JP2004063874A - Method of inspecting multilayered printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of inspecting multilayered printed wiring board by which a build-up multilayered printed wiring board in which interlayer connection is performed by using micro via holes can be inspected for the presence/absence of the positional deviation of a precise wiring pattern immediately after a circuit is formed. <P>SOLUTION: This method of inspecting multilayered printed wiring board comprises a step of forming a ring pattern by forming a clearance pattern having a prescribed diameter on the copper foil provided on the surface of a resin layer on which a circuit pattern is formed, so that the ring pattern may be formed around the clearance pattern and a positional deviation inspection pattern, by continuously forming lands at positions which are separated from the ring pattern by a prescribed distance and laminating build-up layers upon the patterns; a step of forming the micro via holes through the surface copper foil of the build-up layers at the spots corresponding to the clearance pattern and lands of the positional deviation inspection; and a step of plating the micro via holes formed in the preceding step with copper. This method also comprises a step of forming a circuit pattern after the micro via holes are plated with copper in the preceding step and, at the same time, forming terminals in the micro via holes of the positional deviation inspection pattern. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method for inspecting positional deviation between a microvia and a pattern of each layer in a multilayer printed wiring board in which fine interlayer connection is performed by using a microvia.
[0002]
[Prior art]
Build-up multilayer printed wiring boards are manufactured by stacking high-density wiring patterns in multiple layers.The higher the density, the finer the diameter of the microvia holes, and the higher the accuracy of positioning when forming wiring patterns. Is required. Therefore, the permissible range of the positional deviation is further narrowed, and a slight positional deviation between the microvia and each of the layers may possibly result in a defective product. In the method of checking the position shift after the finished product has been completed, the operation cost of the resist process and the printing process after the position shift is wasted. Therefore, a method for confirming the presence or absence of a positional shift immediately after the formation of the circuit on the multilayer printed wiring board has been required.
[0003]
The present applicant has already proposed a method of inspecting and confirming the presence / absence of a positional shift using a through-hole immediately after circuit formation of a multilayer printed wiring board (Japanese Patent No. 3206635). A position shift inspection method using the through-hole will be described with reference to FIGS.
[0004]
In FIG. 4, the multilayer printed wiring board 10 has three substrates 11 to 13 sequentially laminated. A circuit pattern for the inner layer circuit is formed on the opposing circuit forming surfaces between the substrates 11 to 13 of the multilayer printed wiring board 10, and the misalignment inspection patterns 28, 29 and 30 are formed.
[0005]
Of the positional shift inspection patterns 28, 29, and 30, the positional shift inspection pattern 28 is formed on the upper surface of the substrate 11 and, if necessary, on the lower surface of the substrate 13 as shown in FIG. The lands 20, 21, 22 of solid circles that are sufficiently larger than the hole diameter R1 are provided independently at regular intervals (x) on a straight line. As shown in FIG. 5B, on the upper surface of the substrate 12, a ring pattern 23 and a circular land 25 are provided at positions corresponding to the lands 20 and 21, respectively. 23 and the circular land 25 are connected by a connection conductor 24. The ring pattern 23 is formed in a ring shape in which an inner diameter R2 larger than the through-hole hole diameter R1 is cut out, and a half of a difference between the inner diameter R2 and the through-hole hole diameter R1 is a shift limit value at the time of a shift inspection. d. The circular land 25 is a solid circle having the same size as the land 21.
Similarly, as shown in FIG. 5C, the position shift inspection pattern 30 is provided with a ring pattern 23 and a circular land 25 at positions corresponding to the lands 21 and 22, as shown in FIG. 24.
[0006]
After the substrates 11, 12, and 13 formed as described above are stacked to form the multilayer printed wiring board 10, the lands 20, 20 from the upper surface of the substrate 11 (or the lower surface of the substrate 13) are inspected for pattern misalignment inspection. Through holes 14, 15, and 16 having a hole diameter R1 are formed at the centers of the holes 21 and 22, and platings 17, 18, and 19 are applied to inner wall surfaces of the through holes 14, 15, and 16, respectively.
[0007]
In order to inspect the presence or absence of a pattern displacement, one of the two probes of the electric checker is first brought into contact with the land 20 of the first through hole 14 and the other is brought into contact with the land 21 of the second through hole 15. As a result, if there is no conduction, there is no displacement in the inner layer circuit pattern on the circuit formation surface. If the circuit is conductive, the position shift inspection pattern 29 is shifted more than the shift limit value d, and the ring pattern 23 is in contact with the plating 17 of the first through hole 14. It is determined that there is a displacement in the inner layer circuit pattern. Similarly, inspection is performed between the land 21 of the second through hole 15 and the land 22 of the third through hole 16. Further, the space between the land 20 of the first through hole 14 and the land 22 of the third through hole 16 is inspected.
[0008]
As described above, according to the method described with reference to FIGS. 4 and 5, it is possible to specify not only whether or not the inner layer circuit pattern is displaced but also what number of the inner layer circuit pattern is. it can. If the displacement is only one layer, it is presumed that the displacement is caused by a displacement in the circuit forming printing process. If the displacement is caused in two or more layers, the displacement is caused by the lamination pressing process. If the position is estimated to be misaligned and all the patterns are misaligned, the cause becomes apparent, for example, it is assumed to be caused by NC (numerical control) processing when drilling through holes.
[0009]
The above-mentioned inspection method is used when connecting between the layers of the multilayer printed wiring board with through holes. In recent years, however, due to a demand for higher density of the multilayer wiring board, the build-up multilayer printed wiring board has been required. As a manufacturing method of the GaN, a multilayer technique using a so-called RCC (RESIN COATED COPPER: copper foil with resin) has been attracting attention. This is done by laminating a resin-coated copper foil layer on a circuit board, etching away the copper foil, providing an opening in the via-hole formation site, irradiating this opening with a laser, removing the resin layer, and opening the opening. This is a technique of forming a laser via hole (LVH) by plating, and connecting the wiring patterns of each layer by the laser via hole. Further, a method of simultaneously removing a copper foil and a resin layer present thereunder using a high energy excimer laser, a UV laser, a CO2 laser or the like is also used.
[0010]
[Problems to be solved by the invention]
By using the above-described technology for forming a via hole using a laser, it is possible to form a via hole having a significantly smaller diameter than the conventional technology using a through-hole, whereby a higher density build-up can be achieved. It has become possible to manufacture up-multilayer printed wiring boards. However, unlike the through holes penetrating the front and back of the printed wiring board, these build-up multilayer wiring boards have a non-penetrating structure. However, a method for inspecting the positional deviation using the method cannot be used, and a new inspection method is required.
[0011]
The present invention has been made in view of the above problems, and a method for inspecting and confirming the presence or absence of a positional shift in a high-density build-up multilayer printed wiring board using micro vias such as laser via holes immediately after circuit formation of each layer. The purpose is to provide.
[0012]
[Means for Solving the Problems]
In the present invention, a clearance pattern having a predetermined diameter larger than a micro via is cut out in a copper foil on the surface of a resin layer on which a circuit pattern is formed, a peripheral portion thereof is formed as a ring pattern, and a land is formed at a position separated by a predetermined distance from the ring pattern. A build-up layer laminating step of continuously forming misregistration inspection patterns and laminating build-up layers on these patterns; and, on the surface copper foil in the build-up layer, a corresponding portion of a circuit pattern and the misalignment inspection. A micro via forming step of forming a micro via in a pattern clearance pattern and a corresponding portion of a land, a copper plating step of applying a copper plating process to a micro via in a previous step, and a circuit pattern forming after a copper plating step in a previous step As well as forming terminals in the micro vias of the misalignment test pattern An inspection method for a multilayer printed wiring board characterized by comprising the that step.
[0013]
With such a configuration, even in a multilayer printed wiring board in which interlayer connection is performed using a laser via hole, electrical continuity between the ring-shaped portion of the misalignment inspection pattern and the copper plating of the laser via hole is determined. Inspection of the displacement can be performed by the conduction.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
The inspection method according to the present invention is a technique applicable to all multilayer printed wiring boards that perform interlayer connection of a build-up layer using a technique called a micro via having a very small hole diameter, such as a laser via, a photo via, and a via using a conductive paste. In the following embodiments, as an example, an example in which laser via holes are formed in a laminate of RCC layers to perform interlayer connection will be described.
[0015]
FIG. 1 and FIG. 2 illustrate the flow of the work process for performing the position shift inspection according to the present invention when the position shift exceeds the allowable range and when the position shift is within the allowable range, respectively. The work is advanced in the order from (a) to the fifth step (e), and finally a positional deviation inspection is performed.
[0016]
1st process (RCC lamination);
1A and 2A, an RCC layer 31 in which a surface copper foil 32 and a resin layer 33 are integrated is laminated on a circuit pattern formed on an inner resin layer 44. In the resin layer 44, a misalignment inspection pattern 34 made of a conductive material such as a copper foil is formed along with the circuit pattern at a position that does not interfere with the circuit pattern or at a position that is removed after the inspection. . As shown in FIG. 3, the shape of the position shift inspection pattern 34 is such that one end is hollowed out to a predetermined diameter r2 to form a clearance pattern 45, and the outside of the clearance pattern 45 is a ring pattern 35. The circular pattern 36 is formed with a diameter smaller than r2 so that a gap is formed on the entire inner circumference of the clearance pattern 45. The land 37 is continuous with the other end of the clearance pattern 45 at a predetermined length. Although the land 37 is formed to have the same outer diameter and width as the ring pattern 35, the land 37 may have any shape as long as the range includes the maximum positional deviation inspection width, and the shape is not limited to the illustrated one.
[0017]
Second step (window formation);
In FIG. 1B and FIG. 2B, by performing an etching process at a predetermined position on the surface copper foil 32 of the substrate after the RCC lamination in order to perform an interlayer connection with an inner circuit pattern, The surface copper foil 32 is removed to form a window for forming a laser via hole. At this time, the window 38 is also formed on the surface copper foil 32 located above the clearance pattern 45 at one end of the misregistration inspection pattern 34 and the land portion 37 provided at the other end, with the size of the diameter r1. Assuming that the difference between the diameter r2 of the clearance pattern 45 and the diameter r1 of the window is r2−r1 = 2d, の of the difference 2d is the limit value of the interlayer alignment, and a deviation of more than this is considered. Whether or not it has occurred is inspected by using the displacement inspection pattern 34. In other words, the diameter r1 of the microvia and the limit value d of the positional deviation are preset values, so that the diameter r2 of the clearance pattern 45 is formed by the calculation of r2 = r1 + 2d. FIG. 1B illustrates a case where the displacement is out of the allowable range, and FIG. 2B illustrates a case where the position shift is within the allowable range.
[0018]
Third step (laser processing);
Laser processing is performed on the substrate on which the window 38 is formed in the previous step. Then, as shown in FIGS. 1C and 2C, a part of the resin layers 33 and 44 immediately below the portion where the window 38 is formed is removed, and the copper foil portion in the inner layer is exposed. Thus, a laser via hole 39 is formed. At this time, since the laser is reflected at the surface copper foil 32, the resin layers 33 and 44 only at the portion where the window 38 is provided are removed. FIG. 1C shows that the copper foil at the inner diameter portion of the ring pattern 35 is exposed by the laser processing as a result of the misalignment being out of the allowable range. In FIG. 2C, the copper foil of the ring pattern 35 is not exposed due to a positional shift within an allowable range.
Note that the circular pattern 36 provided inside the clearance pattern 45 is provided to prevent the resin layer 44 from being removed more than necessary during laser processing. In FIG. Because the laser layer is large, the resin layer 44 is also partially removed by the laser. However, in FIG. 2C, it can be seen that the removal of the resin layer by the laser stops at the circular pattern 36 because the displacement is small. It is desirable that the circular pattern 36 has a gap as small as possible over the entire inner circumference of the clearance pattern 45 and is formed to be larger than the diameter of the microvia.
[0019]
Fourth step (copper plating);
Copper plating is performed on the surface of the substrate after the laser processing in the previous step. Then, as shown in FIGS. 1D and 2D, the upper surface of the surface copper foil 32, the laser via hole 39 from which the resin layer 33 has been removed, the circular pattern 36 and the ring pattern 35 in the L2 layer. And a portion where the copper foil portion is exposed is subjected to a copper plating process. This copper plating provides an interlayer connection. FIG. 1D shows that the exposed portion 41 of the ring pattern 35 is copper-plated as a result of the displacement. In FIG. 2D, the ring pattern 35 is not subjected to a copper plating process.
[0020]
Fifth step (circuit pattern formation);
By etching the surface of the substrate after the copper plating process in the previous step again, a circuit pattern (not shown) of the L1 layer is formed. At this time, the copper plating portions on both ends of the misregistration inspection pattern 34 are also etched so as to become the terminals, and as shown in FIG. 1E and FIG. Then, a clearance pattern side terminal 43 is formed.
[0021]
When each probe of the electric checker is connected to the land side terminal 42 and the clearance pattern side terminal 43 in the state of FIG. 1 (e), the copper foil of the exposed portion 41 of the ring pattern 35 is in contact with the copper plating. For this reason, the land side terminal 42 and the clearance pattern side terminal 43 enter a conductive state. This is evidence that a displacement has occurred beyond the limit value d and can be determined to be defective.
[0022]
On the other hand, FIG. 2E shows a state in which the window 38 is formed almost directly above the clearance pattern side terminal 43 of the position shift inspection pattern 34 at the stage of forming the window 38 in FIG. 2C, the laser via hole 39 is also formed within the range of the positional deviation limit value d inside the clearance pattern side terminal 43, and as a result, as shown in FIG. 2D. When the copper plating process and the circuit pattern forming process in FIG. 2E are performed, the copper foil of the exposed portion 41 of the ring pattern 35 does not come into contact with the copper plating portion, and the land terminal 42 and the clearance pattern side Even if each probe of the electric checker is connected to the terminal 43 and the inspection is performed, the inspection becomes non-conductive and it can be determined that the product is good.
[0023]
In the above embodiment, as shown in FIGS. 1B and 2B, the window 38 was formed by removing the copper foil on the substrate surface after the RCC lamination by etching or other surface treatment. However, the method for inspecting the displacement according to the present invention is not limited to this case, and the copper foil and the resin layer under the copper foil are simultaneously formed using a strong laser such as an excimer laser, a UV laser, and a CO2 laser. It can also be used in the case of removal (however, the circular pattern 36 is not removed).
[0024]
According to this method, the window forming step shown in FIGS. 1B and 2B is omitted, and the laser via hole 39 is directly formed. In this case, the surface copper foil 32 of the L1 layer can be directly removed by a laser by using a thinner one than in the above embodiment. Then, when the processing by the laser is within the allowable range of the displacement, as in the case shown in FIG. 2C, even if the subsequent copper plating process and the circuit pattern forming process are performed, the ring pattern 35 is exposed. The copper foil and the copper-plated portion of the portion 41 do not come into contact with each other, and even if each of the probes of the electric checker is connected to the land-side terminal 42 and the clearance-pattern-side terminal 43 for inspection, the electrical connection is non-conductive and judged to be good. be able to.
When a displacement occurs during the laser processing, as in the case shown in FIG. 1C, the subsequent copper plating process and the circuit pattern forming process are performed in the exposed portion 41 of the ring pattern 35. When the copper foil and the copper-plated portion come into contact with each other and the probes of the electric checker are connected to the land-side terminals 42 and the clearance-pattern-side terminals 43 and inspected, conduction is established and it can be determined that the product is defective.
[0025]
In the above-described embodiment, the misalignment inspection pattern 34 is configured such that a circular pattern 36 having a diameter smaller than r2 is left inside a clearance pattern 45 hollowed out to a diameter r2, but the present invention is not limited to this. Instead of providing the circular pattern 36, the clearance pattern 45 may be entirely removed. The circular pattern 36 is provided to prevent the resin layer 44 from being unnecessarily removed during the laser processing. For example, the circular pattern 36 may be provided on the discarded substrate at a portion removed after the inspection. In the case where the inspection is performed by providing the pattern, there is no problem even if the lower resin layer 44 is removed. Therefore, the circular pattern 36 may not be provided.
[0026]
In the above-described embodiment, only the connection between the two layers L1 and L2 has been described. However, the present invention is not limited to this. By providing the same misalignment inspection pattern 34 in each layer, the layers are stacked. Immediately after the circuit pattern is formed, the presence / absence of misalignment is determined, and a non-defective product is discriminated from a non-defective product. Then, the next layer is laminated only on the non-defective product, thereby reducing unnecessary cost. it can.
[0027]
【The invention's effect】
According to the first aspect of the present invention, at the time of manufacturing a multilayer printed wiring board using micro vias that are extremely small as compared with through holes, electrical conduction between the ring-shaped portion of the misalignment inspection pattern and the copper plating of the micro vias, Inspection of the displacement can be performed by the non-conduction. In addition, by performing a position shift inspection every time a circuit pattern is formed, useless steps can be eliminated and defective products can be prevented.
[0028]
According to the second aspect of the present invention, by interposing the window forming step, the microvia is accurately formed, and a more accurate positional displacement inspection can be performed.
[0029]
According to the third aspect of the present invention, it is possible to accurately detect a positional shift even in a multilayer printed wiring board in which RCC layers are stacked and interlayer connection is performed by using a laser via hole.
[0030]
According to the fourth aspect of the invention, since the circular pattern having the same center as the clearance pattern is formed inside the clearance pattern, the lower resin layer is not removed more than necessary.
[0031]
According to the fifth aspect of the present invention, the diameter r2 of the clearance pattern is formed by setting r2 = r1 + 2d, where d is the limit value of the displacement of the circuit pattern to be laminated, and r1 is the diameter of the microvia. As a result, the diameter r2 of the clearance pattern can be easily adjusted according to the purpose by setting the diameter r2 of the clearance pattern in accordance with the limit value d of the displacement and the diameter r1 of the microvia, and 360 ° misalignment in any direction can be accurately inspected, and a more reliable inspection can be performed.
In addition, a plurality of inspection patterns having different set values of the diameter r2 of the clearance pattern (or the limit value of the positional deviation d) are arranged on a single work, and the respective inspection results are simultaneously known, so that the micro via processing step is performed. Process stabilization ability at
[Brief description of the drawings]
FIGS. 1A and 1B are flow charts of steps when a method for inspecting a multilayer printed wiring board according to the present invention is performed on a defective product, wherein FIG. 1A is an explanatory view of an RCC laminating step, and FIG. (C) is an explanatory view of a laser processing step, (d) is an explanatory view of a copper plating step, and (e) is an explanatory view of a circuit pattern forming step.
FIGS. 2A and 2B are flow charts when a method for inspecting a multilayer printed wiring board according to the present invention is performed on a non-defective product, wherein FIG. 2A is an explanatory diagram of an RCC laminating process, FIG. (c) is an explanatory view of a laser processing step, (d) is an explanatory view of a copper plating step, and (e) is an explanatory view of a circuit pattern forming step.
FIG. 3 is a plan view showing a misregistration inspection pattern used for misalignment inspection according to the present invention.
FIG. 4 is a diagram illustrating a method for inspecting a positional deviation of a multilayer printed wiring board according to a conventional technique, and is an end view illustrating an arrangement of a positional deviation inspection pattern for a through hole;
5 (a), (b) and (c) are plan views of the misregistration inspection pattern in FIG. 4, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Multilayer printed wiring board, 11 ... board, 12 ... board, 13 ... board, 14 ... 1st through hole, 15 ... 2nd through hole, 16 ... 3rd through hole, 17 ... plating, 18 ... plating, 19 ... Plating, 20 lands, 21 lands, 22 lands, 23 ring patterns, 24 connection conductors, 25 circular lands, 28 misalignment inspection patterns, 29 misalignment inspection patterns, 30 misalignment inspection patterns, 31 ... RCC layer, 32 ... Surface copper foil, 33 ... Resin layer, 34 ... Position displacement inspection pattern, 35 ... Ring pattern, 36 ... Circular pattern, 37 ... Land, 38 ... Window, 39 ... Laser via hole, 40 ... Copper Plating, 41: exposed portion, 42: land side terminal, 43: clearance pattern side terminal, 44: resin layer, 45: clearance pattern.

Claims (5)

In the copper foil on the surface of the resin layer on which the circuit pattern was formed, a clearance pattern with a predetermined diameter larger than the microvia was cut out, and the periphery was used as a ring pattern. A build-up layer laminating step of forming a misalignment inspection pattern and laminating a build-up layer on these patterns; And a micro via forming step of forming micro vias at corresponding locations of the lands, a copper plating step of performing copper plating on the micro vias in the previous step, and forming a circuit pattern after the copper plating processing in the previous step. Forming a terminal in the micro via of the displacement inspection pattern; Inspection method for a multilayer printed wiring board, characterized in that Ranaru. In the copper foil on the surface of the resin layer on which the circuit pattern was formed, a clearance pattern with a predetermined diameter larger than the microvia was cut out, and the periphery was used as a ring pattern. A build-up layer laminating step of forming a misalignment inspection pattern and laminating a build-up layer on these patterns; And a window forming step of forming a window at a corresponding portion of the land, a micro via forming step of forming a micro via at a window forming portion in a previous process, and a copper plating process of applying a copper plating process to the micro via in the previous process. , Circuit pattern after copper plating in the previous process And forming inspection method for a multilayer printed wiring board characterized by comprising the step of forming a terminal on microvias misalignment test pattern. 3. The method for inspecting a multilayer printed wiring board according to claim 1, wherein the build-up layer to be laminated is an RCC layer, and the formed micro via is a laser via hole. 4. The inspection method for a multilayer printed wiring board according to claim 1, wherein a circular pattern larger than the diameter of the micro via is formed with a gap inside the clearance pattern. The diameter r2 of the clearance pattern is formed by setting r2 = r1 + 2d, where d is the limit value of the displacement of the circuit pattern to be laminated and r1 is the diameter of the microvia. 5. The method for inspecting a multilayer printed wiring board according to claim 3 or 4.

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