JP2900587B2 - PCB for cream solder printing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cream solder printing substrate on which cream solder is printed in a predetermined pattern by a screen printing method.

2. Description of the Related Art A conductive portion is formed on a substrate by a pattern such as copper foil, and an electronic circuit component such as a chip component is soldered to the conductive portion by a cream solder printing process, a chip component mounting process, a reflow process, and the like. Attached. If a long period of time elapses after the substrate is manufactured and before the cream solder printing is performed, a conductive portion such as a copper foil is oxidized, and the solder wettability is deteriorated due to the oxide film, which causes inconvenience in soldering. Therefore, conventionally, a pre-flux was applied to prevent the oxidation.

Problems to be Solved by the Invention However, when the substrate is left for a long period of time, there is a problem that the oxidation preventing function is deteriorated due to deterioration of the preflux itself. Also, when soldering chip components on both sides, even though a series of steps of cream solder printing on the first surface, chip component mounting, and reflow can be performed smoothly, the second step is performed by heat in the first surface reflow process. Since the conductive portions on the surface are oxidized, there is a problem that the chip components on the second surface cannot be properly soldered.

An object of the present invention is to solve the above problems. Another object of the present invention is to solve the above-mentioned problems and to provide a cream solder printing substrate capable of performing accurate cream solder printing without bleeding.

Means for Solving the Problems The first invention of the present application is characterized in that an antioxidant sheet is provided on a printed surface of a substrate on a substrate on which cream solder is printed in a predetermined pattern by a screen printing method so as to be peelable. I do.

According to a second aspect of the present invention, in the configuration of the first aspect, both surfaces of the substrate are printing surfaces, and at least one of the antioxidant sheets provided on both surfaces is formed of a heat-resistant resin. .

According to a third aspect of the present invention, a film-shaped mask on which a printed pattern is formed is adhered to a printed surface of a substrate on which a cream solder is printed in a predetermined pattern by a screen printing method. A seat for use.

According to the first aspect of the present invention, the antioxidant sheet is provided on the printed surface of the substrate, which prevents air from contacting a conductive portion such as a copper foil of the substrate, thereby preventing oxidation of the conductive portion for a long time. can do.

According to the second invention of the present application, in addition to the operation and effect of the first invention, when soldering chip parts and the like on both surfaces,
Since at least one of the antioxidant sheets is formed of a heat-resistant resin, the antioxidant sheet formed of the heat-resistant resin allows the conductive portion of the second surface to be used even during the reflow step of the first surface. There is an operational effect that oxidation can be prevented.

According to the third invention of the present application, the following operation and effect are obtained in addition to the operation and effect of the first invention. In other words, even for a substrate with a sled, a film-shaped mask can be adhered along the printing surface, and as a result, it is possible to prevent a minute gap from being generated between the mask and the printing surface of the substrate, It is possible to prevent bleeding from occurring in the cream solder pattern printed on the substrate according to the print pattern of the film-shaped mask, and perform accurate cream solder printing.

Embodiment FIG. 1 shows a cream solder printing substrate P according to an embodiment of the present invention.

In FIG. 1, 1 is a substrate body, 2 is a conductive part such as a copper foil, 3 is a solder resist, 4 is a film-shaped mask,
Reference numeral 5 denotes an antioxidant sheet.

The film-shaped mask 4 is made of polyimide, fluorine resin (for example, Teflon-registered trademark), polypropylene, polyethylene, vinyl chloride, or the like.
It has a thickness of 200200 μm. This film-shaped mask 4 is adhered to the surface of the substrate main body 1 by an adhesive 6, and is positioned at an accurate position in a step before the screen printing step, and adhered in a close contact state.
In addition, it is also possible to adhere the film-shaped mask 4 to the substrate main body 1 using the heat-fusing property, chemical adhesiveness, and the like of the film-shaped mask 4 itself without using the adhesive 6.

On the film-shaped mask 4, a printed pattern 7 having an opening is formed. As a method for forming the print pattern 7, a known etching method, a laser perforation method, or the like may be used, and FIG. 2 shows a case using the laser perforation method. In FIG. 2A, reference numeral 4a denotes a mask material in the form of a film, 8 denotes a metal mask on which a pattern corresponding to the print pattern 7 is formed, and 9 denotes a laser beam. By irradiating the laser light 9 onto the film-shaped mask material 4a covered with the metal mask 8, the film-shaped mask 4 on which the predetermined print pattern 7 is formed as shown in FIG. can get. FIG. 3 shows one of the film-shaped masks 4.
An example is shown.

The antioxidant sheet 5 is formed of a material such as polyimide, fluorine resin, polypropylene, polyethylene, or vinyl chloride, and has a thickness of 25 to 300 μm. The antioxidant sheet 5 is peelably adhered to the film-like mask 4 by an adhesive 10 so as to cover the entire surface thereof. And a film-shaped mask 4
Is adhered on the substrate body 1 and subsequently adhered on the film-shaped mask 4. It is to be noted that the antioxidant sheet 5 is provided on the film-shaped mask 4 in a releasable manner by using the heat-fusing property and the chemical adhesive property of the antioxidant sheet 5 itself without using the adhesive 10. Can be.

Immediately before performing the cream solder printing, the oxidation preventing sheet 5 covering the surface of the substrate P is peeled off. At the time of this peeling, it is preferable that the pressure-sensitive adhesive 10 and the like be configured to be in a non-adhesive state by irradiating ultraviolet rays, because the antioxidant sheet 5 can be automatically peeled off by ultraviolet irradiation.

The substrate P from which the antioxidant sheet 5 has been peeled off is subjected to cream solder printing in a screen printing apparatus 13 shown in FIG. That is, the substrate P with a mask is arranged at a predetermined position,
By spreading the cream solder 11 supplied thereon with a squeegee 12, the cream solder 11 transmitted through the print pattern 7 of the film-shaped mask 4 is printed on the substrate body 1.

After cream solder printing is performed as described above,
The film-shaped mask 4 is peeled from the substrate body 1. As in the case of peeling off the antioxidant sheet 5, if the adhesive 6 and the like are configured to be in a non-adhesive state by irradiating ultraviolet rays, the film-shaped mask 4 is automatically moved from the substrate body 1 by irradiating ultraviolet rays. It is preferable because it can be peeled off.

FIG. 5 shows a cream solder printing substrate Q according to another embodiment of the present invention. The substrate Q has a printing surface on both sides, and both the film-shaped mask 4 and the antioxidant sheet 5 provided on both sides are formed of a heat-resistant resin, for example, polyimide or a fluorine-based resin. . The other components are the same as those shown in FIG. 1, and therefore, are denoted by the same reference numerals, and description thereof is omitted. According to this substrate Q,
After the cream solder printing on the first surface is performed as shown in FIG. 4, chip components are mounted on the first surface, and then the process proceeds to a reflow process. Mask 4 and antioxidant sheet 5 can withstand. Therefore, oxidation on the second surface of the substrate Q can be prevented, and at the time of cream solder printing on the second surface, the film-shaped mask 4 can fully fulfill its function.

FIG. 6 shows a cream solder printing substrate R according to still another embodiment of the present invention. This substrate R is the substrate body 1
Is provided with an antioxidant sheet 5 so as to be directly peelable on the printed surface. The other configuration is the same as that shown in FIG. 1, and therefore, only the common reference is given, and the description is omitted.

The present invention can be configured in various modes in addition to the embodiments described above. For example, in the embodiment shown in FIG. 6, only one surface of the substrate main body 1 has a printing surface. It is possible to provide it releasably, and to form at least one antioxidant sheet 5 with a heat-resistant resin.

Effects of the Invention According to the first invention of the present application, even when the substrate is left for a long time, the oxidation of the conductive portion of the substrate can be reliably prevented.

According to the second invention of the present application, in addition to the effect of the first invention, even when electronic components such as chip components are soldered to both surfaces of the substrate, the device can withstand heat during the reflow process on the first surface, There is an effect that oxidation of the second surface can be prevented.

According to the third invention of the present application, in addition to the effect of the first invention, there is an effect that accurate cream solder printing can be performed without causing bleeding in the cream solder pattern.

[Brief description of the drawings]

1 to 4 show a first embodiment of the present invention, FIG. 1 is an enlarged sectional view of a substrate for printing cream solder, FIG. 2 is a sectional view showing a method of manufacturing a film-shaped mask, 3 is a plan view of a film-like mask, FIG. 4 is a sectional view showing a cream solder printing method, FIG. 5 is an enlarged sectional view of a cream solder printing substrate according to a second embodiment of the present invention, and FIG. FIG. 7 is an enlarged sectional view of a cream solder printing substrate according to a third embodiment of the present invention. PQR: cream solder printing substrate 1: substrate body 4: film mask 5: antioxidant sheet 7: printing pattern

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Shimazaki 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-151895 (JP, A) JP-A-2 -181995 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H05K 3/34 505 H05K 3/28

Claims (3)

(57) [Claims] 1. A cream solder printing substrate, characterized in that, on a substrate on which cream solder is printed in a predetermined pattern by a screen printing method, an antioxidant sheet is provided releasably on a substrate printing surface. 2. The cream solder printing substrate according to claim 1, wherein both surfaces of the substrate are printing surfaces, and at least one of the antioxidant sheets provided on both surfaces is formed of a heat-resistant resin. 3. On a substrate on which cream solder is printed in a predetermined pattern by a screen printing method, a film-shaped mask on which a printed pattern is formed is adhered to a printed surface of the substrate, and the mask is peelably removed on the mask to prevent oxidation. A cream solder printing substrate comprising a sheet.