6B, and a post-connected multilayer wiring board is manufactured (FIG. 6H).
JP-A-6-314878

As described above, the method of electrically connecting the lower layer conductor circuit and the upper layer conductor circuit by the post formed by electrolytic metal plating is excellent at low cost. There is a strong demand for a solution to variations in height due to non-uniform current density because the resist openings are randomly and densely arranged.

The present invention relates to a substrate in a state in which a conductive thin film for feeding is formed on the entire surface of an insulating substrate on which a lower conductor circuit is formed and a plating resist layer on which an opening for forming a circuit connection post is formed is formed as an electrolyte. By applying an anode voltage in the solution, the post is electrolytically plated with metal. The entire conductive thin film for power supply on the lower conductor circuit and a part of the lower conductor circuit are dissolved and removed to increase the plating bonding area. The current density distribution when strengthening the force and applying the anode voltage is similar to the current density distribution during metal electroplating, or the higher current density during electroplating is higher and the lower current is lower current. By applying an anode voltage with the counter electrode laid out so as to obtain a density distribution and dissolving and removing all of the conductive thin film layer for power feeding and part of the circuit conductor, the amount of dissolution removal in the portion with high current density is increased. And favorable uniformity post height is formed by electroless metal plating by reducing the dissolving and removing of the lower part of the flow density.

As described above, in the method of manufacturing a multilayer wiring board having a post connection structure, an insulating base material in a state where an opening for plating a post is formed in a plating resist layer is formed by electrolytic metal plating in an electrolyte solution. The anode current is applied in a state where the counter cathode is laid out so that the current density distribution at the time is similar or the current density distribution at the time of electrolytic plating is higher and the lower current density distribution is lower. Dissolve and remove all of the conductive thin film and part of the lower circuit conductor to increase the plating bonding area between the plated metal forming the post and the lower circuit conductor to obtain good adhesion, and the current density during metal electrolytic plating Depending on the distribution, the amount of dissolution and removal of the lower layer circuit conductor in the part where the current density is high and the amount of dissolution and removal of the lower layer circuit conductor in the part where the current density is low are reduced. The height uniformity of the formation can be improved.
As a result, a stacked via structure multilayer wiring board having high connection reliability can be manufactured without using a new technique such as filled plating and without using expensive equipment such as a laser processing machine.

An embodiment of the present invention will be described below with reference to FIG. In order to simplify the description, the case where there is one insulating layer will be described.
In FIG. 1, FIG. 1- (a) shows a lower layer conductor circuit 102 formed in advance on an insulating base material 101 of a copper-clad substrate to be a core. The circuit formation method is not particularly defined, and can be produced by, for example, a subtract method using an etching resist or a semi-additive method using a plating resist.

FIG. 1- (b) shows a state in which a power supply conductive thin film layer 103 serving as a power supply film is formed on the entire surface of the insulating base material 101 including the lower conductor circuit 102 when a post is formed by electrolytic metal plating. The material used for the conductive thin film layer may be a metal or a conductive organic film, but a metal is preferable in terms of its handling. In the case of a metal, it may be the same kind of metal as the post-forming metal or a different kind of metal. The same kind of metal or different kind of metal may be used. The formation method may be an electroless plating method, a sputtering method, or the like, or a slight electrolytic plating on the thin film layer.

FIG. 1- (c) shows a state in which a plating resist layer 104 is formed on the conductive thin film layer 103 for power supply. Although it does not prescribe | regulate especially as a plating resist material, there exist the method of forming by a curtain coater application | coating or screen printing using photosensitive resin, or the method of thermocompression-bonding a film-like photosensitive resin film with a roll laminator.

FIG. 1D shows a state in which an opening 105 for forming a post is formed in the plating resist layer 104. As the opening method, the photosensitive resin layer may be formed at a predetermined position in accordance with a desired post diameter by exposure and development. If post-curing treatment is applied after development to increase the adhesion of the resist, or removal of resist scum or improvement of plating wettability by modifying the resist material by plasma treatment, etc., better results will be obtained during post formation. It is done.

FIG. 1- (e) shows a state in which an anode voltage is applied to the base material in an electrolyte solution to dissolve and remove all of the power supply conductive thin film layer 103 and a part of the lower conductor circuit 102 under the resist opening. The purpose of this is to increase the adhesion of the post, and to increase the plating junction area between the post-forming plated metal and the lower conductor circuit, and the current density when applying an anode voltage is similar to the current density during electrolytic plating. Alternatively, the amount of dissolution can be reduced by electrolytic metal plating by performing dissolution treatment in a state where the counter electrode is laid out so that the current density distribution at the time of electrolytic plating is higher and the lower portion has a lower current density distribution. This is performed for the purpose of uniformizing the height at the time of post formation since a large amount is removed at a portion where the current density is high and a small amount is removed at a low portion.

At this time, liquid agitation is performed so that the electrolyte solution is circulated well within the opening for forming the post. As this method, there are air agitation and pump circulation agitation, but in order to perform it more effectively, the liquid is directly pumped from the nozzle to the opening. A jet-type stirring method for jetting pressure is effective.

The electrolyte solution includes a mixed solution of sulfuric acid and hydrogen peroxide solution, or ammonium chloride and ammonia water, ammonium persulfate, ferrous chloride and hydrochloric acid, or cupric chloride and hydrochloric acid. A liquid may be used.
Further, by incorporating the electrolytic apparatus and tank for the treatment into the post-forming electrolytic metal plating apparatus, it is possible to perform continuous treatment and to reduce the equipment cost and the number of processing steps.

FIG. 1- (f) shows a state where metal is deposited and filled as a post 106 in the resist opening by electrolytic metal plating. This metal may be the same or different metal from the conductive thin film layer 103 for power feeding and the lower conductor circuit 102, but copper is preferred because of its electrical conductivity and ease of liquid management.

A normal plating rectifier may be used as the current-carrying condition, but the bottom of the resist opening in the initial stage of plating is a step-controlled rectifier for the purpose of further improving post height uniformity and shortening the plating time. Alternatively, when plating the portion close to the bottom, current does not easily enter and the current density distribution deteriorates. Therefore, the current may be lowered, and if the current becomes easier to enter as the plating grows, the current may be increased. Alternatively, the height may be made uniform by applying a pulse current.

When the plating solution is a copper sulfate plating solution, it is effective to use a high concentration copper sulfate or low concentration sulfuric acid bath so that the plating can be plated at a high current density while keeping the plating height uniform. In this case, the effect is further increased by selecting a plating additive suitable for the bath.

As a plating solution stirring method, normal air agitation may be used, but in order to shorten the plating time by efficiently circulating metal ions to the small-diameter resist opening, the plating solution is directly pumped from the nozzle to the resist opening. The effect is great when jet agitation is used. In this case, if the nozzle shape is appropriately selected, the effect is further improved.

FIG. 1- (g) shows a state in which the plating resist is peeled and removed after the metal is deposited and filled in the plating resist opening 105 by electrolytic metal plating. This removal treatment can be carried out without any problems if a treatment liquid corresponding to the resist resin composition used is used. For example, in the case of using an alkali peeling type dry fill, 2 to 3% of water heated to about 30 to 40 ° C. It can be removed by dipping in a sodium oxide solution and stirring or vibrating, or by spray nozzle injection.

When it is difficult to remove the residue, it is effective to pump and agitate the liquid directly from the nozzle or the like in the removal liquid and to stir the jet. In the case of this immersion removal, equipment costs and man-hours can be reduced by incorporating equipment such as a treatment tank in the electroplating apparatus.

FIG. 1- (h) shows a state in which the conductive thin film layer 103 for feeding is removed and the post 106 is formed on the lower conductor circuit 102. The removal can be performed using a remover according to the material used. For example, in the case of metal, it is possible to perform flash etching if the thickness of the thin film layer is appropriate even if the metal is the same as or different from the post forming metal or the lower conductor circuit. Therefore, the post and the lower conductor circuit can be removed without causing damage. However, if the lower conductor circuit is copper and an electroless copper plating layer is used for the thin film layer, it may be necessary to remove Pd etc. of the catalyst layer remaining after flash etching. Can be removed.

FIG. 1- (i) shows a state in which an insulating layer 107 is formed so as to embed a post. The insulating layer used here may be selected from a material that satisfies the characteristics required for the substrate, such as Tg and dielectric constant, etc. According to the properties of the insulating layer, a curtain coater, screen printing, etc. are used for the ink type, and a vacuum laminator is used for the sheet type. If used, it can be formed.

FIG. 1- (j) shows a state in which the insulating layer 107 is ground or polished to uniformize the thickness and post height of the insulating layer, and the flat top of the post is exposed on the surface of the insulating layer. This can be easily treated by using buffing or a belt sander according to the hardness and viscosity of the insulating material used.

FIG. 1- (k) shows a state in which the upper layer conductor circuit 108 is formed in a state where it is electrically connected by a post on the insulating layer where the post head portion flattened by grinding or polishing is exposed. This may be done by first roughening the insulating layer surface 107 to ensure the adhesion of the upper layer circuit, and then forming a conductive layer over the entire surface by electroless copper plating, and then plating the panel copper and forming it by the sub-tra method. A plating resist may be formed after copper plating and formed by a semi-additive method.

Thereafter, it is commercialized by carrying out normal printed wiring board manufacturing processes such as solder resist formation and terminal processing.

In the embodiment described above, a multilayer wiring board having a stacked via structure in which a lower layer circuit and an upper layer circuit are electrically connected by a post is manufactured.

メッキ後ドライフィルムを３５℃の３％水酸化ナトリウム液へ浸漬除去し、次いで無電解銅膜を濃硫酸４０ｃｃ／Ｌ及び３０％過酸化水素水５ｃｃ／Ｌの混合液中にて浸漬して剥離除去しポスト高さ及び密着力を測定した。結果は表ー２へ示す如く高さ均一性及び密着力ともに実用に耐えるものではなかった。また、高さ測定は開口部粗密の中から均等に割り振りｎ＝２５ポスト測定したが、やはりポスト高さは開口部が密になっている部分が大きく、粗の部分が小さかった。密着力測定は高さ３０〜５０μmｔ内にある２０のポストで測定したが高さによる影響は無かった、バラツキはむしろ開口部の下地銅回路表面の活性化のバラツキによると推測した。

表ー２ 測定結果

After forming a lower layer conductor circuit using a commercially available copper-clad laminate (plate thickness: 0.4 mmt, copper foil thickness: 18 μm) of 340 × 406 mm size and mobile phone prototype pattern, electroless copper plating is thick as a conductive thin film for power feeding A dry film having a thickness of 60 μm was laminated thereon, and a resist opening of 90 μmφ was formed by exposure / development processing. The layout of the openings at this time is 6 products, the number of openings is 8,300 per product according to the prototype pattern, the distance between the shortest openings is 300 μm, the distance between the farthest openings is 32 mm, and the density is quite large It became.
Without applying an anode voltage, this base material was plated by copper sulfate plating for panel plating so that the maximum post height did not exceed the dry film under the conditions shown in Table-1.

Table-1 Electrolytic copper plating conditions

After plating, the dry film is dipped and removed in a 3% sodium hydroxide solution at 35 ° C., and then the electroless copper film is dipped in a mixed solution of concentrated sulfuric acid 40 cc / L and 30% hydrogen peroxide 5 cc / L and peeled off. After removal, the post height and adhesion were measured. As a result, as shown in Table-2, the height uniformity and the adhesion were not practical. In addition, the height measurement was evenly distributed from the density of the opening, and n = 25 posts were measured, but the post height was large in the area where the opening was dense and small in the coarse area. The adhesion force was measured with 20 posts within a height of 30 to 50 μm, but there was no effect due to the height. It was estimated that the variation was rather due to the variation in activation of the surface of the underlying copper circuit in the opening.

Table-2 Measurement results

表ー４ 測定結果

A substrate with a resist opening formed in the same manner as in Example-1 was applied with an anodic voltage under the conditions shown in Table 3, and then electrolytic copper plating was performed under the same conditions as in Example-1 to obtain height and adhesion. As a result of measuring with the same place post, both the height and the adhesion were greatly improved.
The reason why the variation as well as the value of the post-adhesion force is small is considered to be that the surface of the circuit conductor was dissolved and removed by applying the anode voltage, and the surface activity was made uniform.

Table-3 Anode voltage application conditions

Table 4 Measurement results

表ー６ 電解銅メッキ条件

表ー７ 測定結果

As shown in Table 5, the substrate having the resist openings formed in the same manner as in Example 1 was applied with an anodic voltage by jet stirring and then the electrolytic copper plating was changed in liquid composition and the jet was jetted. Plating as agitation, height and adhesion were measured on the same place post.
As a result, as shown in Table-6, the height variation was improved despite increasing the current density.
This is considered to be an effect of increasing the exchange rate of the copper ion concentration in the resist opening due to the increased stirring effect and the increased copper ion concentration.

Table-5 Anode voltage application conditions

Table-6 Electrolytic copper plating conditions

Table-7 Measurement results

The jet conditions here are the same for anode voltage application and electrolytic copper plating. As shown in FIG. 7, a PVC pipe (VP25) 702 is vertically arranged from a liquid supply pipe (VP50 PVC pipe) 701 at a pitch of 150 mm. A vertical liquid flow connection was made at a height of 500 mm, and a liquid ejection nozzle was provided on this pipe at a pitch of 50 mm, and this was discharged by pump pressurization at a hydraulic pressure of 2.5 kg / cm ² . Further, the base material 704 that was electrically connected so that the jet liquid uniformly hits the resist openings of the base material was swung left and right at a stroke of 150 mm and a cycle of 20 times / minute.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a method for manufacturing a stacked via structure post connection type multilayer wiring board according to the present invention; Explanatory drawing showing the method of processing circuit connection holes and filling with conductive paste Explanatory drawing of the method of processing holes (VIA) in the insulating layer and filling with filled plating Explanatory drawing of a method of printing a conductive paste on the lower layer circuit to form protrusions and press laminate an insulating layer with copper foil Explanatory drawing of the method of post forming by etching after forming different metal layers on the lower layer circuit and plating the entire surface Explanatory drawing of the method of forming the conductive film on the base material and forming the lower layer conductor circuit, then providing an opening in the plating resist and post-forming by electroplating BRIEF DESCRIPTION OF THE DRAWINGS These are the drawings which outlined the jet stirring structure used in the Example of this invention.

Explanation of symbols

101, 201, 301, 401, 501, 601 Insulating base material 102, 202, 302, 402, 502, 602 Lower conductive circuit 103, 503 Conductive thin film layer 104, 604 Plating resist 105, 605 Resist opening 106, 606 Metal plating posts 107, 203, 303, 404, 506, 607 Insulating layer 108, 206, 306, 406, 507, 608 Upper layer conductor circuit 204 Connection hole (VIA)
205 conductive paste
305 Hole-filled plating layer 403 Conductive protrusion 701 Liquid supply pipe 702 PVC pipe 703 Liquid ejection nozzle 704 Substrate electrically connected

Claims (8)

After a conductive thin film layer for feeding is formed on the entire surface including the lower layer circuit on the insulating base material provided with the lower layer conductor circuit, a plating resist layer is formed on the entire surface, and a post is plated on the lower circuit portion to be connected In the state in which the opening for forming is formed in the resist layer, the base material is anode-connected in the electrolyte solution and a voltage is applied to the post-formed portion of the conductive thin film layer for feeding and one of the lower conductor circuits. A method for producing a multilayer wiring board, comprising: forming a post by depositing metal plating in the opening in a metal plating solution after dissolving and removing the portion.
Insulating base material in which an opening for forming a post on the plating resist layer is formed in an electrolyte solution, the current density distribution during electrolytic metal plating is similar or the current density during electrolytic plating is high An anode voltage is applied in a state where the counter cathode is laid out so that the portion is higher and the lower portion has a lower current density distribution, and all of the conductive thin film for feeding and a part of the lower conductor circuit are dissolved and removed, Increase the plating bonding area between the plated metal and the lower conductor circuit to form a good adhesion, and according to the current density distribution at the time of metal electrolytic plating, the lower conductor circuit dissolved and removed in the portion where the current density is high and A method of manufacturing a multilayer wiring board characterized in that the height uniformity at the time of post formation by metal plating is improved by reducing the amount of the lower conductor circuit dissolved and removed in the portion where the current density is low .
The plating solution at the time of electrolytic metal plating for post formation is a copper sulfate plating bath, and the composition of the solution is such that the copper sulfate concentration ranges from 50 g / L to 200 g / L, the sulfuric acid concentration ranges from 50 g / L to 200 g / L, and the chlorine concentration is A method for producing a multilayer wiring board, which is in a range of 30 mg / L to 70 mg / L.
A method of manufacturing a multilayer wiring board, wherein a power source capable of controlling current stepwise or a pulse power source is used as an electrolytic metal plating power source for forming the post.
3. An electrolysis apparatus and a tank for applying an anode voltage are incorporated in a post-forming electrolytic metal plating apparatus to enable continuous treatment, thereby reducing equipment costs and processing man-hours. The multilayer wiring board manufacturing method described in any of the above.


In the anode voltage application process and post-forming electrolytic metal plating process, as a processing liquid stirring method, the liquid is air-stirred or pump-circulated and stirred, or the liquid is directly applied to the post-forming plating resist layer opening of the insulating substrate. 6. The method for producing a multilayer wiring board according to claim 1, wherein the pump is jetted and stirred.
Sulfuric acid and hydrochloric acid or sulfuric acid and hydrogen peroxide water or ammonium chloride and ammonia water or ammonium persulfate or ferrous chloride and hydrochloric acid or cupric chloride and hydrochloric acid or posts are formed in the electrolyte solution in the anode voltage application treatment. 3. The method for producing a multilayer wiring board according to claim 1, wherein the solution contains any one of the metal plating solutions.
Plating resist removal treatment, power supply conductive thin film layer removal treatment, and Pd removal of the catalyst layer remaining when electroless copper plating is used for the power supply conductive thin film layer, which are treatments after the post-forming electrolytic metal plating is completed The multilayer according to any one of claims 1 to 7, wherein a part or all of the treatment is incorporated into an electrolytic metal plating apparatus for forming a post, thereby enabling continuous treatment and reducing equipment cost and processing man-hours. A method for manufacturing a wiring board.

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