JP2814722B2 - Printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding a printed wiring board widely used for the circuit configuration of various electronic devices, the metal film thickness of each of the circuit patterns formed in the actually used actual region can be accurately and easily determined. The purpose is to provide a printed wiring board that can be inspected in the same way as the inspection pattern formed in the test area in the actual area of the insulating board that is actually used as a printed wiring board by forming circuit patterns and vias An investigation internal pattern having a metal structure is formed between any of the circuit patterns and the via.

[Industrial applications]

The present invention relates to a printed wiring board widely used for circuit configurations of various electronic devices.

2. Description of the Related Art Recently, semiconductor devices mounted on printed circuit boards of various information processing devices are becoming more highly integrated and input / output terminals are increasing, and accordingly, printed wiring boards are made of multi-layer metal for high-speed signal transmission. Fine conductor patterns and bonding pads are formed at a high density in an actual region actually used as a printed wiring board. In order to control the thickness of each metal layer of these conductor patterns and bonding pads, a test pattern is formed in a test area outside the actual area, and the thickness of each metal layer of this test pattern is Since the conductor pattern formed in the region is formed thicker, there is a demand for a printed wiring board capable of accurately and easily examining the metal film thickness of each of the circuit patterns formed in the actual region.

[Conventional technology]

As shown in FIG. 3, a conventionally widely used printed circuit board has an insulating substrate 1 in which an insulating layer 1-2 of an organic thin film such as polyimide is provided on a surface of a base material 1-1 made of ceramic as shown by a broken line. As shown in the drawing, the actual area 4 is actually used as a printed wiring board, and the test area 2 is formed outside the broken line. In the actual area 4, a circuit pattern 5 and a via 6 are formed on the surface. The test region 2 forms a survey pattern 3 for examining the thickness of each metal layer of the circuit pattern 5 and the via 6.

FIG. 4 is a cross-sectional view of a circuit pattern 5 having a plurality of types of metal structures. An insulating layer 1-2 is an organic thin film such as polyimide applied to the surface of a base material 1-1 made of ceramic, and a base metal 5-1. Is a film which selects a metal having good compatibility with the insulating layer 1-2 to guarantee the adhesion strength, and a conductive metal layer 5-
Reference numeral 2 denotes a film made of, for example, copper capable of minimizing a DC drop relating to DC resistance, and a barrier metal layer 5-3 includes a solder supplied for bonding directly contacting the conductor metal layer 5-2. The film made of, for example, nickel plating for preventing the conductive metal layer 5-2 from being corroded, and the oxidation preventing metal layer 5-4 is a gold plating film for guaranteeing the solder leakage.

[Problems to be solved by the invention]

The problem with the conventional printed wiring board described above is that, as shown in FIG.
That is, a via 6 on which an LSI (not shown) is mounted and a circuit pattern 5 for signal transmission are formed inside, and a test pattern 3 for checking the reliability of the via 6 and the circuit pattern 5 is located outside thereof, that is, the test area 2. Therefore, during the manufacturing process, a location close to the plating electrode, that is, the insulating substrate 1
Has a disadvantage that the metal layer of the circuit pattern 5 and the via 6 becomes thicker than the investigation pattern 3 due to the feature that a large amount of metal arrives on the outer periphery of the substrate.

Therefore, the thickness of the conductive metal layer 5-2 needs to be formed to a certain thickness or more in order to guarantee the DC drop value of the circuit pattern 5, and the printed wiring board (not shown in the drawing) In order to change the wiring of the pattern, pattern cutting may be performed with a laser. In this case, if the film thickness is too large, laser cutting may not be performed, so it is necessary to control the maximum film thickness. .

In addition, the minimum thickness of the barrier metal layer 5-3 has a function as a via metal, and the maximum thickness has to be controlled to a constant value in order to avoid the above-described laser cut property and pad peeling due to plating stress. Has occurred.

Further, as a method of examining the thickness of each metal layer of the multilayered circuit pattern 5, for example, there is a destructive inspection using a fluorescent X-ray apparatus, but in this method, three or more layers are measured. There is also a problem that it cannot be done.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a printed wiring board capable of accurately and easily examining the metal film thickness of each circuit pattern formed in an actual region to be actually used. .

[Means for solving the problem]

In the present invention, the circuit pattern 5 and the via 6 are formed as shown in FIG.
A first pattern for inspection 13-1 composed of a base metal layer 5-1 and a conductive metal layer 5-2 of FIG.
-1 is further formed with a second inspection pattern (13-2) on which a barrier metal layer 5-3 and an antioxidant metal layer 5-4 are applied.

(Operation)

In the present invention, when the first and second patterns for inspection 13-1 and 13-2 formed in the actual region 4 of the insulating substrate 1 are inspected by a fluorescent X-ray apparatus, the first metal layer 13-1 for the first inspection is obtained. 51 and the thickness of the conductive metal layer 5-2 can be measured. In the second pattern for inspection 13-2, the barrier metal layer 5-3 and the oxidation prevention metal layer 5 provided on the first pattern for inspection 13-1 can be measured.
Since the film thickness of −4 can be measured, the thickness of each metal layer of the circuit pattern 5 formed simultaneously with the first and second patterns for inspection 13-1 and 13-2 can be estimated from the measured value. As a result, the quality determination accuracy of the printed wiring board is improved, and the occurrence state of the failure of the circuit pattern 5 can be grasped.

Further, since the first and second patterns for inspection 13-1 and 13-2 are formed near the circuit pattern 5, the first and second patterns for inspection have characteristic impedances of 13-1 and 13-2, respectively. The quality of the circuit pattern 5 can be estimated by measuring the DC resistance and the adhesion strength of the metal film.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a plan view showing a printed wiring board according to the present embodiment, and FIG. 2 is a cross-sectional view of an inspection pattern according to the present embodiment, in which the same members as those in FIGS. 3 and 4 are the same. The reference numerals 13-1 and 13-2 indicate investigation patterns formed in the actual area.

As shown in FIG. 2 (a), the first pattern for inspection 13-1 is formed on an insulating substrate 1 in which an insulating layer 1-2 of an organic thin film such as polyimide is formed on the surface of a base material 1-1 made of ceramic. ,
This is obtained by applying a base metal layer 5-1 and a conductor metal layer 5-2 identical to the circuit pattern formed in the actual region.

As shown in FIG. 2 (b), the second inspection pattern 13-2 is formed by applying a barrier metal layer 5-3 and an antioxidant metal layer 5-4 on the first inspection pattern 13-1. This has the same metal configuration as the circuit pattern formed in the actual region.

In the printed wiring board of the present invention, as shown in FIG. 1, a test pattern 3 similar to the conventional one is formed in a test area 2 outside a broken line of an insulating substrate 1 and a circuit pattern 5 is formed in an actual area 4. In addition to forming the via, the first pattern for inspection 13-1 and the second pattern for inspection 13-2 are formed continuously at an arbitrary position where the circuit pattern 5 and the via 6 are not formed.

The first pattern for survey 13-1 and the second pattern for survey
The formation method of 13-2 is to form a base metal layer 5-1 and a conductor metal layer 5-2 simultaneously with the circuit pattern 5 and the via 6 formed in the actual region 4 of the insulating substrate 1, and to form the conductor metal layer 5- First part 13-1 for investigation by coating a part of 2
Then, a barrier metal layer 5-3 and an antioxidant metal layer 5-4 are sequentially applied on the other portion of the conductive metal layer 5-2 to form a second pattern for inspection 13-2.

As a result, the first and second patterns 13-1, 13-
2 can be examined with a fluorescent X-ray apparatus, and based on the values, the underlying metal layer 5-1 of the circuit pattern 5, the conductor metal layer 5-2, the barrier metal layer 5-3, and the antioxidant metal layer 5- 4 can be measured, and the quality of the circuit pattern 5 can be improved by taking a countermeasure according to the failure occurrence state.

The first and second patterns 13-1, 13-
The quality of the circuit pattern 5 can be estimated by measuring the characteristic impedance, the DC resistance, and the adhesion strength of the metal film.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, by forming a very simple internal pattern for inspection at an arbitrary position in the actual region, each metal film of the circuit pattern formed in the actually used actual region is formed. Provided is a printed wiring board that has an advantage that the thickness can be accurately and easily investigated, and that the measures for improving the quality of the circuit pattern can be easily performed, and that significant economical and reliability improvement effects can be expected. be able to.

[Brief description of the drawings]

FIG. 1 is a plan view showing a printed wiring board according to one embodiment of the present invention, FIG. 2 is a cross-sectional view showing a pattern for inspection of this embodiment, FIG. 3 is a plan view showing a conventional printed wiring board, FIG. 4 is a cross-sectional view showing the layer configuration of the circuit pattern. In the figure, 1 is an insulating substrate, 2 is a test area, 3 is a test pattern, 4 is an actual area, 5 is a circuit pattern, 6 is a via, 5-1 is a base metal layer, 5-2 is a conductive metal layer, 5 -3 indicates a barrier metal layer, 5-4 indicates an antioxidant metal layer, 13-1 indicates a first pattern for inspection, and 13-2 indicates a second pattern for inspection.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H05K 1/02 H05K 1/09 H05K 3/24

Claims (3)

(57) [Claims] A circuit pattern (5) and a via (6) are formed in an actual area (4) of an insulating substrate (1) actually used as a printed wiring board, and in a test area (2). A printed wiring board, wherein an internal pattern for inspection (13) having the same metal structure as the pattern for inspection (3) is formed between any of the circuit patterns (5) and the via (6). 2. The inspection internal pattern (13) comprises a base metal layer (5-1) and a conductor metal layer (5-2) of the circuit pattern (5) formed on the insulating substrate (1). A first pattern for investigation (13-1), and a first pattern for investigation having a barrier metal layer (5-3) and an antioxidant metal layer (5-4) formed on the first pattern (13-1). The printed wiring board according to claim 1, wherein a second pattern (13-2) is formed. 3. A base metal layer (5-1) and a conductive metal layer (5-2) are formed simultaneously with the formation of the circuit pattern (5) and the via (6) in the actual region (4). A first pattern (13-1) for inspection is formed by coating a part of the conductive metal layer (5-2), and the other conductive metal layer (5-2) is formed.
-2), a barrier metal layer (5-3) and an antioxidant metal layer (5-4) are sequentially applied to form a second pattern (13-
2. A method for manufacturing a printed wiring board, wherein 2) is formed.