JP5200575B2 - Circuit board, circuit board inspection method, and circuit board manufacturing method - Google Patents

Description

  The present invention relates to a circuit board used in various electronic devices such as a personal computer, a mobile communication telephone, and a video camera.

  In recent years, as electronic devices have higher functionality and higher density, electronic components are becoming increasingly smaller, highly integrated, faster, and multi-pinned.

  For this reason, circuit boards are becoming increasingly denser and lighter. In addition, there is an increasing demand for circuit boards that are fast and inexpensive and that are highly reliable.

  A conventional circuit board will be described below.

  First, a method for manufacturing a two-layer circuit board that serves as a base of the multilayer circuit board will be described. 5A to 5F are process cross-sectional views of a conventional method for manufacturing a two-layer circuit board.

  In FIG. 5, reference numeral 1 denotes a prepreg sheet of substrate material (hereinafter referred to as prepreg), for example, a composite material in which a glass cloth is impregnated with a thermosetting epoxy resin. Reference numerals 2a and 2b denote release films, which are plastic sheets each having a Si-type release agent applied on one side, and for example, polyethylene terephthalate is used. Reference numeral 5 denotes a through hole, which is formed using a laser 4 processing method or the like. The through holes 5 are filled with a conductive paste 8 electrically connected to metal foils 9a and 9b such as Cu to be attached to both surfaces of the prepreg 1.

  First, as shown in FIG. 5A, the release films 2 a and 2 b are thermocompression bonded to the top and bottom of the prepreg 1. Next, as shown in FIG. 5B, through holes 5 are formed at predetermined locations of the bonded prepreg 1 by a laser 4 processing method.

  Next, as shown in FIG. 5C, the through-hole 5 is filled with the conductive paste 8. As a method for filling the conductive paste 8, the prepreg 1 having the through holes 5 is placed on a table of a printing machine (not shown), and the conductive paste 8 directly uses the squeegee 6 from above the release film 2. Printed.

  Next, as shown in FIG. 5 (d), the release films 2 a and 2 b are peeled from the peeling trigger portions 3 a and 3 b on both sides of the prepreg 1.

  Next, as shown in FIG. 5E, a positioning via (not shown) is placed on a metal foil 9b placed on a positioning stage (not shown) and a recognition device (not shown) such as a CCD. ) Is recognized, positioned and stacked. Next, as shown in FIG. 5 (e), the metal foil 9a is laminated so that the prepreg 1 is sandwiched between the metal foil 9b, and the entire surface is heated and pressurized by hot press to be molded and cured, and the prepreg 1 and the metal The foils 9a and 9b are bonded, and the conductive paste 8 is compressed, so that the upper and lower metal foils 9a and 9b are electrically connected by the conductive paste 8 filled in the through holes 5 provided at predetermined positions. The

  Then, as shown in FIG. 5F, the upper and lower metal foils 9a and 9b are selectively etched to obtain a two-layer circuit board 11 on which circuit patterns 10a and 10b are formed.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2004-221236 A

  However, in the step of laminating a release film that serves as a mask when filling the prepreg and the conductive paste, when the temperature of the lamellar roll is low, generally, the resin of the prepreg does not sufficiently melt and the release film Adhesion is insufficient. In that case, as shown in FIG. 6, a gap 12 is generated between the prepreg 1 and the release films 2a and 2b. After that, when the through-hole 5 is formed by laser processing and the conductive paste 8 is filled, the conductive paste 8 enters the gap between the prepreg 1 and the release films 2a and 2b, and the through-hole 5 that is supposed to be embedded originally. In other cases, paste spread 13 may occur. When this paste bleeding 13 occurs, it may short-circuit with the adjacent patterns 10a and 10b, which may cause a defect.

  Further, as shown in FIG. 7, even when the conductive paste is not blotted, when the through hole 5 and the circuit pattern 10a are misaligned during alignment, the through hole 5 and the circuit pattern 10c due to misalignment are generated. May be short-circuited.

  As a conventional method for detecting bleeding, there are a method of visually confirming an arbitrary place of a prepreg immediately after filling with a conductive paste, and a detection method by electrical inspection of a finished product.

  However, there are tens of thousands to hundreds of thousands of through-holes for connecting interlayers in general printed wiring boards, and it is not practical to detect each through-hole visually, and bleeding is efficiently performed. It is necessary to confirm. Although it is possible to detect bleeding by electrical inspection, it will be detected after a few days after filling the paste, so in the case of mass production, the same defect will occur in subsequent lots until then. There was a risk of getting lost.

  The present invention can easily detect bleeding of the conductive paste with high accuracy, and can also detect the state of work-in-process during the manufacturing process. Another object of the present invention is to provide a circuit board inspection method and a circuit board manufacturing method.

  In order to achieve the above object, the circuit board of the present invention has the following configuration. A plurality of conductive layers, insulating layers alternately stacked with the conductive layers, and a conductor that penetrates the insulating layers and electrically connects the conductive layers, and the conductor and the conductor are provided. A circuit board comprising: an inspection coupon comprising a circuit pattern disposed in a first conductive layer adjacent to a formed insulating layer and having an opening formed so that a horizontal position thereof is the same as the conductor. is there.

  With this configuration, it is possible to easily detect bleeding and displacement of the conductive paste with high accuracy, and to detect the state of the work in progress during the manufacturing process.

  According to the circuit board, the circuit board inspection method, and the circuit board manufacturing method of the present invention, not only the opening is observed, but also the presence or absence of electrical connection is confirmed, thereby preventing the conductive paste from spreading and shifting. It can be easily detected with high accuracy. In addition, since it can be detected in the state of work-in-progress during the manufacturing process, it is possible to prevent a processing loss that a defective product is processed in the subsequent process, and at the same time, it feeds back to the previous process at an early stage to continuously generate defects. Can be minimized.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a process sectional view showing a circuit board manufacturing method according to an embodiment of the present invention. In FIG. 1, (a) is the figure which laminated the release film on the prepreg.

  Reference numeral 21 denotes a prepreg sheet (hereinafter referred to as prepreg), for example, a composite material obtained by impregnating a glass cloth base material with a thermosetting epoxy resin.

  22a and 22b are release films, which are plastic sheets having a Si-type release agent applied on one side, and for example, polyethylene terephthalate is used.

  Reference numeral 25 denotes a through hole, which is formed by laser processing of 24 or the like. 25 is filled with a conductive paste 27 for forming conductive holes electrically connected to the metal foils 29a and 29b such as copper to be attached to the top and bottom of the prepreg 21.

  First, the release films 22a and 22b are arranged above and below the prepreg 21, and are passed between rotating heating rolls with the upper and lower two sets as a set, so that the release film 22a as shown in FIG. 1 (a). , 22b is obtained.

  Next, as shown in FIG. 1B, a through hole 25 is formed at a predetermined location of the prepreg 21 to which the release films 22a and 22b are bonded up and down using a laser processing method or the like.

  As shown in FIG. 1C, the through-hole 25 is filled with a conductive paste 27. As a method of filling the conductive paste 27, the prepreg 21 having the through holes 25 is placed on a table of a printing machine (not shown), and the conductive paste 27 is directly applied to the release film 22 a from the top 26. Print using a squeegee. At this time, the release films 22a and 22b serve as a printing mask and prevent the surface of the prepreg 21 from being contaminated.

  Next, as shown in FIG. 1 (d), the release films 22a and 22b are peeled off from the top and bottom of the prepreg 21 from the peeling trigger portions 23a and 23b, and the prepreg filled with the conductive paste as shown in FIG. 1 (d). Can do.

  As shown in FIG. 1E, a positioning via (not shown) is placed on a metal foil 29b placed on a positioning stage (not shown), and a recognition device (not shown) such as a CCD. After the prepreg 21 is recognized and positioned by laminating, the prepreg 21 and the metal foil 29b are temporarily bonded and fixed.

  Next, as shown in FIG. 1 (e), the metal foil 29a is laminated so that the prepreg 21 is sandwiched between the metal foil 29b, and the upper and lower metal foils 29a, 29a, 29b and the prepreg 21 are temporarily bonded and fixed.

  Next, the entire surface is heated and pressed with a hot press so that the prepreg 21 which is molded and hardened to become an insulating layer and the metal foils 29a and 29b are bonded together, and the conductive material filled in the through holes 25 provided at predetermined positions is adhered. The paste 27 is compressed and the upper and lower metal foils 29a and 29b are electrically connected.

  Then, as shown in FIG. 1 (f), a two-layer circuit board 31 having circuit patterns 30a and 30b formed on the back and front surfaces by etching the upper and lower metal foils 29a and 29b is obtained.

  Further, a prepreg filled with the conductive paste shown in FIG. 1 (d) is disposed on both sides of the two-layer circuit board 31 as a core substrate, and a metal foil is disposed on the outer side thereof, followed by heating and pressurization, and a surface layer. By forming a circuit pattern, a four-layer circuit board can be obtained. Further, by repeating the same process using the four-layer substrate as a core substrate, a circuit substrate having six or more layers can be obtained.

  As described above, a circuit board including a plurality of conductive layers, insulating layers alternately stacked with the conductive layers, and a conductor that penetrates the insulating layers and electrically connects the conductive layers can be obtained. In the first embodiment, an example in which the conductive layer is formed by metal foil is shown. However, other well-known methods such as transfer after performing metal plating on the support may be used. Moreover, although the insulating layer showed the example which shape-hardens a prepreg, you may use a resin film etc. Moreover, although the conductor showed the example which fills the through-hole which processed the conductive paste into the prepreg, and it heat-hardens, it can also be formed by the method of penetrating the conductive paste into the prepreg.

  Next, the inspection coupon of this embodiment will be described.

FIG. 2 is a cross-sectional view and a plan view showing an inspection coupon for a circuit board in the same embodiment. FIG. 2 (c) shows an overall image of the inspection coupon 60, and FIG. 2 (a) shows an enlargement of a part thereof. The inspection coupon according to the present embodiment includes a conductor 53 and a circuit pattern formed on the first conductive layer 51 on the upper surface of the insulating layer 56 provided with the conductor 53. An opening 54 is formed in the formed circuit pattern so that the horizontal position of the conductor 53 is the same. The cross-sectional shape of the conductor 53 in the horizontal direction is circular, and the shape of the opening 54 is also circular. Here, the center of the conductor 53 and the center of the opening 54 are at the same horizontal position. In the plan view of the circuit board as viewed from above as shown in FIG. The center of 54 shows that it becomes the same position. The horizontal sectional shape of the conductor 53 is a sectional view in a plane parallel to the above plan view.

  By forming the inspection coupon so that the first conductive layer and the opening 54 are on the surface of the circuit board, the conductor 53 is exposed from the opening 54 and the conductor 53 can be visually observed from the surface. Here, by making the diameter of the opening 54 larger than the diameter of the cross section of the conductor 53, it is possible to visually confirm the bleeding or displacement of the conductor 53. That is, when there is no bleeding or deviation, the conductor 53 is positioned inside the opening 54 so as to be concentric. At this time, it is also effective to design the permissible value 57 of bleeding / deviation set based on the product specifications to be the same as the size of one side of the clearance between the opening 54 and the conductor 53. This is because it is possible to detect the presence or absence of bleeding or deviation depending on whether or not a part of the conductor 53 is in contact with the periphery of the opening 54 as shown in FIG. FIG. 3A shows a paste bleeding portion 58, and FIG. 3B shows a misalignment 59.

  It is also effective to confirm by image recognition using an automatic visual inspection apparatus instead of visual inspection. In this case, it is also possible to obtain the center coordinates of the opening and the center coordinates of the conductor by image recognition, and the difference between the X and Y components of bleeding and deviation can be quantified.

  It is effective to carry out the above inspection every time an inner layer circuit pattern is formed, which is an intermediate process in circuit board manufacture. Immediately after the circuit pattern is formed, the circuit pattern to be inspected is located on the surface layer, so inspection by the visual inspection or visual inspection apparatus described above is possible, and processing loss caused by advancing defective products to the next process can be prevented. It is. In addition, process troubles can be discovered at an early stage, and continuous occurrence of defects can be suppressed.

  Even if the first conductive layer and the opening 54 of the inspection coupon are not in the surface portion of the circuit board but in the inner layer, the transmission image is inspected by the same method by irradiating X-rays. be able to. Also in this case, as in the appearance inspection, the center coordinates of the opening and the center coordinates of the conductor are obtained, and the X and Y components of bleeding and deviation can be quantified based on the difference.

(Embodiment 2)
Next, an example of another inspection coupon will be described as a second embodiment.

  The inspection coupon according to the second embodiment includes a circuit pattern formed on the conductor 53 and the first conductive layer 51 on the top surface of the insulating layer 56 provided with the conductor 53 in FIG. In addition to the form shown in the first embodiment, the circuit pattern formed in the first conductive layer 51 has the opening 54 formed so that the horizontal position of the conductor 53 is substantially the same position. In the case of a non-defective product, the first conductive layer 51 is always provided with a separating portion 62 to indicate open, and a circuit pattern is formed on the second conductive layer 52 on the lower surface of the insulating layer 56 provided with the conductor 53. It is formed so as to be electrically connected to the conductor 53.

  In the second embodiment, when bleeding and deviation exceed an allowable value, the circuit pattern formed on the first conductive layer 51 and the circuit pattern formed on the second conductive layer 52 are electrically short-circuited. Therefore, bleeding and deviation can be detected by electrical inspection.

  What is necessary is just to set suitably the number of the conductors 53 and the opening part 54 in one test | inspection coupon as a selection matter. When the number is large, the conductors 53 may be arranged in series by bending the circuit pattern formed on the first conductive layer 51 in the middle as shown in FIG. 2B.

  Further, as shown in FIG. 2C, the circuit pattern formed on the first conductive layer 51 and the circuit pattern formed on the second conductive layer 52 are respectively inspected lands 55a located on the same surface layer. , 55b, it is convenient for measurement. FIG. 2 (d) conceptually shows the cross-sectional shape of FIG. 2 (c). The inspection lands 55 a and 55 b are formed in the first conductive layer 51.

  In addition, what is necessary is just to select suitably the installation location of an inspection coupon according to the magnitude | size and form of a product. Although it is desirable to detect the bleeding occurrence tendency in the same plane by arranging the inspection coupon on the entire surface of the substrate, for example, in order to evaluate the characteristics of the base material, the method of arranging it perpendicular to the resin impregnation direction, In order to detect abnormalities during printing of the paste filling machine, a method of arranging vertically with the filling of the paste, a method of arranging in the periphery and center of the substrate in order to detect pressure heating unevenness in the pressing process, etc. Abnormalities can be detected, and even in a limited space such as in the product area, it is possible to obtain an effect equivalent to that provided on the entire surface by arranging according to the purpose. In general, the printed wiring board is composed of a product area and a reinforcing discard board portion provided around or part of the periphery of the product area in order to flow a mounting line when soldering and mounting components. If an inspection coupon is installed at least on the discarded substrate portion, it can be used for inspection for assuring bleeding and matching accuracy for each product. In any case, in addition to the disconnection and short inspection normally performed on the product part by one electrical inspection, it is possible to inspect the conductor for bleeding and displacement.

(Embodiment 3)
The circuit board according to the third embodiment is a collective board constituted by a plurality of individual boards. In the mounting process in which components such as IC chips are soldered, it is common to use individual substrates after the collective substrate is divided by cutting, but in the circuit board manufacturing process, for efficient production In general, it is processed in the state of a collective substrate. In the case where the inspection coupon cannot be installed in either the product area or the discarded substrate portion described in the second embodiment, it can be installed in the blank space between and around the individual substrates in the collective substrate state.

  FIG. 4 is a plan view showing a circuit board according to Embodiment 3 of the present invention. In the collective board of a plurality of individual boards 61, a case where inspection coupon areas 60 are installed between and around the individual boards 61 is shown. It is shown.

  The inspection of the circuit board according to the third embodiment should be performed in the state of the collective board before cutting, noting that the inspection coupon 60 is also removed together with the blank portion after being cut into individual substrates 61. I must. By inspecting the inspection coupons 60 installed at the four corners of the individual substrate 61, the operation method of determining the individual substrate 61 surrounded by the inspection coupon 60 at the four corners as a non-defective product only when the inspection result of the four corners is OK. Can respond.

  In addition, when the circuit board according to Embodiment 3 of the present invention is used, the whole or a part of the collective substrate that has been determined to be defective is inspected in the state of the collective substrate in an appropriately selected mid-process, and a subsequent process step Then, it is possible to save useless processing costs by adopting an operation method in which processing is not performed.

  In addition, a preliminary inspection is performed during the manufacturing process of circuit boards that are mass-produced, and the results of the inspection are fed back to the manufacturing process to review the lamination conditions of the release film and prepreg, and improve the accuracy of product matching. It is also possible to make it. For example, the adhesion between the release film and the prepreg is likely to fluctuate due to temperature changes such as seasons. Therefore, the condition of the laminating temperature must be changed each time. Therefore, by periodically inspecting this inspection coupon, the amount of bleeding of the conductor is obtained and fed back to the laminating process to correct the laminating condition. Good. When bleeding of the conductor occurs, it can be improved by increasing the temperature of the laminate roll. Further, the positional accuracy of the circuit pattern on the surface layer is determined by the alignment of the exposure film when exposing a photosensitive resist such as a dry film used as an etching resist. Therefore, by inspecting the inspection coupon 60 after producing the preceding product from the exposure process to the etching, the shift amount of the circuit pattern with respect to the conductor is determined by the X component and the Y component on the two-dimensional plane, and the result is obtained in the exposure process And the alignment position of the exposure film may be corrected. This makes it possible to produce a product with high quality and high accuracy of matching.

  The circuit board, the circuit board inspection method, and the circuit board manufacturing method according to the present invention can easily detect bleeding and displacement of the conductive paste with high accuracy, and are in a state of work in progress during the manufacturing process. By detecting it, it is possible to prevent the processing loss of processing defective products in subsequent processes, and at the same time, it is possible to feed back to the previous process at an early stage and minimize the continuous occurrence of defects. It is useful for various electronic devices such as telephones and video cameras, and it can be said that the industrial applicability is great.

Sectional drawing which shows the manufacturing method of the circuit board in embodiment of this invention Sectional view and plan view showing an inspection coupon for a circuit board in the same embodiment A plan view showing a circuit board inspection method in the same embodiment The top view which shows the circuit board in the embodiment Process sectional drawing which shows the manufacturing method of the circuit board in a prior art example Sectional view showing the mechanism for occurrence of bleeding on the circuit board in the conventional example Sectional drawing which shows the position shift generation | occurrence | production mechanism of the circuit board in a prior art example

Explanation of symbols

21 Prepreg 22a, 22b Release film 23a, 23b Separation trigger 24 Laser 25 Through hole 26 Squeegee 27 Conductive paste 29a, 29b Metal foil 30a, 30b Circuit pattern 31 Two-layer circuit board 51 First conductive layer 52 First 2 Conductive Layer 53 Conductor 54 Opening 55a, 55b Inspection Land 56 Insulating Layer 57 Bleeding / Displacement Allowed Value 58 Pasting Bread 59 Displacement 60 Inspection Coupon 61 Individual Substrate 62 Separation Part

Claims (11)

A plurality of conductive layers, insulating layers alternately stacked with the conductive layers, and a conductor that penetrates the insulating layers and electrically connects the conductive layers,
The conductor is a process of laminating a release film on a prepreg by passing it between rotating heating rolls in which the prepreg is sandwiched from above and below by a release film as a set.
Processing through holes in the prepreg laminated with the release film;
Filling the through hole with a conductive paste;
It is formed by compressing the conductive paste by a manufacturing method comprising a step of laminating and heating and pressing at least the prepreg and a conductive layer,
Wherein the conductor, the conductor is disposed on the first conductive layer adjacent to the insulating layer provided, Ri circuit pattern Tona which an opening is formed,
The center of the conductor and the center of the opening are formed so that the horizontal position is the same position, and has an inspection coupon arranged so that the opening is a surface layer,
A circuit board characterized in that bleeding of the conductor can be detected by the inspection coupon . The opening formed in the circuit pattern of the first conductive layer in the inspection coupon and the horizontal cross-sectional shape of the conductor are both circular, and the diameter of the opening is larger than the diameter of the cross-section of the conductor. The circuit board according to claim 1. A circuit pattern electrically connected to the conductor is arranged on the second conductive layer located on the opposite side of the first conductive layer adjacent to the insulating layer provided with the conductor in the inspection coupon. The circuit board according to claim 1. 4. The circuit board according to claim 3 , wherein the circuit pattern of the first conductive layer and the circuit pattern of the second conductive layer in the inspection coupon are each electrically connected to the inspection land on the surface layer. . The circuit board according to claim 1, wherein the inspection coupon is disposed on a discarded substrate portion formed around or part of the periphery of the product area. The circuit board according to claim 1, wherein the inspection coupon is arranged in a product area. 2. The circuit board according to claim 1, wherein the circuit board is configured by a set of a plurality of individual boards, and an inspection coupon is arranged between or around the individual boards and outside the individual board regions. The circuit board according to claim 7 , wherein the inspection coupon is arranged at four corners of the individual board. A plurality of conductive layers, insulating layers alternately stacked with the conductive layers, and a conductor that penetrates the insulating layers and electrically connects the conductive layers,
The conductor is a process of laminating a release film on a prepreg by passing it between rotating heating rolls in which the prepreg is sandwiched from above and below by a release film as a set.
Processing through holes in the prepreg laminated with the release film;
Filling the through hole with a conductive paste;
In a circuit board formed by compressing the conductive paste by a manufacturing method comprising a step of laminating and heating and pressing at least the prepreg and a conductive layer,
The conductor and a circuit pattern that is disposed in a first conductive layer adjacent to the insulating layer provided with the conductor and in which an opening is formed,
The center of the conductor and the center of the opening are formed so that the horizontal position is the same position, the conductor exposed from the opening of the inspection coupon arranged so that the opening is a surface layer ,
A method for inspecting a circuit board, comprising: detecting blurring of the conductor by confirming visually or by image recognition whether the opening is in contact with the periphery of the opening. A plurality of conductive layers, insulating layers alternately stacked with the conductive layers, and a conductor that penetrates the insulating layers and electrically connects the conductive layers,
The conductor is a process of laminating a release film on a prepreg by passing it between rotating heating rolls in which the prepreg is sandwiched from above and below by a release film as a set.
Processing through holes in the prepreg laminated with the release film;
Filling the through hole with a conductive paste;
In a circuit board formed by compressing the conductive paste by a manufacturing method comprising a step of laminating and heating and pressing at least the prepreg and a conductive layer,
The first conductive layer is disposed in a first conductive layer adjacent to the insulating layer provided with the conductive material and has an opening, and the first insulating layer sandwiched between the insulating layer provided with the conductive material. A circuit pattern disposed on the second conductive layer located on the opposite side of the conductive layer and electrically connected to the conductor;
The circuit pattern of the first conductive layer and the circuit pattern of the second conductive layer are each electrically connected to the inspection land on the surface layer,
The center of the conductor and the center of the opening are formed so that the horizontal position is the same position, and depending on the presence or absence of electrical continuity between inspection lands of the inspection coupon arranged so that the opening is a surface layer A method of inspecting a circuit board, comprising detecting bleeding of a conductor. A process of laminating the release film on the prepreg by passing between two rotating upper and lower heating rolls with the prepreg sandwiched from above and below by the release film;
Processing through holes in the prepreg laminated with the release film;
Filling the through hole with a conductive paste to form a conductor;
Laminating at least the prepreg and a conductive layer and heating and pressing; and
Forming a circuit pattern on the conductive layer;
An inspection coupon comprising a conductor formed simultaneously with the formation of the conductor and a circuit pattern in which an opening is formed simultaneously with the formation of the circuit pattern,
The center of the conductor and the center of the opening are formed so that the horizontal position is the same position, and an inspection coupon is provided so that the opening is a surface layer ,
In the laminating step, the presence or absence of bleeding of the conductor exposed from the opening of the inspection coupon is confirmed, and when the bleeding is detected, the temperature of the heating roll is increased. Production method.

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