JP4990419B1 - Substrate reference hole processing method - Google Patents

Abstract

The present invention provides a method for forming a fixation hole on the substrate of the package by inserting a pin between a substrate fixation hole and a wiring pattern formed on the substrate surface so as to acquire a highly precise fixation hole for the substrate. Wherein an incident laser beam L is introduced to scan a filler layer 5 which is exposed to a first port pattern 8, from a first conductor pattern 6a side along the edge 8a of the first port pattern 8 so as to eliminate the filler layer 5 and form a bottomed ditch 11 with a second conductor layer 7 as its bottom. Afterwards the dummy part of the substrate 12 the region where the filler layer 5 being encircled by the bottomed ditch 11 and the region where the second conductor layer 7 being laminated are eliminated by squeezing operation thereby forming the sophisticated substrate fixation hole 10.

Description

  The present invention relates to a method for processing a substrate reference hole provided on a printed wiring board, for example, for positioning the substrate during component mounting or processing.

  In recent years, a printed wiring board for a semiconductor package is provided with a through-hole that is not electrically conductive and is not plated on a hole wall surface that is generally referred to as a non-through hole. This through hole is an insertion hole for a positioning pin for determining the position of the substrate when the substrate is cut or counterbored in the manufacturing process of the printed wiring board, and is used as a reference for various processing. Moreover, when mounting an electronic component on a board | substrate, it is used as an insertion hole of the positioning pin which sets a board | substrate position.

  Conventionally, processing of a non-through hole serving as a reference is generally performed by an NC-controlled mechanical drill, but there is a deviation of 50 μm or more between the non-through hole and the wiring pattern. If the deviation between the outer shape of the substrate or the counterbore processing and the wiring pattern can be further reduced, the distance between the wiring pattern and the processed portion can be reduced, and the pattern can be brought closer to the outer shape of the substrate and the product size can be reduced. Also, in the electronic component mounting process, the pattern position when the substrate is set is stable, so that the image recognition of the mounting machine is stable and alignment is easy. Therefore, it is required to reduce the deviation between the substrate reference hole serving as a processing reference and the wiring pattern.

  As an example, a method for forming a through hole in a wiring board by laser processing is to form a hole by scanning a laser beam with a conformal mask provided with an opening by a wiring pattern and a contact mask provided with an opening overlapping the opening. A method to do this has been proposed (Patent Document 1).

JP 2001-127397 A

  A printed circuit board for a package tends to increase rigidity in order to minimize warping, distortion, or dimensional change during component mounting. For this reason, inorganic fine particles called fillers are mixed in the substrate material at a high concentration, or glass fibers with high crystallinity having a small expansion coefficient are used. As a result, when processing the pin insertion hole by irradiating the substrate with a laser, the laser irradiation part, especially the hole wall surface, is in a very rough state due to the difference in processability between the glass cloth and the resin. And the hole dimensions will vary. Further, when punching is performed using a press die, there is a problem that the punch is easily chipped or worn.

  Further, when mounting electronic components on a package substrate, the substrate is fixed to a mold or the like with a positioning pin, but the pin insertion hole may be a long hole in order to cope with expansion and contraction of the substrate. Machining of long holes in the substrate is also performed with a mechanical drill. In that case, drilling is performed by shifting the drilling position, but since the drilling is performed in the vicinity of the hole that has already been drilled, the position of the drill is fluctuated and high-precision machining cannot be performed. Although there is a method of punching with a mold, it is necessary to create an expensive mold. It is required to produce a long hole with high positional accuracy at a low cost.

  The object of the present invention is to solve the above-mentioned problems of the prior art, improve the drilling workability by laser light while maintaining the rigidity required for the package substrate, and improve the substrate reference hole for positioning the substrate and the substrate surface. An object of the present invention is to provide a method for processing a substrate reference hole with high positional accuracy between wiring patterns.

In order to achieve the above object, a substrate reference hole processing method according to the present invention comprises the following arrangement.
That is, a step of drilling a through hole in a substrate having a conductive layer on both surfaces of an insulating resin base material, a step of filling a filler filling the through hole and closing the through hole, and polishing the filler Flattening with the conductive layers formed on both sides of the substrate, and the first and second conductor layers covering the filler by successively performing electroless metal plating and electric field metal plating on both sides of the substrate. And forming the first opening pattern simultaneously with the formation of the first conductor pattern to expose the underlying filler layer by removing the first conductor layer laminated on the filler layer by etching. Forming a second opening pattern exposing the underlying filler layer by removing the second conductor layer by etching, and forming a second conductor pattern facing the first opening pattern; The first conductor Using the first conductor layer as a mask from the side, the filler layer exposed from the first opening pattern is removed by scanning and irradiating the filler light along the edge portion of the first opening pattern. A step of forming a bottomed groove having the conductor layer as a bottom, and a substrate reference hole by pressing and removing at least the unnecessary portion of the substrate on which the filler layer and the second conductor layer are laminated surrounded by the bottomed groove; The size and position of the substrate reference hole is the size and position of the hole in the first conductor layer in which the first opening pattern of the bottomed groove from which the filler layer has been removed is formed. It is determined by.

According to the above configuration, the first opening for processing the substrate reference hole having a desired shape by removing the first conductor layer laminated on the filler layer filled in the through hole simultaneously with the formation of the first conductor pattern. Since the pattern is formed, it is possible to process the substrate reference hole (non-through hole) with very high positional accuracy with respect to the wiring pattern (± 15 μm or less). In particular, the position of the substrate reference hole is determined by the size and position of the first conductor layer in which the first opening pattern of the bottomed groove from which the filler layer has been removed is formed. The accuracy can be increased.
Further, the filler layer exposed from the first opening pattern with the first conductor layer as a mask from the first conductor layer side is simply removed by irradiating the laser beam along the edge portion of the first opening pattern. Forming a bottomed groove, and pressing and removing at least the unnecessary portion of the substrate on which the filler layer and the second conductor layer are laminated surrounded by the bottomed groove to form a hole of a desired shape in the substrate. Therefore, it is possible to efficiently form a round hole, a long hole or the like larger than the spot diameter of the laser beam.
Further, a bottomed groove is formed by irradiating a laser beam using the first conductor layer having the first opening pattern as a mask, and a substrate unnecessary portion surrounded by the bottomed groove is pressed and removed to remove the substrate reference hole. By forming the hole, it is possible to easily perform a drilling process in which the machining shape is almost the same as the design value without using a mold. In addition, by forming a filler layer that can be easily laser processed, the hole wall surface of the substrate reference hole is not roughened, and the substrate reference hole with good positional accuracy and finish can be formed along with the formation of the wiring pattern.
In addition, by using the second conductor pattern as the bottom of the bottomed groove, the filler layer surrounded by the bottomed groove does not fall off the substrate even when laser processing is performed, so the dropped filler layer becomes dust. Next, there is no adverse effect on the setting of the substrate to be processed to the laser processing position.

  The filler is preferably formed by applying a thermosetting-type hole-filling ink containing a filler by screen printing, followed by heat curing to form a filler layer. Thermosetting hole-filling ink is an insulating resin base material that uses glass cloth with a coefficient of thermal expansion by containing inorganic particles (fillers) such as silica in order to increase the connection reliability of copper plating in the through-hole to be filled. It is close to. Since the filler filled in the ink is generally an inorganic substance such as silica, the processability of the filler and the resin by the laser is greatly different. However, since the size of the filler is small (for example, 50 μm or less) and the region where the laser workability is different is very small, the roughness of the processed surface after laser processing is small and good compared to the substrate made of glass cloth and resin. Shows workability.

The substrate reference hole is preferably formed such that a hole size of the first conductor layer in which the first opening pattern is formed is a minimum size.
That is, by adjusting the laser processing conditions to form the hole size of the first conductor layer in which the first opening pattern is formed as the minimum size of the substrate reference hole, it is minimized when inserting a pin into the substrate reference hole. Since the opening portion of the first opening pattern that is the dimension serves as a reference, the first conductor pattern formed on the substrate can be positioned with high accuracy with respect to the pin that fixes the substrate.

It is preferable that an outer dimension of the second conductor pattern forming the bottom portion of the bottomed groove is larger than an outer dimension of the first opening pattern facing each other.
Thereby, the board | substrate unnecessary part enclosed by the bottomed groove | channel can be easily removed only by peeling off adhesion | attachment of a 2nd conductor pattern, a filler layer or a filler layer, and an insulating resin base material. Here, the external dimension refers to the length of the contrasted portion of the shape surrounded by the outer contour line of the conductor pattern or the opening pattern.

  The unnecessary portion of the substrate has the second conductor pattern and the filler layer or the filler layer and the insulating resin base material by applying any external force including pressing by a pressing member, application of air pressure, or vibration. It may be peeled off and removed. Thereby, a board | substrate unnecessary part can be removed easily.

After forming the first opening pattern and the second conductor pattern, the first conductor layer in which the first opening pattern is formed after forming a nickel plating layer and a gold plating layer on at least the first conductor layer. The filler layer may be irradiated with a laser beam using as a mask.
Thereby, since the reflectance of the conductor layer around the first opening pattern is improved, damage to the first conductor layer of the laser light irradiation portion and the filler layer therebelow is reduced, and the first conductor layer can be thinned. it can.

  According to the present invention described above, the drilling workability by the laser beam is improved while maintaining the rigidity required for the package substrate, and the positional accuracy between the substrate reference hole for positioning the substrate and the wiring pattern on the substrate surface is improved. A high substrate reference hole processing method can be provided.

It is sectional drawing which shows the process process of a board | substrate reference | standard hole in the board | substrate for packages. It is a cross-sectional photograph figure of a reference hole.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
A processing method for forming a reference hole in a package substrate will be described with reference to FIGS.

  As shown in FIG. 1A, a double-sided copper-clad substrate 3 having conductive layers (copper foil layers) 2 on both sides of an insulating resin base material 1 (for example, an epoxy resin substrate) is prepared. As shown in FIG. 1B, through holes 4 are drilled in this double-sided copper-clad substrate 3 by machining such as a drill (drilling step).

  Next, as shown in FIG. 1C, a filler that fills the through hole 4 is filled to close the through hole 4. The filler 5 is formed by applying a thermosetting type hole-filling ink containing a filler by screen printing and curing by heating to form the filler layer 5. Next, as shown in FIG. 1D, the filler layer 5 is polished and flattened with the conductive layer 2 formed on both surfaces of the substrate. As the filler, a hole-filling ink that is highly filled with a filler having a fine particle diameter (for example, 50 μm or less) excellent in through-hole filling and polishing properties is preferably used.

  Next, as shown in FIG. 1E, electroless copper plating and electrolytic copper plating are continuously performed on both surfaces of the substrate to cover both surfaces of the filler layer 5 and the conductive layer 2 adjacent thereto. Conductive layers 6 and 7 are respectively formed (lid plating). A first opening pattern and a second conductor pattern are formed on the first and second conductor layers 6 and 7 thickened on the conductor layer 2 as described below.

  Next, in FIG. 1F, after forming the first and second conductor layers 6 and 7, etching is performed to simultaneously form the wiring pattern, the first opening pattern 8 and the second conductor pattern 7b on both surfaces of the substrate. . Specifically, an etching mask (dry film or the like) is laminated on the first and second conductor layers 6 and 7, and then the wiring pattern and the first opening pattern 8 (for example, a circle) are simultaneously exposed, and then the first After the two-conductor pattern 7b (for example, a circle) is exposed, an etching mask pattern is formed by development. Thereafter, etching is performed to form the first opening pattern 8, the second conductor pattern 7b, and the first and second conductor patterns 6a and 7a. That is, by removing the first conductor layer 6 laminated on the filler layer 5 filled in the through hole 4, the first opening pattern 8 for processing the reference hole 10 is formed, and the underlying filler layer 5 is formed. The second conductor pattern 7b having a larger diameter is formed by exposing and removing the second conductor layer 7. Thereby, the first opening pattern 8 and the second conductor pattern 7b can be formed simultaneously with the formation of the wiring pattern on both surfaces of the substrate.

  In addition, after forming the first and second conductor patterns 6a and 7a, a nickel plating layer and a gold plating layer may be further laminated on the first conductor layer 6. Thereby, since the reflectance of the first conductor layer 6 around the first opening pattern 8 is improved, when the drilling process is performed by irradiating the filler layer 5 to be described later with a laser beam, it is the first laser irradiation portion. Damage to the conductor layer 6 and the filler layer 5 therebelow is reduced, and the first conductor layer 6 can be formed thin. As a result, the thickness of the copper forming the wiring pattern is reduced, and a finer wiring pattern can be etched. The nickel plating layer and the gold plating layer may be laminated at least on the first conductor layer 6 side where laser processing is performed, but may also be laminated on the second conductor layer 7 side for plating.

  Next, in FIG. 1G, the edge portion 8a (first edge pattern 8a) of the first opening pattern 8 is formed on the filler layer 5 exposed from the first opening pattern 8 from the first conductor layer 6 side using the first conductor layer 6 as a mask. The bottomed groove 11 having the second conductor pattern 7b (including the conductive layer 2) as the bottom is formed by removing the laser beam L by scanning and irradiating it along the line (see FIG. 1F). For laser processing, an excimer laser, a YAG laser, a carbon dioxide gas laser, or the like is used.

  Next, FIG. 1H shows a cross section of the substrate after laser processing. The outer diameter on the second conductor pattern 7b side, which is the bottom of the bottomed groove 11, is larger than the outer dimension (inner diameter) of the first opening pattern 8 and smaller than the outer dimension (diameter) of the second conductor pattern 7b. As described above, the size of the hole of the substrate reference hole 10 is the minimum diameter (outer dimension) of the hole of the first conductor layer 6 in which the first opening pattern 8 is formed. As a result, when the positioning pin is inserted into the substrate reference hole 10, the first conductor pattern 6 a and the first conductor pattern 6 a on the basis of the opening of the first conductor layer 6 in which the first opening pattern 8 having the minimum diameter is formed as a reference. Positioning can be performed.

  Next, as shown in FIG. 1 (I), the substrate unnecessary portion (hole central portion) 12 where the filler layer 5 and the second conductor layer 7 which are surrounded by the bottomed groove 11 and laminated are pressed is pressed. Then, the substrate reference hole 10 is formed. The unnecessary portion 12 of the substrate peels off the second conductor layer 7 and the filler layer 5 by applying any external force including application of air pressure or vibration in addition to pressing by the pressing member 15 (pressing pin). Removed. At this time, as shown in FIG. 1H, the second conductor pattern 7b is in a state of being laminated (adhered) to the filler layer 5 in a slight overlapping region. Thereby, the board | substrate unnecessary part 12 can be removed easily. The second conductor pattern 7b may be laminated with the filler layer 5 and the insulating resin substrate 1 depending on the laser processing conditions and the arrangement of the second conductor pattern 7b.

  Through the above steps, the filler layer 5 exposed from the first opening pattern 8 is removed by irradiating a laser beam to form a bottomed groove 11 having the second conductor pattern 7b as a bottom portion. The unnecessary substrate portion 12 on which the filler layer 5 and the second conductor layer 7 are laminated is removed. As a result, as shown in FIG. 1J, a package substrate 14 in which the substrate reference hole 10 and the wiring pattern 13 are both formed is manufactured.

  Further, the substrate-unnecessary portion in which the bottomed groove 11 is processed using the conductor pattern formed by etching as a mask, and the filler layer 5 and the second conductor layer 7 stacked by being surrounded by the bottomed groove 11 are stacked. Since the substrate reference hole 10 is formed by pressing and removing 12, not only a round hole but also a long hole or other desired shape can be easily processed without creating an expensive mold. .

  2A is a plan photograph of the laser light incident surface side of the substrate reference hole 10 of the package substrate 14, FIGS. 2B and 2C are half-sectional photograph views including the substrate reference hole 10, and FIG. ) Is a plan view of the substrate reference hole 10 on the laser beam incident surface side.

As shown in FIGS. 2B and 2C, the hole wall surface of the substrate reference hole 10 is not roughened by forming the filler layer 5 that can be easily laser-processed, and the positions of the reference hole 10 and the wiring pattern 14 can be reduced. The reference hole 10 with good accuracy and good finish could be formed.
As the filler, thermosetting type hole filling ink was used, but other members can be used as long as the insulating resin material is highly filled with a fine particle size filler and has good through hole filling, polishing and laser processability. It may be.

  DESCRIPTION OF SYMBOLS 1 Insulation resin base material 2 Conductive layer (copper foil layer) 3 Double-sided copper-clad board 4 Through-hole 5 Filler 6 1st conductor layer 6a 1st conductor pattern 7 2nd conductor layer 7a, 7b 2nd conductor pattern 8 1st opening Pattern 8a Edge portion 9 Second opening pattern 10 Reference hole 11 Bottomed cut hole 12 Substrate unnecessary portion 13 Wiring pattern 14 Package substrate 15 Press member

Claims (6)

A drilling step of drilling through holes in a substrate having a conductive layer on both sides of an insulating resin base;
Filling the through hole with a filler and closing the through hole;
Polishing the filler to planarize the conductive layers formed on both sides of the substrate,
Continuously forming electroless metal plating and electric field metal plating on both sides of the substrate to form first and second conductor layers covering the filler;
Removing the first conductor layer laminated on the filler layer by etching to form a first opening pattern simultaneously with the formation of the first conductor pattern to expose the underlying filler layer;
Removing the second conductor layer by etching to form a second opening pattern that exposes the underlying filler layer and forming a second conductor pattern opposite to the first opening pattern;
Removing the filler layer exposed from the first opening pattern from the first conductor layer side by using the first conductor layer as a mask by scanning and irradiating the filler layer along the edge portion of the first opening pattern. And forming a bottomed groove having the second conductor layer as a bottom,
Forming a substrate reference hole by pressing and removing at least the unnecessary portion of the substrate on which the filler layer and the second conductor layer are stacked surrounded by the bottomed groove,
The size and position of the substrate reference hole is determined by the size and position of the hole of the first conductor layer in which the first opening pattern of the bottomed groove from which the filler layer is removed is formed. Hole processing method.   The substrate reference hole processing method according to claim 1, wherein the filler is filled with a thermosetting hole-filling ink containing a filler by screen printing and is cured by heating to form a filler layer.   3. The substrate reference hole processing method according to claim 1, wherein the substrate reference hole is formed such that a hole of the first conductor layer in which the first opening pattern is formed has a minimum dimension.   4. The substrate reference hole according to claim 1, wherein an outer dimension of the second conductor pattern forming a bottom portion of the bottomed groove is formed larger than an outer dimension of the first opening pattern facing each other. 5. Processing method.   The unnecessary portion of the substrate includes the second conductor pattern and the filler layer or the filler layer and the insulating resin base material by applying any external force including pressing by a pressing member, application of air pressure, or vibration. The substrate reference hole processing method according to any one of claims 1 to 4, wherein the substrate reference hole is removed by peeling.   After forming the first opening pattern and the second conductor pattern, a nickel plating layer and a gold plating layer are laminated on at least the first conductor layer, and then laser light is applied to the filler layer through the first opening pattern. The method for processing a substrate reference hole according to any one of claims 1 to 5, wherein irradiation is performed.

Images