JP2009206298A - Multi-layer printed wiring board, its inspecting method and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when a result of visual inspection in a state of an inner layer substrate is clearly expressed with the use of oil markers or stickers to detect the result after multi-layering, there is a risk of outflow of defective products due to erasing of the markers or peeling of the stickers, or the problem that, in a method of working with a retractable knife, a drill, or a metal mold, a surface of a printed wiring board is scratched when the board is laminated or foreign matters are stuck to the surface in a post process owing to machining dust produced at working or burr of the worked part. <P>SOLUTION: An inspecting pattern is constituted by a conductive pattern of each layer and a conductor electrically connecting the conductor pattern of each layer. The inspecting pattern corresponding to an individual wiring board with defects in an inner layer circuit has a configuration wherein a resistance value between the conductive pattern and the conductor is varied to indicate the presence of defects in the corresponding individual wiring board by the resistance value of the pattern. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer printed wiring board used in various electronic devices such as a personal computer, a mobile communication device, and a video camera, and a manufacturing method thereof.

  In recent years, as electronic devices have higher functionality and higher density, electronic components that make up electronic devices are becoming increasingly smaller, highly integrated, faster, and more functional. For this reason, various forms of printed wiring boards have been proposed and put into practical use.

  In particular, a through-hole is required for drilling and metal plating because the technology for stacking and integrating the conductive paste directly after filling the adhesive layer that adheres the inner layer substrate and copper foil when multilayering is established. Thus, any layer can be electrically connected by IVH (inner-stitial via hole).

  A method for manufacturing the above-described conventional printed wiring board will be described below. 5A to 5J are cross-sectional views showing a conventional method for manufacturing a printed wiring board.

  First, as shown in FIG. 5 (a), films 2 such as PET (polyethylene terephthalate) are laminated on both sides of the prepreg 1, and vias 3 are formed thereon by drilling or carbon dioxide laser processing as shown in FIG. 5 (b). . Next, as shown in FIG. 5C, the via 3 is filled with the conductive paste 4 as a conductor by a method such as printing, and then the film 2 is peeled off from the prepreg 1 so as to be shown in FIG. Thus, the prepreg 1 in which the conductive paste 4 is filled in the via 3 is obtained. Then, as shown in FIG. 5 (e), the copper foils 5 are arranged on both sides thereof and heated and pressed by hot press to obtain FIG. 5 (f). Thereafter, the conductive patterns 6 are formed on the copper foils 5 by etching or the like. The double-sided substrate formed as shown in FIG. The completed double-sided substrate is used as the inner layer core substrate. As shown in FIG. 5 (h), the conductive paste is provided in the via 3 prepared by the same method as described above, outside the inner layer core substrate. 4 is disposed, and a copper foil 5 is disposed outside the prepreg 1, and then heated and pressed by hot press to form FIG. 5 (i), and a conductive pattern is formed on the copper foil 5 on both sides by etching or the like. The four-layer substrate shown in FIG. 5 (j) is completed.

  As a method for detecting defects such as disconnection or short-circuit of the conductive pattern 6 of the printed wiring board thus completed, a dedicated inspection in which an inspection probe is disposed at a position corresponding to an inspection point selected from a mounting land of a product conventionally. An electrical inspection is generally performed in which a jig is manufactured for each product, and this inspection probe is brought into contact with an inspection point of the product to determine whether the electrical conduction is present or not, and whether the electrical resistance value is large or small. It was. However, in recent years, as the pattern width and the pattern gap become smaller as the density of the conductive pattern 6 increases, in addition to the electrical inspection described above, it cannot be detected as a disconnection or short circuit by an appearance inspection that recognizes the shape of the conductive pattern 6. It has been required to detect potential defects such as defects, dents, thinnings, fats, and copper residues.

  In a multilayer printed wiring board, it is necessary to perform this appearance inspection for each layer. Since the inner layer is hidden inside after being multi-layered, the appearance inspection must be performed in the state of the inner layer substrate. If a defect is detected at this stage, it must be discarded on the spot, or some measure must be taken to make the inspection result detectable even after multi-layering.

  Generally, at the stage of the inner layer substrate, the printed wiring board 1 is in a state of a collective printed wiring board constituted by a plurality of individual wiring boards, that is, the individual wiring boards are arranged in two rows and three columns in one collective printed wiring board. In this state, eight are arranged in 2 rows and 4 columns, and 24 are arranged in 3 rows and 8 columns. In the mounting process of soldering parts such as IC chips, it is common to use individual individual wiring boards after dividing the collective printed wiring board by cutting, but in the manufacturing process of the printed wiring board, it is efficient. In general, it is processed in the state of a collective printed wiring board for production.

  Therefore, even if an individual wiring board that becomes defective in the inner layer board is found, it is normally not discarded to make use of other good individual wiring boards arranged in the same printed wiring board. Production will continue. And after multi-layering, the quality is judged and selected for each individual wiring board. At this time, in addition to the result of the disconnection and short circuit by the electrical inspection as a finished product, the result of the appearance inspection performed for each layer must be confirmed again, and only those that are good in all of these must be regarded as good.

  Conventionally, the following method has been used as means for detecting the result of the appearance inspection performed in the state of the inner layer substrate after multilayering. As a simple method widely adopted, there is a method of marking with an oil marker in an individual wiring board in which a defect is detected, and visually discriminating this after multilayering. There are also known a method of sticking a seal instead of marking with an oil marker, and a method of peeling a predetermined land with a cutter knife or the like. In any method, the marking, seal, and land inside are distinguished from the outside through the insulating resin layer. It is necessary to select a position where the marking or the like can be discriminated without being hidden by the conductive pattern 6 on the outer layer.

  As another method, a method in which a part of the conductive pattern 6 in the product is intentionally processed into a complete disconnection state and is detected as a disconnection defect by an electrical inspection of the finished product has been used. As a processing method for making a disconnection state, there are a method of peeling with a sharp object such as a cutter knife, a method of spot facing with a drill, and a method of punching with a drill or a die. Instead of processing the conductive pattern 6 in the product into a disconnected state, a method is also known in which a dedicated inspection pattern is provided and a circuit in this inspection pattern is processed into a disconnected state.

For example, Patent Documents 1 and 2 are known as prior art document information related to the invention of this application.
JP 2001-68819 A JP 2003-318553 A

  However, the above-described conventional printed wiring board has the following problems.

  That is, as a means for detecting the result of the appearance inspection performed in the state of the inner layer substrate after the multilayering, when it is clearly indicated by an oily marker or a seal, mechanical polishing such as buffing, acid, alkali, The oily marker disappears or the seal peels off after the treatment with the organic solvent, and as a result, even if it is visually inspected after multilayering, it may not be recognized as a defective product and may flow out as a good product. Had problems. In addition, even if the markings and seals remain until after multi-layering without disappearing or peeling off in this way, there is a problem that there is a risk of leaking out by misjudgment as long as human judgment makes it. It was.

  In addition, in the method of processing with a cutter knife, drill, or mold, the surface is damaged when the printed wiring board is overlaid due to processing waste generated by processing or burrs on the processed part, There has been a problem that foreign matter adhesion failure occurs.

  The present invention solves the above-mentioned conventional problems, and multi-layers the results of the appearance inspection performed in the state of the inner layer substrate without causing a detection failure and without causing secondary defects such as scratches and foreign matter adhesion. An object of the present invention is to provide a multilayer printed wiring board that can be detected later and a method for manufacturing the same.

  In order to solve the above conventional problems, in the multilayer printed wiring board of the present invention, the inspection pattern is composed of a conductive pattern provided in each layer and a conductor that electrically connects the conductive pattern of each layer, and the inner layer circuit is defective. The inspection pattern corresponding to the individual wiring board having a resistor has a resistor between the conductive pattern and the conductor. With this configuration, when there is a defective individual wiring board in the inner layer circuit, the inspection pattern corresponding to this individual wiring board has a higher resistance value than the normal connection state between the conductive pattern and the conductor. Since it has been processed, it is possible to detect the presence or absence of a defect in the inner layer circuit by measuring the resistance value of the inspection pattern by electrical inspection after multilayering. Furthermore, by adding a resistor, the resistance value of the inspection pattern is made higher than that of the normal connection state, and no drilling or notching processing is performed on the inspection pattern as in the past. In addition, there is no risk of burring on the machined portion, and there is no risk of scratches or foreign matter adhesion. In addition, since the quality is determined by electrical inspection using an inspection facility, there is no risk that defects will be leaked due to erroneous determination.

  In the multilayer printed wiring board of the present invention, the inspection pattern is composed of a conductive pattern provided in each layer and a conductor electrically connecting the conductive pattern of each layer, and the inspection pattern corresponds to an individual wiring board having a defect in the inner layer circuit. The pattern is characterized in that the resistor is made of the same resin as that constituting the multilayer printed wiring board between the conductive pattern and the conductor. With this configuration, the resistor is formed of the same resin as that constituting the multilayer printed wiring board. Therefore, when the inner layer substrate is heated and pressed to form a multilayer, the resistor resin melts and is individually separated from the inspection pattern portion. Even if the resin flows into the product area of the wiring board, the resin that flows into the wiring board is the same resin as that of the multilayer printed wiring board that originally exists, so that the product characteristics are not adversely affected.

  The multilayer printed wiring board of the present invention has a configuration in which at least a conductive layer in a region corresponding to the individual wiring board on the surface layer is in a solid state before forming a circuit. The conductive layer in a region corresponding to the inspection pattern on the surface layer is formed with a circuit. With this configuration, even in the so-called inner layer circuit-containing substrate in which the inner layer circuit is formed and the outer layer portion remains as a conductive layer before the circuit formation, the test result of the inner layer circuit is referred to as the presence or absence of a resistor in the test pattern. Therefore, if the circuit formation of the conductive layer of the inspection pattern part is performed, the resistance value of the inspection pattern is measured without forming the outer layer circuit of the product part of the individual wiring board. The presence or absence can be detected.

  Further, the multilayer printed wiring board of the present invention has two inspection patterns corresponding to the individual wiring boards, and one of the inspection patterns corresponding to the individual wiring board having a defect in the inner layer circuit is included in the inspection pattern. A resistor is formed between the conductive pattern and the conductor. The multilayer printed wiring board inspection method of the present invention measures the resistance value of two inspection patterns, compares the difference between the two resistance values with a reference value, and determines the individual wiring corresponding to the inspection pattern according to the magnitude. It is characterized by determining the presence or absence of a defective board. With this configuration, even if the etching amount varies depending on the location in the multilayer printed wiring board and the presence or absence of the resistor cannot be detected by the absolute amount of the resistance value of the inspection pattern, the etching amount can be reduced by arranging them at positions close to each other. The presence / absence of the resistor can be detected by obtaining the difference between the resistance values of the two inspection patterns formed to be almost equal.

  According to the multilayer printed wiring board and the manufacturing method thereof of the present invention, the results of the appearance inspection performed in the state of the inner layer substrate are multilayered without causing a detection failure and without causing secondary defects such as scratches and foreign matter adhesion. A printed wiring board that can be detected later and a method for manufacturing the same are obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a multilayer printed wiring board according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram of the multilayer printed wiring board according to Embodiment 1 of the present invention.

(Embodiment 1)
FIG. 2 is a schematic diagram showing the multilayer printed wiring board according to Embodiment 1 of the present invention.

  In FIG. 2, the multilayer printed wiring board is composed of an individual wiring board 11 and an inspection pattern 12. The individual wiring board 11 is in a solid state without forming a circuit in order to reduce damage due to conveyance or the like, and the inspection pattern 12 has a conductive pattern 6 and a conductor 9 in each layer.

  FIG. 1 shows a schematic diagram of a cross section of the multilayer printed wiring board shown in FIG. The insulating layer 7 is a cured body of the prepreg 1 and is a cured product obtained by impregnating a glass woven fabric with a thermosetting resin. The insulating layers 7 and the conductive layers are alternately formed and formed in multiple layers. In this layer, there is a conductor 9, and the upper and lower surfaces of the conductive pattern 6 formed in the conductive layer arranged for each layer are connected to form an electronic circuit. The inspection pattern 12 is provided with a resistor 8 on the surface of the conductive pattern 6 when a defect is detected in the same layer.

  When there is a defect in the inner layer portion, the resistance value of the inspection pattern 12 differs by applying the resistor 8. Therefore, the resistance value of the inspection pattern 12 is measured after multilayering and compared with a reference value. It is easy to see that there is a defective part inside.

As the thermosetting resin used for the insulating layer 7, for example, an epoxy resin, a phenol resin, or a cyanate resin can be used, and among them, the epoxy resin is more preferable because of its high heat resistance. Further, an inorganic filler such as _{SiO 2, Al 2 O 3,} Al (OH) 3 may be kneaded into the resin. The conductive pattern 6 is made of a material having electrical conductivity, for example, Cu (copper) foil or various conductive resin compositions, and Cu foil is used in the present embodiment. The conductive paste 4 is a thermosetting electric conductive material made of a conductive resin composition in which, for example, metal particles and a thermosetting resin are mixed. Au, Ag, Cu, or the like is used as the metal particles. be able to. Au, Ag, or Cu as the metal particles is preferable because of high electrical conductivity and thermal conductivity, and Cu is more preferable because of its high electrical conductivity, low migration, and low cost. The resistor 8 is interposed between the conductive paste 4 and the conductive pattern 6 and has a function of hindering conduction between the two, and preferably has a high resistance including an insulator, and is a resin, organic or inorganic filler. Containing resins are preferred. More preferably, a resin impregnated in the prepreg used for the insulator is used. In the present embodiment, the same thermosetting resin as the prepreg used for the insulator is used.

  Next, a method for applying the resistor 8 will be described. FIG. 3 is a schematic diagram of an inner layer plan view of the A surface of the multilayer printed wiring board shown in FIG. Since the defect B is generated in the conductive pattern 6 of the individual wiring board 11 part, the uncured material of the same thermosetting epoxy resin as the insulating layer is formed on the conductive pattern 6 part of the inspection pattern 12 with 2-butanone. It melt | dissolved and this solution was apply | coated and it was set as the resistor. In this embodiment, the resin was applied with a brush, dried at room temperature, and cured at 100 ° C. for 30 minutes. However, the resistance value between the conductive paste and the conductive pattern changed without performing the curing process, and the inspection pattern was changed. The resistance value of 12 changes. Thereby, in this Embodiment, after lamination | stacking, the resistance value of the test pattern 12 became infinite, and it turned out that there exists a defect in the conductive pattern of an inner layer.

  As another method for applying the resistor 8, it is also effective to attach a sheet-like resistor to the conductive pattern 6 portion of the inspection pattern 12. As the sheet-like resistor, a highly heat-resistant material such as a polyimide film is preferable.

(Embodiment 2)
FIG. 4 shows an example in which a plurality of test patterns 12 are used in order to detect the resistance value difference more accurately, and the resistance value difference depending on the presence or absence of the resistor 8 is used. When a defect is detected in the same layer, the resistor 8 is applied to the surface of the conductive pattern 6 of one inspection pattern 12. By inspecting whether there is a defect in the inner layer based on the difference between the resistance values of the two inspection patterns, it is possible to absorb product characteristic such as the thickness of the insulating layer, the width of the conductive pattern of the inspection pattern, and variations during manufacturing. .

  The resistor 8 was applied using the same method as in the first embodiment.

  The multilayer printed wiring board and the manufacturing method thereof according to the present invention are obtained after multilayering the results of the appearance inspection performed in the state of the inner layer substrate without causing a detection failure and without causing secondary defects such as scratches and foreign matter adhesion. Since it can be detected, it is useful for various electronic devices such as personal computers, mobile communication devices, and video cameras.

Sectional schematic diagram of the multilayer printed wiring board in Embodiment 1 of the present invention Schematic diagram of multilayer printed wiring board in Embodiment 1 of the present invention Schematic diagram of multilayer printed wiring board in Embodiment 1 of the present invention Sectional schematic diagram of the multilayer printed wiring board in Embodiment 2 of the present invention Sectional drawing which shows the manufacturing method of the conventional printed wiring board

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Prepreg 2 Film 3 Via 4 Conductive paste 5 Copper foil 6 Conductive pattern 7 Insulating layer 8 Resistor 9 Conductor 11 Individual wiring board 12 Inspection pattern

Claims (13)

Consists of a plurality of individual wiring boards and one or more inspection patterns corresponding to the individual wiring boards,
A conductive layer and an insulating layer alternately stacked with the conductive layer;
At least the conductive layer of the inner layer is subjected to circuit formation,
The inspection pattern is composed of a conductive pattern provided in each layer and a conductor that electrically connects the conductive pattern of each layer,
A multilayer printed wiring board, wherein the inspection pattern corresponding to an individual wiring board having a defect in an inner layer circuit has a resistor between the conductive pattern and the conductor. The multilayer printed wiring board according to claim 1, wherein the resistor includes a resin. The multilayer printed wiring board according to claim 2, wherein the resin of the resistor is a thermosetting resin. 3. The multilayer printed wiring board according to claim 2, wherein the resin of the resistor is the same as the resin constituting the multilayer printed wiring board. The multilayer printed wiring board according to claim 1, wherein the resistor includes an inorganic or organic filler. 2. The multilayer printed wiring board according to claim 1, wherein the conductive layer in a region corresponding to at least the individual wiring board on the surface layer is in a solid state before circuit formation. 7. The multilayer printed wiring board according to claim 6, wherein the conductive layer in a region corresponding to the inspection pattern on the surface layer is formed with a circuit. One of the inspection patterns corresponding to the individual wiring board having two inspection patterns corresponding to the individual wiring board and having a defect in the inner layer circuit is provided with a resistor between the conductive pattern and the conductor. The multilayer printed wiring board according to claim 1, wherein the multilayer printed wiring board is formed. A resistance value of an inspection pattern of the multilayer printed wiring board according to claim 1 is measured, and the presence or absence of a defect of the individual wiring board corresponding to the inspection pattern is determined based on the magnitude of the resistance compared with a reference value. Inspection method for printed wiring boards. A resistance value of two inspection patterns of the multilayer printed wiring board according to claim 8 is measured, a difference between the two resistance values is compared with a reference value, and a size of the individual wiring board corresponding to the inspection pattern is determined based on a magnitude thereof. A method for inspecting a multilayer printed wiring board, characterized by determining the presence or absence. A step of preparing an inner layer substrate having a plurality of individual wiring boards and one or more inspection patterns corresponding to the individual wiring boards, and having an inner layer circuit and a conductive pattern for the inspection pattern on the surface;
Inspecting the inner layer circuit;
Forming a resistor on the surface of the conductive pattern for the inspection pattern corresponding to the individual wiring board having a defect in the inner layer circuit;
Preparing a prepreg with vias filled with conductive paste;
Laminating the prepreg on the surface of the inner layer substrate and further laminating a conductive layer on the outermost layer, heating and pressurizing the laminated inner layer substrate, the prepreg, and the outermost conductive layer, at least the inner layer substrate And a step of electrically connecting the conductive pattern for the inspection pattern and the outermost conductive layer to each other through the conductive paste. 12. The method of manufacturing a multilayer printed wiring board according to claim 11, wherein the step of forming the resistor comprises applying a liquid resistor material containing a resin to the surface of the conductive pattern for the test pattern and temporarily drying the resist pattern. . 12. The method of manufacturing a multilayer printed wiring board according to claim 11, wherein the step of forming the resistor includes attaching a sheet-like resistor to the surface of the conductive pattern for the inspection pattern.

Images