JP2011228437A - Electrolytic plating formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic plating formation method in which a resist and electrically-conductive ink can be exfoliated in one step by using electrically-conductive ink having low adhesiveness to a print board in place of electrically conductive paste.SOLUTION: In an electrolytic plating formation method of forming an electrolytic plating layer 7 on the surface of an island pattern 4 on a print board 1 having a wiring pattern 3 and the island pattern 4 which is formed electrically independently of the wiring pattern 3, the wiring pattern 3 and the island pattern 4 are electrically connected to each other by electrically-conductive ink 5, a resist 6 is formed on the electrically-conductive ink 5, electrolytic plating is conducted, and then the resist 6 is removed together with the electrically-conductive ink 5.

Description

  The present invention relates to an electrolytic plating method for forming an electrolytic plating layer on an island pattern on a printed circuit board including a wiring pattern and an island pattern that is electrically independent of the wiring pattern.

  When an element is mounted on a printed circuit board (FPC: Flexible Print Circuit, etc.) having a wiring pattern and an island pattern formed independently of the wiring pattern, the terminal of the element and the connection target A part of the pattern is plated with Au or the like for the purpose of improving the connection reliability with the pattern and the surface treatment for bonding connection.

  At present, the plating on the island pattern is performed by electrically connecting in advance, for example, by integrally forming the wiring pattern and the island pattern, and after performing the electrolytic plating on the wiring pattern and the island pattern, This is done by punching out electrically connected connection patterns to electrically separate the wiring pattern and the island pattern. As another method, it is conceivable to apply electroless plating to the island pattern.

  However, the method of punching and electrically separating the wiring pattern and the island pattern has a problem that a hole is formed in the printed circuit board and a problem that the accuracy is low because the punching is mechanically performed.

  In the method of applying electroless plating, there is a problem that electroless plating is more expensive than electrolytic plating. Moreover, in order to reduce the manufacturing cost, a printed circuit board is manufactured by an RtoR (roll-to-roll) process. However, electroless plating in the RtoR process, particularly Au electroless plating is difficult and There is a problem of high cost.

  As a method for solving these problems, in Patent Document 1, a wiring pattern and an island pattern are electrically connected with a conductive paste, a resist is formed on the conductive paste, and electrolytic plating is formed on the island pattern. A method for sequentially removing the resist and the conductive paste later is disclosed.

JP-A 62-296595

  However, in the method of Patent Document 1, since the resist and the conductive paste are removed in separate steps, there are problems that the number of steps increases and the manufacturing cost increases.

  Accordingly, an object of the present invention is to provide an electrolytic plating forming method capable of peeling a resist and a conductive ink in one step by using a conductive ink having a weak adhesive force with a printed circuit board instead of a conductive paste. There is to do.

  The present invention was devised to achieve the above object, and the invention of claim 1 is a printed circuit board provided with a wiring pattern and an island pattern formed electrically independent of the wiring pattern. In the electrolytic plating formation method of forming an electrolytic plating layer on the surface of the island pattern, the wiring pattern and the island pattern are electrically connected with a conductive ink, a resist is formed on the conductive ink, and electrolysis is performed. In this method, the resist is removed together with the conductive ink after plating.

  According to a second aspect of the present invention, the adhesive ink between the printed board and the conductive ink is weaker than the adhesive force between the conductive ink and the resist, so that the conductive ink is removed when the resist is peeled off. The method for forming an electrolytic plating according to claim 1, wherein the two are simultaneously peeled off.

  According to a third aspect of the present invention, the resist includes a first resist formed on the conductive ink and a second resist formed on the wiring pattern, and the resist is formed of the first resist and the second resist. The electrolytic plating formation method according to claim 1 or 2, wherein the solubility or / and swelling property with respect to the resist stripping solution is different.

  According to the present invention, there is provided an electrolytic plating forming method capable of peeling a resist and a conductive ink in one step by using a conductive ink having a weak adhesive force with a printed board instead of a conductive paste. Can do.

It is a top view which shows an example of the printed circuit board to which this invention is applied. (A)-(e) is a schematic diagram which shows the electrolytic plating formation method of this invention. (A)-(f) is a schematic diagram which shows the modification of the electrolytic plating formation method of this invention.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  The present invention is a method for forming an electrolytic plating layer on the surface of an island pattern on a printed circuit board.

  As shown in FIG. 1, a printed circuit board 1 to which the present invention is applied includes a wiring pattern 3 and an island pattern 4 formed electrically independent from the wiring pattern 3 on an insulating substrate 2. It is. These wiring pattern 3 and island pattern 4 are formed by etching a metal film formed on the insulating substrate 2. Examples of the material of the insulating substrate 2 include polyimide and polyethylene naphthalate. Moreover, as a material of the wiring pattern 3 and the island pattern 4, for example, copper is used in terms of conductivity and cost. The printed circuit board 1 is an FPC, for example, and is continuously manufactured by an RtoR process.

  When the island pattern 4 is subjected to electrolytic plating (Au electrolytic plating, Ni electrolytic plating, Cu electrolytic plating, etc.), the wiring pattern 3 is energized. As shown in FIG. 2A, the wiring pattern 3 and the island pattern 4 are energized. Are electrically separated, and the island pattern 4 cannot be energized as it is, so the wiring pattern 3 and the island pattern 4 are first electrically connected.

  As shown in FIG. 2B, the conductive ink 5 containing conductive particles such as Ag, Cu, Au, and C is used for electrical connection between the wiring pattern 3 and the island pattern 4. The conductive ink 5 may be a nano ink containing nanoparticles of the materials described above. About the material of the conductive ink 5, it is good to select suitably from surfaces, such as a price. Here, as the conductive ink 5, an ink having an adhesive force between the conductive ink 5 and the insulating substrate 2 weaker than an adhesive force between the conductive ink 5 and the resist 6 to be formed next is used.

  Electrical connection between the wiring pattern 3 and the island pattern 4 by the conductive ink 5 is performed by applying and sintering the conductive ink 5 between the wiring pattern 3 and the island pattern 4.

  Thereafter, a resist 6 is formed on the conductive ink 5 as shown in FIG. The resist 6 is used to prevent the electroconductive ink 5 from being electroplated. As a material of the resist 6, for example, polyimide having a composition different from that of the insulating substrate 2, acrylic, or the like is used.

  Next, as shown in FIG. 2 (d), electricity is supplied from the wiring pattern 3 to form an electrolytic plating layer 7 on the surface of the island pattern 4. In this embodiment, the electrolytic plating layer 7 is also formed on the wiring pattern 3. However, the resist 6 is formed on the wiring pattern 3, and the electrolytic plating layer 7 is formed only on the island pattern 4. You may make it do.

  Finally, by removing the resist 6 together with the conductive ink 5, the electrolytic plating on the island pattern 4 is completed. The resist 6 is physically stripped using a resist stripping solution. At this time, since the adhesive force between the conductive ink 5 and the insulating substrate 2 is weaker than the adhesive force between the conductive ink 5 and the resist 6, the conductive ink 5 can be peeled off simultaneously when the resist 6 is peeled off. it can.

  Thus, according to the electrolytic plating forming method according to the present embodiment, the adhesive force between the conductive ink 5 and the insulating substrate 2 is made weaker than the adhesive force between the conductive ink 5 and the resist 6. When the resist 6 is peeled off, the conductive ink 5 can be peeled off simultaneously, and the resist 6 and the conductive ink 5 can be removed in one step.

  Next, another embodiment of the present invention will be described.

  First, similarly to the above-described method, as shown in FIGS. 3A and 3B, the conductive ink 5 is applied and sintered between the wiring pattern 3 and the island pattern 4.

  Thereafter, as shown in FIG. 3C, a first resist 8 is formed on the conductive ink 5, and a second resist 9 is formed on the wiring pattern 3. At this time, the first resist 8 and the second resist 9 are made of materials having different solubility or / and swelling property with respect to the resist stripping solution. For example, the first resist 8 is configured to peel off faster than the second resist 9.

  And as shown in FIG.3 (d), it supplies with electricity from the wiring pattern 3, and forms the electroplating layer 7 on the surface of the island pattern 4. As shown in FIG. At this time, since the wiring pattern 3 is covered with the second resist 9, only the island pattern 4 is subjected to electrolytic plating.

  Thereafter, as shown in FIG. 3E, the first resist 8 and the conductive ink 5 are peeled off simultaneously.

  Finally, as shown in FIG. 3F, the second resist 9 is peeled off, and the electrolytic plating on the island pattern 4 is completed.

  In this way, by allowing the resist to be removed step by step, a plurality of types of electrolytic plating can be applied as necessary. For example, an Au electrolytic plating layer can be formed on the surface of the island pattern 4, and a Ni electrolytic plating layer can be formed on the surface of the wiring pattern 3.

  In this electrolytic plating forming method, the first resist 8 and the conductive ink 5 can be removed in one step, as in the above-described electrolytic plating forming method.

  In short, according to the electrolytic plating forming method of the present invention, the resists 6 and 8 and the conductive ink 5 can be removed in one step, and the manufacturing cost can be reduced. Moreover, since the plating on the island pattern 4 can be performed by electrolytic plating, the adhesion strength between the island pattern 4 and the electrolytic plating layer 7 can be improved.

DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Board | substrate 3 Wiring pattern 4 Island pattern 5 Conductive ink 6 Resist 7 Electroplating layer

Claims (3)

In the electrolytic plating formation method of forming an electrolytic plating layer on the surface of the island pattern on a printed circuit board comprising a wiring pattern and an island pattern formed electrically independent of the wiring pattern,
The wiring pattern and the island pattern are electrically connected with a conductive ink, a resist is formed on the conductive ink, and after electroplating, the resist is removed together with the conductive ink. Electrolytic plating forming method.   2. The conductive ink is peeled simultaneously when the resist is peeled by making the adhesive force between the printed circuit board and the conductive ink weaker than the adhesive force between the conductive ink and the resist. The method for forming an electrolytic plating as described in 1. The resist comprises a first resist formed on the conductive ink and a second resist formed on the wiring pattern,
3. The electrolytic plating method according to claim 1, wherein the first resist and the second resist have different solubility or / and swelling property with respect to a resist stripping solution. 4.

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