JPH114067A - Method of confirming soldered state, printed wiring board, and method of mounting circuit part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and quickly judge whether a soldering state is good or not without changirng soldering lands in size and artangement from an initial state by a method wherein an X-ray checking land other than a circuit part soldering land is provided onto a printed wiring board. SOLUTION: An X-ray check land 12 other than a soldering land 11 which is used for soldering a BGA is previously formed on a printed wiring board 10 when the printed wiring board 10 is manufactured. Then, a soldering paste layer is formed on the soldering land 11, and a soldering layer different in shape from the X-ray check land 12 is formed on the X-ray check land 12 and its vicinity, and a BGA is soldered to the printed wiring board 10. Then, the wiring board 10 is loaded into a reflow oven to undergo reflow processing, and the behavior of a shape change in the soldering paste layer before and after reflow processing is checked with an X-ray check apparatus, whereby it is judged whether a soldering state is good or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for checking a soldered state, a printed wiring board, and a method for mounting circuit components. The present invention relates to a method for checking a soldering state when mounting on a printed circuit board, a printed wiring board suitable for checking the soldering state, and a method for mounting circuit components on the printed wiring board.

[0002]

2. Description of the Related Art In order to protect a semiconductor element and at the same time facilitate connection with wiring formed on a printed wiring board (mother board), the semiconductor element is provided in various packages. In recent years, with high integration of semiconductor devices, electronic devices have been rapidly increasing in performance and miniaturization.
uadFlat Package) and other packages with external connection terminals around the package, including PGA (Pin Grid Array) and BG
A is changing to a type suitable for high-density mounting in which external connection pins and solder balls are arranged in a matrix on the bottom surface as shown in FIG.

FIG. 5 (a) shows a B having a semiconductor element therein.
FIG. 5B is a bottom view schematically showing GA, and FIG.
FIG. 4 is a cross-sectional view schematically showing a state in which A is mounted on a printed wiring board.

As shown in FIG. 1A, a rectangular central portion 4 is formed on a bottom surface 47 of a wiring board 41 constituting the BGA 40.
Except for 9, a large number of solder balls 42 as external connection terminals are fixed to a solder ball pad (not shown) in a matrix. Further, as shown in FIG. 2B, a semiconductor element 43 is fixed to a central portion of the upper surface 48 of the wiring board 41 via an adhesive 44, and a pad portion (not shown) of the semiconductor element 43 is The pad portion (not shown) formed at 48 is connected by a wire 45.
The portion including the semiconductor element 43 and the wire 45 is sealed with a sealing resin 46.

The BGA 40 is connected to and fixed to a soldering land 51 of a printed wiring board 50 via a solder ball 42 and a solder layer 52.

Usually, the printed wiring board 50 of the BGA 40
Mounting on the electronic component is performed using an electronic component mounting machine. First, when the printed wiring board 50 is supplied to the electronic component mounting machine, the printed wiring board 50 is placed on a rail for transport and transported to the solder paste application section. In the solder paste application section, a stencil (metal mask) having an opening of a predetermined pattern is placed on the printed wiring board 50, and a squeegee or the like holding the solder paste moves on the metal mask. Land for attachment 51
Then, a solder paste layer having a predetermined shape is formed. Next, the printed wiring board 50 is transported to the BGA fixing section, and the position of the printed wiring board 50 after the movement is changed to the printed wiring board 5.
The position of the solder ball 42 of the BGA 40 was accurately measured by a CCD camera or the like based on the position recognition mark printed on the BGA 40 so as to be directly above the soldering land 51 of the printed wiring board 50. After that, the BGA 40 is placed on the printed wiring board 50,
Temporarily fixed. Next, the printed wiring board 50 to which the BGA 40 is temporarily fixed is carried into a reflow furnace and subjected to a reflow process, and the BGA 40 is connected to the soldering land 51 of the printed wiring board 50 via the solder balls 42 and the solder layer 52. Connected and fixed.

The printed wiring board 50 on which the BGA 40 has been mounted by the above steps needs to be inspected to determine whether or not the soldering has been properly performed. Since the ball 42 is present, it is difficult to visually determine the quality of the soldered state.

[0008] Therefore, usually, an X-ray inspection apparatus is used to perform BG.
An image is taken by X-rays from above A40, and a solder layer 52 is formed on the entire soldering land 51 of the printed wiring board 50.
Is determined based on whether or not the soldering state is formed.

[0009]

Normally, however, the size of the soldering land 51 is almost the same as the size of the solder ball 42 in plan view, so that the solder ball 42 becomes a hindrance and There is a problem that it is very difficult to judge whether the soldering condition is good or not, because it overlaps with the formed solder ball pad.

Therefore, there has been proposed a printed wiring board 70 in which the size of the soldering land 51 is made larger than the size of the solder ball 42 in a plan view or a special shape.

FIG. 6A is a cross-sectional view schematically showing the printed wiring board and the BGA, and FIG. 6B is a plan view.

As shown in FIG. 2B, since the soldering land 71a on the left side is formed to be considerably larger than the solder ball 62 in plan view, the solder layer (not shown) is formed after the reflow process. Land for soldering 71a
When it spreads over the entire area, the shape of the solder layer can be recognized from the X-ray photograph, and it can be determined that the soldering state is good.

A projection is formed on the soldering land 71b on the right side. Therefore, when the solder layer (not shown) spreads over the projection of the soldering land 71b after the reflow process, X The shape of the solder layer can be recognized from the line photograph, and it can be determined that the soldering state is good.

However, as shown in FIG. 6, wirings 72 are connected to the soldering lands 71a and 71b, respectively. If the shapes of the soldering lands 71a and 71b are enlarged, the wiring 72 is drawn out. There is a problem that there is no area, the number of soldering lands 71a and 71b must be reduced, and it is difficult to realize high-density mounting.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a soldering state checking method for judging whether a circuit component is soldered to a printed wiring board using an X-ray inspection apparatus. A method for checking the soldering state, which can easily and quickly determine the quality of the soldering state of the circuit components to the printed wiring board without changing the land size and arrangement state from the case of the conventional printed wiring board. An object of the present invention is to provide a printed wiring board suitable for checking a soldering state and a method for mounting circuit components.

[0016]

In order to achieve the above object, a method for confirming a soldered state (1) according to the present invention comprises: (a) soldering circuit components to a printed wiring board; In the method of checking a soldering state for inspecting pass / fail using an X-ray inspection apparatus, an X-ray inspection land different from the soldering land of the circuit component may be used.
After forming a solder paste layer having a shape different from that of the X-ray inspection land on a portion including the X-ray inspection land and the vicinity thereof, the reflow processing is performed. It is characterized in that the quality of the soldering state is determined based on how the shape of the solder paste layer before and after changes.

According to the soldering state checking method (1), the X-ray inspection land different from the soldering land of the circuit component is formed on the printed wiring board. There is no need to change the size and arrangement of the attachment lands from those of the conventional printed wiring board, and the external connection terminals fixed to the circuit components such as solder balls become obstacles to imaging of the X-ray inspection lands. Nothing. Further, after a solder paste layer having a shape (including size) different from the X-ray inspection land is formed, a reflow process is performed, and a soldering state is determined according to a change in the shape of the solder paste layer before and after the reflow process. , The quality of the soldered state can be easily and quickly determined. Therefore, it is possible to reliably prevent a product with poor soldering from being shipped.

The soldering state checking method (2) according to the present invention is the soldering state checking method (1) according to the above (1), wherein the X-ray inspection land and the vicinity thereof are larger in area than the X-ray inspection land. After forming a solder paste layer having a large size, a reflow process is performed, and the quality of the soldering state is determined based on whether the solder paste layer substantially overlaps with the X-ray inspection land.

According to the soldering state checking method (2), a solder paste layer having a larger area than the X-ray inspection land is formed before the reflow processing, so that the reflow state is good. And the solder paste layer is repelled at portions other than the X-ray inspection lands,
The area is reduced until it substantially overlaps the line inspection land. However, if the reflow state is bad, the area of the solder paste layer does not decrease until it substantially overlaps with the X-ray inspection land. Therefore, after forming a solder paste layer having a larger area than the X-ray inspection land on the X-ray inspection land, a reflow process is performed to determine whether the solder paste layer substantially overlaps the X-ray inspection land. By doing so, the quality of the soldered state can be easily and accurately determined.

[0020] The method (3) for checking a soldering state according to the present invention is the method according to the method (1) for checking a soldering state, wherein the solder paste has a smaller area than the X-ray inspection land. After forming the layer, a reflow process is performed, and the quality of the soldering state is determined based on whether the solder paste layer spreads and substantially overlaps the X-ray inspection land.

According to the soldering state checking method (3), a solder paste layer having a smaller area than the X-ray inspection land is formed before the reflow processing, so that the reflow state is good. Then, the area of the solder paste layer increases until it substantially overlaps with the X-ray inspection land.
However, if the reflow state is bad, the solder paste layer does not increase in area until it substantially overlaps the X-ray inspection land. Therefore, the X-ray inspection land is
After forming a solder paste layer having a smaller area than the line inspection land, a reflow process is performed, and it is easily determined whether or not the soldering state is good by determining whether the solder paste layer substantially overlaps with the X-ray inspection land. It can be determined accurately.

The method (4) for confirming the soldered state according to the present invention includes the method (1) for confirming the soldered state described above.
(3) The method according to (3), wherein at least one X-ray inspection land is formed, and a solder paste layer is formed on a portion including all the X-ray inspection lands.

According to the soldering state confirming method (4), the quality of the soldering state can be easily determined by forming at least one X-ray inspection land. Further, when two or more X-ray inspection lands are formed at different positions, the solder paste state can be accurately determined over the entire printed wiring board. By examining the change in the shape of the printed wiring board in detail, it is possible to know the heat distribution of the printed wiring board during the reflow.

Further, the method (5) for checking the soldered state according to the present invention comprises the method (1) for checking the soldered state described above.
(3) In any one of (3), after forming a plurality of the X-ray inspection lands, forming a solder paste layer on a part including the X-ray inspection lands and judging the quality of the soldering state, When the soldering state is determined to be defective, the solder layer is once removed and a solder paste layer is formed again, and at this time, a solder paste layer is formed on a portion including the remaining X-ray inspection lands, It is characterized in that it is used for judging the quality of soldering.

According to the soldering state checking method (5), the solder paste layer is formed only on a part of the plurality of X-ray inspection lands before the first reflow processing. If the soldering state is determined to be defective, a solder paste layer can be formed on the portion including the remaining X-ray inspection lands before the second reflow process, whereby the soldering failure In the case where the circuit components are re-soldered to the printed wiring board due to the above-mentioned factors, the quality of the soldered state can be easily and quickly determined.

Further, the printed wiring board (1) according to the present invention
Is characterized in that the X-ray inspection land used for checking the soldering state is formed.

According to the printed wiring board (1), since the X-ray inspection lands for use in checking the soldering state are formed, the soldering state checking methods (1) to (5) are used. The printed wiring board (1) can be used for any of the methods (1) and (2).

Further, the method of mounting a circuit component (1) according to the present invention uses the land for X-ray inspection for confirming the soldering state and for recognizing the position of a printed wiring board when mounting the circuit component. Features.

According to the method (1) for mounting circuit components,
Since the X-ray inspection lands can also be used for recognizing the position of a printed wiring board when mounting circuit components, it is necessary to accurately recognize the position of the printed wiring board when mounting the circuit components. And reflow processing can be performed by placing the circuit component at an accurate position on the printed wiring board to which the solder paste has been applied, thereby preventing displacement between the printed wiring board and the circuit component. Can be.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method for checking a soldered state, a printed wiring board, and a method for mounting circuit components according to the present invention will be described below with reference to the drawings. In the method for checking the soldering state according to the embodiment, first,
BGA40 (Fig. 5)
X different from the soldering land for soldering
A line inspection land is formed on the printed wiring board. Next, a solder paste layer is formed on the soldering land, and a solder paste layer having a shape different from that of the X-ray inspection land is formed on a portion including the X-ray inspection land and the vicinity thereof. BG on the wiring board
Solder A40. Next, the printed wiring board to which the BGA 40 is soldered is carried into a reflow furnace to perform a reflow process, and a change in the shape of the solder paste layer before and after the reflow process is inspected using an X-ray inspection device. The quality of the soldering state is determined.

FIG. 1 is a partially enlarged plan view schematically showing a printed wiring board used for a method of checking a soldered state according to an embodiment.

As shown in FIG. 1, the printed wiring board 1
In FIG. 0, a large number of soldering lands 11 are formed in a matrix around the center portion 15 except for a substantially square central portion 15. Wiring (not shown) is connected to each of the soldering lands 11. I have. The arrangement of the soldering lands 11 corresponds to the arrangement of the solder balls 42 of the BGA 40 (FIG. 5). Therefore, in a normal printed circuit board for the BGA 40, no wiring or land is formed at the center. Not. Therefore, in this printed wiring board 10,
Four square-shaped X-ray inspection lands 12 are formed in the square of the central portion 15.

The number of X-ray inspection lands 12 is not limited to four, but may be one or an appropriate number of two or more. FIG. 2 shows a printed wiring board 20 as an example in which a large number of X-ray inspection lands 12 are formed in a central portion 15.

FIGS. 1 and 2 show an example in which the X-ray inspection lands 12 are formed in the central portion 15. However, in the case where the soldering lands 11 are also formed in the portion including the central portion 15. The X-ray inspection lands 12 may be formed in a part of the region where the soldering lands 11 are formed.

In the method for checking the soldering state according to the embodiment, as described above, the soldering land 1 is used.
1 and a X-ray inspection land 1 and a portion including the X-ray inspection land 12 and its vicinity.
A solder paste layer having a shape (size) different from that of the solder paste layer 2 is formed.

FIGS. 3A to 3D are plan views schematically showing the shape of the X-ray inspection land and the shape of the solder paste layer applied to the X-ray inspection land.

In FIGS. 3A and 3B, square X-ray inspection lands 12a and 12b are formed.
In (c) and (d), a circular X-ray inspection land 32 is used.
a and 32b are formed, but the X-ray inspection lands 12
The shapes of a, 12b, 32a, and 32b are not limited to these.

These X-ray inspection lands 12a, 12b,
As a method of forming a solder paste layer on 32a, 32b, there are a method of forming solder paste layers 13a, 33a having an area smaller than the X-ray inspection lands 12a, 32a;
A method of forming the solder paste layers 13b and 33b having a larger area than the line inspection lands 12b and 32b can be given. Solder paste layers 13a, 13b, 33a, 33b
Is formed by a method using a metal mask described in the section of “Prior Art”.

Next, the BG is attached to the printed wiring boards 10 and 20.
A40 is soldered, and subsequently, the printed wiring boards 10 and 20 to which the BGA 40 is soldered are carried into a reflow furnace to perform a reflow process.

As shown in FIGS. 3A and 3C, when the solder paste layers 13a and 33a having smaller areas than the X-ray inspection lands 12a and 32a are formed, if the reflow process is performed well, Solder paste layers 13a, 33a
Spreads over the entire surface of the X-ray inspection lands 12a and 32a and substantially overlaps with the X-ray inspection lands 12a and 32a.

On the other hand, as shown in FIGS. 3B and 3D, when the solder paste layers 13b and 33b having a larger area than the X-ray inspection lands 12b and 32b are formed, the reflow process is performed satisfactorily. And the printed wiring board 10,
The solder paste layers 13b and 33b formed on the resin portion of the surface 20 are repelled and have a reduced area, and substantially overlap the X-ray inspection lands 12b and 32b. When the solder paste layers 13b and 33b having a larger area than the X-ray inspection lands 12b and 32b are formed, the solder paste layers 13b and 33b can be used even when the reflow process is performed well. It is difficult to overlap with
Not preferred.

When the reflow process is not performed well (for example, when the temperature at the time of reflow is low), the solder paste layers 13a, 13b, 33a, and 33b do not expand or contract sufficiently, and the X-ray inspection is performed. Lands 12a, 12b, 3
Does not overlap with 2a and 32b.

Therefore, the quality of the soldering state can be determined by inspecting the manner of change in the shape of the solder paste layers 13a,... Before and after the reflow processing using an X-ray inspection apparatus.

When a large number of X-ray inspection lands 12 are formed on the printed wiring board 20 as shown in FIG. 2, the change in the shape of the solder paste layers 13a,. Thereby, the heat distribution of the printed wiring board 20 at the time of the reflow processing can be known.

When a plurality of X-ray inspection lands 12a, 12b, 32a and 32b are formed on the printed wiring boards 10 and 20, all of them are solder paste layers 13a and 13a.
3b, 33a and 33b may be formed, but considering the case where the soldering state is determined to be defective after the reflow processing, first, some of the X-ray inspection lands 12a and
It is desirable to form the solder paste layers 13a,... Only on the portions including 2b, 32a, 32b.

FIGS. 4A and 4B show that a solder paste layer is formed only on a part of the X-ray inspection lands 12a before mounting the BGA 40, and that the solder paste layer is formed on the other X-ray inspection lands 12a after the reflow processing. FIG. 5 is a partially enlarged plan view showing a case where a paste layer is formed, and FIG. 4 omits a soldering land 11 (FIGS. 1 and 2).

As shown in (a), first, two out of four X-ray inspection lands 12a are applied to the solder paste layer 1.
3a is formed in advance. If the soldering state is determined to be defective after the reflow processing, the solder layer 14 is once removed and the solder paste layer is formed again. However, since it is difficult to completely remove the solder layer 14, (b)
The solder layer 14 remains as shown in FIG. Therefore, in this case, a solder paste layer 13a is formed on the remaining two X-ray inspection lands 12a to determine the quality of the soldered state.

X-ray inspection lands 12a, 12b, 32
a and 32b can be used not only for checking the above-mentioned soldered state but also for recognizing the positions of the printed wiring boards 10 and 20 when mounting circuit components.

As described in the section of "Prior Art", B
Printed circuit board 1 for circuit components such as GA40 (FIG. 5)
When mounting on 0 and 20 using an electronic component mounter,
The printed wiring boards 10 and 20 are placed and transported on rails for transport, and the solder paste application section applies soldering lands 11 and X-ray inspection lands 12a to solder paste layers 13a,.・ Is formed. Next, the printed wiring boards 10 and 20 are conveyed to and fixed to the BGA fixing section. For example, the moving member gripping the BGA 40 moves and the soldering lands 1 of the printed wiring boards 10 and 20 are moved.
After accurately positioning the BGA 40 so that each of the solder balls 42 of the BGA 40 comes directly above the 1,
The BGA 40 is placed and temporarily fixed on the printed wiring boards 10 and 20, and reflow processing is performed. In order to perform the above operation, it is necessary to know the exact positions of the printed wiring boards 10 and 20. Usually, a plurality of marks for position recognition are printed on the printed wiring boards 10 and 20, and the marks of the marks are printed. The position is photographed with a CCD camera or the like, and the position is measured. However, when the X-ray inspection lands 12a,... Are formed on the printed wiring boards 10, 20, these X-ray inspection lands 12a,.
Can be used for position recognition.

As described above, according to the soldering state checking method according to the embodiment, the X-ray inspection land 12a, which is different from the soldering land 11 for soldering the BGA 40 (FIG. 5), .. To the printed wiring board 10,
Since the soldering lands 11 are formed on the X-ray inspection lands 12, there is no need to change the size and arrangement of the soldering lands 11 from the conventional case.
a,... does not become an obstacle. Also, after the solder paste layers 13a, 13b, 33a, 33b having different shapes from the X-ray inspection lands 12a,... Are formed, reflow processing is performed, and the solder paste layers 13a,. Since the quality of the soldered state is determined based on the manner of change in the shape, the quality of the soldered state can be easily and quickly determined. Therefore, it is possible to reliably prevent a product with poor soldering from being shipped.

In the method of checking the soldering state according to the embodiment, when the solder paste layers 13b and 33b having a larger area than the X-ray inspection lands 12b and 32b are formed, it is determined that the reflow state is good. , Solder paste layers 13b and 33b are X-ray inspection lands 12b and 3
The area is reduced until it substantially overlaps with 2b. However, if the reflow state is bad, the solder paste layers 13b, 3b
The area 3b is not reduced until it substantially overlaps the X-ray inspection lands 12b and 32b. Therefore, the X-ray inspection lands 12b,
After the solder paste layers 13b and 33b having a larger area than the X-ray inspection lands 12b and 32b are formed on the 32b, a reflow process is performed.
By judging whether or not they substantially overlap the line inspection lands 12b and 32b, it is possible to easily judge whether the soldering state is good or not.

In the soldering state checking method according to the embodiment, when the solder paste layers 13a, 33a having a smaller area than the X-ray inspection lands 12a, 32a are formed on the X-ray inspection lands 12a, 32a, If the reflow state is good, the solder paste layers 13a, 33a
Increases in area until it substantially overlaps the X-ray inspection lands 12a and 32a. However, if the reflow state is bad,
The solder paste layers 13a and 33a are lands 1 for X-ray inspection.
The area does not increase until it substantially overlaps with 2a and 32a. Therefore, the solder paste layer 1 having a smaller area than the X-ray inspection lands 12a and 32a is provided on the X-ray inspection lands 12a and 32a.
After the formation of the solder paste layers 13a, 33a, the X-ray inspection lands 12a,
By judging whether or not it substantially overlaps with 32a, the quality of the soldering state can be easily judged.

According to the method of checking the soldering condition according to the embodiment, the quality of the soldering condition can be easily determined by forming at least one X-ray inspection land 12a,. Can be. When a large number of X-ray inspection lands 12a,... Are formed at different positions, in addition to the above-described effects, changes in the shapes of the solder paste layers 13a,. Of the printed wiring board 20 can be known.

According to the soldering state checking method according to the embodiment, a plurality of X-ray inspection lands 1 formed are formed.
2a,... Only part of solder paste layer 13a
Is formed, if the soldering state is determined to be defective, a solder paste layer 13a can be formed on the portion including the remaining X-ray inspection lands 12a,. In the case where the BGA 40 is re-soldered to the printed wiring board 10 due to, for example, the quality of the soldered state can be easily and quickly determined.

According to the circuit component mounting method according to the embodiment, the X-ray inspection lands 12 can be used for recognizing the positions of the printed wiring boards 10 and 20 when the BGA 40 is mounted. When the BGA 40 is mounted, the positions of the printed wiring boards 10 and 20 can be accurately recognized, and the BGA 40 is fixed at the correct position of the printed wiring boards 10 and 20 to which the solder paste has been applied, and reflow processing is performed. Can be printed wiring board 1
The displacement between 0, 20 and the BGA 40 can be prevented.

[Brief description of the drawings]

FIG. 1 is a partially enlarged plan view schematically showing a printed wiring board used for a method for checking a soldered state according to an embodiment of the present invention.

FIG. 2 is a partially enlarged plan view schematically showing a printed wiring board used in a method for checking a soldered state according to another embodiment.

FIGS. 3A to 3D schematically show the shape of an X-ray inspection land and the shape of a solder paste layer applied to the X-ray inspection land in the soldering state checking method according to the embodiment; FIG.

FIGS. 4A and 4B show a part of X before mounting a BGA in a method of checking a soldering state according to an embodiment;
FIG. 4 is a partially enlarged plan view showing a case where a solder paste layer is formed only on a line inspection land and a solder paste layer is formed on another X-ray inspection land after reflow processing.

FIG. 5A shows a BGA 40 on which a semiconductor element is mounted.
FIG. 2B is a bottom view schematically showing the BGA, and FIG. 2B is a cross-sectional view schematically showing a state in which the BGA is mounted on a conventional printed wiring board.

FIG. 6A shows a printed wiring board in which the size of a soldering land is made larger than the size of a solder ball in plan view, or a projection is formed on a soldering land.
FIG. 2B is a cross-sectional view schematically showing a BGA and a BGA, and FIG.

[Explanation of symbols]

11, 20 Printed wiring board 11 Soldering land 12, 12a, 12b, 32a, 32b X-ray inspection land 13a, 13b, 33a, 33b Solder paste layer 14 Solder layer

Claims (7)

[Claims] In a method of checking a soldering condition using an X-ray inspection apparatus after soldering a circuit component to a printed wiring board, a soldering land of the circuit component is defined as: Another X-ray inspection land was formed on the printed wiring board, and a solder paste layer having a shape different from that of the X-ray inspection land was formed on the portion including the X-ray inspection land and the vicinity thereof. A method of confirming a soldered state, comprising: performing a post-reflow process; and determining whether the soldered state is good or not based on a change in the shape of the solder paste layer before and after the reflow process. 2. The X-ray inspection land and its vicinity,
After forming a solder paste layer having a larger area than the X-ray inspection land, a reflow process is performed, and whether the soldering state is good or not is determined based on whether or not the solder paste layer substantially overlaps with the X-ray inspection land. Claim 1.
How to check the soldering state described. 3. A reflow process is performed after a solder paste layer having a smaller area than the X-ray inspection land is formed on the X-ray inspection land, and the solder paste layer spreads and substantially overlaps with the X-ray inspection land. 2. The method according to claim 1, wherein whether the soldering condition is good or not is determined based on whether the condition is satisfied or not. 4. The method according to claim 1, wherein at least one X-ray inspection land is formed, and a solder paste layer is formed on a portion including all the X-ray inspection lands.
The method for confirming a soldering state according to any one of the above items. 5. A plurality of X-ray inspection lands are formed,
After forming a solder paste layer on a portion including a part of the X-ray inspection land and judging the quality of the soldering state, if the soldering state is judged to be defective, the solder layer is temporarily removed. 4. The solder paste layer according to claim 1, wherein a solder paste layer is formed again on the portion including the remaining X-ray inspection lands, and a soldering state is determined. A method for checking a soldering state according to any of the above items. 6. A printed wiring board, wherein said X-ray inspection lands for use in checking a soldered state are formed. 7. A method of mounting a circuit component, wherein the X-ray inspection land is used for confirming a soldering state and for recognizing a position of a printed wiring board when mounting the circuit component.