JPH04235337A - Inspecting method for multilayered printed wiring board - Google Patents

Abstract

PURPOSE:To improve reliability in inspection by performing black color oxidation of the main body of a multilayered wiring board wherein a through hole is formed, and thereafter performing the inspection. CONSTITUTION:At the stage before the inspection of the inner layer of a multilayered printed wiring board, a through hole 24 is formed in the main body 20A of the multilayered wiring board so as to penetrate the inner layer, and the main body 20A undergone black color oxidation. The black color oxidation is performed by submerging the main body 20A into heated mixed liquid of potassium peroxide and caustic soda. Thus, a black oxide film 25 is formed on only exposed surfaces 22a and 23a of inner layers 22 and 23 made of copper. The main body 20B of the multilayered wiring board which has undergone the black color oxidation becomes an object for inspection, and the inspection is performed. Here, the inside of the hole 24 has the green color when a substrate 21 is made of glass epoxy and has a brown color when the substrate is made of glass polyimide. The black film 25 is visually recognized. Therefore, the constrast of the exposed surfaces 22a and 23a with respect to the substrate 21 becomes clear, and the inspection with regard to the deviation of the inner layer can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method in the manufacturing process of multilayer printed wiring boards.

Generally, multilayer printed wiring boards are manufactured through the steps shown in FIG. First, in step 1, a plurality of substrates on which wiring patterns are formed are laminated to form a multilayer printed wiring board body, then step 2 is performed to form through holes, and then step 3 is performed to form through holes. Finally, step 4 is performed to form a surface circuit pattern.

[0003] After each process, inspection processes 5, 6, and 7 are included, and in-process inspection is performed. In recent years, multilayer printed wiring boards have become denser, through-holes have become smaller in diameter, patterns have become finer, and the reliability of in-process inspection has become a problem.

0004

[Prior Art] Conventional in-process inspections are carried out after the previous process has been completed.
were inspected as they were as objects to be inspected.

[0005]

[Problems to be Solved by the Invention] However, as the diameter of through holes becomes smaller and patterns become finer, it becomes difficult to determine the presence or absence of defects, and defects may be overlooked.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for inspecting a multilayer printed wiring board, which makes it possible to improve the reliability of inspection.

[0007]

[Means for Solving the Problems] The invention according to claim 1 provides a method for inspecting a copper inner layer of a multilayer printed wiring board.
A step of black oxidizing the multilayer printed wiring board body in which a through hole is formed so as to penetrate the inner layer is performed, and a step of inspecting the multilayer printed wiring board body subjected to the black oxidation treatment as an object to be inspected. It is something.

The invention of claim 2 is a method for inspecting copper through holes in a multilayer printed wiring board, including the step of black oxidizing the multilayer printed wiring board body in which the copper through holes are formed. The apparatus is configured to perform a process of inspecting a processed multilayer printed wiring board body as an object to be inspected.

The invention according to claim 3 is a method for inspecting a copper surface circuit pattern of a multilayer printed wiring board, including the step of black oxidizing the multilayer printed wiring board body on which the copper surface circuit pattern is formed; This apparatus is configured to perform an inspection process using a multilayer printed wiring board body subjected to black oxidation treatment as an object to be inspected.

0010

[Operation] In the invention according to claim 1, the black oxidation treatment improves the contrast of the inner layer.

In the second aspect of the invention, the black oxidation treatment improves the contrast of the through holes.

In the third aspect of the invention, the black oxidation treatment improves the contrast of the surface circuit pattern.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a method for inspecting inner layer displacement according to a first embodiment of the present invention. This inspection is performed in inspection step 5 in FIG.

Assume that the state after performing the through-hole forming step 2 in FIG. 7 is the state shown in FIG. 2(A).

In FIG. 2(A), 20A is the main body of the multilayer printed wiring board, 21 is a base material made of glass epoxy or glass polyimide, 22 and 23 are inner layers made of copper, and 22a and 23a are through holes among the inner layers 22 and 23. This is the surface exposed into the hole 24.

As a step before performing the inspection step 11, a black oxidation treatment step 10 is performed. In this black oxidation treatment, the main body 20A of the multilayer printed wiring board shown in FIG. 2(A), which has completed the through-hole forming step 2 in FIG. This is done by immersing it in warm water for 4 to 5 minutes.

As a result, as shown by the matte pattern in FIG. 2(B), the exposed surfaces 22a,
A black oxide film 25 is formed only on 23a.

The multilayer printed wiring board main body 20B subjected to this black oxidation treatment is the object to be inspected, and the next inspection step 11 is carried out.
I do.

Paying attention to the inside of the hole 24, the color of the base material 21 is light green in the case of glass epoxy, and brown in the case of glass polyimide.
is visible.

Therefore, the contrast between the inner layer exposed surfaces 22a and 23a with respect to the base material 21 is clearer than when the black oxidation treatment is not performed (the brown of the copper background appears in the pale green or brown color). Therefore, the inspection regarding the displacement of the inner layer can be performed more reliably than in the past.

In the case shown in FIG. 2(B), it is determined that the upper inner layer 22 has shifted. After the inspection, an oxide film removal step 12 in FIG. 1 is performed.

In step 12, the substrate body 20B that has been inspected is immersed in hydrochloric acid having a concentration of 10%. As a result, the black oxide film 25 is removed, and the copper inner layers 22, 23 are removed.
is exposed and becomes the original substrate main body 20A shown in FIG. 2(A), and only non-defective products are transferred to the next process.

FIG. 3 shows a through-hole inspection method according to a second embodiment of the present invention. This inspection is performed in inspection step 6 in FIG.
It is carried out in

As a step before performing the inspection step 31, a black oxidation treatment step 30 is performed. This black oxidation treatment is performed in the same manner as described above for the multilayer printed wiring board main body 20C in FIG. 4A, on which the through-hole forming step 3 in FIG. 7 has been completed and the copper through-hole plating layer 40 has been formed. .

As a result, as shown in FIG. 4B, a black oxide film 41 is formed on the surface of the copper through-hole plating layer 40 as shown in a satin pattern.

The multilayer printed wiring board main body 20D subjected to this black oxidation treatment is the object to be inspected, and the next inspection step 31 is carried out.
I do.

If the through hole has a defect indicated by reference numeral 42, a pale green or brown portion is visible on a part of the black background inside the through hole. For this reason, the contrast is clearer than when a pale green or brown color appears on a part of the brown background of copper when black oxidation treatment is not performed, and inspections for through-hole defects are easier than before. Performed reliably.

The one shown in FIG. 4(B) is judged to have a through-hole defect. After the inspection, an oxide film removal step 32 in FIG. 3 is performed in the same manner as the above step 22 to remove the black oxide film 31. As a result, the base material main body 20D is as shown in FIG.
The original board main body 20C shown in (A) is obtained, and only non-defective products are transferred to the next process.

FIG. 5 shows a surface circuit pattern inspection method according to a third embodiment of the present invention. This inspection is performed in inspection step 7 in FIG.

As a step before performing the inspection step 51, a black oxidation treatment step 50 is performed. This black oxidation treatment is performed in the same manner as described above for the multilayer printed wiring board main body 20E of FIG. 6A, which has completed the surface circuit pattern forming step 4 in FIG.

As a result, a black oxide film 61 is formed on the surface of the copper surface circuit pattern 60 as shown in a satin pattern as shown in FIG. 6(B).

The multilayer printed wiring board main body 20F that has been subjected to this process becomes the object to be inspected, and the next inspection step 51 is performed.

If the surface circuit pattern 60 has a defect as shown by the reference numeral 62, the surface circuit pattern 60 has a black line extending in a light green or brown background color.
It is visually recognized that part of this black line is missing. Therefore, the contrast between the line and the ground color of the base material 21 is clearer than in the case where the brown line extends on a pale green or brown background in the case where the black oxidation treatment is not performed. is performed more reliably than in the past.

The one shown in FIG. 6(B) is determined to have a defect. After the inspection is completed, oxide film removal step 5 in FIG.
Step 2 is carried out in the same manner as the above step. As a result, the black oxide film 61 is removed, and the substrate main body 20F in FIG. 6(B) is returned to the original substrate main body 20E in FIG. 6(A), and only non-defective products are transferred to the next process.

[0035] Inspection step 1 in each of the above embodiments
1, 31, and 51 may be performed optically in addition to visual inspection, and can be inspected with high reliability as in the case of visual inspection.

Furthermore, the inspection method of the present invention can be applied to a multilayer printed wiring board having a structure in which the base material is ceramic, and has similar effects.

[0037]

As described above, according to the invention of claim 1, it is possible to reliably inspect the presence or absence of displacement in the copper inner layer of a multilayer printed wiring board.

According to the second aspect of the invention, the presence or absence of defects in copper through-holes in a multilayer printed wiring board can be inspected with high reliability.

According to the third aspect of the invention, the presence or absence of defects in the copper surface circuit pattern of a multilayer printed wiring board can be inspected with high reliability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a method for inspecting inner layers of a multilayer printed wiring board according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the multilayer printed wiring board main body during the inspection of FIG. 1;

FIG. 3 is a diagram showing a method for inspecting inner layers of a multilayer printed wiring board according to a second embodiment of the present invention.

FIG. 4 is a diagram showing the multilayer printed wiring board main body during the inspection of FIG. 3;

FIG. 5 is a diagram showing a method for inspecting a surface circuit pattern of a multilayer printed wiring board according to a third embodiment of the present invention.

FIG. 6 is a diagram showing the multilayer printed wiring board main body during the inspection of FIG. 5;

FIG. 7 is a diagram illustrating the manufacturing process of a general multilayer printed wiring board.

[Explanation of symbols]

1 Lamination process 2 Through-hole formation process 3 Through-hole formation process 4 Surface circuit pattern formation process 10, 30, 50 Black oxidation treatment process 11, 31, 5
1 Inspection process 12, 32, 52 Black oxide film removal process 20A, 20
C, 20E Multilayer printed wiring board body 20B, 20D
, 20F Black-treated multilayer printed wiring board 22, 23 Copper inner layer 22a, 23a Exposed surface 24 Through hole 25, 41, 61 Black oxide film 40 Copper through-hole plating layer 42, 62 Defect 60 Copper surface circuit pattern

Claims (3)

[Claims] 1. A method for inspecting a copper inner layer of a multilayer printed wiring board, comprising a step (10) of black oxidizing a multilayer printed wiring board main body (20A) in which a through hole is formed so as to penetrate the inner layer. A method for inspecting a multilayer printed wiring board, characterized in that the step (11) of inspecting a multilayer printed wiring board main body (20B) which has been subjected to a black oxidation treatment as an object to be inspected. 2. In a method for inspecting copper through holes in a multilayer printed wiring board, a step (30) of black oxidizing the multilayer printed wiring board body (20C) in which the copper through holes are formed, A method for inspecting a multilayer printed wiring board, characterized in that the step (31) of inspecting an oxidized multilayer printed wiring board main body (20D) as an object to be inspected. 3. A method for inspecting a copper surface circuit pattern of a multilayer printed wiring board, comprising: a multilayer printed wiring board body (20E) on which the copper surface circuit pattern is formed;
A multilayer printed wiring board characterized in that it is configured to perform a step (50) of subjecting it to black oxidation treatment, and a step (51) of inspecting the black oxidized multilayer printed wiring board main body (20F) as an object to be inspected. inspection method.