JP2006024858A - Printed wiring board manufacturing method and printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a printed-wiring board by which the generation of a land peeling phenomenon can be effectively prevented by forming a land coat layer consisting of solder resist on the peripheral edge of a land of conventional size, while securing an effective contact area with an electrode of a mounted component even when a positional deviation is generated in the solder resist, and to provide the printed-wiring board. <P>SOLUTION: In the method for manufacturing the printed-wiring board 11 which includes a process of forming a land 13 on the prescribed position of a printed board 12 and a process of forming solder resist 23 on a prescribed region of the printed board 12, the solder resist 23 is formed integrally with a land coat layer 25 formed on a partial region in the outer edge 14 of the land 13 to prevent the land 13 from peeling off. Even if positional deviation is generated on the solder resist 23, the land 13 can secure a necessary contact area with the electrode of the mounted component. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a printed wiring board and a technique related to the printed wiring board that can effectively prevent a land peeling phenomenon that tends to occur in a land included in the printed wiring board.

  A printed wiring board is formed by, for example, forming a through hole by drilling or through-hole plating, or etching a plated layer and copper foil on a printed circuit board made of a glass epoxy copper-clad laminate with copper foil laminated on both sides. It is formed through a process of forming wirings and lands and forming a solder resist.

  FIG. 8A shows a conventional example of the positional relationship between the land 2 and the solder resist 4 in the printed wiring board 1. The land 2 having a rectangular planar shape is larger in size than the land 2. The solder resist 4 is formed in the blank portion 6 which has a similar shape and does not exist. That is, the land 2 is formed in a state where the gap 7 is interposed between the outer edge 3 a and the edge 5 of the solder resist 4 that defines the blank portion 6. The reason why the gap 7 is interposed between the land 2 and the solder resist 4 in this way is that the solder resist 4 enters the land 2 side in consideration of the positional deviation that tends to occur during resist ink printing. The purpose is to secure a margin for not covering this.

  On the other hand, with respect to solder used for soldering printed wiring boards, lead-free solder has recently been used due to problems related to lead toxicity. The lead-free solder mainly contains, for example, 90-98% tin mixed with silver, copper, antimony, and contains a small amount of bismuth, indium, nickel, zinc, etc. There is.

  The lead-free solder composed of the above components has a melting temperature of 210 to 230 ° C. and a melting temperature higher than that of a conventional tin-lead eutectic solder having a melting temperature of about 183 ° C.

  When the lead-free solder having a high melting temperature is applied to the land 2 shown in FIG. 8A as described above, the land peeling phenomenon that does not occur much when the conventional leaded solder is used frequently occurs. There is a tendency. The cause of the land peeling phenomenon is not necessarily certain, but is estimated to be due to thermal shrinkage and solidification shrinkage of lead-free solder.

For this reason, as a method for suppressing or preventing the occurrence of the land peeling phenomenon, the land covering layer 8 is formed by inserting the solder resist 4 into the outer edge 3 of the land 2 as shown in FIG. A structure with the above structure has already been proposed.
JP 2001-332851 A

  However, in the case of the prior art disclosed in FIG. 8B, if a positional shift occurs during printing of the resist ink, it is only required between the electrode of the component and the land 2 when the component is mounted. There was an inconvenience that a sufficient contact area could not be secured. In addition, when a design that takes into account the positional deviation that tends to occur during resist ink printing under the conventional method of FIG. 8B is to be performed, a land having a size larger than the normal size is formed in advance. However, if the land size is increased, the lands tend to be short-circuited when mounting components at a minute pitch, so this is not a practical solution.

  In view of the above-described problems of the prior art, the present invention provides a solder resist at the periphery of a land of a conventional size while ensuring a necessary contact area between the electrode of the mounted component and the land even if the solder resist is displaced. An object of the present invention is to provide a printed wiring board manufacturing method and a printed wiring board capable of effectively preventing the occurrence of a land peeling phenomenon by forming a land covering layer made of

  The present invention has been made to achieve the above object, and a first invention (manufacturing method) includes a step of forming lands at predetermined locations of a printed circuit board, and a solder resist in a predetermined area of the printed circuit board. The solder resist is integrally formed including a land coating layer provided on a partial region in the outer edge of the land. .

  The land according to the first aspect of the present invention has a square planar shape, and the land covering layer is formed on partial regions of the outer edge located at the four corners, or the planar shape is elliptical or substantially oval. The land covering layer can be formed on at least a partial region of the outer edge where the arcuate portion is located.

  The most important feature of the second invention (printed wiring board) is the printed wiring board manufactured according to the first invention.

  According to the first aspect of the present invention, since the solder resist can be integrally formed including the land coating layer on the partial region of the outer edge of the land, the land coating layer is formed. It is possible to effectively prevent the lands from being peeled through the gap. Further, even when the land covering layer is displaced, a sufficient contact area necessary for the relationship with the electrode of the mounted component can be secured on the land side when the component is mounted.

  According to the manufacturing method according to claim 2, by forming land coating layers at the four corners of the land having a substantially square shape, the land can be fixed in position at four locations and the separation of the land can be prevented more effectively. it can. Further, even if the land cover layer is displaced, a sufficient contact area can be secured on the land side in relation to the electrodes of the mounted components.

  According to the manufacturing method according to claim 3, the land covering layer is formed on the arc-shaped portion of the land having a substantially elliptical shape or a substantially oval shape, thereby fixing the land in at least two places and peeling the land. It can be effectively prevented. Further, even if the land cover layer is displaced, a sufficient contact area can be secured on the land side in relation to the electrodes of the mounted components.

  On the other hand, according to the second aspect of the present invention, when the component is soldered to the land provided in the printed wiring board at a relatively high temperature, it is possible to effectively prevent the problem that the land side peels off. Can promote the use of environmentally friendly lead-free solder. Even if the land cover layer is displaced, a sufficient contact area can be ensured on the land side in relation to the electrodes of the mounted component, and soldering can be performed reliably.

  FIG. 1 to FIG. 4 are explanatory views showing the mutual positional relationship by pattern when a land and solder resist are formed by applying the method of the present invention (first invention).

  The land 13 and the solder resist 23 included in the printed wiring board 11 shown in these drawings include a step of forming a land 13 made of copper foil or the like at a predetermined position of the printed circuit board 12, and a solder resist 23 in a predetermined area of the printed circuit board 12. The method for manufacturing a printed wiring board according to the present invention including the step of forming (first invention) is included.

  Examples of the solder resist 23 in the present invention include a thermosetting resin film, an ultraviolet curable resin film, a photosensitive resin film, and a laminate film.

  That is, when the solder resist 23 is, for example, a thermosetting resin film, after the thermosetting resin is printed on the surface of the printed circuit board 12 by a screen printing method on a partial region of the outer edge portion 14 of the land 13. The land coating layer 25 formed by heat treatment is integrally formed (hereinafter, a solder resist 23 made of a thermosetting resin film will be described as an example).

  More specifically, based on the example shown in FIG. 1, the land 13 is formed with a rectangular planar shape. In addition, after the solder resist 23 is printed on the surface of the printed circuit board 12 by a screen printing method so as to form a blank portion 24 having an elliptical shape and the solder resist 23 does not exist, It is formed by heat treatment.

  In addition, since the blank portion 24 is formed to have a size that can enter only the four corners when facing the land 13, the blank portion 24 of the outer edge portion 14 positioned at the four corners of the land 13 is formed. The land coating layer 25 integrated with the solder resist 23 can be formed in each of the partial regions, that is, the corner portions 15.

  Further, according to FIG. 2, the land 13 is formed in a square shape in plan view. Also, the solder resist 23 is printed on the surface of the printed circuit board 12 by a screen printing method so that a blank portion 24 having a circular shape and free of the solder resist 23 is formed, and then heat treatment is performed. Formed.

  In addition, since the blank portion 24 is formed to have a size that can enter only the four corners when facing the land 13, the blank portion 24 of the outer edge portion 14 positioned at the four corners of the land 13 is formed. The land coating layer 25 integrated with the solder resist 23 can be formed in each of the partial regions, that is, the corner portions 15.

  Furthermore, according to FIG. 3, the land 13 is formed with an elliptical planar shape. In addition, the solder resist 23 is printed on the surface of the printed circuit board 12 by a screen printing method so that a blank portion 24 having a rectangular shape and free of the solder resist 23 is formed, and then heat treatment is performed. Formed.

  In addition, since the blank portion 24 is formed to have a size that can enter only the arc-shaped portions located vertically and horizontally when facing the land 13, The land coating layer 25 integrated with the solder resist 23 can be formed on the partial regions of the outer edge portions 14 located on the left and right sides, that is, on the upper, lower, left and right arc-shaped portions 16 respectively.

  Furthermore, according to FIG. 4, the land 13 is formed so that the planar shape is an oval. In addition, the solder resist 23 is printed on the surface of the printed circuit board 12 by a screen printing method so that a blank portion 24 having a rectangular shape and free of the solder resist 23 is formed, and then heat treatment is performed. Formed.

  In addition, since the blank portion 24 is formed to have a size that can be inserted only into the arc-shaped portion positioned above and below when facing the land 13, the space portion 24 is positioned above and below the land 13. Thus, the land coating layer 25 integrated with the solder resist 23 can be formed in a partial region of each outer edge portion 14, that is, in each of the upper, lower, left and right arc-shaped portions 16.

  Therefore, in the printed wiring board 11 according to the second invention manufactured by the method of the present invention, the land covering layer 25 integrated with the solder resist 23 is formed in a partial region of the outer edge portion 14 of each land 13. As a result, when the component is soldered to the land 13 at a relatively high temperature, it is possible to effectively prevent the problem that the land side peels off.

  Moreover, even if the land covering layer 25 is displaced, each land 13 can secure a sufficient contact area necessary for the relationship with the electrode of the component when mounting the component. Parts can be soldered securely.

  Next, examples of the present invention will be described below together with conventional examples (comparative examples). That is, FIG. 5 is an explanatory diagram of a comparative example that more specifically shows the positional relationship between lands and solder resists shown in FIG. 8A as a conventional example.

According to the figure, each land 3 having a rectangle with a length (a) of 1.4 mm and a width (b) of 0.4 mm has an interval (c) of 0. It is formed by setting it to 65 mm. Each land 3 is formed with a gap 7 between the outer edge 3a and the edge 5 of the solder resist 4 adjacent thereto. That is, each land 3 is arranged in a blank portion 6 which is provided in the solder resist 4 and has a rectangular shape with a vertical (d) of 1.5 mm and a horizontal (e) of 0.5 mm. Therefore, the effective area of each land 3 in FIG. 5 is 0.56 mm ² which is a (vertical) × b (horizontal).

  FIG. 6 is an explanatory diagram of a comparative example that more specifically shows the positional relationship between lands and solder resists shown in FIG. 8B as a conventional example. Of these, (a) shows a state in which no position shift has occurred in the solder resist 4, and (b) shows a state in which the position of the solder resist 4 has shifted.

  As shown in FIG. 5, each land 3 having a rectangle with a length (a) of 1.4 mm and a width (b) of 0.4 mm, as shown in FIG. It is formed by setting the interval (c) to 0.65 mm. Each land 3 has a land coating layer 8 formed by inserting the solder resist 4 into the outer edge 3.

Then, as shown in FIG. 6B, the position of the blank portion 6 of the solder resist 4 is shifted by 0.1 mm in each of the vertical and horizontal directions, so that the effective area of each land 3 indicated by hatching becomes 0.3125 mm ^2. Therefore, it was confirmed that the effective area of the conventional example shown in FIG.

  On the other hand, FIG. 7 is an explanatory view showing more specifically the positional relationship between the land and the solder resist in the embodiment of the present invention. Among them, (a) shows a state where the position of the solder resist 23 is not shifted, and (b) shows a state where the position of the solder resist 23 is shifted.

As shown in FIG. 5, each land 13 having a rectangle with a length (a) of 1.4 mm and a width (b) of 0.4 mm, as shown in FIG. It is formed by setting the interval (c) to 0.65 mm. Each land 13 is arranged in a blank portion 24 having an oval shape with land covering portions 25 made of solder resist formed only at the four corners. For this reason, the effective area of each land 13 in the state of FIG. 7A is an approximate value substantially equal to 0.56 mm ² which is a (vertical) × b (horizontal).

Therefore, when the land coating layer 25 made of the solder resist 23 is formed by applying the method of the present invention, as shown in FIG. 7B, the blank portions 24 of the solder resist 23 are each 0.1 mm in the vertical and horizontal directions. The effective area of each land 13 indicated by hatching is 0.47 mm ² due to the shift of the position of FIG. 6, which is reduced to 84% of the effective area shown in FIG. It was confirmed that the effective area did not decrease as much as the comparative example shown (conventional example).

  In other words, when the solder resist 23 is formed by applying the method of the present invention, not only is it effective for land peeling, but also a sufficient contact area with the mounted components is ensured without increasing the size of the land 13 itself. It was confirmed that

  The above is the description of the present invention based on the illustrated example, and the specific configuration is not limited thereto. For example, the solder resist 23 may be made of an ultraviolet curable resin film, a photosensitive resin film, a laminate film, or the like. The shape of the land 13 and the shape of the blank portion 24 on the solder resist 23 side are the portions of the outer edge portion 14 of the land 13 outside the blank portion 24 when the land 13 and the blank portion 24 face each other. As long as the target region can be located, it can be selected as desired.

Explanatory drawing which shows the 1st pattern of the mutual arrangement | positioning relationship at the time of forming a land and a soldering resist by applying this invention method (1st invention). Explanatory drawing which shows the 2nd pattern. Explanatory drawing which shows the 3rd pattern. Explanatory drawing which shows the 4th pattern. Explanatory drawing which shows the mutual arrangement | positioning relationship of the land and solder resist about the prior art example shown as the comparative example 1 at the time of describing the Example of this invention. It is explanatory drawing which shows the mutual arrangement | positioning relationship between the land and solder resist about the prior art example shown as the comparative example 2 at the time of describing the Example of this invention, (a) of which a position shift arises in a solder resist (B) shows the case where a position shift has occurred in the solder resist. It is explanatory drawing which shows the mutual arrangement | positioning relationship between the land and solder resist about the Example of this invention, (a) is a case where position shift has not arisen in the solder resist, (b) is located in solder resist Each case where a deviation occurs is shown. It is explanatory drawing which shows the mutual arrangement | positioning relationship between the land and solder resist about a prior art example, (a) of them is an example in which the solder resist does not enter the land side, (b) is an example in which the solder resist enters the land side. Each example is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Land 3 Outer edge part 3a Outer edge 4 Solder resist 5 End edge 6 Blank part 7 Gap 8 Land covering part 11 Printed wiring board 12 Printed circuit board 13 Land 14 Outer edge part 15 Corner part 16 Arc-shaped part 23 Solder resist 24 Blank part 25 Land cover

Claims (4)

In a method for manufacturing a printed wiring board, including a step of forming a land at a predetermined location on a printed circuit board, and a step of forming a solder resist on a predetermined area of the printed circuit board.
The method of manufacturing a printed wiring board, wherein the solder resist is integrally formed including a land coating layer provided on a partial region in an outer edge portion of the land.   2. The method for manufacturing a printed wiring board according to claim 1, wherein the land has a substantially square planar shape, and the land coating layer is formed on partial regions of the outer edge located at four corners of the land.   2. The printed wiring board according to claim 1, wherein the land has a substantially elliptical shape or an oval shape in a planar shape, and the land covering layer is formed on at least a partial region of the outer edge portion where the arc-shaped portion is located. Method. A printed wiring board manufactured by the method for manufacturing a printed wiring board according to claim 1.

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