JP2011009263A - Hole processing method of substrate for printed circuit board and substrate for printed circuit board manufactured by the hole processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hole processing method of a substrate for a printed circuit board, capable of forming conductive holes on the substrate for the printed circuit board with a smaller number of processes, thereby reducing time and effort of work and cost, and to provide the substrate for the printed circuit board manufactured by using the hole processing method.SOLUTION: The hole processing method of a substrate for a printed circuit board includes forming a hole 50 via an insulating layer 20 in a substrate 10 for the printed circuit board having a multilayer structure in which conductive layers 30, 40 are laminated on both sides of an insulating layer 20. In this method, metals eliminated from the conductive layers 30, 40 in forming the hole 50 are deposited on an inner wall of the hole 50 of the insulating layer 20, thereby integrally forming a hole layer 60 having conductivity on the inner wall of the hole 50 of the insulating layer 20.

Description

  The present invention relates to a printed wiring board substrate and a printed wiring board substrate using the hole processing method.

Conventionally, printed circuit board substrates include single-sided boards, double-sided boards, and multilayer boards. In a double-sided board or a multilayer board, a conductive hole including a through hole and a non-through hole is formed so that the front and back conductive layers can be electrically connected via an insulating layer.
As an example of a method for forming a hole having electrical conductivity on a printed wiring board substrate, an example of a generally performed method will be described with reference to FIG. In this drilling method, a double-sided board (multilayer board) 1 is prepared (A), and holes 5 are formed in the board 1 through the insulating layer (base material) 2 and the conductive layers 3 and 4 on the front and back sides (B). . The hole 5 can be opened by machining such as drilling or punching, laser processing, or other methods. Then, a conductive thin layer 6 is formed on the inner wall of the hole 5 by electroless plating, application of carbon paste, or other methods (C), and then a thick film is formed by electroplating using the conductive thin layer 6 as a base layer. A plating layer 7 is formed (D). As a result, a conductive hole is formed.
In the hole drilling method described above, as a hole drilling method using a laser, for example, in Japanese Patent Laid-Open No. 1-266983 (Patent Document 1), a copper foil portion of a substrate is drilled with an excimer laser of UV wavelength, and resin A method is disclosed in which a portion of the insulating layer made of is drilled with an infrared wavelength carbon dioxide laser.
US Pat. No. 5,593,606 (Patent Document 2) discloses a method of drilling a conductive layer and an insulating layer using a laser having a UV wavelength.

JP-A-1-266683 US Pat. No. 5,593,606

However, in both the hole drilling method of the substrate using the laser disclosed in Patent Documents 1 and 2 and the hole drilling method by the conventional machining, after the hole is drilled, as a separate process, A ground treatment for forming a conductive layer was required. Then, after the base treatment, a thickening process such as electroplating was performed to finish the hole with conductivity.
For this reason, there existed a problem that there existed many preparation processes of a hole with electrical conductivity, and the manufacturing cost became high.
In addition, the ground treatment of the conductive layer has been performed by electroless plating or carbon paste coating, but it has been difficult to eliminate defects by these methods.

  Therefore, the present invention solves the above-described problems in the prior art and can form a conductive hole in fewer steps in the printed wiring board substrate, thereby reducing labor and cost. It is an object of the present invention to provide a hole processing method for a printed wiring board substrate and a printed wiring board substrate using the hole processing method.

The printed wiring board substrate drilling method of the present invention that solves the above-described problems is a printed wiring board substrate having a laminated structure in which conductive layers are laminated on the front and back of an insulating layer. A method for drilling a printed wiring board substrate to be formed, wherein when forming a hole, an inner wall of the hole in the insulating layer is formed by fixing a metal excluded from the conductive layer to the inner wall of the hole in the insulating layer. The first feature is that a hole layer having conductivity is collectively formed.
In addition to the first feature, the hole drilling method for a printed wiring board substrate according to the present invention uses a laser to form a hole, and removes the metal evaporated or melted from the conductive layer to the hole of the insulating layer. The second feature is to form a hole layer having conductivity by vapor deposition or welding on the inner wall.
In addition to the second feature described above, the hole drilling method for a printed wiring board substrate of the present invention has a third feature that a pulse laser having a pulse peak energy of 20 kW or more at an infrared wavelength is used as the laser. .
The printed wiring board substrate drilling method according to the present invention includes, in addition to any one of the first to third features described above, after forming the hole, the plating means is used to conduct the conductivity of the inner wall of the insulating layer. The fourth feature is that a plating layer is laminated on a hole layer having a property to increase the thickness.
The printed wiring board substrate of the present invention has a fifth feature that the printed wiring board substrate drilling method described in any one of the first to fourth aspects is used.

According to the hole drilling method for the printed wiring board substrate according to the first feature, when the hole is formed, the metal removed from the conductive layer is fixed to the inner wall of the hole of the insulating layer, thereby forming the hole of the insulating layer. By collectively forming a conductive layer on the inner wall,
It is not necessary to form the hole layer having conductivity as a separate step after the step of forming the hole. Therefore, it is possible to reduce the number of steps for forming the conductive hole by one. As a result, it is possible to reduce the labor and associated costs.
According to the hole drilling method for the printed wiring board substrate according to the second feature, in addition to the function and effect of the first feature, the hole is formed using a laser and is evaporated or melted from the conductive layer. By depositing or depositing a metal on the inner wall of the hole of the insulating layer to form a hole layer having conductivity,
A hole layer having conductivity can be formed using the metal of the conductive layer evaporated or melted by a laser, and a separate raw material for forming the hole layer having conductivity is not required. Therefore, equipment for supplying raw materials is not required, and, of course, complicated operation is unnecessary, and cost reduction can be promoted.
Further, since the obtained conductive layer is of the same type as the metal of the conductive layer, bonding between the two can be easily performed, and good electrical bonding can be achieved.
Further, since the hole layer having conductivity obtained is formed by vapor deposition or welding, it can be applied to the inner wall of the hole widely and uniformly, and a layer with few defects can be obtained. Therefore, the subsequent thickening process can be performed satisfactorily.
According to the hole drilling method for a printed wiring board substrate according to the third feature, in addition to the function and effect of the second feature, a pulse laser having a pulse peak energy of 20 kW or more at an infrared wavelength is used as the laser. By
Holes can be drilled in a single operation (work) not only for insulating layers such as polyimide resin, PET, PC, but also for conductive layers made of copper, gold, silver, and other metal layers with low light absorption. . At that time, the metal of the conductive layer is evaporated or melted by light absorption heat by infrared rays having high pulse peak energy, and the evaporated or melted metal is deposited on the inner wall of the hole formed in the insulating layer. Or, it can be welded. Thereby, the hole layer which has electroconductivity can be formed in a hole inner wall simultaneously with a drilling process.
An infrared wavelength pulsed laser can be constructed using a MOPA type fiber laser and is therefore easy to handle.
According to the hole drilling method for a printed wiring board substrate according to the fourth feature, in addition to the function and effect of any one of the first to third features, after forming the hole, using a plating means, By laminating a plating layer on the hole layer having conductivity on the inner wall of the hole of the insulating layer to increase the thickness,
It is possible to reliably ensure the conductivity of the holes formed between the multilayers via the insulating layer.
According to the printed wiring board substrate according to the fifth feature, since the hole drilling method for a printed wiring board substrate according to any one of the first to fourth is used,
A multilayer printed wiring board substrate that is easy to manufacture and has holes with good electrical conductivity can be provided at low cost.

According to the hole drilling method for a printed wiring board substrate of the present invention, when the hole is formed, the metal removed from the conductive layer is fixed to the inner wall of the hole of the insulating layer, thereby being electrically conductive to the inner wall of the hole of the insulating layer. By forming the hole layer having the properties in a lump, the hole layer having conductivity can be formed simultaneously with the drilling step. Therefore, the number of steps for forming a conductive hole can be reduced by one, and the labor and cost associated therewith can be reduced.
In particular, the hole is formed by using a laser, and a metal which is evaporated or melted from the conductive layer is deposited or deposited on the inner wall of the hole of the insulating layer to form a hole layer having conductivity. The formation of the hole by the step and the ground treatment of the hole layer having conductivity to the inner wall of the hole can be performed in one step. Moreover, the hole which has favorable electroconductivity can be formed in the board | substrate for printed wiring boards.

It is a figure explaining the hole drilling method of the board | substrate for printed wiring boards which concerns on embodiment of this invention, (A), (B), (C) has each shown sectional drawing of the board | substrate for printed wiring boards. It is a figure explaining the detail when forming the hole of the hole processing method of the board | substrate for printed wiring boards which concerns on embodiment of this invention, (A), (B), (C), (D) is a printed wiring board, respectively FIG. In the hole drilling method for a printed wiring board substrate according to the embodiment of the present invention, a more realistic situation will be described in which metal evaporated or melted in the conductive layer is deposited or welded on the inner wall of the hole in the insulating layer. In the figure, a cross-sectional view of a printed wiring board substrate is shown. It is a figure explaining the hole drilling method of the board | substrate for printed wiring boards in the past, (A), (B), (C), (D) has each shown sectional drawing of the board | substrate for printed wiring boards.

  With reference to the drawings, embodiments of a printed wiring board substrate drilling method according to the present invention and a printed wiring board substrate using the hole drilling method will be described for the understanding of the present invention. . However, the following description is an embodiment of the present invention, and does not limit the contents described in the claims.

First, referring to FIG. 1, a method for drilling a printed wiring board substrate according to an embodiment of the present invention will be described.
Referring to FIG. 1A, a printed wiring board substrate 10 according to an embodiment is a so-called double-sided board that includes an insulating layer 20 and conductive layers 30 and 40 laminated on the front and back thereof.
In the present embodiment, the insulating layer 20 is an insulating base material made of a polyimide resin. Moreover, the conductive layers 30 and 40 of the front and back are comprised by bonding copper foil on the insulating layer which is an insulating base material.
The drilling of the printed wiring board substrate 10 is performed by a drilling operation using a laser L made of, for example, a MOPA type fiber laser.

Next, referring to FIG. 1B, the hole forming operation is performed by forming a hole 50 penetrating through the conductive layer 30, the insulating layer 20, and the conductive layer 40 with the laser L.
When the hole 50 is formed, a hole layer 60 having conductivity is collectively formed on the inner wall of the hole 50. Here, the collective formation means that both the hole 50 and the hole layer 60 having conductivity are formed at the same time by one operation during the same hole forming operation.
The hole layer 60 having conductivity is formed by evaporating or welding copper evaporated or melted from the conductive layers 30 and 40 on the inner wall of the hole 50 when the hole 50 is formed by the laser L.

Next, referring to FIG. 1C, a plating layer 70 by electroplating is laminated on the inner wall of the hole 50 in which the hole layer 60 having conductivity is formed, and the film thickness is increased. The hole 50 having stable conductivity is obtained by laminating the plating layer 70 with the hole layer 60 having conductivity as a base.
By the above method, a hole having a conductive property is formed, and the printed wiring board substrate 10 capable of electrical connection between the conductive layer 30 and the conductive layer 40 is obtained.

With reference to FIG. 2, the principle that the inner wall of the hole is made conductive at the time of forming the hole is presumed as follows.
Now, when the printed wiring board substrate 10 is irradiated with the laser L (A), the copper of the conductive layer 30 on the surface is evaporated or melted by light absorption heat, and a hole 50 is formed in the conductive layer 30 ( B). When the laser L reaches the insulating layer 20, a hole 50 is formed in the polyimide resin of the insulating layer 20 (C). Further, when the laser L reaches the conductive layer 40 on the back surface, the copper of the conductive layer 40 is evaporated or melted to make a hole 50 in the conductive layer 40 (D). At that time, the copper evaporated or melted from the conductive layer 40 is deposited or deposited on the inner wall of the hole 50 of the insulating layer 20 to form the hole layer 60 having conductivity made of a conductive thin film. The hole layer 60 having conductivity is formed in a state of being electrically connected to the conductive layers 30 and 40 on the front and back sides in the hole 50.

With reference to FIG. 3, an example of a more realistic situation when transpiration or melted metal is deposited or deposited on the inner wall of the hole 50 of the insulating layer 20 will be described.
Now, when the hole 50 is opened from the conductive layer 30 on the front surface to the conductive layer 40 on the back surface through the insulating layer 20 by irradiation with the laser L, the hole 50b formed in the insulating layer 20 itself is formed in the conductive layer 30, Unlike the 40 straight holes 50a, 50c, the insulating layer 20 is formed in a recessed shape. In addition, it can be said that it is preferable to select such a condition that the shape becomes concave. By forming the hole 50b of the insulating layer 20 in such a depressed shape, the metal particles M evaporated or melted by the conductive layer 40 are within the hole 50b outside the laser L passing region. Evaporated or welded well. As a result, the hole layer 60 having uniform and good conductivity is formed on the inner wall of the hole 50b.

As the laser L, a pulse laser having an infrared wavelength is used. As a pulse laser having this infrared wavelength, for example, a MOPA type fiber laser having a wavelength of 1060 nm can be used.
The laser L having an infrared wavelength has a pulse peak energy of 20 kW or more. However, those having a pulse peak energy of 30 kW or more are preferably used.
By using an infrared wavelength laser having a pulse peak energy of 20 kW or more, the conductive layers 30 and 40 made of copper, gold, silver, or other highly conductive metals with little light absorption in the infrared region. On the other hand, it is possible to evaporate or melt and perforate by light absorption heat.
An infrared wavelength laser L having a pulse peak output of 20 kW or more is used. However, an average output power of at least 10 W is used. With the infrared pulse laser having the average output and the pulse peak output as described above, the hole 50 penetrating the insulating layer 20 and the conductive layers 30 and 40 on the front and back sides can be formed well and can be made conductive.
Conventional infrared fiber lasers have not been used for drilling this type of printed wiring board substrate because they hardly absorb copper and polyimide, which are typical materials constituting printed wiring board substrates. . However, when the pulse peak output is irradiated to the printed wiring board substrate with a pulse peak output of 20 kW or more, it is absorbed by the printed wiring board substrate material due to multiphoton absorption or the like, and holes can be formed.

As the laser L having an infrared wavelength, a laser having a wavelength of 1.06 μm, a pulse width of 5 to 20 ns, and a repetition frequency of 50 to 100 kHz can be used. However, these values are changed and adjusted according to the material and thickness of the insulating layer 20 and the conductive layers 30 and 40.
The irradiation time is 0.16 to 1 second and the focal length is actually 99.3 mm, for example, but these values are also changed and adjusted according to the material and thickness of the insulating layer 20 and the conductive layers 30 and 40. The

As the insulating layer 20, glass epoxy resin, PET, and PC are used in addition to polyimide resin. In addition, paper phenol, PASF (polyallyl sulfone), and PVA (polyvinyl alcohol) are objects of this processing method.
As the conductive layers 30 and 40, copper, gold, silver, aluminum, and other highly conductive materials are objects of this processing method.
In addition to the double-sided board, the printed wiring board substrate 10 is a multilayer board in which conductive layers are laminated on the front and back of an insulating layer.
In addition to the through hole, the hole 50 is a non-through hole.

  In the above description, an embodiment in which a hole is drilled and a conductive layer is formed on the inner wall of the insulating layer using a laser as a hole drilling method for a printed wiring board substrate is described. did. However, it is not always necessary to use a laser. In short, the conductive material removed from the conductive layer may be moved into the hole of the insulating layer and fixed to the inner wall when drilling the printed wiring board substrate. This makes it possible to simultaneously form a hole (hole formation) and form the hole layer 60 having conductivity without preparing a separate conductive material and without requiring a separate process. The movement of the conductive material from the conductive layer to the insulating layer is performed by mechanically performing a hole forming operation, accompanied by melting, accompanied by transpiration, or a combination thereof. obtain. The solid phase, liquid phase, and vapor phase conductive materials are fixed to the inner surface of the hole, welded, and deposited. What has been welded and vapor deposited adheres as a result.

  ADVANTAGE OF THE INVENTION According to this invention, the industrial utilization in the manufacture field | area of a printed wiring board board | substrate is high as a processing method of a printed wiring board board | substrate, and a printed wiring board board | substrate.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Insulating layer 3 Conductive layer 4 Conductive layer 5 Hole 6 Conductive layer thin layer 7 Plating layer 10 Printed wiring board substrate 20 Insulating layer 30 Conductive layer 40 Conductive layer 50 Hole 50a Conductive layer hole 50b Insulating layer hole 50c Hole portion of conductive layer 60 Hole layer having conductivity 70 Plating layer L Laser M Particle

Claims (5)

  In a printed wiring board substrate having a laminated structure in which conductive layers are laminated on the front and back of an insulating layer, the printed wiring board substrate has a hole processing method for forming a hole through the insulating layer. A printed wiring board characterized in that a hole layer having conductivity is collectively formed on the inner wall of the hole of the insulating layer by fixing the metal excluded from the conductive layer to the inner wall of the hole of the insulating layer. Drilling method for printed circuit boards.   The hole is formed using a laser, and a metal that is evaporated or melted from the conductive layer is deposited or deposited on the inner wall of the hole of the insulating layer to form a conductive hole layer. Item 2. A method for drilling holes in a printed wiring board substrate according to Item 1.   The method for drilling a printed wiring board substrate according to claim 2, wherein a pulse laser having a pulse peak energy of 20 kW or more at an infrared wavelength is used as the laser.   4. The method according to claim 1, wherein after forming the hole, a plating layer is used to deposit a plating layer on the hole layer having conductivity on the inner wall of the hole of the insulating layer to increase the thickness. A method for drilling holes in a printed wiring board substrate as described in 1.   The printed wiring board board | substrate formed using the hole drilling method of the printed wiring board as described in any one of Claims 1-4.

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