JP2007288087A - Circuit board fabrication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for fabricating a circuit board with prepreg materials whose properties rarely vary to cope with requirements for increasing circuit board diversification in terms of property and structure. <P>SOLUTION: This method measures a glass transition temperature of at least one prepreg among multiple prepregs, selects only the prepregs with a glass transition temperature in a certain glass transition temperature range, and uses them as circuit board materials. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a circuit board used for various electronic devices.

  In recent years, with the miniaturization, weight reduction, and high-density mounting of electronic devices, there has been a strong demand for circuit boards with high wiring capacity and high-density mounting, such as multilayering and fine wiring. .

  A conventional method for manufacturing a circuit board will be described below.

  The substrate material 21 shown in FIG. 4 (a) is a so-called prepreg in which a glass fiber woven fabric used for a circuit board is impregnated with a thermosetting epoxy resin or the like and semi-cured by a method such as drying. As shown in FIG. 4B, an organic film 22 is attached to both surfaces of the substrate material 21 by a laminating method using a hot roll or the like.

  Next, as shown in FIG.4 (c), after forming the through-hole 23 in the board | substrate material 21 by processing methods, such as a laser, electroconductive particles, such as copper powder, thermosetting resin, and hardening | curing agent are set in the through-hole 23. Then, the conductive paste 24 kneaded with a solvent or the like is filled with a printing method or the like to obtain the configuration shown in FIG.

  Next, the organic film 22 is peeled off to obtain a shape in which the conductive paste 24 protrudes as shown in FIG. And the copper foil 25 is arrange | positioned at the both sides, and also the board | substrate material 21 is thermosetting as shown in FIG.4 (f) by further sandwiching between metal intermediate plates, such as SUS, and heat-pressing with a hot press (not shown). The conductive paste 24 is compressed and the copper foils 25 on the front and back sides are electrically connected to vias.

  Further, the copper foil 25 is processed into a desired pattern by a method such as photolithography etching to form a circuit wiring layer 26, thereby obtaining a double-sided circuit board as shown in FIG.

  In FIG. 4, the surface finishing process such as the plating process on the solder resist or the circuit wiring layer 26 of the outer layer portion normally disposed on the circuit board is not shown, but it is disposed as necessary.

  Further, when manufacturing a multilayer circuit board, as shown in FIG. 5A, the substrate material 36 and the copper foil 34 obtained by the manufacturing method described in FIG. A layered cured product as shown in FIG. 5C can be obtained by overlapping and hot pressing while aligning.

  The surface layer of the laminated cured product is processed into a desired pattern by using a copper foil 34 by a method such as photolithography etching to form a circuit wiring layer 37 to obtain a multilayer circuit board as shown in FIG.

  In FIG. 5, the surface finishing process such as the plating process on the solder resist or the circuit wiring layer 37 of the outer layer portion normally disposed on the circuit board is not shown, but it is disposed as necessary.

  It should be noted that a multilayered circuit board can be obtained by repeating the above manufacturing method.

  In such a circuit board, a method of electrically connecting a plurality of layers of circuit patterns with interstitial via holes is indispensable. For example, a circuit board for high-density mounting has been proposed in which an interstitial via hole is formed with a conductive paste or a thin fine layer having several laser plating vias is provided on the surface layer. For these circuit boards, strict management may be required for grasping the characteristics of the prepreg which is a material for forming the insulating layer.

  In other words, since the insulating layer is thinner than a general circuit board, if there are large variations in the performance and characteristics of the prepreg used in actual manufacturing, there will also be variations in circuit board performance such as circuit board flatness and insulating layer thickness. It may become large and adversely affect board characteristics such as component mountability or impedance.

  In particular, in the circuit board having a new configuration having the paste connection via described above, variations in performance and characteristics of the prepreg greatly affect the electrical connection of the via.

  On the other hand, with the trend toward higher density of circuit boards described above, circuit boards having performance such as high frequency compatibility, built-in components, or ultra-thinness are also required, and diversification is progressing.

  Along with this recent trend, the required performance of the prepreg material has become diverse, and therefore, the accuracy of grasping the characteristics of the prepreg material has been required to be stricter than before.

  As described above, grasping and managing the prepreg characteristics for circuit boards in the future are more strict than ever, requiring accuracy, and are extremely important matters.

  However, conventional prepreg property testing methods generally use tests such as resin content, resin flow, and curing time defined in JIS standard C6521.

  The test items that are particularly important are the resin flow and the curing time that affect the moldability of the circuit board. These items indirectly represent the semi-cured state of the prepreg resin as a numerical value, which is used to determine the performance of the prepreg. It is used as a value.

As prior art document information related to the invention of this application, for example, Patent Documents 1 and 2 are known.
JP-A-6-268345 JP-A-7-27726

  A conventional method for testing prepreg characteristics will be described below.

  First, a resin flow test method is to sample a prepreg in a predetermined size, for example, 100 mm square, heat and press it with a hot press at a predetermined temperature, for example, 175 ° C., and then cut it into a predetermined size, for example, 70.7 mm square. In this method, the change in weight before and after pressing is measured and the fluidity of the resin is evaluated.

  The disadvantage of this method is that measurement may be impossible or the variation may be significantly increased when the melt viscosity of the prepreg resin is extremely small or when the resin content of the prepreg is small.

  Next, the curing time test method is a method in which the resin is scraped off from the prepreg, only the resin is taken out, and the time until it is gelled on a hot plate at a specified temperature, for example, 170 ° C., is measured. .

  The disadvantage of this method is that the determination of the gelled state may depend on the measurer, and the measurer variation is included in the curing time.

  Further, when the melt viscosity of the prepreg resin is extremely small, or when the resin content of the prepreg is small, it is extremely difficult and complicated to take out only the resin from the prepreg.

  As described above, the conventional prepreg property testing method is simple and is very suitable for the prepreg production site. However, there is a limit in managing the cured state of the prepreg resin without variation.

  Further, as described above, the required performance of the prepreg material has become diverse, and prepreg materials whose performance cannot be sufficiently grasped by conventional test methods have begun to be used.

  Specifically, it is a prepreg difficult to sample, a prepreg impregnated with a highly-filled resin having a large variation, a non-flow type prepreg in which the resin flow is extremely suppressed, or a film type prepreg.

  Therefore, in the conventional test method of prepreg characteristics, if the circuit board is not manufactured by accurately grasping the characteristics of those prepreg materials and managing / selecting them, it will meet various demands for future circuit boards, Realizing and supplying is difficult.

  That is, the present invention quantifies the semi-cured state of the prepreg resin without variation in order to overcome the drawbacks of the conventional prepreg test method, and the prepreg test method is not affected by the type or structure of the resin impregnated in the prepreg. Sorting and manufacturing a circuit board using a prepreg material with very little characteristic variation.

  Accordingly, it is an object of the present invention to provide a method of manufacturing a circuit board that does not cause molding defects due to prepreg characteristics, to realize various requirements in terms of characteristics or structure, and to provide a highly reliable circuit board. Is.

  In order to solve the above problems, the present invention provides a step of preparing a plurality of prepregs comprising at least a reinforcing material and a semi-cured resin, and a step of measuring a glass transition temperature of at least one prepreg of the plurality of prepregs. And a step of selecting only a prepreg having a glass transition temperature within a specific glass transition temperature range, a step of forming a laminate by overlaying metal foils on both sides of the selected prepreg, or a core substrate and a selected prepreg The present invention provides a method for manufacturing a circuit board, comprising at least one step of forming a laminate by superimposing a metal foil and a step of heating and pressing the laminate.

  The glass transition temperature (sometimes referred to as the softening temperature) is a temperature at which the resin state changes. Specifically, by heating the prepreg, the resin physical properties such as the elastic modulus, thermal expansion and specific heat of the resin change rapidly. Temperature.

  The present inventor believes that the glass transition temperature directly reflects the molecular structure of the semi-cured resin, which is extremely effective for numerical evaluation of the prepreg characteristics, specifically the physical properties of the prepreg resin. I figured it out.

  In other words, since the glass transition temperature can detect the fluctuation of the prepreg characteristic sensitively and without variation, using this as a management index can greatly improve the accuracy and reliability of the characteristic management. it can.

  This will be described in detail as follows.

  That is, in the conventional measurement method, if the amount of resin is constant, a correlation should be established between the resin flow and the curing time.

  However, when tight tolerances are required, there is almost no correlation between them, because the ratio of measurement variation to tolerances is large.

  For example, in a prepreg having a curing time of 100 seconds, when 10% is required as the tolerance, variation by the measurement method is included about 8%. That is, 80% of the tolerance is a variation in the measurement method. Therefore, prepreg production requiring a tolerance of 10% as a curing time is extremely difficult and practically impossible. The same can be said for the resin flow.

  From the above, it is expected that the tolerances of the required specifications for the prepreg will naturally become stricter as the finer, multi-layered and diversified circuit boards in recent years.

  Therefore, for the technical development of circuit boards, the problem is how to manufacture and manage the prepreg, which is the basic material, without variation.

  In order to meet this requirement, the present invention can make the prepreg characteristic test almost non-uniform, and a physical measurement method that can cope with severe demand crossings is used for the prepreg characteristic test method. A prepreg satisfying the intersection is selected, and a circuit board is manufactured using only the selected non-defective product as a substrate material.

  In addition, as a specific method for measuring the glass transition temperature, the present inventor includes a dynamic viscoelasticity measuring device (DMA), tolerance thermal scanning calorimetry (DSC), thermomechanical measurement (TMA), and the like. It was confirmed that the glass transition temperature can be determined by a change in elastic modulus, a change in specific heat by DSC, and a change in coefficient of thermal expansion by TMA.

  In other words, the glass transition temperature measured by DMA confirmed by the present inventor is sensitive to the molecular structure of the resin, so that this measurement method is most preferable by repeating experimental evaluation. .

  In particular, this method cuts the prepreg into a predetermined size and can be measured as it is with a measuring device, so there is no judgment variation by the measurer, and there is no processing such as taking out the resin from the sample or heating and pressing the sample. Also, variations due to sample processing are not included.

  In addition, since sample processing is unnecessary, not only general glass epoxy prepreg and aramid epoxy prepreg which has been mass-produced in recent years, but also high filler filling type, thermoplastic resin blend type, non-flow type, to which conventional methods are not applied, The prepreg characteristics such as film type can be managed with high accuracy.

  Next, the invention described in each claim of the present invention and the function and effect thereof will be described below.

  The invention according to claim 1 of the present invention measures a step of preparing a plurality of prepregs made of at least a reinforcing material and a semi-cured resin, and measures a glass transition temperature of at least one prepreg of the plurality of prepregs. A process, a process of selecting only a prepreg having a glass transition temperature within a specific glass transition temperature range, a process of forming a laminate by overlaying metal foils on both sides of the selected prepreg, or a core substrate and a selected prepreg And a method of manufacturing a circuit board, comprising at least one step of forming a laminate by superimposing metal foil and a step of heating and pressing the laminate, The semi-cured state of the prepreg resin can be directly quantified as a physical property value, there is no measurement variation, and it is excellent in accuracy and reliability. Plus prepreg only can be selected. Then, by manufacturing a circuit board using the selected prepreg as a board material, it is possible to provide a high-quality circuit board excellent in accuracy and reliability.

  The invention according to claim 2 of the present invention is that the glass transition temperature is measured by directly or partially sampling the prepreg and heating it from a low temperature to a high temperature in the semi-curing in the prepreg. The method for producing a circuit board according to claim 1, wherein the temperature at which the state of the resin changes is used as a determination index. In particular, the glass transition temperature is a molecular structure of the semi-cured resin. Since it is directly reflected, it has the effect that it is extremely effective and easy to evaluate the physical properties of the prepreg resin numerically.

  In addition, since it is possible to measure in the prepreg state as it is without the need for sample processing, the prepreg characteristic test method with a wide application range that does not depend on whether the measurement is possible or not depends on the resin system, structure, etc. of the prepreg, Only a prepreg satisfying the required crossing can be selected, and a circuit board can be manufactured using the selected prepreg as a substrate material, thereby providing a high-quality circuit board excellent in accuracy and reliability.

  The invention according to claim 3 of the present invention is the method for producing a circuit board according to claim 2, wherein the glass transition temperature is obtained by a dynamic viscoelasticity measurement method. Since the elasticity measurement method reacts sensitively to the molecular structure of the resin, it is possible to select a highly accurate prepreg with no variation in measurement.

  The invention according to claim 4 of the present invention is characterized in that a loss Tanδ, which is a phase difference between the storage elastic modulus and the loss elastic modulus, is obtained by a dynamic viscoelasticity measurement method. The storage elastic modulus and loss elastic modulus in the dynamic viscoelasticity measurement method react sensitively to the molecular structure of the resin, and the measurement results can be obtained accurately and easily. By calculating the loss Tanδ, which is a phase difference, it is possible to select a highly accurate prepreg without variation in measurement.

  The invention according to claim 5 of the present invention is a method for manufacturing a circuit board according to claim 4, characterized in that the temperature at which loss Tan δ reaches a peak is obtained. In addition, it is possible to select a highly accurate prepreg that can be obtained accurately and free from measurement errors and variations.

  The invention according to claim 6 of the present invention is the method for manufacturing a circuit board according to claim 1, wherein the prepreg is formed by impregnating an aramid nonwoven fabric reinforcing material with an epoxy resin. It is possible to eliminate variations in measurement results caused by resin sampling in an aramid nonwoven fabric, and to conduct a highly accurate prepreg characteristic test free from errors and variations. Thereby, it has the effect that the prepreg provided with the aramid nonwoven fabric reinforcing material can be employed on a circuit board that requires high performance in terms of flatness, component mounting property, impedance, and the like.

  The invention according to claim 7 of the present invention is characterized in that the prepreg is made by impregnating a glass fiber reinforcing material with a resin, and the impregnation ratio of the resin is 40 wt% or less. A low-resin content type prepreg in which the resin impregnation ratio is 40 wt% or less is low in the resin flow, and the sensitivity to detect the semi-cured state of the resin is poor, which is a conventional method resulting from it. It is possible to eliminate errors and variations in the measurement results and to select a highly accurate prepreg.

  In particular, since the temperature change of the resin characteristics is directly measured, the change in physical properties can be detected even when the resin content is extremely small, and therefore, it is extremely effective for measuring the prepreg characteristics.

  As a result, it is possible to adopt a glass epoxy prepreg of a low resin content type, and it is possible to produce and provide a thin circuit board easily and with a high process yield.

  The invention according to claim 8 of the present invention is characterized in that the prepreg is formed by impregnating a resin in which a glass fiber reinforcing material is filled with a filler, and a filling ratio of the filler is 20 to 30 wt%. The method for producing a circuit board according to Item 1, which solves the problem that the characteristic test could not be performed due to the resin sample variation and the resin flow suppression due to the presence of the filler in the prepreg, and is highly accurate. A prepreg can be selected. This makes it possible to adopt a high-filler type glass epoxy prepreg, and to produce and provide a circuit board excellent in heat resistance, dielectric properties, and mechanical strength easily and at a high process yield. Have.

  The invention according to claim 9 of the present invention is the method for producing a circuit board according to claim 1, wherein the prepreg is formed by impregnating a glass fiber reinforcing material with a non-flow type resin, This type of prepreg solves the problem that the resin is not melted and there is no resin flow, and measurement is impossible in the conventional characteristic test, and a highly accurate prepreg can be selected. Thereby, it becomes possible to employ a non-flow type glass epoxy prepreg, and it is possible to produce and provide a circuit board excellent in flatness and dimensional stability easily and at a high process yield.

  The invention according to claim 10 of the present invention is the method for manufacturing a circuit board according to claim 1, wherein the prepreg is formed by impregnating a glass fiber reinforcing material with a thermoplastic resin and an epoxy resin. In addition, since this thermoplastic blend type prepreg changes the measurement temperature, it solves the problem of being impossible to measure in the conventional characteristic test, and it is possible to select a highly accurate prepreg. Accordingly, it is possible to employ a thermoplastic blend type glass epoxy prepreg, and it is possible to produce and provide a new type circuit board easily and at a high process yield.

  The invention according to claim 11 of the present invention is the method for producing a circuit board according to claim 1, wherein the prepreg is formed by applying a thermosetting resin to both surfaces or one surface of the organic film reinforcing material. This film-type prepreg solves the problem that sampling or measurement itself is extremely difficult due to its thinness, and was impossible to measure in the characteristic test by the conventional method, and a high-precision prepreg is selected. It becomes possible. As a result, it is possible to employ a polyimide film with a double-sided adhesive, and it is possible to produce and provide a new circuit board having a reduced thickness and flexibility with high process yield.

  Invention of Claim 12 of this invention is a manufacturing method of the circuit board of Claim 1 characterized by the specific glass transition temperature range being the range of 50 to 100 degreeC, By selecting a prepreg with a glass transition temperature range of 50 ° C. to 100 ° C. as a quality criterion and selecting the temperature range as a non-defective product, the selection judgment can be quantified. Then, by manufacturing a circuit board using the selected prepreg as a board material, it is possible to provide a high-quality circuit board excellent in accuracy and reliability.

  As described above, according to the method for producing a circuit board of the present invention, the semi-cured state of the prepreg resin can be directly quantified as a physical property value, so that the non-defective product having excellent accuracy and reliability without extremely variation. It is possible to select only prepregs.

  In addition, since there is no need for sample processing and measurement can be performed in the prepreg state as it is, a prepreg having a wide application range that does not depend on whether or not measurement is possible depends on the resin system, structure, etc. of the prepreg is selected and selected. By manufacturing a circuit board using only a good prepreg as a substrate material, a high-quality circuit board excellent in accuracy and reliability can be provided. In addition, it is possible to provide a new type of circuit board that has conventionally been difficult to manufacture a good circuit board for manufacturing management.

(Embodiment)
The present invention will be described below using specific embodiments.

  First, the step of measuring the glass transition temperature of the prepreg, which is a constituent requirement of the circuit board manufacturing method of the present invention, that is, a prepreg test method will be described.

  In particular, in the test method in the present embodiment, the glass transition temperature of the prepreg by DMA (dynamic viscoelasticity measuring apparatus) was used as a measured value.

  Specific test methods and samples will be described below.

  The sample was cut into a length of 40 mm and a width of 10 mm, and the sample was subjected to DMA measurement using the following measurement equipment and measurement conditions.

  As a result of the measurement, as shown in FIG. 3, the storage elastic modulus E ′ and loss elastic modulus E ″ of the material and the loss Tanδ, which is the phase difference between them, are obtained as numerical data.

  In the test method according to the present embodiment, the numerical data used as the determination method is the Tanδ peak temperature in FIG.

Measuring device: DMS6100 (manufactured by SII Nano Technology)
Measurement conditions: Frequency 10Hz
Temperature increase rate 3 ℃ / min
Measurement temperature range 25-100 ° C
Next, a conventional test method will be described as a comparative example.

(Conventional method 1)
Place 0.2 g of a sample made of resin only on a heating plate kept constant at 170 ° C., and after the resin has melted, stir the resin at a constant speed with a Teflon (registered trademark) stirring rod to cure the resin. The time until gelation is measured with a stopwatch. This curing time was used as judgment numerical data.

  In addition, the measurement start time was set to 0 when all the resins were placed on the hot platen. In addition, the resin sample is obtained by cracking the prepreg and collecting the resin, or 10 sheets of 50 mm × 50 mm prepregs are stacked, release films are stacked on both sides, and the pressure is maintained at 130 ° C. for 30 seconds, 5.0 MPa. The resin was extruded by heating and pressurizing at either of the steps.

(Conventional method 2)
Three samples were cut into 100 mm × 100 mm, and the weight W1 of the three sheets was measured to the mg unit. Next, release sheets were stacked on top and bottom of the three stacked samples, placed on a hot press hot platen maintained at a temperature of 170 ° C., and heated and pressurized at a pressure of 1.5 MPa for 10 minutes.

  Next, the heated and pressurized sample was taken out, the release sheet was removed, and the resin component protruding from the sample was further removed. The sample weight W2 at this time was similarly measured to the mg unit.

  The weight of each sample was applied to the following calculation formula to determine the resin flow rate, and this was used as judgment numerical data.

Formula: (W2−W1) / W1 × 100 (%)
From the above, it can be seen that the test method in the present embodiment is a method for directly measuring the semi-cured state of the prepreg.

  That is, if it is the conventional method 1, the process which takes out a resin part is required, and if it is the conventional method 2, the process of press molding is required.

  Furthermore, in the conventional method 1, the gelation determination may depend on the measurer, and variations among measurers are included in the evaluation determination.

  A comparison between the test method in the present embodiment and the conventional test methods (conventional method 1) and (conventional method 2) will be described in detail below for each prepreg type.

1. Comparison with glass epoxy prepreg (Example 1)
A glass epoxy prepreg having a resin content of 60 wt% and a thickness of 0.1 mm was sampled to a length of 40 mm and a width of 10 mm in the bias direction, and the glass transition temperature of the sample was measured by the test method in the present embodiment. It was obtained as numerical data of the semi-cured state.

(Comparative Example 1)
A glass epoxy prepreg having a resin content of 60 wt% and a thickness of 0.1 mm was manually squeezed to sample only the resin content. Using the resin sample, the curing time was measured by the conventional method 1 and obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 2)
Sampling 3 sheets of 100mm x 100mm from glass epoxy prepreg with resin content of 60wt% and thickness 0.1mm, and measuring the amount of resin flow by conventional method 2, and using it as numerical data of semi-cured state of prepreg Asked.

2. Comparison with aramid epoxy prepreg (Example 2)
Sampling from an aramid epoxy prepreg having a resin content of 50 wt% and a thickness of 0.1 mm to a length of 40 mm and a width of 10 mm, and measuring the glass transition temperature of the sample by the test method in the present embodiment, it is semi-cured of the prepreg Obtained as numerical data of the state.

(Comparative Example 3)
On a hot press hot platen where the resin content is 50 wt%, 0.1 mm thick aramid epoxy prepreg, 10 sheets are cut into 50 mm x 50 mm, they are stacked, and release sheets are stacked on top and bottom of the aramid epoxy prepreg. The sample was sampled only for resin by heating and pressurizing at a pressure of 5.0 MPa for 30 seconds. Using the resin sample, the curing time was measured by the conventional method 1 and obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 4)
Three samples of 100 mm x 100 mm were sampled from an aramid epoxy prepreg with a resin content of 50 wt% and a thickness of 0.1 mm, and the sample was measured for the resin flow rate by the conventional method 2 and used as numerical data for the semi-cured state of the prepreg. Asked.

3. Comparison with low epoxy resin type glass epoxy prepreg (Example 3)
A glass epoxy prepreg with a resin content of 40 wt% and a thickness of 0.1 mm is sampled to a length of 40 mm and a width of 10 mm, and the glass transition temperature is measured by the test method in the present embodiment. Was obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 5)
A low resin content type glass epoxy prepreg having a resin content of 40 wt% and a thickness of 0.1 mm was manually crushed and only the resin content was sampled. Using the resin sample, the curing time was measured by the conventional method 1 and obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 6)
Three pieces of 100 mm x 100 mm were sampled from a low resin content type glass epoxy prepreg with a resin content of 40 wt% and a thickness of 0.1 mm, and the resin flow rate was measured by the conventional method 2 and the sample was semi-cured. Obtained as numerical data of the state.

4). Comparison with high-filler type glass epoxy prepreg (Example 4)
The resin content is 30 wt%, the filler is 20 to 30 wt%, a 0.1 mm thick filler high filling type glass epoxy prepreg is sampled to a length of 40 mm and a width of 10 mm, and the sample is subjected to the test method in this embodiment. The glass transition temperature was measured and determined as numerical data of the semi-cured state of the prepreg.

(Comparative Example 7)
A resin-filled glass epoxy prepreg having a resin content of 30 wt% and a filler content of 20 to 30 wt% and a thickness of 0.1 mm was crushed by hand, and only the resin content was sampled. Using the resin sample, the curing time was measured by the conventional method 1 and obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 8)
Three samples of 100 mm x 100 mm were sampled from a highly filled glass epoxy prepreg with a resin content of 30 wt%, filler of 20-30 wt%, and a thickness of 0.1 mm. It was determined as numerical data of the semi-cured state of the prepreg.

5). Comparison with non-flow type glass epoxy prepreg (Example 5)
A non-flow type glass epoxy prepreg having a resin content of 50 wt% and a thickness of 0.1 mm was sampled to a length of 40 mm and a width of 10 mm, and the glass transition temperature of the sample was measured by the test method in the present embodiment. It was determined as numerical data of the semi-cured state of the prepreg.

(Comparative Example 9)
A non-flow type glass epoxy prepreg having a resin content of 50 wt% and a thickness of 0.1 mm was manually squeezed to sample only the resin content. Using the resin sample, the curing time was measured by the conventional method 1 and obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 10)
Three non-flow-type glass epoxy prepregs with a resin content of 50 wt% and a thickness of 0.1 mm were sampled at 100 mm x 100 mm, and the resin flow rate was measured by the conventional method 2, and the prepreg was semi-cured. Was obtained as numerical data.

6). Comparison with glass epoxy prepreg of thermoplastic resin blend type (Example 6)
A thermoplastic resin blend type glass epoxy prepreg composed of a PPO resin and an epoxy resin with a resin content of 50 wt% and a thickness of 0.1 mm is sampled to a length of 40 mm and a width of 10 mm, and the sample is subjected to the test method in this embodiment. The glass transition temperature was measured and determined as numerical data of the semi-cured state of the prepreg.

(Comparative Example 11)
A thermoplastic resin blend type glass epoxy prepreg composed of a PPO resin and an epoxy resin having a resin content of 50 wt% and a thickness of 0.1 mm was manually crushed and the resin content alone was sampled. Using the resin sample, the curing time was measured by the conventional method 1 and obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 12)
Three samples of 100 mm x 100 mm were sampled from a thermoplastic resin blend type glass epoxy prepreg composed of PPO resin and epoxy resin with a resin content of 50 wt% and a thickness of 0.1 mm. It was determined as numerical data of the semi-cured state of the prepreg.

7). Comparison with polyimide film with double-sided adhesive (Example 7)
A film type prepreg having a resin layer with a thickness of 0.005 mm on both sides of a 0.012 mm polyimide film was sampled to a length of 40 mm and a width of 10 mm, and the sample was subjected to the glass transition temperature by the test method in this embodiment. It was measured and obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 13)
Only the resin content was scraped from the surface and sampled from a film type prepreg having a 0.005 mm thick resin layer on both sides of a 0.012 mm polyimide film. Using the resin sample, the curing time was measured by the conventional method 1 and obtained as numerical data of the semi-cured state of the prepreg.

(Comparative Example 14)
Sampling 15 pieces of 100 mm × 100 mm from a film type prepreg having a 0.005 mm thick resin layer on both sides of a 0.012 mm polyimide film, and measuring the resin flow rate by the conventional method 2, It was determined as numerical data of the semi-cured state of the prepreg.

  About the above Examples 1-7 and Comparative Examples 1-14, the content and result were put together in (Table 1).

  In addition, the determination of ○ △ × of the evaluation result of the accuracy of the table is as follows.

○: The occupancy rate of the variation with respect to the required tolerance is within 30% △: The occupancy rate of the variation with respect to the required tolerance is within 60% ×: The occupancy rate of the variation with respect to the required tolerance is 60% or more or measurement is impossible.

  In addition, “Embodiment” in the item “Measurement method” in the table indicates a test method in the present embodiment.

  Based on the above results, the following discussion will be given regarding the above seven types of prepregs.

(1) About glass epoxy prepreg (Example 1, Comparative Examples 1 and 2) For general-purpose glass epoxy prepreg, as described above, the accuracy of the curing time measurement method of Conventional Method 1 depends on the measurer. This is inferior to Example 1 of the present invention.

  However, with regard to the resin flow of the conventional method 2, there is no significant difference in measurement accuracy only by the difference in the presence or absence of sample processing.

  Therefore, if it is a general-purpose glass epoxy, it is possible to manage the prepreg characteristics without problems even by the conventional method.

  However, in the prepreg types 2 to 7 (Examples 2 to 7 and Comparative Examples 3 to 14), it is difficult to grasp the characteristics of the prepreg by the test methods of (Conventional method 1) and (Conventional method 2). This is a prepreg type that reaches the limit.

  These prepregs are high-value-added prepregs for realizing higher density of circuit boards and diversification of board characteristics, and such prepregs are expected to increase in the future.

  Based on these points, prepreg types 2 to 7 will be described below.

(2) About aramid epoxy prepreg (Example 2, Comparative Examples 3, 4) The prepreg used here is an aramid epoxy prepreg, which is a prepreg in which an aramid nonwoven fabric is impregnated with an epoxy resin.

  A circuit board using this is typically a circuit board using a conductive paste for interstitial vias. Recently, there is an example in which a part is used for a build-up layer on a surface layer of a circuit board.

  Now, from (Table 1), it can be seen that the accuracy of the test method in the present embodiment is excellent when looking at the results for the aramid epoxy prepreg. As a reason for this difference, the conventional method 1 is susceptible to the influence of sampling and measurement by the measurer described so far.

  Furthermore, in the case of an aramid prepreg, there is a problem in resin sampling, and the resin cannot be squeezed out like glass epoxy because of the nonwoven fabric. Therefore, it is necessary to melt and extrude the resin with a press or the like, and the sample before the measurement is temporarily heated, which causes a variation.

  On the other hand, in the conventional method 2, the resin flow inside the prepreg becomes complicated due to the random structure of the nonwoven fabric, resulting in an increase in the resin flow variation.

  On the other hand, in Example 2, since the prepreg is cut into a predetermined size as it is and the temperature change of the resin characteristics is directly measured, the possibility of depending on the measurer is low, and resin sampling is unnecessary. Furthermore, it is hardly affected by the structure of the nonwoven fabric, and it can be said that it is extremely excellent for measuring the prepreg characteristics.

(3) About glass epoxy prepreg of low resin content type (Example 3, Comparative Examples 5 and 6) The prepreg used here is compared with the above glass epoxy prepreg (Example 1, Comparative Examples 1 and 2). It is a low resin content type glass epoxy prepreg, and is a prepreg required when a circuit board is made thin.

  The difference between Example 3 and Comparative Examples 5 to 6 depends on the measurer as already described in the conventional method 1.

  Further, in the case of the low resin content type, since the resin content of the prepreg is small, the weight difference due to the conventional method 2 is small. Therefore, the resin flow obtained from the difference in weight before and after the prepreg treatment has a small difference, and the sensitivity for detecting the semi-cured state of the resin is inevitably deteriorated.

  On the other hand, in Example 3, since the temperature change of the resin characteristics is directly measured, the change in physical properties can be detected even if the resin content is extremely small, and thus it can be said that it is extremely excellent for measuring the prepreg characteristics. .

(4) Highly filled glass epoxy prepreg (Example 4, Comparative Examples 7 and 8), non-flow type glass epoxy prepreg (Example 5, Comparative Examples 9 and 10), thermoplastic resin blend type glass epoxy About prepreg (Example 6, Comparative Examples 11 and 12), polyimide film with double-sided adhesive (Example 7, Comparative Examples 13 and 14) In any case, measured by the conventional method for the reason shown in the remarks of (Table 1) Is difficult.

  Among them, the thermoplastic resin blend type glass epoxy prepreg (Example 6, Comparative Examples 11 and 12) can be measured by changing the measurement temperature (for example, 200 ° C.), but the measurement described so far. There is a problem with the accuracy of the law itself.

  In this case, since the measurement temperature changes, side-by-side comparison with other types of prepreg characteristics becomes impossible, and comparison with the molding conditions accumulated when determining the molding conditions of the circuit board becomes impossible.

  Therefore, this is a demerit for the development efficiency of a new type of circuit board.

  Furthermore, for a completely new prepreg such as a film type, sampling or measurement itself becomes extremely difficult due to its thinness, and it is impossible to manage the prepreg characteristics by the conventional method.

  On the other hand, the test method according to the present embodiment does not require sample processing and can be directly measured by the apparatus in the prepreg state, so that it does not depend on the resin system or structure of the prepreg. Therefore, by using the test method in the present embodiment, it is possible to realize management of prepreg characteristics that are excellent in accuracy and reliability and have a wide application range.

  As an example of the case where the test method in the present embodiment is used, a method for manufacturing a circuit board using a glass epoxy prepreg of a low resin content type as a board material will be described.

  First, the prepreg to be used is a prepreg used when the circuit board is thinned, and it is expected that the opportunities to be employed will increase in the future.

  Specifically, a prepreg as a substrate material impregnated with a thermosetting epoxy resin or the like in a glass fiber woven fabric and made into a semi-cured state by a method such as drying, wherein the resin content is 40 wt% and the thickness is 0.1 mm There is a low resin content type glass epoxy prepreg.

  First, a prepreg composed of a plurality of lots is prepared for management in manufacturing a circuit board.

  In the present embodiment, a case where 5 lots of 30 prepregs, that is, 150 prepregs are prepared will be described.

  Next, the prepreg characteristics are measured by the following procedure using the test method in the present embodiment described above.

  (1) A part that does not affect the circuit board as a product, for example, a sample having a length of 40 mm and a width of 10 mm from the end of the prepreg.

  (2) The glass transition temperature of the sample is measured by the test method in the present embodiment, and it is obtained as numerical data of the semi-cured state of the prepreg.

  (3) A prepreg having a glass transition temperature in a glass transition temperature range of 50 ° C. to 100 ° C. is determined as a non-defective product, and the prepreg is selected as a substrate material.

  Note that the frequency of measurement of the prepreg may be the total number of 150 sheets or may be extracted. In the present embodiment, three of the first, fifteenth and thirty sheets are extracted from one lot, and the characteristics of a total of 15 prepregs in five lots are measured.

  As for the measurement results of the 1st to 4th lots, all 12 sheets were determined as non-defective products. On the other hand, in the measurement result of the fifth lot, two of the three sheets were judged as non-defective products, and one sheet was out of the glass transition temperature range.

  Next, the manufacturing method of the circuit board of this invention is demonstrated below using drawing.

  First, as shown in FIG. 1A, the selected prepreg 1 is prepared by sorting as a non-defective product by the test method in the present embodiment.

  Next, as shown in FIG.1 (b), the organic film 2 is affixed on both surfaces of the prepreg 1 by the laminating method using a hot roll etc. As shown in FIG.

  Next, as shown in FIG.1 (c), after forming the through-hole 3 in the prepreg 1 by processing methods, such as a laser, electroconductive particles, such as copper powder, a thermosetting resin, a hardening | curing agent, A conductive paste 4 kneaded with a solvent or the like is filled with a printing method or the like to obtain the configuration shown in FIG.

  Next, the organic film 2 is peeled off to obtain a shape in which the conductive paste 4 protrudes as shown in FIG. Then, copper foils 5 are arranged on both sides, and further sandwiched between metal intermediate plates such as SUS and heated and pressed by a hot press (not shown), so that the prepreg 1 is cured and molded as shown in FIG. Then, the conductive paste 4 is compressed and the copper foils 5 on the front and back sides are electrically connected.

  Further, the copper foil 5 is processed into a desired pattern by a method such as photolithography etching to form a circuit wiring layer 6 to obtain a double-sided circuit board as shown in FIG.

  In FIG. 1, the surface finishing process such as the plating process on the solder resist or the circuit wiring layer 6 of the outer layer part normally disposed on the circuit board is not shown, but it is disposed if necessary.

  When manufacturing a multilayer circuit board, as shown in FIGS. 2 (a) and 2 (b), above and below the core substrate 11 once completed, as shown in FIGS. 1 (a) to 1 (d). FIG. 2C shows the selected prepreg and the prepreg prepared separately according to the manufacturing method. The substrate material 16 for interlayer adhesion and the copper foil 14 are overlapped and hot-pressed while being aligned. A laminated cured product as shown in FIG.

  The surface layer of the laminated cured product is processed into a desired pattern by using the copper foil 14 by a method such as photolithography etching to form a circuit wiring layer 17 to obtain a multilayer circuit board as shown in FIG.

  In FIG. 2, the surface finishing process such as the plating process on the solder resist or the circuit wiring layer 17 of the outer layer part usually disposed on the circuit board is not shown, but it is disposed if necessary.

  It should be noted that a multilayered circuit board can be obtained by repeating the above manufacturing method.

  A multilayer circuit board as shown in FIG. 2 (d) was manufactured by using the circuit board manufacturing method of the present invention and 120 prepregs of the first to fourth lots selected as non-defective products as substrate materials. No defects occurred.

  For the fifth lot in which one prepreg outside the glass transition temperature range was detected, 100% inspection was performed again by the test method in the present embodiment. As a result, two of the 30 prepregs were in the glass transition temperature range. Detected as outside.

  On the other hand, when 30 prepregs of the fifth lot were measured by the conventional method 1, the total number was in the glass transition temperature range.

  The conventional method 2 is not carried out because the amount of resin impregnated in the prepreg is small and measurement is extremely difficult.

  Next, when a multilayer circuit board as shown in FIG. 2 (d) is manufactured by using the above-mentioned circuit board manufacturing method as the substrate material of the prepregs of the fifth lot, two molding defects occur, This coincided with that detected by the test method in the present embodiment as outside the glass transition temperature range.

  From the above, when a prepreg controlled by the conventional method is used, a formation failure may occur suddenly even though the test result satisfies the required tolerance.

  This indicates that the prepreg characteristics seem to meet the required tolerance due to measurement variations in the conventional method, but the prepreg characteristics do not actually fall within the required tolerance.

  On the other hand, the process of measuring the glass transition temperature of the prepreg in the method for producing a circuit board of the present invention has very small measurement variation, so when only a good prepreg satisfying the required tolerance is selected, it is used as the substrate material. It shows that when a circuit board is manufactured, molding defects of the circuit board can be prevented.

  That is, the circuit board manufacturing method of the present invention measures the characteristics of the prepreg by the test method in the present embodiment, selects only the prepreg satisfying the required tolerance, and drills, fills, laminates, and heats the prepreg. By manufacturing a circuit board through a process such as pressure, a high-quality circuit board excellent in accuracy and reliability can be provided without causing unexpected molding defects.

  In addition, although the manufacturing method of the circuit board in this Embodiment showed the case where the low epoxy resin type glass epoxy prepreg was used as a board | substrate material, the general purpose glass epoxy prepreg or the aramid epoxy prepreg was used as a board | substrate material. It is also effective in some cases.

  In particular, when a non-flow type, a high filler filling type, a thermoplastic resin blend type glass epoxy prepreg, and a polyimide film with a double-sided adhesive, which are difficult to measure the prepreg properties by the conventional method, are used as a substrate material, the present invention These effects are remarkable. By using the circuit board manufacturing method of the present invention, it is possible to adopt these board materials, and as a result, it is possible to provide a new type of circuit board.

  As described above, the method of manufacturing a circuit board according to the present invention includes a method for manufacturing a prepreg resin, which quantifies the semi-cured state of the prepreg resin without variation and includes a prepreg property test method independent of the resin system or structure of the prepreg. Yes, it is easy to select a good prepreg that satisfies the required tolerance. And by manufacturing a circuit board using the above-mentioned non-defective prepreg, a high-quality circuit board excellent in accuracy and reliability can be provided, 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 drawing which shows the manufacturing method of the circuit board in embodiment of this invention The figure which shows the dynamic viscoelasticity (DMA) measurement data of the prepreg in embodiment of this invention Sectional drawing which shows the manufacturing method of the conventional circuit board Sectional drawing which shows the manufacturing method of the conventional circuit board

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Prepreg 2 Organic film 3 Through-hole 4 Conductive paste 5, 14 Copper foil 6, 17 Circuit wiring layer 11 Core substrate 16 Substrate material

Claims (13)

Preparing a plurality of prepregs comprising at least a reinforcing material and a semi-cured resin; and
Measuring the glass transition temperature of at least one prepreg of the plurality of prepregs;
Selecting only prepregs having a glass transition temperature within a specific glass transition temperature range;
At least one of a step of forming a laminate by stacking metal foil on both surfaces of the selected prepreg or a step of forming a laminate by stacking the core substrate and the selected prepreg and metal foil;
And a step of heating and pressurizing the laminated body. The glass transition temperature is measured by directly or partially sampling the prepreg, and in the process of heating it from a low temperature to a high temperature, the temperature at which the state of the semi-cured resin in the prepreg changes is used as a judgment index. The method for manufacturing a circuit board according to claim 1, wherein the method is performed by a method. The method for producing a circuit board according to claim 2, wherein the glass transition temperature is obtained by a dynamic viscoelasticity measurement method. 4. The method of manufacturing a circuit board according to claim 3, wherein a loss Tanδ, which is a phase difference between the storage elastic modulus and the loss elastic modulus, is obtained by a dynamic viscoelasticity measurement method. 5. The method for manufacturing a circuit board according to claim 4, wherein a temperature at which the loss Tan δ reaches a peak is obtained. The method for producing a circuit board according to claim 1, wherein the prepreg is formed by impregnating an aramid nonwoven fabric reinforcing material with an epoxy resin. The method for producing a circuit board according to claim 1, wherein the prepreg is formed by impregnating a glass fiber reinforcing material with a resin, and the impregnation ratio of the resin is 40 wt% or less. The method for producing a circuit board according to claim 1, wherein the prepreg is formed by impregnating a resin in which a glass fiber reinforcing material is filled with a filler, and a filling ratio of the filler is 20 to 30 wt%. 2. The circuit board manufacturing method according to claim 1, wherein the prepreg is formed by impregnating a glass fiber reinforcing material with a non-flow type resin. The method for producing a circuit board according to claim 1, wherein the prepreg is formed by impregnating a glass fiber reinforcing material with a thermoplastic resin and an epoxy resin. The method for producing a circuit board according to claim 1, wherein the prepreg is formed by applying a thermosetting resin to both surfaces or one surface of the organic film reinforcing material. The method for manufacturing a circuit board according to claim 1, wherein the specific glass transition temperature range is from 50C to 100C. The process of forming a laminate by overlapping metal foil on both sides of the selected prepreg,
It includes a step of laminating an organic film on both surfaces of the prepreg, a step of forming a through hole in the same, a step of filling the through hole with a conductive paste, and a step of peeling the organic film. The method for manufacturing a circuit board according to claim 1.

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