JPH07304Y2 - Mask for solder paste printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a solder paste printing mask used in a process of soldering an electronic component to a conductor portion on an insulating substrate.

[Prior Art] A solder paste printing mask is for printing and applying a solder paste on a mounting position of an electronic component on an insulating substrate.
Usually, a mask plate made of metal such as Cu, SUS, and Cu-Ni alloy having a thickness of 0.1 mm to 0.5 mm is used.

For example, as shown in the drawing of Japanese Utility Model Laid-Open No. 60-124070, this type of mask has a through hole formed beforehand by means such as etching in accordance with the conductor position of the insulating substrate on which the solder paste is to be printed. Has been. Then, the mask is overlaid on the insulating substrate, and when the solder paste on the mask is spread with a squeegee in this state, the solder paste is printed at a predetermined position on the insulating substrate through the through hole.

This will be described in detail with reference to FIG. 3. The lower conductor 2 and the upper conductor 4 formed on the insulating substrate 1 intersect at the crossover portion 10, but these conductors 2 and 4 are insulated from each other by the crossover glass 3. Has been done. The surfaces of the upper conductor 4, the lower conductor 2 and the crossover glass 3 are surface-treated with the overcoat glass 5.

When the solder paste is printed on the conductor positions on the insulating substrate 1, the mask plate 6 having a plurality of through holes 7 is superposed on the insulating substrate 1, and then the solder paste is placed on the mask plate 6. 9 is moved by the squeegee 8 in the direction of the arrow. Then, the solder paste 9 is printed at the position of the through hole 7 on the conductor 2.

[Problems to be Solved by the Invention] In recent years, as the integration density of ICs has increased and the mounting density of electronic components on an insulating substrate has increased, the above-described crossing of wiring on the insulating substrate 1, that is, crossover, has occurred. It is inevitable.
However, since the lower conductor 2, the crossover glass 3 and the conductor 4 overlap each other in multiple layers in the crossover portion 10 formed in accordance with this, the height from the insulating substrate 1 is 40 μm to 60 μm, which is higher than other portions. It's getting higher. Therefore, when the mask plate 6 is superposed on the insulating substrate 1, the mask plate 6 is locally lifted at the crossover portion, and the mask plate 6 and the insulating substrate 1 are separated from each other.

However, when the mask plate 6 is separated from the surface of the insulating substrate 1 in this way, the height from the surface of the lower conductor 2 to the upper surface of the mask plate 6 becomes particularly high, so that the through holes 7 are filled in when the solder paste is printed. The amount of solder paste
The amount is larger than the amount determined in advance by the thickness of 16 and the area of the through hole 17. Therefore, for example, as shown in FIG.
When a lead pin r of an electronic component such as an IC is soldered to a predetermined position of the lower conductor 2, so-called solder dripping due to excessive solder causes a very high probability of short-circuiting between the lead pins r with solder 9 after reflow. Become.

As the number of wiring layers increases, the above-mentioned short circuit between the conductors that occurs during the solder paste printing process reduces the reliability of the electronic circuit.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a mask plate which is effective in preventing the occurrence of solder shorts when printing a solder paste.

[Means for Solving the Problem] The structure of the present invention will be described with reference to the reference numerals of FIG. 1 and FIG. 2. A mask plate constituting a solder printing mask.
Reference numeral 11 has through holes 17 corresponding to the soldering points of the electronic components on the insulating substrate 11 on which the wiring pattern is formed. In this invention, a recess 23 is formed on the lower surface of the mask plate 16 corresponding to the crossover portion 20 where the lower conductor 12 and the upper conductor 14 intersect with each other across the crossover glass 13 on the insulating substrate 11. .

[Operation] In the mask according to the present invention, when the mask plate 16 is superposed on the insulating substrate 11 in the solder paste printing process, a crossover portion that is particularly protruding on the insulating substrate 11 is formed.
20 is housed and contained in the recess provided in the mask plate 16. Therefore, when the solder paste is printed on the insulating substrate 11, the mask plate is not deformed, so that a certain amount of the solder paste is always printed on the insulating substrate.

Therefore, so-called sagging due to excessive solder does not occur, and the probability of short-circuiting between conductors due to solder after reflow is reduced.

Further, since the recesses 23 may be provided only on the lower surface portion of the mask plate 16 corresponding to the crossover portion 20 on the insulating substrate 11, the number of recesses 23 and the area thereof can be small, and the mask plate 16 at the time of printing can be reduced. Positioning is also easy.

[Embodiment] Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, reference numerals 12 and 14 denote a lower conductor and an upper conductor formed on an insulating substrate 11, which intersect with each other while being insulated from each other by a crossover glass 13. Reference numeral 15 is an overcoat glass that covers the conductors 12 and 14 and the crossover glass 13. Reference numeral 16 denotes a metal mask plate which constitutes a solder printing mask, and a plurality of through holes 7 are formed on the insulating substrate 11 at positions where solder paste is printed.

In the solder paste printing mask as described above, in the present invention, the concave portion 23 is formed on the lower surface of the mask plate 16 corresponding to the crossover portion 20 on the insulating substrate 11.

According to this structure, the convex portion caused by the crossover on the insulating substrate is completely accommodated and included in the concave portion of the mask plate. Therefore, when the solder paste is printed, the mask plate is almost entirely over the insulating substrate 11. It does not float up from the substrate. Therefore, the amount of the solder paste 19 to be printed is an amount corresponding to the volume determined by the area of the through hole 17 formed in the mask plate 16 and the thickness of the mask plate 16, and excess solder paste is not filled or printed. .
Therefore, the problem of solder short circuit between conductors due to so-called solder sag is solved.

Next, as a manufacturing example of the mask of the present invention described above, a manufacturing method by a photoresist method will be described with reference to FIG.

First, on both sides of the material a of the mask plate 16 shown in FIG.
A resist b is applied as shown in FIG. Next, as shown in (C), the position where the through hole 17 is opened and the recess 23
The film film c printed corresponding to the position for forming is adhered onto the resist b and developed as shown in FIG. As a result, the resist b applied to the opening position of the through hole 17 of the mask plate 16 and the position where the recess 23 is to be formed.
Are removed. As a matter of course, regarding the position where the concave portion 23 is formed, the resist b on the lower surface side of the mask plate 16 is formed.
Remove only.

Further, when the mask plate 16 is dipped in an etching solution and etched, a through hole 17 and a recess 23 are formed in the mask plate 16. Finally, the resist is peeled off to obtain the solder paste printing mask of the present invention.

[Advantages of the Invention] As described above, when the solder paste is printed by forming the concave portion 23 on the lower surface of the mask plate 16 for accommodating and containing the crossover portion 20 where the conductors 12 and 14 intersect on the insulating substrate 11. Deformation of the mask of is eliminated and the mask plate is placed on the conductor 12.
Only a predetermined amount of solder paste determined by the thickness of 16 and the cross-sectional area of through hole 17 is printed. As a result, the problem of solder short circuit is solved and a reliable electronic circuit can be constructed.

Further, since the number of recesses 23 and the area thereof on the lower surface of the mask plate 11 are small, the mask can be manufactured easily and inexpensively, and the alignment is easy, so that the solder paste can be printed efficiently and economically. Is possible.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an insulating substrate and a solder paste printing mask showing an embodiment of the present invention, FIG. 2 is a flow chart showing an example of manufacturing the solder paste printing mask of the present invention, and FIG. 3 is a solder paste printing. Sectional view showing a conventional example of a mask for
FIG. 4 is an explanatory view showing a soldering state when the same mask is used. 11 ... Insulating substrate, 12 ... Lower conductor, 14 ... Upper conductor, 16 ... Mask plate, 17 ... Through hole, 18 ... Squeegee, 19 ... Solder paste, 23
… Recessed

Claims (1)

[Scope of utility model registration request] 1. A solder paste printing mask comprising a mask plate 16 having through holes 17 corresponding to soldering positions of electronic components on an insulating substrate 11 on which a wiring pattern is formed. A crossover portion 20 where the lower conductor 12 and the upper conductor 14 intersect with each other with the crossover glass 13 in between.
A solder paste printing mask, characterized in that a concave portion (23) is formed on the lower surface of the mask plate (16) at a position corresponding to.