A method for calculating the alignment deviation of LTCC substrate stacking

Abstract

This invention relates to a method for calculating the stacking alignment deviation of LTCC substrates. The method includes the following steps: punching alignment deviation marking holes and stacking alignment holes; filling the alignment deviation marking holes with slurry; printing cutting lines on the topmost green ceramic sheet; performing stacking, isostatic pressing, and green cutting processes on the green ceramic sheet; and calculating the stacking alignment deviation of each green ceramic sheet layer in the substrate. This invention can accurately determine the stacking alignment deviation of the substrate down to any specific layer, thus providing specific stacking deviation data for each substrate. For substrates with specific requirements for stacking accuracy, it provides screening data, eliminating substrates with deviations that do not meet the requirements, thereby improving production quality.

Description

Technical Field

[0001] This invention relates to the field of LTCC substrate manufacturing technology, and more specifically to a method for calculating the alignment deviation of LTCC substrate stacks. Background Technology

[0002] LTCC substrates are widely used in TR components and various passive chip components due to their excellent microwave dielectric properties. The manufacturing process involves filling through-holes in each layer of LTCC green ceramic wafer and printing metal paste to achieve metallization. Then, the different layers are stacked together according to a designed sequence and sintered into a dense multilayer substrate. The main processing flow of LTCC substrates is as follows: First, circular through-holes are punched into the LTCC green ceramic wafer using laser or mechanical methods; then, the holes are filled with metal paste to interconnect different layers; next, designed conductor wiring is printed on the surface of each green ceramic wafer, and after the paste conductors dry, all green ceramic wafers are stacked layer by layer; then, co-firing, dicing, post-printing, and post-firing processes are performed; finally, the desired multilayer substrate is formed.

[0003] According to design requirements, the number of layers in LTCC multilayer substrates typically ranges from 6 to 30. During the layer-by-layer stacking process, some layers may exhibit varying degrees of horizontal positional deviation, leading to horizontal offset of the vias filled with metal paste between different layers. For substrates with strict alignment accuracy requirements, it is necessary to determine the final actual stacking offset of each substrate. Furthermore, for production cost control, if there is a good method to screen and reject substrates with stacking deviations that do not meet the requirements after stacking, it can prevent them from flowing into subsequent processes and wasting material costs and human resources. However, currently, there is still a lack of quantitative calculation methods in actual production that can provide the interlayer offset of each substrate.

[0004] Therefore, a method for calculating the alignment deviation of LTCC substrate stacks is needed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for calculating the alignment deviation of LTCC substrate stacking. This method can overcome the shortcomings of the prior art and realize the calculation of the alignment deviation generated during the stacking of LTCC green ceramic sheets.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for calculating the alignment deviation of an LTCC substrate stack includes the following steps:

[0008] S1. Punching of lamination alignment deviation marking holes and lamination alignment holes.

[0009] A substrate is fabricated using green ceramic sheets, with each layer of green ceramic sheet divided into multiple square regions of the same size. A set of marking holes is fabricated on the outer side of each side of each square region as marking holes for lamination alignment deviation. Each set of marking holes includes multiple circular marking holes of the same diameter that are evenly distributed, and the centers of the circular marking holes in the same set are located on the same straight line. A set of lamination alignment holes is fabricated on both sides of each layer of green ceramic sheet along the X direction. Each set of lamination alignment holes includes multiple circular alignment holes of the same diameter that are evenly distributed, and the centers of the circular alignment holes in the same set are located on the same straight line.

[0010] S2. Fill the holes marked with slurry to indicate the alignment deviation of the laminated layers.

[0011] Based on the position of the stacking alignment deviation marking holes on each layer of green ceramic sheet, multiple filling screens corresponding one-to-one with each layer of green ceramic sheet are made. At the corresponding position of the filling screen corresponding to each layer of green ceramic sheet, multiple through holes of the same size and corresponding one-to-one with the stacking alignment deviation marking holes on that layer of green ceramic sheet are cut out. The filling paste to be filled is spread on the filling screen, and the green ceramic sheet corresponding to the filling screen is placed on the vacuum adsorption stage of the printing press. The printing press is used to press the filling paste on the filling screen into each stacking alignment deviation marking hole to fill the holes with paste. The green ceramic sheet after the paste filling is completed is then dried.

[0012] Specifically, the perforated green ceramic sheet is placed on the vacuum adsorption table of the printing press, and the filling slurry is spread on the filling screen. The squeegee pressure generated by the reciprocating motion of the printing press is used to press the filling slurry into the alignment deviation marking holes of each layer of green ceramic sheet. After all the green ceramic sheets have been filled with slurry, they are placed in an oven to dry the slurry. After drying, they are taken out.

[0013] S3. Print cutting lines on the top layer of raw ceramic tiles.

[0014] Make a printing screen and design multiple cutting lines on it; each cutting line is located directly above the straight line containing the centers of all the marking holes in the same row or column; place the top layer of raw ceramic sheet on the vacuum adsorption stage of the printing press, and use the printing press and printing screen to print the cutting lines on the top layer of raw ceramic sheet, forming 8 cutting lines directly above all the marking holes of the top layer of raw ceramic sheet; after the cutting lines are printed, dry them.

[0015] Specifically, the first layer of raw ceramic sheet (i.e., the topmost layer of raw ceramic sheet) is placed on the vacuum adsorption stage of the printing machine. Using a printing screen, cutting lines are printed on the first layer of raw ceramic sheet, forming 8 cutting lines directly above all the marking holes on the same straight line in the raw ceramic sheet. After the printing of the raw ceramic sheet is completed, it is placed in an oven to dry the paste. After drying, it is taken out.

[0016] S4. Perform layering, isostatic pressing, and green cutting on the green ceramic slabs.

[0017] All the green ceramic sheets are stacked in the design order, then sealed and placed in an isostatic press to adhere all the layers of green ceramic sheets together. After the pressed whole plate of green ceramic sheets is taken out, it is placed in a hot cutter. Along the center of all the printed cutting lines, the whole plate of green ceramic sheets is cut along the X and Y directions to obtain multiple substrates. After the cutting is completed, the four sets of marking holes around the perimeter of each substrate are cut longitudinally to expose the filling paste.

[0018] S5. Calculate the stacking alignment deviation of each layer of green ceramic sheets in the substrate.

[0019] The horizontal length L of the paste exposed by each marking hole around each green ceramic sheet of the substrate is obtained. Based on the length L and the diameter D of the marking hole, the lamination alignment deviation of each green ceramic sheet along the X direction and the lamination alignment deviation along the Y direction are calculated, and then the lamination alignment deviation of the green ceramic sheet is determined.

[0020] According to a preferred embodiment of the present invention, in step S5, calculating the stacking alignment deviation of each green ceramic sheet in the substrate specifically includes the following steps:

[0021] S51. Obtain the horizontal length L of the paste exposed through each marking hole around each layer of green ceramic sheet on the substrate.

[0022] S52. Using formula (1), calculate the stacking alignment deviation of each marking hole along the X direction and the stacking alignment deviation of each marking hole along the Y direction respectively:

[0023] (1);

[0024] S53. The average value of the stacking alignment deviation of each mark hole distributed along the X direction is obtained. The average value of the stack alignment deviation of each marked hole distributed along the Y direction is calculated. ; This represents the deviation of the substrate along the X direction. This represents the deviation of the substrate along the Y direction;

[0025] S54. Using formula (2), calculate the lamination alignment deviation of each layer of green ceramic tiles. :

[0026] (2).

[0027] According to a preferred embodiment of the present invention, in step S1, each group of marking holes includes 3 circular marking holes, and the vertical distance between the center of each circular marking hole and the side length of the corresponding square area is 3 mm; the diameter of the marking hole is 0.3 mm; each group of overlapping alignment holes includes 5 circular alignment holes.

[0028] Four sets of marking holes are mechanically punched around the outline of each substrate in the green ceramic sheet: the area of ​​each layer of green ceramic sheet is divided into a corresponding number of regions according to the number of substrates distributed on it, and the area of ​​each region is larger than the outline area of ​​the substrate. Using a mechanical drilling machine, three equally spaced circular marking holes are punched on each of the four sides of the green ceramic sheet substrate, 3mm away from the outline. The centers of the three marking holes on each side are all located on the same straight line, for a total of 12 holes. All 12 marking holes have the same diameter, denoted as D. Simultaneously, a mechanical drilling machine is used to process stacking alignment holes for each layer of green ceramic sheet, distributed on both sides of the green ceramic sheet, totaling 10 holes.

[0029] According to a preferred embodiment of the present invention, in step S2, the thickness of the perforated screen is 0.05 mm, and the material of the perforated screen is stainless steel; the temperature in the oven is 50°C, and the drying time is 30 minutes.

[0030] For all the pre-punched through holes and marking holes, a corresponding 0.05mm thick stainless steel stencil is fabricated. A laser cutter is used to cut circular holes on the stencil with the exact same diameter and position as the alignment and marking holes on the green ceramic sheet. The punched green ceramic sheet is placed on the printing press table and vacuum-adhesive is applied. The filling paste is spread on the stainless steel stencil, and the pressure of the reciprocating squeegee of the printing press forces the filling paste into all the through holes and marking holes in that layer of green ceramic sheet. After all the green ceramic sheets have been filled, they are placed in a 50℃ oven to dry the paste for 30 minutes before being removed.

[0031] According to a preferred embodiment of the present invention, in step S3, the width of the cutting line is 0.3 mm; the temperature in the oven is 50°C; and the drying time is 30 minutes.

[0032] Based on the conductor design pattern of each layer of the substrate, corresponding printing screens are made. Simultaneously, a 0.3mm wide cutting line is designed in each printing screen, positioned directly above the marking holes to ensure that the center of all marking holes is aligned with a straight line after printing. The green ceramic sheets are then placed on the vacuum adsorption stage of the printing machine to complete the printing of the substrate conductor pattern and cutting lines for each layer of the green ceramic sheet. After all green ceramic sheets have been printed, they are uniformly placed in a 50℃ oven to dry the paste for 30 minutes before being removed.

[0033] According to a preferred embodiment of the present invention, in step S4, the operating parameters of the isostatic press are: temperature 75°C, pressure 3000 psi, and time 20 min.

[0034] According to a preferred embodiment of the present invention, in step S4, during the stacking process of green ceramic sheets, positioning pins are inserted into the corresponding stacking alignment holes of each layer of green ceramic sheets to position each layer of green ceramic sheets.

[0035] Compared with the prior art, the advantages of the present invention are:

[0036] (1) This invention involves punching four sets of lamination alignment deviation marking holes at the same position on each layer of green ceramic sheet before co-firing the substrate, filling the holes with slurry, printing cutting lines, isostatic pressing, and hot cutting. By comparing the positional changes of the marking holes in any layer of green ceramic sheet relative to the surface marking holes, the direction of the lamination alignment deviation of that layer of green ceramic sheet can be obtained. In LTCC production practice, usually only 2mm diameter alignment holes are punched on the edge of the entire green ceramic sheet for lamination alignment on the alignment posts of the lamination plate. After each substrate is cut, the edge is all white ceramic, but the alignment deviation between the layers inside the substrate cannot be known due to the opacity of the ceramic body. In this invention, by punching smaller diameter marking holes around the outline edge of each substrate of the green ceramic sheet and then filling them with slurry, the deviation of any layer of the substrate can be quantitatively calculated by observing the deviation of the slurry in the marking holes after cutting without damaging the internal structure of the substrate. Therefore, the present invention can accurately measure the alignment deviation of the substrate stack down to any specific layer, thereby providing specific stacking deviation data for each substrate and providing screening data for certain substrates with specific requirements for stacking accuracy.

[0037] (2) Since the processing flow of LTCC multilayer substrates is relatively complex, it usually involves drilling, filling, printing, lamination, isostatic pressing, co-firing, dicing, post-printing, and post-firing. Therefore, this invention can remove substrates that do not meet the lamination alignment deviation before co-firing, so that unqualified substrates do not have to go through the remaining processes for unnecessary production, which can save manpower. At the same time, since the post-printing of the substrate uses metal pastes such as gold, palladium and silver, the early removal of unqualified substrates can also reduce the waste of paste and save material costs. For LTCC substrates in certain specific application scenarios, such as radio frequency terminal substrates, the lamination alignment accuracy of the microwave signal transmission layer in the substrate is extremely important. Conventional substrate production processes cannot provide the lamination alignment deviation of this layer in each substrate. However, in this invention, by calculating the lamination deviation of this layer, a basis can be provided for screening the substrate lamination deviation, removing substrates with deviations that do not meet the requirements, and improving production quality. Attached Figure Description

[0038] Figure 1This is a flowchart of the method for monitoring and calculating the alignment deviation of LTCC substrate stacks in this invention;

[0039] Figure 2 This is a schematic diagram showing the distribution of marking holes in the green ceramic sheet during step S1 of the method described in this invention;

[0040] Figure 3 This is a schematic diagram of the distribution of the marking hole cutting lines in step S3 of the method described in this invention;

[0041] Figure 4 This is a magnified view of the front and a portion of the marking hole after cutting in step S4 of the method described in this invention;

[0042] Figure 5 This is a schematic cross-sectional view of the marking hole after cutting in step S4 of the method described in this invention;

[0043] Figure 6 This is a schematic diagram illustrating the calculation principle of the alignment deviation of the laminated layers.

[0044] in:

[0045] 1. Green ceramic tile; 2. Lamination alignment hole; 3. Outline of substrate; 4. Lamination alignment deviation marking hole; 5. Marking hole cutting line. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings:

[0047] This invention includes a method such as Figure 1 The method for calculating the alignment deviation of LTCC substrate stack-up is shown. The main steps of this method are: marking hole punching, marking hole slurry filling, printing cutting lines, stacking, isostatic pressing, green cutting, and calculation of stack-up deviation.

[0048] The following is a specific embodiment of the method for monitoring and calculating the alignment deviation of LTCC substrate stack-up, which includes the following steps:

[0049] S1. Select a raw ceramic sheet to make a substrate. Mechanically punch out 4 sets of stacking alignment deviation marking holes around the outline of each substrate in the raw ceramic sheet. Punch out 2 sets of stacking alignment holes on the left and right sides of the raw ceramic sheet.

[0050] S11. Select 6 green ceramic tiles 1 with dimensions of 170×170×0.127mm. The substrate to be processed is a 60×60mm square. A total of 4 substrates can be divided within the effective area of ​​each green ceramic tile.

[0051] S12. Based on the number of substrates, each layer of green ceramic sheet is divided into 4 square areas of the same size. Each square area corresponds to a substrate outline 3. At the same time, it is necessary to ensure that the area of ​​each area is larger than the area of ​​the substrate outline so as to reserve a marking hole area for the stacking alignment deviation at the edge of the substrate outline.

[0052] S13. Four sets of stacking alignment deviation marking holes 4 are mechanically punched around each square area, that is, around each substrate outline 3 in the green ceramic sheet 1. A set of stacking alignment holes 2 are processed on both sides of each green ceramic sheet 1 along the X direction; each set of stacking alignment holes 2 includes multiple circular alignment holes with the same diameter and distributed at equal intervals, and the centers of each circular alignment hole in the same set of stacking alignment holes 2 are located on the same straight line;

[0053] Specifically, a mechanical punching machine is used to punch lamination alignment holes and lamination alignment deviation marking holes for each layer of green ceramic sheet. All holes penetrate vertically from the upper surface of the green ceramic sheet to the lower surface. The lamination alignment holes 2 have a diameter of 5mm and are distributed on both sides of the green ceramic sheet 1, totaling 10 holes. These holes are used to align all layers by fitting them into the corresponding positioning pins on the lamination plate during subsequent lamination steps. The lamination deviation identification marking holes have a diameter of 0.3mm and are evenly distributed around the perimeter of the substrate, 3mm from the outline, with 3 holes on each side. The centers of all the marking holes are located on the same straight line, totaling 12 holes. Figure 2 As shown.

[0054] S2. Fill the marking holes around the substrate outline in the green ceramic tile with slurry.

[0055] S21. Arrange the six green ceramic tiles 1 in a stacked order from top to bottom, labeling them layers 1-6, with layer 1 on top and layer 6 on the bottom. Based on the relative positions of the pre-punched marking holes in layers 1-6, fabricate six stainless steel perforated stencils with a thickness of 0.05mm. Divide these six stencils into six plates: Stencil 1, Stencil 2, Stencil 3, Stencil 4, Stencil 5, and Stencil 6, corresponding to layers 1-6 of the green ceramic tiles. Use a laser cutter to cut circular holes in the stainless steel stencils with the same diameter and position as the marking holes on the green ceramic tiles.

[0056] S22. Place the first layer of green ceramic sheet with punched holes on the worktable of a semi-automatic printing machine for vacuum adsorption. Apply the Ag paste to be filled onto the corresponding No. 1 stainless steel filling screen. Set the printing parameters as follows: distance between the stainless steel filling screen and the green ceramic sheet: 0mm; squeegee filling speed: 10mm / s; squeegee filling pressure: 100N. Under these parameters, the squeegee pressure from the reciprocating motion of the printing machine forces the filling paste into all the marked holes of this layer of green ceramic sheet. At this point, all the marked holes in each green ceramic sheet are filled with Ag paste, and the paste in each hole forms a solid cylinder with a height of 0.127mm and a diameter of 0.3mm. Repeat the above process for filling the holes of the second to sixth layers of green ceramic sheets. After all the green ceramic sheets (layers 1-6) have been filled, place them in a 50℃ oven to dry for 30 minutes before removing them.

[0057] S3. Print cutting lines above all the marking holes in the first layer of green ceramic tile.

[0058] S31. Create a printing screen and design eight straight lines, each 0.3 mm wide and 150 mm long, as cutting lines 5 for the subsequent green cutting process. A cutting line 5 is placed directly above each marking hole on the same straight line.

[0059] S32. Place the raw ceramic sheet on the vacuum adsorption table of the printing machine. After laying the Ag paste to be printed on the printing screen, set the printing parameters as follows: distance between the printing screen and the raw ceramic sheet: 1mm; printing speed of the printing machine squeegee: 30mm / s; printing pressure of the squeegee: 70N.

[0060] S33. Start the printing press to print the cutting lines of the first layer of green ceramic tile. After printing, the center of all the marking holes is located at the center of the cutting lines, and the surface of the first layer of green ceramic tile after printing is as follows: Figure 3 As shown. After printing, the first layer of green ceramic sheet is placed in an oven at 50°C and dried for 30 minutes before being removed.

[0061] S4. After filling and printing, perform lamination, isostatic pressing and raw cutting on the 1-6 layers of raw ceramic tiles.

[0062] S41. Stack all the dried green ceramic tiles sequentially: Set up a stacking cover plate with positioning pins. Place the 6th layer of green ceramic tiles on the stacking cover plate through the positioning pins, and then stack the 5th-1st layer one by one, placing them on top of the 6th layer of green ceramic tiles. During the stacking process of each green ceramic tile, use positioning pins inserted into the corresponding stacking alignment holes 2 of each layer of green ceramic tiles to position each layer of green ceramic tiles.

[0063] S42. After sealing each layer of green ceramic sheet in plastic, place it in an isostatic press. Set the isostatic pressing parameters of the isostatic press: temperature: 75℃; pressure: 3000psi; time: 20min. Since green ceramic sheets contain organic colloids, this process aims to use temperature and pressure to adhere all layers of green ceramic sheets together. After isostatic pressing, the 6 layers of green ceramic sheets are pressed together to form a whole.

[0064] S43. After taking out the pressed whole plate of green ceramic sheet, put it into the hot cutting machine, place it in the center along all the printed cutting lines, and cut the whole plate of green ceramic sheet vertically downward along the X and Y directions respectively. After a total of 8 cuts, 4 green blanks with an area larger than the outline of the substrate are formed, which serve as the substrate.

[0065] S44. After green cutting, the paste filling the holes marked with the stacking alignment deviation at the edge of each green blank is divided in two, with only half of the paste remaining around the substrate outline. Figure 4 As shown, the longitudinal section is exposed on the side wall.

[0066] S5. Calculate the stacking deviation of each layer of green ceramic sheets in the substrate.

[0067] The horizontal length L of the paste exposed by each marking hole around each green ceramic sheet of the substrate is obtained. Based on the length L and the diameter D of the marking hole, the lamination alignment deviation of each green ceramic sheet along the X direction and the lamination alignment deviation along the Y direction are calculated, and then the lamination alignment deviation of the green ceramic sheet is determined.

[0068] According to a preferred embodiment of the present invention, in step S5, calculating the stacking alignment deviation of each green ceramic sheet in the substrate specifically includes the following steps:

[0069] S51. Obtain the horizontal length L of the paste exposed through each marking hole around each layer of green ceramic sheet on the substrate.

[0070] S52. Using formula (1), calculate the stacking alignment deviation of each marking hole along the X direction and the stacking alignment deviation of each marking hole along the Y direction respectively:

[0071] (1);

[0072] S53. The average value of the stacking alignment deviation of each mark hole distributed along the X direction is obtained. The average value of the stack alignment deviation of each marked hole distributed along the Y direction is calculated. ; This represents the deviation of the substrate along the X direction. This represents the deviation of the substrate along the Y direction;

[0073] S54. Using formula (2), calculate the lamination alignment deviation of each layer of green ceramic tiles. :

[0074] (2).

[0075] Specifically, the lamination alignment deviation of each green ceramic sheet in the substrate is calculated based on the horizontal length of the exposed paste in the marking holes around the substrate and the diameter of the marking holes, as well as the lamination alignment deviation. The four sets of marking holes around each substrate are longitudinally cut to expose the filled cylindrical paste; the marking holes on the topmost green ceramic sheet of the substrate are uniformly cut into two pieces of equal area along the hole diameter, and the horizontal length of the exposed paste is equal to the diameter of the marking hole.

[0076] Taking the topmost green ceramic sheet of the substrate as a reference, the exposed paste lengths along the horizontal direction of the remaining green ceramic sheets may not be equal due to possible lamination deviations. The horizontal length of the paste exposed through the marking holes in the green ceramic sheets other than the topmost one is denoted as L. A shorter L indicates a larger alignment deviation in that green ceramic sheet. Specifically, the deviation is... mm, where D is the diameter of the marking hole; for any layer of green ceramic sheet, the lamination alignment deviation of that layer can be decomposed into a component in the horizontal X direction and a component in the vertical Y direction. There are a total of 6 marking holes in the horizontal X direction. The deviation of each of the 6 holes is calculated according to Formula 1, and the average value is taken as the deviation component of the green ceramic sheet in the vertical Y direction, denoted as [missing information]. There are also a total of 6 marking holes in the vertical Y direction. The deviation of each of the 6 holes is calculated according to Formula 1, and the average value is taken. This average value represents the deviation component of the green ceramic tile layer along the horizontal X direction, denoted as [missing information]. The two deviation components in the horizontal X direction and the vertical Y direction mentioned above can be obtained through... mm, and finally the lamination alignment deviation of the green ceramic tile layer was calculated.

[0077] After each substrate is cut, the four sets of marking holes around its perimeter are cut longitudinally to expose the semi-cylindrical filling material. The marking holes on the top layer of green ceramic sheet (i.e., the first layer of green ceramic sheet) are cut into two pieces of the same area along the diameter of the marking holes by the cutting line. The exposed material is exactly 0.3 mm long in the horizontal direction, which is the diameter of the marking hole.

[0078] The following describes the calculation process of the lamination alignment deviation in this embodiment:

[0079] First, determine the formula for calculating the deviation. Taking the first layer of green ceramic slabs as a reference, the length of the exposed slurry along the horizontal direction on the marking holes of the remaining layers of green ceramic slabs may differ from that of the first layer due to lamination deviations. The shorter the length, the greater the alignment deviation of that layer. Figure 5 As shown, The length of the slurry exposed after the marked holes in different layers are cut. , representing different layers. Figure 6 This is a schematic diagram showing the result after cutting any marked hole with a deviation. Figure 6 From this, we can derive the formula for calculating the deviation (1): mm, where D is the diameter of the marking hole, which is 0.3 mm in this embodiment.

[0080] Secondly, the stacking deviation components of each green ceramic sheet in the substrate along the X and Y directions are obtained respectively.

[0081] Depend on Figure 4 It can be seen that the stacking deviation of the substrate along the Y direction is reflected in the length of exposed paste after each mark is cut in the X direction; similarly, the stacking deviation of the substrate along the X direction is reflected in the length of exposed paste after each mark is cut in the Y direction. The average value obtained by averaging the alignment deviation values ​​of the six mark holes in the X direction of the substrate (calculated by Formula 1) is the deviation of the substrate along the Y direction, denoted as... The deviation of the substrate along the X direction is obtained by averaging the alignment deviation values ​​of the six marking holes in the Y direction of the substrate (calculated by Formula 1), denoted as . .

[0082] Finally, the stacking alignment deviation of any layer of ceramic wafers on the substrate.

[0083] Since the deviation value can be decomposed into components along the X and Y directions, after the stacking alignment deviation components of any layer of green ceramic sheet in the X and Y directions are obtained in step S52, the alignment deviation of the green ceramic sheet can be obtained by formula (2). mm was calculated.

[0084] In the actual production of LTCC substrates, for layers with specific alignment deviation requirements in the design, the alignment deviation of that layer is calculated for each substrate. If the deviation is within the required range, the next process continues; if the deviation exceeds the required range, the substrate is rejected to avoid wasting labor and material costs in subsequent processes. This invention can pinpoint the alignment deviation of substrate stacking to any specific layer, thus providing specific stacking deviation data for each substrate and offering screening data for substrates with specific requirements for stacking accuracy. In this invention, by calculating the stacking deviation of each layer, a basis for screening substrate stacking deviations can be provided, rejecting substrates with deviations that do not meet the requirements and improving production quality.

[0085] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for calculating the alignment deviation of an LTCC substrate stack, characterized in that, The method includes the following steps: S1. Punching of lamination alignment deviation marking holes and lamination alignment holes. A substrate is fabricated using green ceramic sheets, with each layer of green ceramic sheet divided into multiple square regions of the same size. A set of marking holes is fabricated on the outer side of each side of each square region as marking holes for lamination alignment deviation. Each set of marking holes includes multiple equally spaced circular marking holes with a diameter of D, and the centers of all the circular marking holes in the same set are located on the same straight line. A set of lamination alignment holes is fabricated on both sides of each green ceramic sheet along the X direction. Each set of lamination alignment holes includes multiple equally spaced circular alignment holes with the same diameter, and the centers of all the circular alignment holes in the same set are located on the same straight line. S2. Fill the holes marked with slurry to indicate the alignment deviation of the laminated layers. Based on the position of the stacking alignment deviation marking holes on each layer of green ceramic sheet, multiple filling screens corresponding one-to-one with each layer of green ceramic sheet are made; at the corresponding position of the filling screen corresponding to each layer of green ceramic sheet, multiple through holes of the same size and corresponding one-to-one with the stacking alignment deviation marking holes on that layer of green ceramic sheet are cut out; the filling paste to be filled is spread on the filling screen, the green ceramic sheet corresponding to the filling screen is placed on the vacuum adsorption stage of the printing press, and the filling paste on the filling screen is pressed into each stacking alignment deviation marking hole by the printing press to fill the holes with paste, and the green ceramic sheet after the paste filling is completed is dried; S3. Print cutting lines on the top layer of raw ceramic tiles. Create a printing screen and design multiple cutting lines on it. Each cutting line is located directly above the straight line containing the centers of all the marking holes in the same row or column. Place the top layer of raw ceramic sheet on the vacuum adsorption table of the printing press. Using the printing press and the printing screen, print the cutting lines on the top layer of raw ceramic sheet, forming 8 cutting lines directly above all the marking holes on the top layer of raw ceramic sheet. After the cutting lines are printed, dry them. S4. Perform layering, isostatic pressing, and green cutting on the green ceramic slabs. All the green ceramic sheets are stacked in the design order, then sealed and placed in an isostatic press to adhere all the layers of green ceramic sheets together; after pressing the whole plate of green ceramic sheets, they are taken out and placed in a hot cutter. Along the center of all the printed cutting lines, the whole plate of green ceramic sheets is cut along the X and Y directions to obtain multiple substrates; after cutting, the four sets of marking holes around the perimeter of each substrate are cut longitudinally to expose the filling paste; S5. Calculate the stacking alignment deviation of each layer of green ceramic sheets in the substrate. The horizontal length L of the paste exposed by each marking hole around each green ceramic sheet of the substrate is obtained. Based on the length L and the diameter D of the marking hole, the stacking alignment deviation of each green ceramic sheet along the X direction and the stacking alignment deviation along the Y direction are calculated respectively, and then the stacking alignment deviation of the green ceramic sheet is determined. In step S5, the stacking alignment deviation of each green ceramic sheet in the substrate is calculated, which specifically includes the following steps: S51. Obtain the horizontal length L of the paste exposed through each marking hole around each layer of green ceramic sheet on the substrate. S52. Using formula (1), calculate the stacking alignment deviation of each marking hole along the X direction and the stacking alignment deviation of each marking hole along the Y direction respectively: （1）； S53. The average value of the stacking alignment deviation of each mark hole distributed along the X direction is obtained. The average value of the stack alignment deviation of each marked hole distributed along the Y direction is calculated. ; This represents the deviation of the substrate along the X direction. This represents the deviation of the substrate along the Y direction; S54. Using formula (2), calculate the lamination alignment deviation of each layer of green ceramic tiles. : （2）。 2. The method for calculating the alignment deviation of LTCC substrate stack according to claim 1, characterized in that, In step S1, each group of marking holes includes 3 circular marking holes, and the vertical distance between the center of each circular marking hole and the side length of the corresponding square area is 3mm; the diameter of the marking hole is 0.3mm.

3. The method for calculating the alignment deviation of LTCC substrate stack according to claim 1, characterized in that, In step S1, each set of stacked alignment holes includes 5 circular alignment holes.

4. The method for calculating the alignment deviation of LTCC substrate stack according to claim 1, characterized in that, In step S2, the thickness of the perforated screen is 0.05 mm, and the material of the perforated screen is stainless steel; the temperature in the oven is 50°C, and the drying time is 30 minutes.

5. The method for calculating the alignment deviation of LTCC substrate stack according to claim 1, characterized in that, In step S3, the width of the cutting line is 0.3 mm; the temperature in the oven is 50°C; and the drying time is 30 minutes.

6. The method for calculating the alignment deviation of LTCC substrate stack according to claim 1, characterized in that, In step S4, the operating parameters of the isostatic press are: temperature 75℃, pressure 3000psi, and time 20min.

7. The method for calculating the alignment deviation of LTCC substrate stack according to claim 1, characterized in that, In step S4, during the stacking of green ceramic sheets, positioning pins are inserted into the corresponding stacking alignment holes of each layer of green ceramic sheets to position each layer of green ceramic sheets.

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