JP4201659B2 - Manufacturing method of build-up multilayer printed wiring board having end face through hole - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer printed wiring board having end face through holes, and more particularly, to a method for manufacturing a build-up multilayer printed wiring board having end face through holes obtained by dividing blind via holes.
[0002]
[Prior art]
Conventionally, when forming an end face through hole in a printed wiring board, if the through hole is directly cut (for example, punching or dicing), the conductor of the through hole is peeled off or the through hole is crushed. Since there was a problem such as loosening, the through hole was filled with resin, and the resin was removed after cutting.
[0003]
However, the process of filling the resin has a large number of work steps, and the process becomes complicated. If the resin cannot be completely removed, there is a concern that the solder wettability is lowered.
[0004]
As an example of solving such a problem, a method for manufacturing a printed wiring board as shown in FIG. 3 has already been reported (for example, see Patent Document 1).
[0005]
First, as shown in FIG. 3 (1), an insulating substrate 16 provided with a metal foil 4 is prepared on the front and back of an insulating base material 15, drilled from one surface to the other surface, and the other The hole 6a is drilled to the vicinity of the metal foil 4, and then, as shown in FIG. 3 (2), the resin of the remaining insulating base material 15 is removed with a laser, and the non-through hole 6 is drilled. Next, as shown in FIG. 3 (3), the plating 9 is deposited so that the metal foils 4 on the front and back sides are electrically connected to each other, and then the wiring pattern is formed on the front and back sides. The blocked blind via hole 10 is obtained (FIG. 3 (4)). Then, the printed wiring board 17 having the end face through hole 12a shown in FIG. 3 (5) is obtained by cutting along the substantially center line 14 of the blind via hole 10 and from the side where the bottom land 2 is formed. Get.
[0006]
In this way, instead of the penetrating through hole, a blind via hole in which one side is closed by the bottom land is formed, and cutting is performed along the substantially center line of the blind via hole and from the bottom land forming side. Therefore, the plating in the blind via hole can be protected at the time of cutting without filling the blind via hole (through hole mentioned above) with resin, , Plating peeling and the like can be suppressed.
[0007]
[Patent Document 1]
JP-A-10-65298 gazette
By the way, there is a module board as an application of a printed wiring board having an end face through hole. As the module board becomes smaller and more functional, the printed wiring board becomes smaller and has higher density wiring. As a connecting means, a through-through hole (the one shown in FIG. 3 is a blind via hole in shape, but as a result, it is considered to be the same as the through-hole connecting the front and back) Since the degree of freedom in forming the wiring pattern is hindered, the demand for a build-up multilayer printed wiring board in which wiring layers are connected by blind via holes is increasing as a form of a printed wiring board having the end face through hole. .
[0009]
[Problems to be solved by the invention]
Here, it is assumed that the blind via hole formed in the build-up multilayer printed wiring board is subjected to the same cutting process as above (processing method for cutting from the bottom land side so that the blind via hole is not crushed). Since the bottom land is not exposed on the surface, it is very difficult to cut along the substantially center line of the bottom land (that is, blind via hole).
[0010]
The reason for this is that the blind via hole is obtained by etching and removing the metal foil in the laser processing planned portion based on the through hole drilled with a drill (through hole drilled with reference to the reference mark formed in the lower layer). In addition to forming an opening, a reference mark (opening) for laser processing is formed at the same time, and then formed by performing laser processing with reference to the reference mark for laser processing. Is processed on the basis of the through-hole, so that the laser processing accuracy in forming the blind via hole (registration error for two steps of forming the reference mark for laser processing and laser processing is small). This is because the processing accuracy of the cutting process is greatly different.
[0011]
The present invention has been made in view of the above problems, and the object of the present invention is to easily perform the blind via hole when cutting from the bottom land forming side of the blind via hole provided in the build-up multilayer printed wiring board. An object of the present invention is to provide a method for manufacturing a build-up multilayer printed wiring board having an end face through-hole that can be cut along substantially the center line.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 is directed to a build-up multilayer printed wiring board having end face through holes formed by cutting along substantially the center line of blind via holes connecting wiring layers. In the manufacturing method of the above, at least during laser cutting, a non-through hole for a blind via hole reaching from the upper layer to the intermediate layer is drilled in the laminated substrate, and at the time of cutting processing reaching the lowermost layer opposite to the upper layer. A step of drilling a non-through hole for a reference mark, a step of passing through the non-through hole for a reference mark to form a through hole for a reference mark, and conduction between the through hole for the reference mark and the non-through hole for the blind via hole After the processing, the step of forming the wiring pattern of the outer layer and the brazing from the surface opposite to the upper layer on the basis of the reference mark through hole. Characterized by a step of cutting along the approximate center line of the command via holes.
[0013]
Thus, since the reference mark non-through hole for cutting is formed simultaneously with the laser processing of the blind via hole non-through hole, the reference mark through-hole formed from the non-through hole for the reference mark is formed. By using the reference, even if cutting is performed from the bottom land formation side, cutting can be performed along the substantially center line of the blind via hole with high accuracy.
[0014]
According to a second aspect of the present invention, there is provided a method for manufacturing a build-up multilayer printed wiring board having an end face through-hole, which is formed by cutting along substantially the center line of a blind via hole connecting wiring layers. In addition, a blind via hole non-through hole reaching from the upper layer to the intermediate layer is formed on the laminated substrate from which a part of the lowermost layer located in the reference mark through hole forming portion at the time of cutting is removed in advance by laser processing. After drilling and drilling a reference mark through hole at the time of cutting that penetrates to the surface opposite to the upper layer, and conducting the conduction process of the reference mark through hole and the blind via hole non-through hole The step of forming the wiring pattern of the outer layer and the blind via hole from the surface opposite to the upper layer with reference to the through hole for the reference mark Characterized by a step of cutting along the approximate center line.
[0015]
As described above, the reference mark through hole for cutting is formed simultaneously with the laser processing of the blind via hole non-through hole. Even if it is cut, it can be cut along the center line of the blind via hole with high accuracy.
[0016]
According to a third aspect of the present invention, a plurality of the blind via hole non-through holes are formed on a straight line, and the reference mark through hole is formed on a substantially center line of the plurality of blind via hole non-through holes. And formed on both outermost sides of the plurality of blind via holes.
[0017]
Thereby, since the through-hole used as the reference | standard of a cutting process is formed in both outermost sides of the blind via hole formed in a straight line, the quality determination of the said cutting process can be performed easily after a cutting process. .
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be briefly described with reference to FIGS. For convenience, the drawing shows only the blind via hole to be cut and the reference mark used at the time of the cutting. Further, in the figure, (a) is an enlarged sectional explanatory view of the build-up multilayer printed wiring board, (b) is a plan explanatory view of the printed wiring board, and the LL line is a cutting line of the sectional view of (a). (C) is a bottom explanatory view of the printed wiring board.
[0019]
First, as shown in FIG. 1A, an interlayer insulating layer 3 and copper are formed on the front and back of a core substrate 1 on which an inner layer wiring pattern (not shown) including a bottom land 2 (including an alignment inner layer mark) is formed. A metal foil 4 such as a foil is sequentially laminated, or a metal foil with a resin in which a metal foil is laminated on an interlayer insulating layer, and then an inner layer mark for alignment (not shown) is recognized by an X-ray punch. Then, the alignment inner layer mark is drilled, and an exposure reference hole (not shown) is drilled. Next, on the basis of the exposure reference hole, one of the metal foils 4 located in the laser mark reference mark, the blind via hole 10 and the cutting reference mark 11 forming portion (not shown) is removed by etching. Opening 5 is formed. Next, laser processing is performed with reference to a reference mark for laser processing (not shown), and a non-through hole 6 for the blind via hole 10 reaching the bottom land 2 is drilled, and at the time of cutting processing reaching the other metal foil 4 The reference mark non-through hole 7 to be used is drilled (see FIG. 1 (2)).
[0020]
Here, the reference mark non-through hole 7 includes a plurality of blind vias formed on a straight line so that it can be easily confirmed whether or not the cutting process performed after forming the blind via hole 10 has been accurately performed. The non-through holes 6 for the holes 10 are provided almost on the center line and on the outermost sides of the plurality of non-through holes 6.
[0021]
Next, as shown in FIG. 1 (3), the other metal foil 4 located at the reference mark non-through hole 7 forming portion is removed by etching, and the reference mark non-through hole 7 is used for the reference mark. After forming the through-hole 8, electroless plating and electrolytic plating are performed to deposit plating 9 (for example, copper plating) on the entire surface including the non-through-hole 6 (see FIG. 2 (4)).
[0022]
Here, as a means for drilling the reference mark through-hole 8, the reference mark non-through-hole 7 reaching the other metal foil 4 is once drilled, and then etched and positioned at the reference mark non-through-hole 7 forming portion. However, the other metal foil 4 located in the reference mark non-through-hole 7 forming portion is removed by etching in advance, and then the reference mark laser is used. The through hole 8 can also be drilled.
[0023]
Next, as shown in FIG. 2 (5), an outer layer wiring pattern is formed to form the blind via hole 10 and the reference mark 11 for cutting, and then a desired solder resist 18 is formed. Then, as shown in FIG. 2C, the reference mark 11 is recognized from the other surface, and punching or dicing is performed along the center line 14 connecting the centers of the reference marks 11. By performing the cutting process, the build-up multilayer printed wiring board 13 of FIG. 2 (6) provided with the end face through holes 12 is obtained.
[0024]
The present invention is characterized in that the reference mark (through hole) at the time of cutting is formed simultaneously with the laser processing at the time of forming the non-through hole for the blind via hole.
[0025]
Thereby, when cutting from the bottom land formation side (the other surface side in the figure) of the blind via hole on the basis of the reference mark, the processing accuracy of the end face through hole is such that the laser processing machine and the cutting processing machine Therefore, the machining position accuracy is improved as compared with the conventional case, and the cutting process can be easily performed along substantially the center line of the blind via hole.
[0026]
Further, as described above, if the reference marks 11 are provided on both outermost sides of the blind via holes 10 formed on a straight line, the quality of the cutting process can be easily confirmed.
[0027]
【Example】
An embodiment of the present invention will be briefly described with reference to FIGS.
[0028]
First, the inner layer wiring pattern including the bottom land of φ0.450 mm and the inner layer mark for alignment are formed on the front and back of the 0.1 mm thick core substrate, on the 0.04 mm thick interlayer insulating layer, A copper foil with resin on which a copper foil having a thickness of 12 μm is laminated, and then drilled at the position of the inner layer mark by an X-ray punch to drill a reference hole for φ2.0 mm (see FIG. Not shown). Next, etching is performed using the exposure reference hole as a reference, and a 0.35 mm opening is formed in the φ0.5 mm laser processing reference mark (opening), the blind via hole forming portion, and the cutting reference mark forming portion. The part is formed on one metal foil (corresponding to FIG. 1 (1)). Next, with reference to the reference mark for laser processing, a carbon dioxide laser is used to drill a non-through hole of φ0.25 mm reaching the bottom land under a condition of a pulse width of 10 μs and 3 shots, and a pulse width of 12 μs, Under the condition of 10 shots, a reference mark non-through hole reaching the other metal foil is drilled (corresponding to FIG. 1 (2)). Next, the other metal foil located in the non-through hole for the reference mark is removed by etching to form an opening of φ0.35 mm, and the non-through hole for the reference mark is used as the through hole for the reference mark (see FIG. 1 (3)), and then a desmear treatment, an electroless copper plating, and an electrolytic copper plating treatment are performed to deposit a copper plating having a thickness of 20 μm on the entire surface including the non-through holes (FIG. 2 (4)). Fall under). Next, an outer layer wiring pattern is formed by etching, a reference mark for cutting with a land diameter of φ0.45 mm is formed, and then a desired solder resist is formed (corresponding to FIG. 2 (5)). Then, by recognizing the reference mark from the other surface and performing dicing along the center line connecting the reference marks, a build-up multilayer printed wiring board having end face through holes was obtained (FIG. 2 (6). )reference).
[0029]
【The invention's effect】
By producing a build-up multilayer printed wiring board having end face through holes obtained by cutting blind via holes by the manufacturing method of the present invention, a build-up multilayer printed wiring board having end face through holes with high processing accuracy is obtained. Can be easily obtained.
[Brief description of the drawings]
FIG. 1 is a schematic production process diagram of a build-up multilayer printed wiring board having an end face through-hole according to the present invention.
FIG. 2 is a schematic manufacturing process diagram following FIG. 1;
FIG. 3 is a schematic manufacturing process diagram of a printed wiring board provided with a conventional end surface through-hole.
[Explanation of symbols]
1: Core substrate 2: Bottom land 3: Interlayer insulating layer 4: Metal foil 5: Opening 6: Non-through hole 6a: Hole 7: Non-through hole for reference mark 8: Through hole for reference mark 9: Plating 10: Blind Via hole 11: Reference mark 12, 12a: End face through hole 13: Build-up multilayer printed wiring board 14: Center line 15: Insulating substrate 16: Insulating substrate 17: Printed wiring board 18: Solder resist

Claims (3)

A method of manufacturing a build-up multilayer printed wiring board having an end face through-hole, which is formed by cutting along a substantially center line of a blind via hole connecting wiring layers. Drilling a blind via hole non-through hole reaching from the upper layer to the intermediate layer, and drilling a reference mark non-through hole at the time of cutting reaching the lowermost layer opposite to the upper layer, and the reference mark A step of passing through the non-through hole for a reference mark to form a through hole for a reference mark, and a step of forming a wiring pattern of an outer layer after conducting the conduction treatment of the through hole for the reference mark and the non-through hole for the blind via hole Then, cutting from the surface opposite to the upper layer along the substantially center line of the blind via hole with reference to the through hole for the reference mark. Method of manufacturing a build-up multilayer printed wiring board characterized by having the step of. A method of manufacturing a build-up multilayer printed wiring board having an end face through-hole formed by cutting along substantially the center line of a blind via hole connecting wiring layers, at least by laser processing. A non-through hole for a blind via hole reaching from the upper layer to the intermediate layer is drilled in the laminated substrate from which a part of the lowermost layer located in the through hole forming portion for the reference mark is removed in advance, and to the surface opposite to the upper layer A step of drilling a through hole for a reference mark at the time of cutting processing to penetrate, a step of forming a wiring pattern of an outer layer after conducting a conduction process of the through hole for the reference mark and the non-through hole for the blind via hole, Using the reference mark through hole as a reference, cut from the surface opposite to the upper layer along the center line of the blind via hole. Method of manufacturing a build-up multilayer printed wiring board, characterized by a step. A plurality of blind via hole non-through holes are formed on a straight line, and the reference mark through hole is substantially on the center line of the plurality of blind via hole non-through holes and the plurality of blind via holes. The method of manufacturing a build-up multilayer printed wiring board according to claim 1, wherein the multilayer printed wiring board is formed on both outermost sides.

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