JP2006013354A - Manufacturing method of multilayer circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of a multilayer circuit board, wherein its dimensional accuracy is improved by suppressing its contraction in the surface-direction, and by suppressing the generations of its deformation and its delamination. <P>SOLUTION: The manufacturing method has a first process of so laminating first insulating layers 1a, 1b, second insulating layers 1c, 1d, 1e whose contraction-initiating temperature is higher than the one for the first insulating layers; and third insulation layers 1f, 1g whose contraction initiating temperature is higher than the one of the second insulation layers as to interpose the second insulating layer between the first and third insulating layers; a second process for so heating a laminate 1 obtained in the first process at a temperature which is lower than the contraction-initiating temperature of the second insulation layers, and is not lower than the contraction-initiating temperature of the first insulating layers as to contract the first insulation layers in the thickness-direction of them largely in comparison with the surface-direction of them; a third process of so heating the laminate 1 at a temperature which is lower than the contraction-initiating temperature of the third insulating layers, and is not lower than the contraction-initiating temperature of the second insulating layers as to contract the second insulating layers in their thickness-direction large, in comparison with their surface-direction; and a fourth process of so heating the laminate 1 at a temperature which is not lower than the contraction-initiating temperature of the third insulating layers as to contract the third insulating layers in the thickness-direction of them by a large amount and as to complete the sintering of the laminate 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer wiring board used for semiconductor devices, composite electronic components, and the like.

  Conventionally, multilayer circuit boards have been used for semiconductor devices and composite electronic components.

  As such a conventional multilayer circuit board, for example, a wiring conductor and a via-hole conductor are provided inside a laminated body in which a plurality of insulating layers made of an inorganic composition are laminated, and these are connected to each other. A structure having a mounting portion for connecting an electronic component element on the surface is known. In recent years, there has been a demand for improvement in dimensional accuracy of multilayer circuit boards. A first insulating layer as two types of insulating layers having different shrinkage start temperatures, and a second insulating layer that starts shrinking at a higher temperature than the first insulating layer, There has been proposed a method for manufacturing a multilayer circuit board in which a dimensional change due to firing shrinkage is suppressed by forming a laminated body using a material (see, for example, Patent Document 1).

  When the multilayer circuit board described above is manufactured, first, a plurality of insulating layers 51a to 51e are prepared as shown in FIG. 3, and a wiring conductor 52 and a via-hole conductor 53 are provided in each insulating layer. Thereafter, the insulating layers 51a to 51e are stacked and integrally fired to manufacture a multilayer circuit board. At this time, the temperature at which shrinkage starts with firing is different between the inorganic composition forming the insulating layers 51a, 51b, and 51c and the inorganic composition forming the insulating layers 51d and 51e.

According to such a method for manufacturing a multilayer circuit board, when an insulating layer having a low shrinkage start temperature starts to shrink, shrinkage in the surface direction is suppressed by the insulating layer having a high shrinkage start temperature in an unsintered state. . On the other hand, when an insulating layer having a high shrinkage start temperature starts to shrink, shrinkage in the surface direction is suppressed by the insulating layer having a low shrinkage start temperature. Attempts have been made to increase the dimensional accuracy of the multilayer circuit board by suppressing the shrinkage in the plane direction of the laminate and greatly shrinking in the thickness direction by the mechanism as described above.
JP 2001-15875 A

  However, in the above-described conventional manufacturing method, since the laminate is formed using only two types of insulating layers having different shrinkage start temperatures, when there are regions where shrinkage behavior overlaps between the two types of insulating layers, That is, when the contraction of the second insulating layer starts before the contraction of the first insulating layer is completed, both the first insulating layer and the second insulating layer contract, and the multilayer circuit board There was a drawback that the dimensional accuracy was lowered. Then, after completing the contraction of the first insulating layer, a method of suppressing the contraction of each insulating layer by sintering the laminated body so as to start the contraction of the second insulating layer is conceivable. In this case, the adhesive strength between the first insulating layer and the second insulating layer is low at the interface between the first insulating layer and the second insulating layer, and delamination and deformation of the stacked body are likely to occur. When such delamination and deformation occur, the disadvantage of inducing deterioration of the insulation and strength of the laminate is induced.

  The present invention has been devised in view of the above-described drawbacks, and its purpose is to provide a multilayer circuit that has high dimensional accuracy and can effectively suppress the occurrence of deformation and delamination by suppressing shrinkage in the surface direction. It is to provide a method for manufacturing a substrate.

  The method for manufacturing a multilayer circuit board of the present invention includes a first insulating layer, a second insulating layer that starts shrinking at a higher temperature than the first insulating layer, and a first insulating layer that starts shrinking at a higher temperature than the second insulating layer. Forming a stacked body by stacking 3 insulating layers with the second insulating layer interposed between the first insulating layer and the third insulating layer; and A step B in which the first insulating layer is greatly contracted in the thickness direction as compared to the surface direction by heating at a temperature lower than the contraction start temperature of the insulating layer and not less than the contraction start temperature of the first insulating layer; By heating the laminated body at a temperature lower than the shrinkage start temperature of the third insulating layer and not less than the shrinkage start temperature of the second insulating layer while the shrinkage of the first insulating layer continues. A step C of contracting the second insulating layer in the thickness direction relative to the surface direction; After the contraction of the insulating layer is completed, in a state where the contraction of the second insulating layer continues, the stacked body is heated at a temperature equal to or higher than the contraction start temperature of the third insulating layer. And a step D of greatly contracting the insulating layer in the thickness direction as compared to the surface direction.

  Further, in the method for manufacturing a multilayer wiring board according to the present invention, the first insulating layer corresponds to 90% of the total contraction amount until the second insulating layer starts contracting in the step C. The volume shrinkage is completed.

  Furthermore, in the method for manufacturing a multilayer wiring board according to the present invention, in the step D, the second insulating layer corresponds to 90% of the total shrinkage until the third insulating layer starts to shrink. The volume shrinkage is completed.

  According to the method for manufacturing a multilayer circuit board of the present invention, the laminate is heated at a temperature lower than the shrinkage start temperature of the second insulating layer and equal to or higher than the shrinkage start temperature of the first insulating layer. The insulating layer is greatly shrunk in the thickness direction as compared to the surface direction, and then the laminate is at a temperature lower than the shrinkage start temperature of the third insulation layer and higher than the shrinkage start temperature of the second insulation layer. By heating, the second insulating layer is greatly shrunk in the thickness direction as compared to the surface direction, and finally, the first and second are heated at a temperature equal to or higher than the shrinkage start temperature of the third insulating layer. And the third insulating layer is sintered. What is important here is that the stacked body is formed by interposing the second insulating layer between the first insulating layer and the third insulating layer, and at the start of shrinkage of the second insulating layer, Make sure that the contraction continues, and that the contraction of the first insulating layer is completed at the start of contraction of the third insulating layer, and that the contraction of the second insulating layer continues. It is.

  By sintering the laminate as described above, when the first insulating layer first shrinks, the shrinkage in the surface direction of the first insulating layer is caused by the unsintered second insulating layer and the third insulating layer. Suppressed by rigidity. Next, at the start of contraction of the second insulating layer, both the first insulating layer and the second insulating layer contract, but the contraction in the plane direction of the first insulating layer and the second insulating layer is the third in the unsintered state. It is suppressed by the rigidity of the insulating layer. During this time, diffusion of the inorganic composition constituting the first insulating layer and the inorganic composition constituting the second insulating layer occurs at the boundary surface between the first insulating layer and the second insulating layer, and the first insulating layer and the second insulating layer 2 Adhesion with the insulating layer is maintained well. At the start of contraction of the third insulating layer, both the second insulating layer and the third insulating layer contract. However, the contraction in the surface direction of the second insulating layer and the third insulating layer is already sintered. It is suppressed by the rigidity of one insulating layer. During this time, diffusion occurs between the inorganic composition constituting the second insulating layer and the inorganic composition constituting the third insulating layer at the boundary surface between the second insulating layer and the third insulating layer, and the second insulating layer and the third insulating layer. Good adhesion to the insulating layer is maintained. As a result, the shrinkage in the plane direction of the laminate is suppressed, the occurrence of warpage of the multilayer circuit board can be suppressed, the dimensional accuracy can be increased, and delamination between insulating layers can be effectively prevented.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a multilayer circuit board manufactured by the manufacturing method of the present invention, in which 1a and 1b are first insulating layers, 1c to 1e are second insulating layers, 1f and 1g are third insulating layers, 2 is a wiring conductor and 3 is a via-hole conductor.

  A multilayer circuit board 10 shown in FIG. 1 has a structure in which first insulating layers 1a and 1b, second insulating layers 1c to 1e, and third insulating layers 1f and 1g are stacked. A wiring conductor 2 is formed inside and on the surface layer of the multilayer circuit board 10, and the surface layer wiring conductor mainly functions as a connection pad serving as an electronic component element mounting portion, and the inner wiring conductor and via-hole conductor are It mainly functions as wiring for electrically connecting each circuit element, and circuit elements such as inductors and capacitors.

  The first insulating layers 1a and 1b, the second insulating layers 1c to 1e, and the third insulating layers 1f and 1g are composed of inorganic compositions having different shrinkage start temperatures at the time of firing. Examples of the materials of these inorganic compositions include: A glass-ceramic material that can be fired at a relatively low temperature of 800 ° C. to 1200 ° C. is preferably used. The glass-ceramic material includes a glass powder and a ceramic powder. The glass powder is, for example, 30 to 100 parts by weight, and the material excluding the glass powder is a ceramic powder. In this embodiment, for example, the first insulating layer is made of a material composed of 87 parts by weight of glass powder, the second insulating layer is made of 67 parts by weight of glass powder, and the third insulating layer is made of a material composed of 55 parts by weight of glass powder. did.

As a specific composition of the glass powder, for example, as essential components, 20 to 70 parts by weight of SiO ₂ , 0.5 to 30 parts by weight of Al ₂ O ₃ , 3 to 60 parts by weight of MgO, and optional components 0 to 35 parts by weight of CaO, 0 to 35 parts by weight of BaO, 0 to 35 parts by weight of SrO, 0 to 20 parts by weight of B ₂ O ₃ , 0 to 30 parts by weight of ZnO, 0 to 10 parts of TiO ₂ Part by weight, 0 to 3 parts by weight of Na ₂ O and 0 to 5 parts by weight of Li ₂ O can be mentioned.

The ceramic powder includes at least one selected from Al ₂ O ₃ , SiO ₂ , MgTiO ₃ , CaZrO ₃ , CaTiO ₃ , Mg ₂ SiO ₄ , BaTi ₄ O ₉ , ZrTiO ₄ , SrTiO ₃ , BaTiO ₃ and TiO _2. Can be mentioned.

  According to the combination of the glass powder and the ceramic powder having the above composition, low-temperature sintering at 1000 ° C. or lower is possible, and silver (melting point: 960 ° C.), copper (melting point: 1083 ° C.), gold (melting point) as the wiring conductor. 1063 ° C.) or the like, and a low-loss circuit can be created. Also, the dielectric constant can be controlled, which is suitable for circuit miniaturization and low loss due to high dielectric constant, or high-speed transmission due to low dielectric constant. In addition, by controlling various compositions within the above range, the firing shrinkage behavior can be easily controlled and changed.

  The wiring conductor 2 and the via-hole conductor 3 are made of a conductive material containing any one of silver, copper, and gold, and the thickness thereof is set to 5 to 25 μm, for example.

  Moreover, the diameter of the via-hole conductor 3 can be set arbitrarily, and when the thickness of the insulating layer in which the via-hole conductor 3 is embedded is 10 to 300 μm, the diameter of the via-hole conductor 3 is set to 50 to 300 μm, for example.

  Next, the manufacturing method of the multilayer circuit board mentioned above is demonstrated using figures.

(Process A)
In FIG. 2, 1a and 1b are first insulating layers, 1c to 1e are second insulating layers, and 1f and 1g are third insulating layers. These insulating layers are, for example, a powder obtained by combining the above-described glass powder and ceramic powder, mixed with an organic binder, an organic solvent, and, if necessary, a plasticizer to form a slurry, and using this slurry, a doctor blade method or the like It is a ceramic green sheet obtained by tape-molding and cutting to a predetermined dimension. At this time, the first insulating layers 1a and 1b are thinner than the second insulating layers 1c to 1e, and the second insulating layers 1c to 1e are thinner than the third insulating layers 1f and 1g. The thickness of each of the first insulating layers 1a and 1b is set to, for example, 2 to 80 μm, the thickness of each of the second insulating layers 1c to 1e is set to, for example, 5 to 150 μm, and the third insulating layer 1f Each thickness of 1 g is set to 10 to 300 μm, for example.

  Next, through holes are formed in each insulating layer by punching or the like, a conductive paste that becomes the via-hole conductor 3 is filled in the through holes, and a conductor paste that becomes the wiring conductor 2 is screen-printed on the main surface of each insulating layer Deposit by law.

In this embodiment, for example, the inorganic material constituting the first insulating layer is glass powder, 40 parts by weight of SO ₂ , ₂ parts by weight of Al ₂ O ₃ , 15 parts by weight of MgO, 1 part by weight of CaO, 15 parts by weight of BaO, 20 parts by weight of B ₂ O ₃ , 1 part by weight of ZnO, 0.5 parts by weight of TiO ₂ , 0.5 parts by weight of Na ₂ O, 5 parts by weight of Li ₂ O, ceramic The powder is composed of 15 parts by weight of MgTiO _3, and the inorganic composition constituting the second insulating layer is glass powder, 40 parts by weight of SO ₂ , ₂ parts by weight of Al ₂ O ₃ , and 15 parts by weight of MgO. Part, CaO 1 part, BaO 15 part, BO ₃ 20 part, ZnO 1 part, TiO ₂ 0.5 part, Na ₂ O 0.5 part, Li ₂ O 5 parts by weight, ceramic _powder, or a material containing 45 parts by weight of Al 2 _{O 3} Made, the inorganic material glass powder constituting the third insulating layer, the SO ₂ 40 parts by weight, _Al 2 _{O 3} and 2 parts by weight, 15 parts by weight of MgO, 1 part by weight of CaO, 15 parts by weight of BaO, 20 parts by weight of B ₂ O ₃ , 1 part by weight of ZnO, 0.5 part by weight of TiO ₂ , 0.5 part by weight of Na ₂ O, 5 parts by weight of Li ₂ O, ceramic powder, MgTiO ₃ The composition is 82 parts by weight. Thus, the shrinkage start temperature can be varied for each insulating layer by changing the glass content of the inorganic composition constituting the insulating layer. A slurry obtained by adding an acrylic binder as an organic binder and toluene as an organic solvent to these inorganic compositions was prepared to form ceramic green sheets serving as a first insulating layer, a second insulating layer, and a third insulating layer, respectively. . The material of the wiring conductor 2 and the via-hole conductor 3 is formed, for example, by adding ethyl cellulose as an organic binder and 2-2-4-trimethyl-3-3-pentadiol monoisobutyrate as an organic solvent to silver powder. A paste was used.

  The laminated body 1 is formed by laminating the insulating layers thus obtained in a predetermined order so that the second insulating layer is interposed between the first insulating layer and the third insulating layer. In the present embodiment, when the first insulating layer is A, the second insulating layer is B, and the third insulating layer is C, the respective insulating layers are stacked in the order of ABCBCBA stacking.

(Process B)
Next, the obtained laminated body 1 is heated at a temperature lower than the shrinkage start temperature of the second insulating layer and equal to or higher than the shrinkage start temperature of the first insulating layer, whereby the first insulating layers 1a and 1b are heated. It is contracted greatly in the thickness direction compared to the surface direction. In the step B, when the first insulating layers 1a and 1b contract, the contraction in the surface direction of the first insulating layers 1a and 1b is unsintered second insulating layers 1c to 1e and the third insulating layer 1f, It is suppressed by the rigidity of 1 g.

  In the present embodiment, the composition of the inorganic composition is adjusted such that the first insulating layer has a shrinkage start temperature of 690 ° C., and the second insulating layer has a shrinkage start temperature of 765 ° C., for example, the firing temperature is 750 ° C. The laminated body is heated for a predetermined time while being kept at ° C.

(Process C)
Next, in a state in which the first insulating layers 1a and 1b continue to contract, the stacked body 1 is at a temperature lower than the contraction start temperature of the third insulating layer and equal to or higher than the contraction start temperature of the second insulating layer. By heating, the second insulating layers 1c to 1e are contracted greatly in the thickness direction as compared to the surface direction. In the step C, by starting contraction of the second insulating layers 1c to 1e in a state where the contraction of the first insulating layers 1a and 1b is continued, a boundary surface between the first insulating layer and the second insulating layer, That is, diffusion occurs between the inorganic composition constituting the first insulating layer and the inorganic composition constituting the second insulating layer at the interface between the insulating layer 1a and the insulating layer 1c and at the interface between the insulating layer 1b and the insulating layer 1e. Adhesion between the insulating layer and the second insulating layer is improved. In addition, since the second insulating layers 1c to 1e are heated at a temperature equal to or higher than the shrinkage start temperature while the first insulating layers 1a and 1b continue to contract, the first insulating layer and the second insulating layers 1c to 1e are heated. In the meantime, the shrinkage in the surface direction of the first insulating layers 1a and 1b and the second insulating layers 1c to 1e is suppressed by the rigidity of the unsintered third insulating layers 1f and 1g. Is done.

  In this embodiment, the composition of the inorganic composition is adjusted so that the shrinkage start temperature of the third insulating layer is 835 ° C. In this step C, the firing temperature is kept at 800 ° C. for a predetermined time. Then, the laminated body is heated.

(Process D)
Next, after the contraction of the first insulating layers 1a and 1b is completed, the contraction start temperature of the third insulating layers 1f and 1g is reduced in the state in which the contraction of the second insulating layers 1c to 1e continues. By heating at the above temperature, the third insulating layer is greatly contracted in the thickness direction as compared to the surface direction. In the step D, the interface between the second insulating layer and the third insulating layer is started by starting the contraction of the third insulating layers 1f and 1g while the contraction of the second insulating layers 1c to 1e is continued. That is, the inorganic composition constituting the second insulating layer at the interface between the insulating layer 1c-insulating layer 1f, the insulating layer 1f-insulating layer 1d, the insulating layer 1d-insulating layer 1g, and the insulating layer 1g-insulating layer 1e Diffusion with the inorganic composition constituting the third insulating layer occurs, and adhesion between the second insulating layer and the third insulating layer is improved. Further, while the second insulating layers 1c to 1e and the third insulating layers 1f and 1g are both contracted, the contraction in the plane direction of the second insulating layers 1c to 1e and the third insulating layers 1f and g is contracted. Is suppressed by the rigidity of the first insulating layers 1a and 1b.

  In this step D, for example, the second insulating layers 1c to 1e and the third insulating layers 1f and 1g are contracted by continuing to heat the laminated body while maintaining the firing temperature at 860 ° C., and heating is continued in that state. As a result, first, the second insulating layers 1c to 1e are sintered, and then the third insulating layers 1f and 1g are sintered, whereby the entire laminate is sintered.

  Here, the start of contraction means that contraction accompanying the sintering of the inorganic composition constituting the insulating layer is started. The organic binder contained in the insulating layer is decomposed and removed by heating, and in this case, shrinkage of about 0 to 1% may occur. This is due to the removal of the binder, and the inorganic composition is sintered. This is different from the substantial shrinkage caused by. The binder removal temperature varies depending on the binder to be used, but it ends by about 500 ° C. for an acrylic or methacrylic binder and about 600 ° C. for a butyral binder. Regarding the shrinkage start temperature in firing, the difference in temperature is preferably 10 ° C. or higher, more preferably 20 ° C. or higher.

  Regarding the volume shrinkage in firing, the first insulation layers 1a and 1b have a volume shrinkage corresponding to 90% of the total shrinkage amount until the second insulation layers 1c to 1e start shrinking in Step C. The heating time is set to complete. This is because when the shrinkage amount of the first insulating layer is less than 90%, the variation of the shrinkage suppression effect becomes large, and as a result, the dimensional accuracy in the surface direction varies. Therefore, it is desirable that the first insulating layers 1a and 1b have completed volume shrinkage corresponding to 90% of the total shrinkage amount until the second insulating layers 1c to 1e start shrinking, Furthermore, it is desirable that 95% or more is completed. For the same reason, the second insulating layers 1c to 1e have a volume shrinkage corresponding to 90% of the total shrinkage amount until the third insulating layers 1f and 1g start shrinking in the process D. It is desirable that it is completed, and more preferably 95% or more.

  Further, in the present invention, the completion of contraction of the insulating layer means the time when the contraction of the entire volume of the insulating layer has progressed 99% or more.

  Regarding the thickness of each insulating layer, the second insulating layers 1c to 1e that start shrinking at a higher temperature than the first insulating layers 1a and 1b with application of heat are made thicker than the first insulating layers 1a and 1b. At the same time, the third insulating layers 1f and 1g that start shrinking at a higher temperature than the second insulating layers 1c to 1e with the application of heat are thicker than the second insulating layers 1c to 1e. Thereby, the first insulating layers 1a and 1b having a low shrinkage start temperature have a small stress due to the shrinkage, and thus the shrinkage in the plane direction is more effectively suppressed by the second insulation layers 1c to 1e having a high shrinkage start temperature. The Rukoto. The same applies to the thickness relationship between the second insulating layer and the third insulating layer.

  Each insulating layer is laminated so that the first, second, and third insulating layers are vertically symmetrical with respect to the second insulating layer 1d disposed in the center in the laminating direction, that is, ABCBCBA. .

  By sintering the laminate through the above steps A to D, it is possible to increase the dimensional accuracy of the multilayer circuit board and effectively prevent delamination between insulating layers.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible within the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, when the laminated body 1 is manufactured, each insulating layer is formed by using ceramic green sheets and laminated. However, instead of this, the first insulating layer having a relatively thin thickness is used. The inorganic composition constituting 1a and 1b may be formed into a paste and applied directly to the main surface of the ceramic green sheet used for forming the second insulating layer by printing or the like. In this case, the first insulating layer having a small thickness can be formed relatively easily by applying a paste or the like, and the first insulating layer is compared with the case where the first insulating layer having a small thickness is made of a ceramic green sheet or the like. There is an advantage that the workability in forming the substrate becomes good and the productivity of the multilayer circuit board can be improved.

  Further, in the above-described embodiment, when the laminated body 1 is heated, if a weight of a size capable of covering the entire upper surface is placed on the laminated body, the multilayer circuit board is deformed by the weight of the weight. And delamination can be more effectively prevented.

  Furthermore, in the above-described embodiment, the first, second, and third insulating layers are stacked in the order ABCBCBA. However, the stacking order is not limited to this, and there are various types depending on the balance with the distribution conductor distribution and the like. For example, a stacking order (ABBCCCC or the like) in which the first, second, and third insulating layers are distributed somewhat unevenly in the thickness direction of the stacked body may be used.

  Furthermore, in the present embodiment, as the conductor paste used for forming the wiring conductor or the like, a paste in which the inorganic components are all made of silver powder is used, but a predetermined amount of an additive such as glass frit is added thereto. Needless to say, it may be used. For example, when the silver powder content is 99.9% or higher, the first insulating layer starts to contract from a temperature lower than the temperature at which the first insulating layer starts to contract (650 ° C. or lower). The compactness is enhanced by the compression effect due to the contraction of the first insulating layer and the second insulating layer, and the conductor resistance value of the circuit can be lowered. The solid content of such a conductive paste is preferably set in the range of 90% to 99.9%, for example, so that the denseness of the wiring conductor can be improved.

  Furthermore, after the firing shrinkage is finished, the surface of the wiring conductor may be subjected to a surface treatment such as a plating treatment. In the present invention, a multilayer circuit board that is densely sintered even by low-temperature firing is obtained. The liquid or the like is less likely to erode the laminate, and the surface treatment process can be made more efficient.

  Furthermore, the manufacturing method of the present invention can also be applied to the case where a plurality of mother boards for manufacturing a plurality of multilayer circuit boards can be manufactured. Such a plurality of mother boards for use have a plurality of board areas corresponding to a multilayer circuit board in a one-to-one correspondence, and are cut along a boundary between adjacent board areas to form a plurality of multilayer circuit boards. It is used in a method of obtaining a plurality of multilayer circuit boards by dividing them at the same time, and when the present invention is applied to such a substrate substrate for obtaining a plurality of dicing lines, the dicing line is fired in the laminate. Since there is almost no inconvenience such as deviation or distortion from the design position due to deformation etc. due to deformation, there is also an advantage that the mother board can be cut accurately and a multilayer circuit board with high dimensional accuracy can be obtained. .

1 is a cross-sectional view of a multilayer circuit board according to an embodiment of the present invention. It is a figure explaining the manufacturing process of the multilayer circuit board which concerns on one Embodiment of this invention. It is a figure explaining the manufacturing process of the conventional multilayer circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... multilayer body 1a, 1b ... 1st insulating layer 1c-1e ... 2nd insulating layer 1f, 1g ... 3rd insulating layer 2 .... Wiring conductor 3. Via hole conductor

Claims (3)

A first insulating layer; a second insulating layer that starts shrinking at a higher temperature than the first insulating layer; and a third insulating layer that starts shrinking at a higher temperature than the second insulating layer. Forming a laminate by laminating the second insulating layer between the first insulating layer and the third insulating layer; and
The laminated body is heated at a temperature lower than the shrinkage start temperature of the second insulating layer and equal to or higher than the shrinkage start temperature of the first insulating layer, thereby making the first insulating layer in the thickness direction as compared to the surface direction. Step B for large shrinkage,
By heating the laminated body at a temperature lower than the shrinkage start temperature of the third insulating layer and not less than the shrinkage start temperature of the second insulating layer while the shrinkage of the first insulating layer continues. A step C of contracting the second insulating layer greatly in the thickness direction compared to the surface direction;
After the shrinkage of the first insulating layer is completed, the laminate is heated at a temperature equal to or higher than the shrinkage start temperature of the third insulating layer while the shrinkage of the second insulating layer is continued. And a step D of contracting the third insulating layer largely in the thickness direction as compared to the surface direction. The volume contraction corresponding to 90% of the total contraction amount of the first insulating layer is completed before the second insulating layer starts contracting in the step C. Item 8. A method for manufacturing a multilayer circuit board according to Item 1. In the step D, until the third insulating layer starts to contract, the second insulating layer has completed volume contraction corresponding to 90% of the total contraction amount. A method for manufacturing a multilayer circuit board according to claim 1 or 2.

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