JP3070908B2 - Film master and substrate having alignment marks - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern exposure process in a process of manufacturing a printed circuit board and a hybrid IC, etc.
The present invention relates to a solder resist and a film original used in a silk printing process, and more particularly, to a film original having an alignment mark suitable for alignment with a substrate and a printed circuit board on which the alignment mark is formed.

[0002]

2. Description of the Related Art In a pattern exposure process, a solder resist and a silk character printing process in a manufacturing process of a printed circuit board, a hybrid IC, etc., positioning of a substrate and a film original is an important process for determining the quality of a product. It needs to be done correctly. The procedure of the alignment work will be described with reference to FIG. 5 taking a pattern exposure step as an example. FIG. 5 is a perspective view showing a state where the film original 2 is about to be overlaid on the substrate 1 by general manual alignment. The film master 2 has a product area 21 and a product area 22 outside the product area.
The pattern 6 is drawn in the product area 21. Outside the product area 22, alignment marks (hereinafter, referred to as alignment marks) 51, 52, 53 (hereinafter, referred to as alignment marks 50 as a general generic name of the alignment marks 51, 52, 53) are arranged. I have. Usually, the alignment marks 50 are provided at three places on opposite sides of the substrate 1 as shown in FIG. 5 in order to prevent displacement in the θ direction in addition to the x and y directions, and their positions are fixed. .

In the conventional aligning operation, a film master 2 is superimposed on a substrate 1 as a “rough alignment” in an initial stage of the operation.
The alignment mark 50 on the film master 2 is roughly positioned in the alignment hole 4 previously drilled in the substrate 1 by the operator's intuition. FIG. 6 shows an example of the shape of the alignment mark 50 conventionally used.
Basically, concentric circles are superimposed on the center of the crosshair, and the size of the mainstream is relatively small, with the long side 13 being 8 to 10 mm and the short side 14 being 3 to 5 mm. The alignment marks 50 in FIG. 6A are of the same shape, both of which are arranged in a positive direction, and those of FIG. 6B are in the case of different sizes. Further, in the “precision alignment” in the latter half of the alignment operation, the center of the alignment hole 4 (FIG. 5) is centered on the circle of the alignment mark 50 and the line segment extending from the center of the circle, and the circle and the circumference of the alignment hole 4 are aligned. After confirming that the gap between them is uniform, a series of operations is completed by fixing the film original 2 to the substrate 1.

Since the alignment mark 50 and the pattern 6 and the through hole 3 and the alignment hole 4 on the substrate 1 are composed of the same CAD (Computer Aided Design) processing information, their relative positional accuracy is guaranteed. ing. Therefore, even if the pattern shape of the product area 21 is seemingly complicated, the position accuracy of the through hole 3 and the pattern 6 in the product area 21 is maintained by overlapping and matching the alignment mark 50 with the alignment hole 4. Has become. On the other hand, in today's high-density mounting board, since the pattern 6 is minute relative to the through-hole 3, it is difficult to ensure the positional accuracy of both. That is, the precision of the alignment work is required. The quality of this work determines most of the positional accuracy of the through-hole 3 and the pattern 6, and an alignment mark having a shape that facilitates the alignment work is required.

FIGS. 7A and 7B show an example in which conventional alignment marks 50 are arranged in a product pattern.
Indicates a positive film, and FIG. 7B indicates a negative film. A positive film refers to a film original having an opaque (black) pattern portion 6 and a transparent background, while a negative film refers to a film original having a transparent pattern portion and an opaque background. Usually, a positive film is created in an automatic painting machine using CAD, and a negative film is created by optically inverting the positive film. The use of positive and negative films depends on the substrate manufacturing method. That is, the positive film is applied to the manufacture of a high-density mounting substrate in which the gap between the hole diameter and the land diameter (referred to as land residue) having a hole diameter of 0.3 mm and a land diameter of 0.5 mm or less by a solder peeling method is small. The negative film is applied to a substrate of normal density having a larger land residue than the above by a subtractive method. That is, the negative film is used for manufacturing a substrate whose alignment accuracy is less strict than the above.
However, recently, since the solder stripping method requires more man-hours, there are more opportunities to use negative films by a subtractive method and reduce the man-hours while making various modifications.

[0006]

In recent years, it has been more important than ever to reduce the number of steps and to improve the production yield in order to reduce the cost of a substrate. As one of the man-hour reductions, the above-mentioned shortening of the aligning operation time is raised, and the improvement of the production yield includes prevention of product remanufacturing due to defective aligning operation. FIG. 8 shows an example of a board failure due to a failure in the alignment operation. this is,
Since the etching solution penetrated into the through-hole 3 during the etching in the substrate manufacturing process, the through-hole plating was dissolved, resulting in a disconnection failure. The cause of this inconvenience was that, since a substrate with a small land residue was manufactured by the subtractive method, the accuracy of the aligning operation could not follow the accuracy required for the manufacturing of the substrate. It has been done. In the above-described conventional alignment, particularly when a negative film is used, there is a problem that the position of the alignment hole cannot be easily confirmed because the background of the film original is opaque. In practice, the alignment holes of the substrate and the alignment marks of the film original are often fixed, respectively. Therefore, the film original is overlaid on the substrate, and the film original is x-
It becomes the work to find the matching hole while shifting in the y direction,
There was a problem that it took time. SUMMARY OF THE INVENTION An object of the present invention is to provide a film master having alignment marks, which facilitates the work of aligning a substrate and a film master, reduces the number of steps, and improves the production yield of printed circuit boards and the like. Further, by forming the alignment mark of the present invention on a substrate, it is intended to improve the working efficiency and to facilitate inspection and confirmation of positional accuracy.

[0007]

According to the present invention, in order to attain the above object, a positive mark and an inverted negative mark are used as an alignment mark provided on a film original. It is characterized by. In other words, a normal film original is created with a positive, but a part of the alignment mark is negative. As described above, in the present invention,
By integrating the positive and negative alignment marks, one mark is always positive even when the film original is optically inverted. In other words, one of the alignment marks is always positive even when a positive film created by an automatic painting machine is optically inverted into a negative film because of a substrate manufacturing method that requires a negative film. As a result, the work of aligning the substrate and the film master becomes extremely easy, and the production yield of the substrate is also improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. 1, 2, 4 and 5. FIG. FIG. 1 is a top view of the alignment mark 5 applied to the present invention, and FIG.
(B) is a plan view in which alignment marks 5 applied to the present invention are arranged on a positive film and a negative film, respectively. As shown in FIG. 1, the shape of the alignment mark 5 shown in the present embodiment is such that a line segment 501 extending in four directions is superimposed on a circle 502,
A positive portion 5A having a transparent background and a negative portion 5B having an opaque background are optically inverted, and a negative line 5B having an opaque background is formed into a rectangular shape.
It is surrounded by and integrated. In this example, the circle 50 is used.
2, the outer diameter D1 is 3 mm, the inner diameter D2 is 1.6 mm, and the diameter of the matching hole 4 is 1.4 mm. The size of the alignment mark 5 is such that the long side 11 is 15 to 25 mm and the short side 12 is 5 mm.
The size is set to 10 mm, which is slightly larger than the conventional alignment mark 50 shown in FIGS. 6A and 6B, so that the operator can easily understand the arrangement positions on the film original 2 and the printed circuit board 1.

FIG. 2A shows a film master 2 directly drawn by an automatic drawing machine, which is positive, and the background of the alignment mark 5 outside the product area 22 is transparent. Therefore, when the film master 2 is stacked on the substrate 1,
The position of FIG. 4 can be easily recognized. On the other hand, FIG.
Shows a case where the film original 2 of the present invention is reversed to a negative. Since a part of the alignment mark 5 is always positive, this part serves as a “confirmation window” when searching for the alignment hole 4. In addition, the work efficiency of "coarse matching" in the initial stage of the matching operation can be remarkably improved. At the same time, it is possible to reduce the burden on the worker's eyesight and concentration. FIG. 3 shows, as a reference, a case where the film original 2 having the conventional alignment mark 50 is used as a negative, and since the background is entirely opaque, it can be understood that the position of the alignment hole 4 is extremely difficult to find.

FIG. 4 shows a state in which the gap 504 between the inner diameter D2 of the circle 502 of the alignment mark 5 and the circumference of the alignment hole 4 is made uniform in the "precise alignment" in the latter half of a series of alignment operations. The example of FIG. 4A shows a case where the dimensional shrinkage of the substrate 1 and the film master 2 are the same, and the circle 50 of the positive portion 5A is shown.
2 indicates that the inner diameter D2 and the circumference (indicated by a dotted line) of the mating hole 4 are concentric. However, in actual work, it is rare that the dimensional shrinkage of the substrate 1 and the film master 2 are the same. After confirming the shrinkage amount of both using the alignment mark 5, fine adjustment is made to an appropriate position with respect to the alignment hole 4. Must be repositioned. FIG. 4B shows an example of the positional relationship between the circle 502 of the alignment mark 5 and the circumference of the alignment hole 4 (indicated by a dotted line) when the pattern 6 is shifted in the y direction in FIG. A method of fine correction in a state where the pattern shift has occurred will be described with reference to FIG.
The deviation amount between the alignment marks 51 and 53 is distributed to the center. That is, the inner diameter D of the circle 502 of the alignment mark 5
2 and the gap 504 between the circumference of the alignment hole 4 and the alignment marks 51 and 53 are made to be the same in opposite directions. Here, in the work of distributing the gaps 504 equally,
In the film master 2, a circle portion 502 of the alignment mark 5
Is transparent and the other parts are opaque.
It has been empirically found that the alignment mark of is easier to work because the contrast can be removed and the visual load on the operator is less, so that the concentration can be maintained. That is, in the operation of finely correcting the position of the pattern 6, it is preferable that the alignment mark 5 is negative regardless of whether the product area 21 is positive or negative.

Summarizing the above, in the alignment operation, in the “rough alignment” in the initial stage of the operation, the alignment mark 5 is preferably positive irrespective of whether the product area 21 is positive or negative. On the contrary, in the operation of finely correcting the position of the pattern 6 by “precision alignment”, it is understood that the alignment mark 5 is preferably negative. That is, it is ideal that the alignment mark 5 has both the positive and the negative as in the present invention. Here, as the design value of the alignment mark 5 shown in the present embodiment, the outer dimension is such that the long side l1 is 2
0 mm, short side 12 is 7 mm, outer diameter D1 of circle 502 is 3 mm, inner diameter D2 is 1.6 mm, line segment 50 extending from circle 502 in all directions.
1 has a line width of 0.4 mm, and the diameter of the matching hole 4 is 1.4.
mm. The reason why the design value of the alignment mark 5 is set as described above is as follows. That is, the outer dimensions l1 and l2 of the alignment mark 5 are preferably as small as possible from the viewpoint of the efficiency of removing the product part of the substrate material. On the other hand, considering the burden on the visual acuity of the worker in the visual adjustment work,
The external dimensions of the alignment mark 5 are preferably as large as possible. Therefore, in this embodiment, the positive portion 5A
And the negative portion 5B are arranged side by side, so that the work efficiency is prioritized even if the plate removing efficiency is slightly sacrificed, and the outer dimensions are set slightly larger than before.

Next, a circle 502 is added to the determined external dimensions.
The outer diameter D1 of the positive part 5A and the negative part 5B
It was decided in consideration of the balance of the area. Further, the hole diameter of the matching hole 4 was set corresponding to the diameter of the circle 502.
In addition, in this case, in particular, in consideration of a fine correction operation in a state where a pattern shift has occurred, a size of the gap 504 between the inner diameter D2 of the circle 502 and the alignment hole is set to be easily seen by an operator. Further, the line width of the line segment 501 extending in all directions from the circle 502 is
The area occupied by the background, holes, and circles is subtracted from the entire area of the alignment mark 5, and the line width that can be physically provided in the remaining area is determined.
Regardless of the positive portion 5A and the negative portion 5B, they can be formed technically sufficiently. Based on the above design concept, the design specification of the alignment mark 5 shown in FIG. 1 was determined.

Next, a second embodiment of the present invention will be described with reference to FIG.
Will be described with reference to FIG. FIG. 9 shows a pattern forming step (etching step) using a tenting method using a film master 2 (FIG. 2) having a type in which the frame width of the alignment mark 5 of the present invention is wide. When completed, a substrate alignment mark 5 'formed on the printed circuit board 1 is shown. On the substrate 1, the negative portion 5D of the substrate alignment mark 5 'corresponding to the positive portion 5A of the film master 2
Is present as it is because the copper 31 is masked, and in the positive portion 5C of the substrate alignment mark 5 'corresponding to the negative portion 5B of the original film 2, the copper is etched and the base material 30 is exposed. FIG. 10 is a flowchart showing a manufacturing process of the printed circuit board 1 after pattern formation. After the pattern formation of the printed circuit board 1, solder resist, silk character printing, surface treatment, and outer shape processing are continued. Here, in the process of forming the solder resist and the silk character printing on the substrate 1, the above-described substrate alignment mark 5 ′ formed on the substrate 1 is effective as described below.

FIG. 11 shows the state of the substrate alignment mark 5 'on the substrate 1 after each step, and explains its effectiveness. Step (a) comprises:
This shows a state after pattern formation after etching is completed, and step (b) shows a state in which a solder resist is printed using a screen plate (not shown). A solder resist is formed on the base portion 30 (hatched portion) of the alignment mark 5 '. Normally, the solder resist often uses a resin mainly composed of green epoxy. In the formation of the solder resist, first, a screen plate is superimposed on the alignment mark 5 'of the printed circuit board 1 to perform printing positioning. In this positioning method, “precision alignment” is performed on the pattern in the product area after “rough alignment” is performed as in the above-described pattern alignment operation. At this time, the first effectiveness when the substrate alignment mark 5 ′ of the present invention is used is that the alignment mark 5 ′ formed on the printed circuit board 1 is used.
In contrast, the positive part of the alignment mark of the screen plate is transparent and serves as a "confirmation window".
The efficiency of positioning work between the upper alignment mark 5 'and the alignment mark of the screen plate is greatly improved.

The second effectiveness is that by measuring the gap DS1 between the frame 505 of the alignment mark 5 'formed on the substrate 1 and the frame 506 of the alignment mark of the solder resist, the pattern and the solder are measured. It is possible to inspect the positional accuracy (deviation direction, displacement amount) of the resist. FIG. 11 (c)
Indicates a state in which silk characters are printed on the substrate 1 using a screen plate (not shown), and is printed on the copper portion 31 (horizontal hatched portion) of the alignment mark 5 ′. That is, all the portions of the copper 31 formed in the step (a) are silk-printed. Normally, silk characters often use a resin containing white or yellow epoxy as a main component. In the silk character printing process, "rough alignment" is performed in the same way as solder resist
There are two advantages that the work efficiency can be improved and the position accuracy (shift direction and shift amount) of the pattern and the silk character can be inspected.

In particular, FIG. 11 shows a type in which the width of the frame line 505 of the alignment mark 5 'is wide. In this case, the following effects are obtained. That is, as shown in the enlarged view of the part A in the step (c), when the substrate 1 is not shrunk and there is no displacement of the silk character printing, basically, the frame line 505 of the alignment mark 5 ′ formed on the substrate 1 The frame line 507 of the alignment mark in the silk character printing is formed at the matching position. However, usually, there is a deviation between the two due to various factors. Therefore, if the width of the frame line is widened, the frame by the silk character printing is placed on the frame line 505 of the alignment mark 5 ′ on the substrate 1. Line 50
7 is printed out of alignment, the difference between the outlines of the two frame lines, D
By measuring S2, the amount of deviation can be quantified and applied to process management. Furthermore, after printing the silk character, by measuring the gap between the alignment mark frame lines of the pattern, the solder resist, and the silk character, the total positional accuracy of the three can be inspected. In addition, every time the substrate manufacturing process is performed, the alignment mark 5 ′ on the substrate 1
As shown in FIG. 11, the solder resist is overprinted with ink of different colors of silk characters, so that the pattern,
It is easy to visually confirm (qualitatively) the print misregistration in each step of the solder resist and the silk character.

[0017]

As described above, according to the present invention,
In the alignment work between the printed circuit board and the film master,
Regardless of whether the original film is positive or negative, the aligning operation can be facilitated, the number of steps can be reduced, and the burden on the operator can be reduced. Further, since the production yield of the substrate can be improved, it is possible to contribute to a reduction in substrate cost. Furthermore, in the solder resist and silk printing processes, the use of the alignment mark of the present invention not only improves the working efficiency but also inspects the alignment accuracy,
Confirmation can be facilitated.

[Brief description of the drawings]

FIG. 1 is a plan view of an alignment mark according to an embodiment of the present invention.

FIG. 2 is a plan view of an original film having positive and negative alignment marks according to the present invention.

FIG. 3 is a plan view of a conventional film negative of a negative film having alignment marks.

FIG. 4 is a view showing a positional relationship between alignment marks of a film master of the present invention and alignment holes of a substrate.

FIG. 5 is a perspective view showing a positional relationship between alignment marks and patterns on a substrate and a film original.

FIG. 6 is a plan view showing an example of alignment marks provided on a conventional film original.

FIG. 7 is a plan view of a conventional positive and negative film master having alignment marks.

FIG. 8 is a diagram showing an example of a defect in a work of aligning a substrate and a film original.

FIG. 9 is a plan view showing a board alignment mark formed on the printed board of the present invention.

FIG. 10 is a flowchart showing a manufacturing process of a printed circuit board after pattern formation.

FIG. 11 is a plan view showing a state of each step of the substrate alignment mark of the present invention.

[Explanation of symbols]

1 substrate, 2 film originals, 3 through holes, 30
Base material, 31 copper, 4 alignment holes, 5 alignment mark of film original, 5A positive part of alignment mark of original film, 5B negative part of alignment mark of original film, 5C
Positive part of alignment mark of substrate, 5D negative part of alignment mark of substrate, 501 Center line of alignment mark, 502
Circle of alignment mark, 503 Frame of alignment mark, 5
05 Alignment mark frame line formed on substrate, 506
Solder resist alignment mark frame, 507 silk character alignment mark, 6 patterns.

Claims (4)

(57) [Claims] 1. A film original used in a pattern exposure step, a resist step, and the like in a process of manufacturing a printed circuit board, wherein an alignment provided outside a product area of the film original to align with an alignment hole provided in the substrate. As a mark, the inside is transparent and it is
Opaque with a large inner diameter and a predetermined line width
An original film having an alignment mark, wherein a positive portion composed of a circular circle, a transparent background portion on the outer side thereof , and an optically inverted negative portion are arranged in parallel to form an integrated shape. 2. The opaque circle according to claim 1,
Is characterized in that a plurality of line segments having a predetermined width extending outward from the center of the opaque circle are provided, and the positive portion and the negative portion are surrounded by a rectangular frame line having a predetermined width. Film master with alignment marks. 3. The opaque circle according to claim 2, wherein
The diameter is 1.0 mm to 1.8 mm, the line width of the plurality of outwardly extending lines is 0.3 mm to 0.5 mm, and the diameter of the mating hole is 0.3 mm.
An original film having an alignment mark having a thickness of 6 mm to 1.5 mm. 4. In order to align a film original used in a process of manufacturing a printed circuit board with a mating hole provided in the printed circuit board, outside the product area of the film original, the inside is transparent, and Large within specified dimensions
An opaque circle having a diameter and a predetermined line width;
In the process of manufacturing a printed circuit board using the film master having an integrated alignment mark in parallel with a positive portion composed of a transparent background portion on the side and a negative portion obtained by optically inverting the positive portion, Outside the product area of the board,
A substrate comprising: a screen plate alignment mark corresponding to the alignment mark of the film original.