JP2012256699A - Manufacturing method of ceramic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a ceramic circuit board capable of improving a manufacturing yield by simply and highly accurately detecting presence and absence of circuit pattern failures at an early stage of a manufacturing process.SOLUTION: A manufacturing method of a ceramic circuit board comprises the steps of: forming a through hole on a ceramic green sheet; filling the through hole of the ceramic green sheet with a conductor paste; printing a circuit pattern by the conductor paste on the ceramic green sheet; and burning the ceramic green sheet which passed each step as a single layer or a laminate. This manufacturing method performs each of the above steps per lot. For a prescribed number per lot, the circuit pattern and an auxiliary pattern which connects the circuit pattern in series are printed in advance, a conduction inspection is performed, and the step of printing the circuit pattern per lot on the basis of the conduction inspection result is performed.

Description

  The present invention relates to a method for manufacturing a ceramic circuit board.

  Conventionally, ceramic circuit boards for mounting electronic components such as semiconductor elements and piezoelectric vibrators are generally formed by forming desired through holes in a plurality of ceramic green sheets and filling them with a conductive paste, followed by screen printing. After the circuit pattern is formed by the above method, the manufacturing method is employed in which the circuit pattern is laminated and fired. In addition, such a ceramic circuit board is usually manufactured on a lot basis.

  In the process of manufacturing the ceramic circuit board, a defect such as a missing circuit pattern or a short circuit caused by a problem of a screen printing plate or a foreign substance causes a serious electric characteristic defect in the obtained ceramic circuit board. For this reason, in the manufacturing process, there is an inspection for the presence or absence of circuit pattern defects. However, when this inspection is performed after firing, there are many cases where the degree of trouble becomes large, for example, defects are detected in units of manufacturing lots. .

  Therefore, a method of inspecting the presence or absence of a defective circuit pattern in an unsintered state is performed before printing and laminating a circuit pattern on a ceramic green sheet. Specifically, a method has been proposed in which a printed circuit pattern is used as an image of a CCD camera or the like to inspect for the presence or absence of defects in a non-contact manner (see Patent Document 1 and Patent Document 2). However, since these methods require time and cost to increase detection accuracy, there is an efficient method for manufacturing a ceramic circuit board that incorporates a system that can detect the presence or absence of a circuit pattern defect more simply and with high accuracy. It was sought after.

JP-A-10-65345 JP-A-8-31580

  An object of the present invention is to provide a method for manufacturing a ceramic circuit board that improves the manufacturing yield by detecting the presence or absence of a defective circuit pattern easily and accurately at an early stage of the manufacturing process.

  The method for manufacturing a ceramic circuit board according to the present invention includes a step of forming a predetermined through hole in a ceramic green sheet, a step of filling a predetermined through hole of the ceramic green sheet with a conductive paste, and a conductive paste on the ceramic green sheet. A ceramic circuit board that includes a step of printing a circuit pattern according to the above and a step of firing the ceramic green sheet that has undergone each of the above steps as a single layer or a laminated body in which a plurality of layers are laminated, In the manufacturing method, the circuit pattern printing step is performed by printing the circuit pattern and an auxiliary pattern for connecting the circuit pattern in series on a predetermined number of ceramic green sheets in advance for each lot. Based on the results of the continuity test. And performing in.

In the method for manufacturing a ceramic circuit board according to the present invention, in order to increase the accuracy of the continuity test, drying is preferably performed before the continuity test.
In the method for producing a ceramic circuit board according to the present invention, the circuit pattern is printed by screen printing using a screen plate, and the minimum line width of the circuit pattern is 1-2 of the minimum printable line width of the screen plate. When it is doubled, a particularly remarkable effect is exhibited. The auxiliary pattern is also printed by screen printing using a screen plate. In this case, the minimum line width of the auxiliary pattern is at least twice the minimum printable line width of the screen plate. Preferably, 3 times or more is more preferable.

  According to the manufacturing method of the present invention, the presence / absence of a circuit pattern defect can be detected easily and with high accuracy at an early stage of the manufacturing process, whereby a ceramic circuit board can be manufactured with a high yield.

It is a figure which shows an example of the ceramic circuit board to which the manufacturing method of this invention is applied. It is a figure which shows the flowchart at the time of manufacturing the ceramic circuit board shown in FIG. 1 by an example of embodiment of the manufacturing method of this invention. It is a figure which shows the ceramic green sheet on which the circuit pattern was printed. It is a figure which shows the ceramic green sheet on which the auxiliary pattern was printed in addition to the circuit pattern.

Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is limited to the following description and is not interpreted.
FIG. 1 is a diagram showing an example of a ceramic circuit board to which the manufacturing method of the present invention is applied. FIGS. 1A and 1B are a plan view of the ceramic circuit board 1 as viewed from above and a cross-sectional view taken along the line XX, respectively. FIG.1 (c) is the figure which expand | deployed the ceramic circuit board 1 in three layers according to the laminated structure of the ceramic green sheet at the time of manufacture. Hereinafter, the three layers are indicated by symbols of the L1, L2, and L3 layers in order from the top as necessary. A ceramic circuit board is simply called a circuit board, and a ceramic green sheet is simply called a green sheet.

The circuit board 1 has a substantially flat base 2 and a frame 3 joined to the upper surface of the base 2, and is formed with a part of the upper surface of the base 2 as a bottom surface and an inner wall surface of the frame 3 as a side surface. The light emitting element mounting circuit board 1 has mounting portions 22 for mounting four light emitting elements in two vertical and horizontal rows in the center of the bottom surface of the cavity 4. The frame 3 is composed of an L1 layer, and the substrate 2 is composed of two layers, an L2 layer and an L3 layer. However, since these are sintered bodies of the green sheet laminate, each layer is sufficiently bonded.
Here, in the present specification, the “substantially flat substrate” refers to a substrate having a flat surface at a level at which the upper and lower main surfaces can be recognized as a flat plate shape on a visual level. Similarly, the abbreviations indicate levels that can be recognized on the visual level unless otherwise specified. Hereinafter, the upper surface of the substrate 2 is referred to as a mounting surface 21, and the lower surface is referred to as a non-mounting surface 23. The mounting surface 21 is an upper surface of the L2 layer, and the non-mounting surface 23 is a lower surface of the L3 layer.

  Each of the L2 layer and the L3 layer has the following electric circuits for causing the light emitting element to be mounted to emit light. In the following description, when differentiating between the anode conductor and the cathode conductor for each conductor, the symbol “a” for the anode is used for the anode after the reference numeral of each conductor, as used in the drawings. Uses a symbol with c. In addition, without distinguishing between the anode and the cathode, when describing them as a combined electrode or as a conductor, only numerical symbols are used without a or c.

  On the upper surface of the L2 layer, that is, the surface to be the mounting surface 21 of the base 2, two right and two left and right two of the four light emitting elements to be mounted are respectively connected in series. A pair of element connection terminals 5a and 5c constituting the anode and the cathode are formed so as to be substantially symmetrical to the left and right in the form of sandwiching the light emitting element. The through conductors 6a and 6c constituting the anode and the cathode are formed in a pair so as to be substantially symmetrical left and right so as to be electrically connected from the four element connection terminals 5 to the lower L3 layer.

  The L3 layer has an internal printed circuit 7a connected to the through conductors 6a constituting the two anodes of the L2 layer on the upper surface and an internal printed circuit 7c connected to the through conductors 6c constituting the two cathodes. The L3 layer has a pair of external connection terminals 9a and 9c constituting an anode and a cathode electrically connected to an external circuit on the lower surface, that is, the surface to be the non-mounting surface 23 of the base 2, and these are connected to the upper surface. The pair of internal printed circuits 7a and 7c have a pair of through conductors 8a and 8c so that the anode side and the cathode side are electrically connected to each other. Hereinafter, a conductor printed on a plane such as the element connection terminal 5, the internal printed circuit 7, and the external connection terminal 9 is collectively referred to as a printed circuit, and a conductor filled in the through hole is collectively referred to as a through conductor.

FIG. 2 is a diagram showing a flowchart for manufacturing the circuit board 1 shown in FIG. 1 according to an example of the embodiment of the manufacturing method of the present invention.
The flowchart starts with a green sheet manufacturing process for preparing a green sheet. The green sheets, which are the L1 layer, the L2 layer, and the L3 layer, are usually produced with the same size. Therefore, the green sheet can be manufactured without distinction between the L1 layer, the L2 layer, and the L3 layer. A through-hole forming step for forming a predetermined through-hole in the next green sheet, a conductive paste filling step for filling a predetermined through-hole in the green sheet with a conductive paste, and a circuit printing step for printing a circuit pattern with the conductive paste on the green sheet The L1, L2, and L3 layers go through different processes. Thereafter, these are finally laminated together and fired to obtain a circuit board.

  In the embodiment shown in FIG. 1 and FIG. 2, a laminated body in which a plurality of green sheets are laminated is taken as an example, but a circuit board having a single layer also has a circuit printing process for printing a circuit pattern. If so, the manufacturing method of the present invention can be applied.

  Here, in the production method of the present invention, these steps are performed in lot units. There are no particular restrictions on the quantity of green sheets or the like constituting the lot in each process. Further, the number may be the same or different for each process. Usually, when a ceramic circuit board is manufactured, a lot unit can be composed of tens to hundreds of units used.

  In general, ceramic circuit boards are so small that it is difficult to manufacture in units of one unit. Therefore, in order to facilitate handling and increase manufacturing efficiency, a single ceramic circuit board is used. Are manufactured as so-called multi-piece connecting boards, which are obtained simultaneously from a large-area mother board, and a manufacturing method is adopted in which the board is divided into units. For example, when manufacturing a rectangular circuit board having a vertical and horizontal size of about several millimeters using an approximately 150 mm square area in which a surplus portion is left in the vicinity of the outer periphery of the approximately 200 mm square mother board, a single mother board is used. A multi-piece connection board having hundreds to thousands of circuit board sections is manufactured.

In the flowchart shown in FIG. 2, the embodiment of the present invention will be described by taking as an example a multi-piece connecting board having 16 circuit board sections in order to simplify the description. However, the manufacturing method of the present invention can also be applied in the same manner as in the embodiment in the manufacture of a connecting board in which a large number of small circuit boards are taken per connecting board as described above.
In addition, each process of manufacture shown by this flowchart is performed in a predetermined lot unit, respectively. However, the flow from the circuit printing to the continuity inspection performed on the inspection green sheet after the inspection green sheet is extracted is performed only for the number of extracted sheets.
Further, the following steps will be described for one circuit board unit in the connection board, that is, one section unit, unless otherwise specified, but this is the same for all 16 sections. Furthermore, in the following description, the members used for the manufacture will be described with the same reference numerals as the members of the finished product.

  First, the green sheet manufacturing process will be described. As the ceramics of the ceramic circuit board to which the manufacturing method of the present invention is applied, ceramics usually used for manufacturing a ceramic circuit board are not particularly limited. Specifically, a ceramic sintered body containing aluminum as a main component, such as an aluminum oxide sintered body (alumina ceramics), an aluminum nitride sintered body, a mullite sintered body, or a glass containing glass powder and ceramic powder. Examples thereof include a sintered body of a ceramic composition (Low Temperature Co-fired Ceramics, hereinafter referred to as LTCC).

  These ceramic green sheets add a binder resin such as polyvinyl butyral and acrylic resin to the ceramic raw material composition prepared according to the ceramic used, and further add a plasticizer, a dispersant, a solvent, etc. Then, a slurry is prepared, and the slurry is formed into a predetermined sheet by a method such as a doctor blade method.

In the case of LTCC, the ceramic raw material composition is composed of glass powder and ceramic powder such as alumina powder and zirconia powder so that the glass powder is 30 to 50% by mass and the ceramic powder is 50 to 70% by mass, for example. The glass ceramic composition obtained by mixing.
Examples of the raw material of the ceramic sintered body containing aluminum as a main component include, for example, aluminum-containing compounds, minerals containing the compounds, or synthetic products using the compounds as raw materials, and those usually used as these raw materials. The raw material components selected from these are singly or a mixture of two or more is prepared as a ceramic raw material composition.

The green sheet obtained above is divided into L1 layer, L2 layer, and L3 layer lots, and the following steps are sequentially performed for each lot. Before proceeding to the following steps for each layer, a step of laminating a plurality of green sheets may be provided in order to adjust the thickness of the layer as necessary.
In the green sheet to be the L1 layer, a substantially circular through hole for forming the frame 3 in the through hole forming step is formed at the center of the partition. The obtained green sheet is subjected to a green sheet laminating step as an L1 layer.

  In the green sheet to be the L2 layer, there are four through holes in the vicinity of the four corners of each section for forming through conductors 6a, 6c provided in pairs so as to be substantially symmetrical to the left and right in the through hole forming step. Formed. Then, through the conductive paste filling step, the through paste at the four locations is filled with the conductive paste to form the through conductor paste layer 6. Next, in the circuit printing step, the conductor paste is printed at four positions on the upper surface of the green sheet in a predetermined shape that covers the four through-conductor paste layers 6, and each pair of elements that are substantially symmetrical to the left and right Connection terminal paste layers 5a and 5c are formed. The obtained green sheet with a conductor paste is used for a green sheet lamination process as L2 layer.

In the green sheet to be the L3 layer, through holes for forming a pair of through conductors 8a and 8c are formed at two positions at predetermined positions in the through hole forming step. Here, in the present embodiment, the predetermined positions of the through conductors 8a and 8c are near the upper left and lower right corners of the respective sections. Subsequently, the conductor paste is filled in the two through holes in the conductor paste filling step to obtain the through conductor paste layer 8.
Since the L3 layer has printed circuits on both the upper surface and the lower surface, the circuit printing process is performed in two steps, an upper surface printing process and a lower surface printing process.

  Through the upper surface printing step, a conductive paste is printed on the upper surface of the green sheet to be the L3 layer to cover the through conductor paste layer 8a constituting the anode of the L3 layer and to form the two anodes of the L2 layer The internal printed circuit paste layer 7a in a predetermined shape connected to the layer 6a and the through conductor paste layer 8c constituting the cathode of the L3 layer and connected to the through conductor paste layer 6c constituting the two cathodes The internal printed circuit paste layer 7c is formed in the shape. In addition, this upper surface printing process is specifically performed by the circuit printing process which concerns on the manufacturing method of this invention mentioned later.

  In addition, a conductor paste is printed on the lower surface of the green sheet serving as the L3 layer by the lower surface printing process, and the external connection terminal paste layer 9a and the through holes constituting the canode are formed in a predetermined shape covering the through conductor paste layer 8a constituting the anode. External connection terminal paste layer 9c is formed in a predetermined shape covering conductor paste layer 8c. The obtained green sheet with a conductor paste is used for a green sheet lamination process as L3 layer.

  As the conductor paste used in the conductor paste filling step and the circuit printing step, a paste obtained by adding a vehicle such as ethyl cellulose to a metal powder and, if necessary, a solvent or the like is used. Here, the metal powder to be used is appropriately selected depending on the ceramic type of the ceramic green sheet. For example, when the ceramic is a ceramic that is fired at a high temperature, such as a ceramic containing aluminum as a main component, a metal powder mainly composed of a refractory metal such as tungsten or molybdenum is used as the metal powder. Moreover, in the case of LTCC, the metal powder which has copper, silver, gold | metal | money etc. as a main component is mentioned, Preferably, the metal powder which consists of silver, silver, platinum, or silver and palladium is mentioned.

  Usually, screen printing is used as a method of filling the through hole with the conductor paste in the conductor paste filling step and a method of printing the circuit pattern with the conductor paste in the circuit printing step. The manufacturing method of the present invention is particularly characterized in the circuit printing step among the conductive paste layer forming steps for constructing an electric circuit such as a conductor paste filling step and a circuit printing step.

  Here, in the present embodiment, as shown in the flowchart of FIG. 2, the circuit printing process is performed three times, that is, the upper surface printing process in the L2 layer, the upper surface printing process in the L3 layer, and the lower surface printing process. Among the three circuit printing processes, the circuit printing process of two times excluding the upper surface printing process in the L3 layer has a low risk of occurrence of defects in the shape of the printed circuit pattern. The circuit printing process performed by the following method according to the manufacturing method of the present invention is applied only to the upper surface printing process in the L3 layer.

  The circuit board in which the manufacturing method of the present invention is particularly effectively used is a circuit board having a fine line width in which the line width of the printed circuit pattern has a high risk of occurrence of defects such as disconnection. With regard to the shape of the circuit pattern, the risk of occurrence of defects is high when the complicated shape or the line width is narrow, and a particularly remarkable effect is obtained when the circuit printing process, which is a feature of the manufacturing method of the present invention, is applied. As an example, there is a case where the minimum line width of the circuit pattern is 1 to 2 times the minimum printable line width of the screen plate used for screen printing. In the present embodiment, the circuit pattern printed by the upper surface printing process in the L3 layer is, for example, a circuit pattern including a line width pattern that is 1 to 2 times the minimum printable line width of the screen plate to be used. By applying the circuit printing process according to the manufacturing method of the present invention to the printing process, the risk of occurrence of defects can be greatly reduced.

  Here, the minimum printable line width when screen printing a circuit pattern depends on the paste used for printing and the printing conditions, but also depends on the specifications of the screen plate used. A rough value can be estimated from the wire diameter, opening, and the like. Generally, the minimum printable line width can be reduced by increasing the number of meshes and decreasing the mesh wire diameter. The standard values of the minimum line width that can be printed on the screen plate are 500 mesh, mesh wire diameter 16 μm, opening 35 μm is 43 μm, mesh number 325, mesh wire diameter 28 μm, opening 50 μm is 84 μm, mesh 165, screen It is 139 μm when the wire diameter is 50 μm and the opening is 104 μm. With a mesh 840, a screen wire diameter of 11 μm, and an opening of 19 μm, the minimum printable line width is 34 μm. From the above example, it can be said that the minimum line width that can be printed by the screen plate used in the circuit printing process in the production of the circuit board is 30 μm to 140 μm.

  In this way, in the circuit printing process, depending on the size of the circuit board to be manufactured and the circuit pattern to be printed, for example, the minimum printable line width is 30 μm to 140 μm. In view of productivity and quality, a screen plate having a minimum printable line width of about 70 to 100 μm is generally used. For example, when a circuit pattern is printed using a screen plate having a minimum printable line width of 70 μm, there is a risk of occurrence of defects when a circuit pattern including a line width of 70 to 140 μm is printed as described above. Therefore, by applying the circuit printing process according to the manufacturing method of the present invention to this printing, the risk of occurrence of defects can be greatly reduced.

  In the circuit printing process according to the manufacturing method of the present invention, a circuit pattern actually used is printed in advance on a predetermined number of green sheets for each lot, and an auxiliary pattern for connecting the circuit patterns in series is printed. Thereafter, a continuity test is performed, and a circuit printing process is performed in lot units based on the result obtained by the continuity test.

  Specifically, as shown in the flowchart of FIG. 2, in the upper surface printing process in the L3 layer, one sheet is extracted as a green sheet for inspection from the lot where the conductor paste filling process is completed. Note that the number of inspection green sheets can be appropriately selected as necessary.

  A circuit pattern is printed with a conductor paste on the inspection green sheet using a screen plate for screen printing the internal printed circuit paste layer 7a constituting the anode and the internal printed circuit paste layer 7c constituting the cathode. FIG. 3 is a plan view seen from above the connecting substrate green sheet 10 on which the internal printed circuit paste layers 7a and 7c are printed. In the connecting board green sheet 10, a total of 16 circuit board sections 12 are arranged in four rows and four rows in the center of the mother board 11, and the periphery thereof is a surplus portion 13. 3 and 4, the boundary between the circuit board sections 12 and the boundary between the section 12 and the surplus portion 13 are indicated by dotted lines as a partition boundary line 14.

As shown in FIG. 3, the circuit pattern has a configuration in which the internal printed circuit paste layer 7a serving as an anode and the internal printed circuit paste layer 7c serving as a cathode are independently formed for each section 12 serving as a circuit board without contact. It has become. As described above, this circuit pattern includes, for example, a pattern having a line width of 1 to 2 times the minimum printable line width of a screen plate used for printing the circuit pattern.
Next, on the connecting substrate green sheet 10 shown in FIG. 3, an auxiliary pattern 15 having such a shape that the circuit pattern is connected in series in all the circuits on the connecting substrate is screen-printed using a separately prepared screen plate. To do. FIG. 4 is a view showing the connecting substrate green sheet 10 on which the auxiliary pattern 15 is printed in addition to the internal printed circuit paste layer 7.

  As in the present embodiment shown in FIG. 4, the auxiliary pattern 15 may be printed on the surplus portion 13 of the mother board 11. Moreover, it is preferable to have the substantially circular pad area | region 16 for making the needle | hook of a tester contact when performing a continuity test in the both ends of a series circuit. Further, in the example shown in FIG. 4, it is preferable to provide a substantially circular pad region 16 for each predetermined section so that the substantially circular pad region 16 is installed at an intermediate position. The shape of the auxiliary pattern 15 is not particularly limited as long as it is a shape in which the above-described series circuit is formed and the presence or absence of printing failure of the internal printed circuit paste layer 7 can be accurately determined by the following continuity test. It is set as appropriate in consideration of ease. However, the minimum line width is preferably in the following range.

The auxiliary pattern 15 is printed by screen printing using a screen plate prepared separately as described above. The minimum line width of the auxiliary pattern 15 is preferably at least twice the minimum printable line width of the screen plate, and more preferably three times or more.
In the circuit printing process, as described above, for example, a screen plate having a minimum printable line width of 30 μm to 140 μm can be used, and generally a screen plate having a minimum printable line width of about 70 to 100 μm is used. . Here, when a screen plate having a minimum line width of 70 μm that can be printed for screen printing of the auxiliary pattern 15 is used, the minimum line width of the auxiliary pattern is preferably 140 μm or more, and is preferably 210 μm or more. More preferred.

  In the screen printing of the auxiliary pattern 15 including the pad region 16, the conductor paste to be used may be the same as the conductor paste for forming the circuit pattern as long as it can accurately perform the next continuity test. May be. From the viewpoint of economy, a conductive paste prepared by screen printing with a vehicle, a solvent, or the like is preferable in the same manner as the conductive paste for forming the circuit pattern using aluminum as the metal powder. Moreover, you may use copper etc. as said metal powder.

  Next, a continuity test is performed using the connecting substrate green sheet 10 on which the auxiliary pattern 15 is printed as shown in FIG. 4. Preferably, before the continuity test, the internal printed circuit paste layer is used to improve the accuracy of the test. The auxiliary pattern 15 including the pads 7a and 7c and the pad area 16 is dried. The drying condition is preferably a condition in which components other than the metal powder such as a vehicle and a solvent contained in the conductive paste are removed, and examples include a drying condition at 60 to 90 ° C. for about 10 to 30 minutes.

  After the auxiliary pattern is formed, the continuity test, which is preferably performed through a drying process, is performed first by connecting the tester needle for continuity test with the internal printed circuit paste layers 7a and 7c on the test green sheet and the auxiliary pattern 15. This is done by contacting the two pad regions 16 located at the ends of the circuit. If continuity is confirmed by the tester, the flow proceeds to “OK” in the flowchart shown in FIG. 2 and is used for screen-printing the internal printed circuit paste layer 7 on the green sheet for inspection for all the lots. The upper surface printing process in the L3 layer is performed using the screen plate.

  If no continuity is confirmed in the continuity test at both ends of the series circuit on the inspection green sheet, the process proceeds to “NG” in the flowchart shown in FIG. 2 to investigate the cause of the defect. At that time, first, in this case, in order to identify the defective part of the printing of the internal printed circuit paste layer 7, a pad region provided at one end of the series circuit on the inspection green sheet shown in FIG. A tester needle is brought into contact with the pad region 16 provided at a position intermediate between the 16 and the series circuit to conduct a continuity test. Next, a tester needle is brought into contact with the pad region 16 provided at the middle position of the series circuit on the green sheet for inspection and the pad region 16 provided at the other end of the series circuit to conduct a continuity test. When the continuity of the entire series circuit is poor, it is found that at least one of the two continuity tests is a continuity failure, and the defective printing portion exists in the region where the result of the continuity failure is obtained.

  In this way, if the green sheet region where the defective printing portion exists is known, the defective printing portion can be specified by performing, for example, visual observation under a microscope only in that region. In a normal connection board, hundreds to thousands of circuit board sections are arranged on one connection board as described above. For this reason, if the printing defective portion is identified by microscopic observation or the like in the entire area of the green sheet, a great amount of labor and time are consumed, which is a problem in terms of efficiency. In the embodiment shown in FIG. 4, since the number of sections is as small as 16, the pad region 16 is provided only at one intermediate point in the middle of the series circuit. In a connection board with a large number of sections, for example, by providing pad areas 16 at a plurality of locations in the series circuit corresponding to the areas so that continuity inspection is possible for each area having a certain number of sections, The efficiency related to the identification of defective printing portions is greatly improved.

  If a defective printing location is identified, the cause of the failure can be determined relatively easily. Screen screen defects are broadly classified into cases where the screen plate itself has defects and cases where the screen plate is clogged. When a printing failure location on the inspection green sheet is specified by the above method, the position of the screen plate corresponding to the location is observed with a microscope or the like. When a defect of the screen plate itself is confirmed by observing the screen plate, the cause of the defect is removed by replacing the screen plate. In addition, when clogging is confirmed in the screen plate by observing the screen plate, the cause of the defect is removed by cleaning the screen plate. Further, even when there is a cause of failure other than the screen plate, after taking measures to remove each cause of failure, the process may proceed to the next step.

  After removing the cause of the defect as described above, one sheet is again extracted as an inspection green sheet from the lot in which the conductor paste filling process in the L3 layer is completed, and the inspection is performed by the same operation as described above. If the continuity of all the series circuits on the inspection green sheet in the continuity test is confirmed, the process proceeds to “OK” in the flowchart shown in FIG. 2, and if the continuity is not confirmed, the process proceeds to “NG”. The same operation as described above is performed. When the process proceeds to “NG”, the cause of the failure and the removal of the cause of the failure are performed, and the operation of conducting the continuity test is repeated until the result of the continuity test becomes OK.

In this way, it is possible to easily and accurately detect defects that may cause printing defects before the circuit board is baked and before the circuit pattern is printed on a lot basis. By removing it, it is possible to greatly improve the manufacturing yield of the circuit board.
Here, when the circuit printing process is performed by the above method, if a lot constitutes a lot unit, a series of operations from the inspection green sheet extraction to the continuity inspection in the middle of the circuit printing process. May be checked to see if there are any problems with the screen printing plate. Further, in the flowchart shown in FIG. 2, the printed circuit pattern shape has a low risk of occurrence of defects, and in particular, the upper surface printing process in the L2 layer and the lower surface in the L3 layer to which the circuit printing process shown above is not applied. The circuit printing process in the method according to the present invention similar to the above may be applied to the printing process as necessary.

  As shown in the flowchart of FIG. 2, the L3 layer, the L2 layer, and the L1 layer obtained through the through-hole forming step, the conductor paste filling step, and the circuit printing step that are performed on each layer after the green sheet manufacturing step, The layers are stacked in that order from the bottom by the next stacking step. The lamination method of the L3 layer, L2 layer, and L1 layer is not particularly limited, and a lamination method such as thermocompression bonding can be applied.

  The firing process performed after the lamination process has different firing temperatures depending on the ceramics used, and therefore firing conditions corresponding to the ceramics are employed. For example, a suitable firing temperature is 1400 to 1700 ° C. for an aluminum oxide sintered body, 1700 to 1950 ° C. for an aluminum nitride sintered body, and 800 to 930 ° C. for LTCC. The firing time is appropriately adjusted depending on the size of the circuit board. In addition, prior to firing, a degreasing treatment may be performed at 500 to 600 ° C. for about 1 to 10 hours to remove components such as a binder resin used in producing the green sheet.

  Furthermore, as shown in the flowchart of FIG. 2, a process of forming a dividing groove for dividing the connection board into sections of the circuit board is usually provided between the stacking process and the baking process. Thereby, the connection board | substrate obtained by baking can be divided | segmented easily for every division of a circuit board.

  As mentioned above, although the example of embodiment of the manufacturing method of the ceramic circuit board of this invention was given and demonstrated, the manufacturing method of this invention is not limited to these. As long as it does not contradict the spirit of the present invention, the configuration can be changed as necessary.

In screen printing of a circuit pattern similar to that shown in FIG. 3, (1) a screen plate having no defect, (2) a screen plate having defects, and (3) a screen plate having clogging. And a test for detecting a defect by the method of the present invention was conducted. The screen plate used was a screen plate having a minimum printable line width of 100 μm.
An LTCC green sheet was prepared as a ceramic green sheet. A silver paste was prepared as a conductor paste for circuit pattern printing.

  Using the screen plates of (1) to (3) above, screen printing of a circuit pattern having a minimum line width of 0.150 mm was performed using a silver paste on an LTCC green sheet. Next, in the same manner as shown in FIG. 4, each of the obtained green sheets with circuit patterns is provided with auxiliary patterns 15 having a minimum line width of 0.300 mm for connecting all circuit patterns in series, at both ends of the series connection circuit. , And a screen having a substantially circular pad area 16 at the midpoint, and screen printed using another screen plate. The screen plate used for printing the auxiliary pattern was a screen plate having a minimum printable line width of 100 μm. Further, a silver paste was used as the conductive paste for forming the auxiliary pattern.

  The three LTCC green sheets with conductor patterns obtained above were subjected to a drying process at 70 ° C. for 20 minutes, and then contacted with the tester needles at the pad regions 16 at both ends of the series connection circuit to conduct a continuity test. went. Regarding the LTCC green sheet with a conductor pattern obtained using the screen plate of (1) above, the LTCC green sheet with a conductor pattern obtained using the screen plate of (2) and (3) was conducted. It did not conduct.

  The LTCC green sheet with a conductor pattern obtained by using the screen plates of (2) and (3) was further subjected to a continuity test using the pad region 16 at the midpoint to identify a region with a printing defect location. In addition, it was confirmed that this area coincided with an area where the screen plate was missing or clogged.

  Furthermore, in the screen plate of (3), the clogged portion was washed to produce an LTCC green sheet with a conductor pattern in the same manner as described above.

  According to the manufacturing method of the present invention, it is possible to easily and accurately detect the presence or absence of a circuit pattern defect at an early stage in the manufacturing process, and thereby a ceramic circuit board for mounting an electronic component such as a semiconductor element or a piezoelectric vibrator. Can be manufactured with good yield.

DESCRIPTION OF SYMBOLS 1 ... Circuit board, 2 ... Base | substrate, 3 ... Frame, 4 ... Cavity, 5 ... Element connection terminal, 6, 8 ... Through-conductor, 7 ... Internal printed circuit, 9 ... External connection terminal,
21 ... Mounting surface, 22 ... Light emitting element mounting portion, 23 ... Non-mounting surface,
DESCRIPTION OF SYMBOLS 10 ... Connection board | substrate, 11 ... Mother board, 12 ... Section of circuit board, 13 ... Surplus part, 14 ... Section boundary line, 15 ... Auxiliary pattern, 16 ... Pad area | region

Claims (4)

Forming a predetermined through hole in the ceramic green sheet; filling a predetermined paste hole in the ceramic green sheet with a conductive paste; printing a circuit pattern with the conductive paste on the ceramic green sheet; In the method for manufacturing a ceramic circuit board, the ceramic green sheet having undergone the process is fired as a single layer or a laminated body in which a plurality of sheets are laminated, and each of the processes is performed in lot units.
The step of printing the circuit pattern is carried out by printing the circuit pattern and an auxiliary pattern for connecting the circuit pattern in series on a predetermined number of ceramic green sheets in advance for each lot, A method for manufacturing a ceramic circuit board, which is performed for each lot based on a result of a continuity test.   The method for manufacturing a ceramic circuit board according to claim 1, wherein drying is performed before the continuity test.   3. The ceramic according to claim 1, wherein the circuit pattern is printed by screen printing using a screen plate, and the minimum line width of the circuit pattern is 1 to 2 times the minimum printable line width of the screen plate. A method of manufacturing a circuit board.   The auxiliary pattern is printed by screen printing using a screen plate, and the minimum line width of the auxiliary pattern is at least twice the minimum printable line width of the screen plate. A method for producing a ceramic circuit board according to Item.

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