JP2016015359A - Method of evaluating dimension stability of metal-clad laminate and method of manufacturing circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate dimension stability of a metal-clad laminate, with high accuracy even when dimensional variation occur in a plane of the metal-clad laminate.SOLUTION: For intervals between the same two holes 30 before and after etching, a difference L1-L0 of a distance L0 obtained by a first measurement step and a distance L1 obtained by a second measurement step is calculated and is defined as a dimension change Δ. By accumulating the dimension changes Δ, an accumulated dimension change Σ is calculated by the following formula. Σ=Δ+Δ+Δ+...+Δ=ΣΔ[in the formula above, a symbol Σrepresents a total sum of 1 to i, Δrepresents a dimension change of a length of a first interval (a distance between neighboring two holes 30), and Δrepresents a dimension change of a length of the i-th interval (i is a positive integer)].

Description

  The present invention relates to a method for evaluating the dimensional stability of a metal-clad laminate represented by, for example, a copper-clad laminate (CCL), and a circuit board manufacturing method using this evaluation method.

  In recent years, with the progress of downsizing, weight reduction, and space saving of electronic devices, flexible printed wiring boards (FPCs) that are thin, light, flexible, and have excellent durability even after repeated bending are used. The demand for Circuits) is increasing. FPC can be mounted three-dimensionally and densely in a limited space. For example, it can be used for wiring of movable parts of electronic devices such as HDDs, DVDs, mobile phones, and parts such as cables and connectors. It is expanding.

  The FPC is manufactured by etching a metal layer of a metal-clad laminate, which is a material, to process the wiring. In the photolithography process and FPC mounting process for the metal-clad laminate, various processes such as bonding, cutting, exposure, and etching are performed based on the alignment marks provided on the metal-clad laminate. The processing accuracy in these steps is important for maintaining the reliability of an electronic device equipped with an FPC.

  However, since the metal-clad laminate has a structure in which a metal layer and a resin layer having different thermal expansion coefficients are laminated, a stress is generated between the layers due to the difference in the thermal expansion coefficient between the metal layer and the resin layer. The stress is partly or wholly released when the metal layer is etched to process the wiring, thereby causing expansion and contraction and causing a change in the size of the wiring pattern. Therefore, a dimensional change finally occurs at the FPC stage, causing a connection failure between the wirings or between the wirings and the terminals, and reducing the reliability and yield of the circuit board.

  The dimensional change of the metal-clad laminate processed into FPC or the like is evaluated based on IPC-TM-650 (The Institute for Interconnecting and Packaging Electronic Circuits Test Method 650) 2.2.4 (B). In this method, the edge of a test piece cut out in a square shape from a metal-clad laminate is marked vertically and horizontally, and the dimensional change rate is calculated based on the change in the distance between the marks on two opposing sides.

  As a method for evaluating the dimensional accuracy of a wiring board, in Patent Document 1, a lattice-like pattern made of a conductor layer is provided as a dimensional measurement area on the surface of four corners of a disposal allowance area of a large number of wiring boards. There has been proposed a method for evaluating the dimensional accuracy of a mother board by measuring a deviation between a through hole formed based on a dimension and the center position of a dimension measurement region.

  In Patent Document 2, as a method for measuring the dimensional change of a transparent substrate, a reference plate on which an array of reference markers is formed and a transparent substrate on which an array of substrate markers is formed are overlapped, and a reference before and after the processing of the transparent substrate is performed. There has been proposed a method for evaluating a dimensional change of a transparent substrate by measuring the coordinates of a substrate marker with respect to the coordinates of the marker.

JP 2003-198098 A (Claims etc.) Japanese translation of PCT publication No. 2008-539437 (FIG. 1A, etc.)

  When processing FPC from a metal-clad laminate, it is common to take a large number of FPCs from a metal-clad laminate of a certain area. Therefore, accurately grasping the variation in the dimensional change in the plane of the metal-clad laminate is important for ensuring the reliability and improving the yield of electronic equipment incorporating the FPC. In the above IPC-TM-650 2.2.4 (B), in order to measure the distance between two marks formed on the opposite edges of the test piece, the area where the dimensional change is large in the plane of the test piece Even if there is a small area, there is a problem that in-plane variation cannot be accurately evaluated.

  The present invention provides a dimensional stability of a metal-clad laminate that can evaluate the dimensional stability of the metal-clad laminate with high accuracy even when dimensional variation varies within the plane of the metal-clad laminate. The purpose is to provide an evaluation method.

The method for evaluating the dimensional stability of a metal-clad laminate according to the present invention includes a step of preparing a test piece by cutting a long metal-clad laminate in which a metal layer and a resin layer are laminated into a predetermined length. ,
When the longitudinal direction of the metal-clad laminate is the MD direction and the width direction is the TD direction, a virtual regular square having sides parallel to the MD direction and the TD direction is assumed in the test piece. A plurality of marks each including a linear array are formed in a central region including the center and two corner regions including one each of two corners sharing one side of the regular rectangle in the TD direction. And a process.
Moreover, the evaluation method of the dimensional stability of the metal-clad laminate according to the present invention includes a first measurement step of measuring the positions of the plurality of marks and calculating a distance L0 between the adjacent marks,
Etching part or all of the metal layer of the specimen;
A second measuring step of measuring the positions of the plurality of marks after the etching and calculating a distance L1 between the adjacent marks.
Furthermore, the evaluation method of the dimensional stability of the metal-clad laminate according to the present invention includes the distance L0 obtained in the first measurement step and the second measurement step for the same two marks before and after the etching. The difference L1-L0 with respect to the obtained distance L1 is calculated, the difference L1-L0 for two or more of the intervals is accumulated, and the accumulation of the metal-clad laminate in the MD direction and / or the TD direction is accumulated. Obtaining a dimensional change amount.

  In the evaluation method of dimensional stability of the metal-clad laminate of the present invention, in the central region, the plurality of marks may be formed in the MD direction and the TD direction along a cross shape passing through the center. In the corner region, the plurality of marks may be formed in the MD direction and the TD direction along the sides of the regular square.

  In the method for evaluating the dimensional stability of the metal-clad laminate of the present invention, the difference L1-L0 is further converted into a scale of a wiring pattern on a circuit board formed from the metal-clad laminate, and a cumulative conversion dimensional change amount is obtained. A step of representing the obtained and converted cumulative dimensional change amount as a ratio to the sum of the wiring width and the wiring interval of the wiring pattern may be included.

  In the method for evaluating the dimensional stability of the metal-clad laminate of the present invention, the number of marks arranged in a straight line may be at least 11 in each of the MD direction and the TD direction. You may accumulate the said difference about the said space | interval more than a location.

The circuit board manufacturing method of the present invention is a circuit board manufacturing method for manufacturing a plurality of circuit boards from a metal-clad laminate,
Determining the wiring width and wiring spacing of the wiring pattern on the circuit board;
About the metal-clad laminate, a step of calculating a cumulative dimensional change amount by the dimensional stability evaluation method according to any one of claims 1 to 4,
Correcting the dimensions of the wiring width and the wiring interval based on the cumulative dimensional change amount;
A step of performing wiring processing based on the corrected wiring width and the wiring interval;
It is characterized by including.

  According to the dimensional stability evaluation method of the present invention, it is possible to evaluate a dimensional change of a metal-clad laminate with high accuracy including in-plane variations. Further, even when a large number of metal-clad laminates are taken, it is possible to individually evaluate the dimensional stability for each processing region on the circuit board. Therefore, the reliability and yield of the circuit board can be improved by using the dimensional stability evaluation method of the present invention for manufacturing the circuit board.

It is a perspective view which shows schematic structure of a metal-clad laminated body and a test piece. It is drawing explaining the mark position in the test piece which concerns on one embodiment of this invention. It is the elements on larger scale of the center area | region of a test piece. It is the elements on larger scale of the corner area | region of a test piece. It is drawing explaining the dimensional change amount of the space | interval of a hole. It is the elements on larger scale of the center area | region of the test piece in a modification. It is the elements on larger scale of the corner area | region of the test piece in a modification. It is drawing used for description of the evaluation sample in an Example. It is drawing used for description of preparation of the evaluation sample in an Example. 3 is a graph showing the cumulative dimensional change amount in the MD direction in Example 1; 7 is a graph showing the cumulative dimensional change amount in the MD direction in Example 2. 4 is a graph showing a cumulative dimensional change amount in a TD direction in Example 1. 6 is a graph showing a cumulative dimensional change amount in a TD direction in Example 2. It is drawing used for description of the evaluation sample in a comparative example. 5 is a graph showing a positional deviation ratio of wiring in the MD direction in the FPC size based on the evaluation result of Example 1. FIG. 10 is a graph showing a positional deviation ratio of wiring in the MD direction in the FPC size based on the evaluation result in Example 2. 6 is a graph showing a positional deviation ratio of wiring in the TD direction in the FPC size based on the evaluation result of Example 1. FIG. 6 is a graph showing a positional deviation ratio of wirings in the TD direction in the FPC size based on the evaluation result in Example 2.

  Next, embodiments of the present invention will be described with reference to the drawings as appropriate. The dimensional stability evaluation method for a metal-clad laminate according to an embodiment of the present invention includes the following steps (1) to (6). In the present embodiment, the metal-clad laminate is a material for manufacturing an FPC as a circuit board.

(1) Step of preparing a test piece:
In this step, as illustrated in FIG. 1, a test piece 10 is prepared by cutting a long metal-clad laminate 100 into a predetermined length. In the following description, the longitudinal direction of the long metal-clad laminate 100 is defined as the MD direction, and the width direction is defined as the TD direction (the same applies to the test piece 10). It is preferable that the width of the metal-clad laminate 100 (length in the TD direction) is substantially equal to the cutting interval (length in the MD direction) so that the test piece 10 has a shape close to a square. Although not shown, the metal-clad laminate 100 includes an insulating resin layer and a metal layer laminated on one side or both sides of the insulating resin layer.

  The material of the metal layer in the metal-clad laminate 100 is not particularly limited. For example, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, Examples thereof include magnesium, manganese, and alloys thereof. Among these, copper or a copper alloy is particularly preferable.

  The insulating resin layer may be composed of a single layer or a plurality of layers. There is no restriction | limiting in particular as the material of resin which comprises an insulating resin layer, For example, a polyimide resin, a polyamic acid resin, a cardo resin (fluorene resin), a polysiloxane resin, an epoxy resin etc. can be mentioned. Among these, for example, a polyimide resin is preferable.

  Preferred examples of the metal-clad laminate 100 include a single-sided copper-clad laminate (single-sided CCL) or a double-sided copper-clad laminate (double-sided CCL).

  The metal-clad laminate 100 can be prepared by any method. For example, the metal-clad laminate 100 may be prepared by preparing a resin film, sputtering a metal on the resin film to form a seed layer, and then forming a metal layer by plating. The metal-clad laminate 100 may be prepared by laminating a resin film and a metal foil by a method such as thermocompression bonding. Furthermore, the metal-clad laminate 100 may be prepared by applying a resin solution on a metal foil to form an insulating resin layer. For example, when the insulating resin layer of the metal-clad laminate 100 is made of a polyimide resin, a coating solution containing polyamic acid, which is a polyimide resin precursor, is cast on a metal foil and dried to form a coating film, followed by heat treatment And imidizing to form a polyimide layer.

(2) Step of forming a plurality of marks on the test piece:
In this step, as shown in FIG. 2, a virtual regular square 20 having sides parallel to the MD direction and the TD direction is first assumed in the test piece 10. The length of one side of the virtual regular square 20 can be set to a length according to the width (length in the TD direction) of the metal-clad laminate 100. In addition, the area of the virtual regular square 20 is preferably set to an area that can cover the range to be processed into the FPC in order to include in the evaluation object the limit of the range to be processed into the FPC when a large number are taken. Accordingly, the length of one side of the regular square 20 is preferably in the range of 60 to 90% of the length in the TD direction of the test piece 10 (the width of the metal-clad laminate 100), and in the range of 70 to 80%. It is more preferable to use the inside. For example, when the width (length in the TD direction) of the metal-clad laminate 100 is 250 mm, the length of one side of the virtual regular square 20 is preferably set within a range of 150 to 225 mm. It is more preferable to set within the range of ~ 200 mm.

  Next, as shown in FIGS. 2 to 4, the center region 21 including the center 20 a of the virtual square 20 and the two corners 20 b sharing one side in the TD direction of the square 20 are included. A plurality of marks each including a linear array are formed in the two corner regions 23a and 23b. In the present embodiment, the mark is a round hole 30 penetrating the test piece 10. The plurality of holes 30 are preferably formed at equal intervals. The hole 30 as a mark may be a polygonal shape such as a triangle or a rectangle. Further, the mark is not limited to the through-hole as long as the position can be identified, and for example, the mark may be formed by forming a groove, a notch, or the like in the test piece 10 or may be printed using ink or the like. There may be.

<Central area>
Since the center 20a of the virtual regular square 20 serves as a reference for coordinates for measuring the expansion and contraction of the test piece 10, in this embodiment, the center region 21 including the center 20a is set as a measurement target. In the central region 21, as long as a linear array is included, the positions where the plurality of holes 30 are formed are arbitrary. For example, the holes may be arranged in a T shape, an L shape, or the like. Therefore, a cross shape that can be uniformly arranged in the MD direction and the TD direction is preferable. That is, as shown in FIG. 3, it is preferable to form the plurality of holes 30 in the MD direction and the TD direction along the cross shape passing through the center 20a of the virtual regular square 20, and the cross-shaped crossing portion is defined as a virtual shape. More preferably, the regular square 20 is arranged so as to overlap the center 20a. In this case, the holes 30 overlapping the center 20a are counted as the holes 30 constituting the arrangement in both the MD direction and the TD direction.

  Further, in the central region 21, in order to accurately evaluate the dimensional stability including the variation of the dimensional change in the plane of the test piece 10, from the center 20a of the regular square 20 in the MD direction and the TD direction, respectively. The length of one side of the regular square 20 is at least 12.5% or more, preferably in the range of 12.5 to 32.5%, more preferably in the range of 12.5 to 25%. The holes 30 are preferably formed.

<Corner area>
The periphery of the two corners 20b sharing one side in the TD direction of the regular tetragon 20 is an area that is most easily expanded and contracted and has a large dimensional change in the long metal-clad laminate 100 as shown in FIG. . As one of the reasons, for example, when the metal-clad laminate 100 is manufactured by roll press processing, pressure unevenness due to the roll is likely to occur near both ends in the TD direction. Therefore, in the present embodiment, both of the two corner regions 23a and 23b including one of the two corner portions 20b sharing one side in the TD direction of the regular square 20 are set as measurement targets.

  In the corner regions 23a and 23b, the positions where the holes 30 are formed are arbitrary as long as they include a linear arrangement. For example, as shown in FIG. It is preferable to form an L shape in the MD direction and the TD direction along two sides sandwiching 20b. FIG. 4 shows only one corner area 23b, but the same applies to the other corner area 23a. In this case, the holes 30 overlapping the corners 20b are counted as holes 30 constituting an arrangement in both the MD direction and the TD direction.

  In the two corner regions 23a and 23b, in order to accurately evaluate the dimensional stability including the variation of the dimensional change in the plane of the test piece 10, both ends of one side of the regular tetragon 20 in the TD direction (that is, From the corner portion 20b) of the regular square 20 to the center side in the MD direction, the length of one side of the MD direction is at least 12.5%, preferably in the range of 12.5 to 32.5%, More preferably, the holes 30 may be formed over a range of 12.5 to 25%.

  In addition, in the two corner regions 23a and 23b, in order to accurately evaluate the dimensional stability including the variation in the dimensional change in the surface of the test piece 10, both ends of one side of the TD direction in the regular square 20 ( That is, from the corner 20b) of the regular square 20 to the center in the TD direction, the length of one side of the TD direction is at least 12.5%, preferably 12.5 to 32.5%. Of these, it is preferable to form the holes 30 over a range of 12.5 to 25%.

In addition, in order to cover the in-plane of the test piece 10 and accurately grasp the dimensional change for each part, the arrangement range between the holes 30 at both ends arranged linearly in the central region 21 and the corner region In 23a and 23b, the arrangement range between the holes 30 at both ends arranged linearly in the same direction may overlap.
Specifically, at least the positions of both ends of the plurality of holes 30 arranged in the MD direction in the central region 21 and the inside of the plurality of holes 30 arranged in the MD direction in the two corner regions 23a and 23b, respectively. The position of the hole 30 on the innermost side (the side far from the corner 20b) may be arranged to overlap when translated in the TD direction.
Similarly, at least the position of the hole 30 closest to the corner areas 23a and 23b among the plurality of holes 30 arranged in the TD direction in the center area 21 and the TD direction in the two corner areas 23a and 23b. You may arrange | position so that the position of the hole 30 of the innermost side (far side from the corner | angular part 20b) among the several holes 30 arranged may overlap, when it is translated in MD direction.
Considering the above arrangement, it is most reasonable to arrange the plurality of holes 30 in a cross shape in the central region 21, and in the two corner regions 23a and 23b, the plurality of holes 30 are formed in an L shape. It is most reasonable to arrange

  In the virtual square 20 of the test piece 10, the range in which the holes 30 are formed can be adjusted by the size of the holes 30, the number of the holes 30, and the length of the interval between the holes 30.

  The size of the hole 30 is preferably within a range of 20% or less of the length of the interval between the hole 30 and the hole 30 in order to increase the detection accuracy of the dimensional change.

  The plurality of holes 30 formed in the central region 21 and the two corner regions 23a and 23b are formed in order to accurately evaluate dimensional stability including variation in dimensional change in the plane of the test piece 10. Each of the direction and the TD direction preferably includes at least 11 linear arrays, and more preferably includes 20 or more linear arrays. Here, when the number of holes 30 is n, the number of intervals between adjacent holes 30 and holes 30 to be measured in the subsequent step (3) and step (5) is n−1. The interval between the adjacent holes 30 is, for example, 9 when the number of the holes 30 is 10, and 20 when the number of the holes 30 is 21. In this case, the number of holes 30 is preferably the same in the MD direction and the TD direction.

  The distance between the hole 30 and the hole 30 is preferably within a range of 2 mm or more in order to increase the dimensional change detection accuracy.

(3) First measurement process:
In this step, the positions of the plurality of holes 30 are measured. Then, the distance L0 between the adjacent holes 30 is calculated from the measurement result of the position of each hole 30. For example, when the number of the holes 30 is 21, the distance L0 is obtained for 20 intervals between the adjacent holes 30. Here, the distance L0 between the adjacent holes 30 means the distance from the center 30a of a certain hole 30 to the center 30a of the adjacent hole 30 as shown in FIG.

  The measurement of the position of the hole 30 is not particularly limited, and can be performed by, for example, a method of detecting the position of the hole 30 based on the image of the test piece 10.

  Although the measurement of the position of the hole 30 in this step may be performed following the step (2), it is preferable to provide a step of adjusting the condition of the test piece 10 before the measurement. As an example of the condition adjustment of the test piece 10, a humidity control process can be given. The humidity conditioning treatment can be performed by leaving the test piece 10 in a constant environment for a certain time (for example, 24 hours in an environment of 23 ° C. and 50 RH%).

(4) Etching process:
In this step, a part or all of the metal layer of the test piece 10 is etched. In order to evaluate the dimensional stability in accordance with the reality, it is preferable that the content of etching is performed in accordance with the wiring pattern of the FPC formed from the metal-clad laminate 100. When the test piece 10 is prepared from a double-sided metal-clad laminate, the metal layers on both sides may be etched. In the actual FPC processing, when heat treatment is involved, a treatment for heating the test piece 10 at an arbitrary temperature may be performed after the etching.

(5) Second measurement step:
This step is a step of measuring the positions of the plurality of holes 30 again after the etching of (4) above. Then, a distance L1 between the adjacent holes 30 is calculated from the measurement result of the position of each hole 30. The position of the hole 30 in this step can be measured by the same method as in the above step (3).

  Although the measurement of the position of the hole 30 in this step may be performed subsequent to the step (4), it is preferable to provide a step of adjusting the condition of the test piece 10 as in the step (3). In particular, when the condition adjustment is performed in the step (3), it is preferable to perform the condition adjustment under the same conditions before the measurement in this step as well.

(6) Step of obtaining cumulative dimensional change:
In this step, as shown in FIG. 5, the distance L0 obtained in the first measurement step and the distance L1 obtained in the second measurement step are the same between the two holes 30 before and after etching. The difference L1-L0 is calculated. And the difference L1-L0 is similarly calculated about 2 or more of the space | interval of the hole 30 arranged in the same linear form, Preferably about 10 or more, More preferably, all. This difference L1-L0 is defined as “amount of change in dimension Δ”. Then, the dimensional change amount Δ at each interval is accumulated to obtain an accumulated dimensional change amount Σ. This cumulative dimensional change amount Σ can be calculated by the following equation.

Σ = Δ ₁ + Δ ₂ + Δ ₃ +... + Δ _i = Σ _{i = 1} ⁱ Δ _i

In the above formula, the symbol Σ _{i = 1} ⁱ represents the sum from 1 to i. Further, the dimensional change amount Δ is determined based on the distance L1 between the nth hole 30 and the (n−1) th hole 30 after the etching, and the nth hole 30 and the (n−1) th hole 30 before the etching. Represents a value obtained by subtracting the distance L0 from (where n is an integer of 2 or more). Δ ₁ is a dimensional change amount of the length of the first interval (distance between two adjacent holes 30), and Δ _i is an i-th interval (i means a positive integer). This is the amount of dimensional change in length.

  The cumulative dimensional change amount Σ can be obtained for either one of the MD direction and the TD direction of the metal-clad laminate 100, preferably both. The dimensional stability of the metal-clad laminate 100 in the MD direction and the TD direction can be evaluated by the magnitude of the cumulative dimensional change amount Σ. In addition, as shown in examples (for example, FIGS. 10 to 13) described later, a scaled-up approximate straight line is obtained based on the actual measurement value of the cumulative dimensional change amount Σ. 10 to 13, the horizontal axis represents the distance (arrangement length) between both ends of the plurality of holes 30, and the vertical axis represents the cumulative dimensional change amount Σ. 10 to 13 indicates the magnitude of the dimensional change rate, and the magnitude of the variation in the graph slope indicates the size of the in-plane variation of the dimensional change rate.

  In addition to the steps (1) to (6), the dimensional stability evaluation method of the present embodiment can include an arbitrary step. For example, the dimensional stability evaluation method of the present embodiment can further include the following step (7).

(7) Step to convert to wiring scale:
In this step, the dimensional change Δ obtained in step (6) is converted into the scale of the wiring pattern in the FPC formed from the metal-clad laminate 100, and the obtained converted value is used as the wiring width and wiring of the wiring pattern. Expressed as a ratio to the sum of the intervals. By this step, when the metal-clad laminate 100 subjected to the test is actually processed into an FPC, it is possible to easily express the influence of the dimensional change of the metal-clad laminate 100 on the FPC wiring pattern.

  In this step, first, the dimensional change amount Δ is converted into a scale of the wiring width / interval in the L / S wiring pattern in the FPC scheduled to be formed from the metal-clad laminate 100, and the converted dimensional change amount is accumulated. The cumulative conversion dimension change is obtained. For example, when the distance L0 between the two holes 30 before etching is X mm and the wiring width and the wiring interval in the wiring pattern in the FPC to be formed are each 1 / Y of the distance L0, The dimensional change amount Δ is converted into a value when downsized to a 2 × (1 / Y) scale, and a cumulative converted dimensional change amount of the 2 × (1 / Y) scale is obtained.

Cumulative conversion dimensional change = [Σ _{i = 1} ⁱ (2 × Δ _i / Y)]

  In addition, after accumulating the dimensional change amount Δ obtained in the step (6), the cumulative dimensional change amount is a scale of the wiring width / wiring interval in the L / S wiring pattern in the FPC to be formed from the metal-clad laminate 100. It is also possible to calculate the cumulative conversion dimensional change amount.

Next, the wiring misalignment ratio is obtained from the cumulative conversion dimension change amount based on the following equation. The wiring misregistration ratio represents the cumulative conversion dimensional change amount as a ratio to the sum of the wiring width (Lmm) and the wiring interval (Smm) in the L / S wiring pattern to be formed.
Wiring misalignment ratio (%) =
{[Σ _{i = 1} ⁱ (2 × Δ _i / Y)] / [L + S]} × 100

  By plotting the misalignment ratio of the MD and TD wirings in the FPC calculated as described above on a graph, as shown in the examples (for example, FIGS. 15 to 18) described below, approximation according to the FPC size is performed. A straight line is obtained. 15 to 18, the horizontal axis represents the FPC size, and the vertical axis represents the wiring misregistration ratio (%). Here, the “FPC size” means a distance between wirings at the farthest ends among a plurality of wirings formed in the FPC. 15 to 18 indicate the magnitude of the positional deviation of the wiring, and the magnitude of the variation in the inclination of the graph indicates the magnitude of the in-plane variation of the positional deviation of the wiring.

  By this step, when the metal-clad laminate 100 subjected to the test is actually processed into a circuit, it is possible to easily express the influence of the dimensional change of the metal-clad laminate 100 on the FPC wiring pattern. Further, as shown in FIGS. 15 to 18, by creating an approximate straight line graph, the size and surface of the positional deviation of the wiring created from the metal-clad laminate 100 as the DUT according to the FPC size. It is possible to visualize the variation in the inside.

[Modification]
Next, a modification of the present embodiment will be described with reference to FIGS. In the step (2), the holes 30 as marks are arranged linearly in the MD direction and the TD direction, but the plurality of holes 30 can be arranged at an arbitrary angle with respect to the MD direction and the TD direction. It is.

  For example, FIG. 6 shows a case where a plurality of holes 30 arranged in a straight line in the central region 21 are formed in a cross shape so as to have an angle of 45 ° with respect to the MD direction and the TD direction. FIG. 7 shows a case where a plurality of holes 30 arranged in a straight line are formed at a 45 ° angle with respect to the MD direction and the TD direction in the corner region 23b.

  In the example shown in FIGS. 6 and 7, the dimensional change Δ and the cumulative dimensional change Σ in the step (6) can be obtained by the following procedure. First, a change amount in the MD direction and a change amount in the TD direction are extracted from the dimensional change amount Δ in the oblique direction with respect to the MD direction and the TD direction obtained from the measurement results in the step (3) and the step (5). . Next, the accumulated dimensional change amount Σ may be calculated for each of the extracted MD direction change amount and TD direction change amount. Steps other than those described above in this modification can be performed in the same manner as steps (1) to (6) or steps (1) to (7).

  As described above, according to the dimensional stability evaluation method of the present embodiment, the dimensional change of the metal-clad laminate 100 is obtained by the steps (1) to (6) or the steps (1) to (7). It becomes possible to evaluate with high accuracy including variations within the network. Further, even when a large number of pieces are taken from the metal-clad laminate 100, it is possible to individually evaluate the dimensional stability for each processing area to the FPC.

[Circuit board manufacturing method]
The circuit board manufacturing method according to the present embodiment is a circuit board manufacturing method for manufacturing a plurality of circuit boards from the metal-clad laminate 100. Hereinafter, the case where FPC as a circuit board is manufactured from the metal-clad laminate 100 will be described as an example. The circuit board manufacturing method of the present embodiment includes the following steps A to D;
Step A: A step of determining the wiring width and wiring spacing of the wiring pattern in the FPC,
Step B: For the metal-clad laminate 100, a step of calculating a cumulative dimensional change amount by the dimensional stability evaluation method of the above embodiment,
Step C: a step of correcting the dimensions of the wiring width and the wiring interval based on the accumulated dimensional change amount;
as well as,
Step D: A step of performing wiring processing based on the corrected wiring width and wiring interval,
Can be included.

  Step A is a step of determining the width of the wiring pattern and the size of the wiring interval according to the purpose of use of the FPC, etc., and can be performed according to a conventional method.

  Step B is a step of calculating the cumulative dimensional change Σ in the MD direction and the TD direction of the metal-clad laminate 100 by performing the above steps (1) to (6). You may implement the said process (7) as needed.

  Step C is a step of correcting the wiring width and wiring spacing dimensions of the wiring pattern determined in Step A based on the cumulative dimensional change amount or wiring positional deviation ratio obtained in Step B. The dimensional stability evaluation method of the above embodiment can accurately evaluate the dimensional change of the metal-clad laminate 100 in the MD direction and the TD direction, including in-plane variation within the processing range for FPC. Therefore, for example, even when many pieces are taken from the metal-clad laminate 100, optimum correction amounts in the MD direction and the TD direction are individually set for each FPC processed from each FPC processing region. Can be determined.

  Step D is a step of performing wiring processing by etching the metal layer based on the corrected wiring width and wiring interval, and can be performed according to a conventional method.

  In the method of manufacturing a circuit board according to the present embodiment, the FPC is manufactured with the wiring width and the wiring interval of the optimized wiring pattern according to the characteristics of the dimensional change of the metal-clad laminate 100 by the above-described steps A to D. it can. Further, even when a large number of metal-clad laminates 100 are taken, the FPC processed from each processing area to the FPC is individually optimized with the wiring width and wiring interval of the wiring pattern optimized. An FPC can be manufactured. Therefore, according to the circuit board manufacturing method of the present embodiment, it is possible to reduce the connection failure between the wirings or between the wirings and the terminals, and to improve the reliability and yield of the FPC.

  Experimental results confirming the effects of the present invention will be described.

[Preparation of sample for evaluation]
(1) Material of Evaluation Sample The following copper clad laminate (end width: 250 mm) was prepared as a material for the evaluation sample.
Copper-clad laminate 1: long, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name: Espanex (registered trademark), insulating layer thickness: 25 μm, copper foil layer; electrolytic copper foil, copper foil layer thickness: 12 μm After manufacturing a single-sided copper-clad laminate by a casting method, a copper foil is thermocompression bonded to the insulating layer side of the single-sided copper-clad laminate.
Copper-clad laminate 2: long, general laminate material, insulating layer thickness: 25 μm, copper foil layer; electrolytic copper foil, copper foil layer thickness: 12 μm, polyimide film (product made by Kaneka Corporation, product) Name: Pixio) copper foil on both sides.

(2) Preparation of sample for evaluation Said copper clad laminated board was cut | disconnected to length 250mm in MD direction, and it was set as MD: 250mmxTD: 250mm. As shown in FIG. 8, a virtual regular square was assumed in the range of MD: 200 mm × TD: 200 mm in the copper-clad laminate after cutting. In each of the two left and right corner regions (Left and Right) each including two corners sharing one side in the TD direction of the virtual square, and the center region (Center) including the center of the virtual square Samples for evaluation were prepared by drilling 21 holes continuously in the MD and TD directions at intervals of 2.5 mm. In addition, the drilling process used the drill of a 0.105 mm diameter.

[Evaluation of dimensional stability]
The position of each hole before and after removing all the copper foil layers on both sides of the sample for evaluation using a non-contact CNC image measuring machine (trade name; Quick Vision QV-X404PIL-C, manufactured by Mitutoyo) Was measured. From the measured value, the dimensional change amount and cumulative dimensional change amount of the distance between two adjacent holes before and after etching were calculated.

  Here, a method of calculating the cumulative dimensional change amount will be described. The cumulative dimensional change amount (Σ) is calculated by the following equation (1).

Σ = Δ ₁ + Δ ₂ + Δ ₃ +... + Δ ₂₀ = Σ _{i = 1} ²⁰ Δ _i (1)

Δ _i in the above formula (1) is a dimensional change amount of the distance between the i-th adjacent two holes. That is, a value obtained by subtracting the value of the distance between the nth hole and the (n−1) th hole before etching from the value of the distance between the nth hole and the (n−1) th hole after etching. Represents. Here, n is 2 to 21. Further, the symbol sigma _{i = 1} ²⁰ is, i represents the sum from 1 to 20.

(Example 1)
A long copper-clad laminate 1 was prepared, and as shown in FIG. 9, evaluation samples 1 to 3 were prepared.

  The position of each hole before and after etching in Center, Left, and Right was measured for each of the samples for evaluation 1-3. From the measured value, the dimensional change amount of the distance between two adjacent holes before and after etching and the total dimensional change amount (20 places) were calculated. The evaluation results of the evaluation sample 1 are shown in Tables 1 to 6, the evaluation results of the evaluation sample 2 are shown in Tables 7 to 12, and the evaluation results of the evaluation sample 3 are shown in Tables 13 to 18.

(Example 2)
Evaluation samples 4 to 6 were prepared in the same manner as in Example 1 except that the long copper-clad laminate 2 was used instead of the long copper-clad laminate 1.

For each of the evaluation samples 4 to 6, the positions of the holes before and after etching in Center, Left, and Right were measured. A dimensional change amount and a cumulative dimensional change amount of the distance between two adjacent holes before and after etching were calculated from the measured values. The evaluation results of the evaluation sample 4 are shown in Tables 19 to 24, the evaluation results of the evaluation sample 5 are shown in Tables 25 to 30, and the evaluation results of the evaluation sample 6 are shown in Tables 31 to 36.

  Based on the evaluation results in Example 1, the cumulative dimensional change amounts of MD and TD are shown in Table 37, FIG. 10, and Tables 39 and 12, respectively. Based on the evaluation results in Example 2, MD and TD Are shown in Table 38 and FIG. 11, and Table 40 and FIG. 13, respectively. In each figure, the horizontal axis indicates the distance (mm) from the first hole, and the vertical axis indicates the cumulative dimensional change (mm). The graphs in each figure are obtained by plotting numerical values calculated based on actual measurement values and drawing an approximate line based on the plots. The magnitude of the slope of the graph means the magnitude of the dimensional change rate, and the magnitude of the variation in the slope of the graph (the magnitude of the arrow in the figure) means the magnitude of the in-plane variation of the dimensional change rate.

  From Table 37 (Table 39) and FIG. 10 (FIG. 12) and Table 38 (Table 40) and FIG. 11 (FIG. 13), the copper-clad laminate 1 (Example 1) is the copper-clad laminate 2 (Example 2). ), The cumulative dimensional change amount is small in all cases where the distance from the first hole is 10 mm, 30 mm, and 50 mm, that is, the inclination of the graph is small, so it was confirmed that the dimensional change rate is small. . Further, the copper-clad laminate 1 (Example 1) has a smaller difference in the cumulative dimensional change amount of Left, Center, and Right than the copper-clad laminate 2 (Example 2), that is, variation in the slope of the graph. Since the (arrow width) is small, it was confirmed that the in-plane variation of the dimensional change rate was small.

Comparative example About each dimensional change rate of the copper clad laminated boards 1 and 2, it evaluated by the method based on IPC-TM-650 2.2.4 (B). First, it cut | disconnected to 250 mm in MD direction of the copper clad laminated board, and was set as MD: 250mm * TD: 250mm. As shown in FIG. 14, in the cut copper-clad laminate, marking is performed in the range of MD: 200 mm × TD: 200 mm at intervals of 50 mm in the MD and TD directions, and the marking positions before and after etching removal of the copper foil layer are measured. did.

  The dimensional change rate after etching can be calculated by the following equation (2).

Dimensional change rate after etching (%) =
{[(Distance between two points after etching) − (Distance between two points before etching)]
/ Distance between two points before etching} × 100 (2)

  The three values (i) to (iii) and (iv) to (vi) calculated by the above formula were averaged to calculate the dimensional change rate in the MD and TD directions. The results are shown in Table 41.

  From the results in Table 41, it was confirmed that it was difficult to find a difference in dimensional change rate in the conventional method based on the IPC standard. It was also confirmed that it is difficult to clarify the in-plane variation of the dimensional change.

[Evaluation as circuit wiring board]
Based on the results of Examples 1 and 2, the circuit wiring board formed using the copper-clad laminates 1 and 2 as materials was evaluated. As an example, wiring position deviation and in-plane variation in a circuit wiring board of L / S (wiring width / wiring interval) = 0.025 mm / 0.025 mm were evaluated.

First, the dimensional change delta _i of 2 holes distance between adjacent before and after etching (2.5mm spacing), L / S (line width / line spacing) = 0.025 mm / 0.025 mm in terms of the wiring pattern (down The positional deviation of the wiring with respect to the FPC size when sizing is calculated.

Here, the downsizing was converted by multiplying the dimensional change amount at intervals of 2.5 mm by 1/50, and the calculation of the positional deviation of the wiring with respect to the FPC size was calculated by the following equation (3).

Misalignment of wiring (%) = {[Σ _{i = 1} ²⁰ (Δ _i /50)]/0.05}×100 (3)

  FIGS. 15 and 16 and FIGS. 17 and 18 show the results of misalignment of the MD and TD wirings on the circuit wiring board formed using the copper clad laminates 1 and 2 calculated by the above formula (3), respectively. Shown in In each figure, the horizontal axis indicates the FPC size (mm), and the vertical axis indicates the positional deviation (%) of the wiring. Moreover, the graph of each figure plots the numerical value calculated by Formula (3), and draws an approximate line based on the plot. The magnitude of the inclination of the graph means the magnitude of the positional deviation of the wiring, and the magnitude of the fluctuation of the inclination of the graph means the magnitude of the in-plane fluctuation of the positional deviation of the wiring.

  Based on the above results, the wiring deviation (%) at FPC sizes of 10 mm, 30 mm and 50 mm is shown in Tables 42 and 44 (Material: Copper-clad laminate 1), and Tables 43 and 45 (Material: Copper-clad laminate 2). ). The numerical value of “range” in the table means median ± upper and lower ranges.

  From the results of Tables 42 to 45, it is possible to evaluate the positional deviation of the wiring and the in-plane variation for the circuit wiring board (L / S = 0.025 mm / 0.0025 mm) formed using the copper-clad laminates 1 and 2 as materials. confirmed.

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment, A various deformation | transformation is possible.

DESCRIPTION OF SYMBOLS 10 ... Test piece, 20 ... Virtual regular square, 20a ... Center, 20b ... Corner | angular part, 21 ... Center area | region, 23a, 23b ... Corner area | region, 30 ... Hole, 100 ... Metal-clad laminate

Claims (5)

A step of preparing a test piece by cutting a long metal-clad laminate in which a metal layer and a resin layer are laminated to a predetermined length;
When the longitudinal direction of the metal-clad laminate is the MD direction and the width direction is the TD direction, a virtual regular square having sides parallel to the MD direction and the TD direction is assumed in the test piece. A plurality of marks each including a linear array are formed in a central region including the center and two corner regions including one each of two corners sharing one side of the regular rectangle in the TD direction. Process,
A first measuring step of measuring positions of the plurality of marks and calculating a distance L0 between adjacent marks;
Etching part or all of the metal layer of the specimen;
A second measuring step of measuring the positions of the plurality of marks after etching and calculating a distance L1 between adjacent marks;
For the same two marks before and after the etching, a difference L1-L0 between the distance L0 obtained in the first measurement step and the distance L1 obtained in the second measurement step is calculated and The step of accumulating the difference L1-L0 for the interval described above to obtain an accumulated dimensional change amount in the MD direction and / or the TD direction of the metal-clad laminate,
Evaluation method of dimensional stability of metal-clad laminate including In the central region, the plurality of marks are formed in the MD direction and the TD direction along a cross shape passing through the center,
The dimensional stability evaluation method according to claim 1, wherein in the corner region, the plurality of marks are formed in the MD direction and the TD direction along the sides of the regular square.   Furthermore, the difference L1-L0 is converted into a scale of the wiring pattern on the circuit board formed from the metal-clad laminate to obtain a cumulative converted dimensional change, and the obtained cumulative converted dimensional change is The method for evaluating dimensional stability according to claim 1, comprising a step represented by a ratio with respect to a sum of a wiring width and a wiring interval.   The number of marks arranged in a straight line is at least 11 or more in each of the MD direction and the TD direction, and the difference for 10 or more locations is accumulated. 2. The method for evaluating dimensional stability according to item 1. A circuit board manufacturing method for producing a plurality of circuit boards from a metal-clad laminate,
Determining the wiring width and wiring spacing of the wiring pattern on the circuit board;
About the metal-clad laminate, a step of calculating a cumulative dimensional change amount by the dimensional stability evaluation method according to any one of claims 1 to 4,
Correcting the dimensions of the wiring width and the wiring interval based on the cumulative dimensional change amount;
A step of performing wiring processing based on the corrected wiring width and the wiring interval;
A method for manufacturing a circuit board, comprising:

Images