JP2007157851A - Method of supplying solder, method of manufacturing mounting substrate, and mounting substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply a proper amount of solder to a land on which an electronic component is mounted, while suppressing increase in size of a printed circuit board. <P>SOLUTION: The solder supplying method includes a preparation process S1 for preparing a printed board on which, in order to mount two or more electronic components having different shapes using solder, a plurality of lands are formed to correspond to the two or more electronic components; and an applying process S2 for applying a cream solder to the plurality of lands by screen printing. It also includes a dispensing process S4 for dispensing the cream solder to at least either a land where the amount of cream solder applied in the applying process S2 is insufficient or an electronic component that is mounted on the land, selectively using an air dispenser, for soldering an electronic component mounted on the land among a plurality of them. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solder supply method, a mounting substrate manufacturing method using the solder supply method, and a mounting substrate obtainable by the manufacturing method.

  As a method of supplying solder to the land of the printed circuit board, there is screen printing in which the printed circuit board is covered with a mask in which through holes are formed, and cream solder is applied thereon. Electronic components mounted on a printed circuit board have various sizes and shapes, and the amount of solder appropriate for each electronic component may be different. Thus, a method has been proposed for changing the amount of cream solder supplied to different electronic components as appropriate by changing the mask thickness of screen printing for each part (paragraph numbers 0002 to 0004 of Patent Document 1 below). reference).

However, if the amount of cream solder applied is adjusted by changing the mask thickness, it is difficult to significantly change the amount of cream solder applied from place to place because the squeegee followability is limited. Therefore, Patent Document 1 describes a technique for performing a reflow process by screen-printing cream solder on a printed circuit board and then mounting solder pellets together with components on the printed circuit board on a land where the amount of solder applied is insufficient. Has been.
JP 2003-324271 A

  In the technique described in Patent Document 1, since the solder pellet is held by the adhesive force of cream solder, the solder pellet cannot be placed on anything other than the screen-printed cream solder. For the same reason, the electronic component cannot be mounted on a region where the electronic component is mounted (for example, on a lead terminal of the electronic component or on a land on which the lead terminal of the electronic component is mounted). Therefore, if the amount of solder pellets is increased, it is necessary to increase the area of the land to which the cream solder is applied, and the printed circuit board is unnecessarily enlarged.

  Therefore, in the present invention, a solder supply method capable of supplying an appropriate amount of solder for mounting an electronic component while suppressing an increase in the size of the printed circuit board, a method of manufacturing a mounting board using the solder supply method, and its manufacture It is an object to provide a mounting substrate that can be obtained by the method.

  The solder supply method according to the present invention is a preparatory step of preparing a printed circuit board on which a plurality of lands corresponding to two or more electronic components are formed in order to mount two or more electronic components having different forms by soldering. And an application process in which cream solder is applied to each of the lands by screen printing, and the amount of cream solder applied in the application process in order to solder electronic components mounted on the lands among the lands. And a replenishing step of selectively replenishing the solder with at least one of the insufficient land and the electronic component mounted on the land using an air dispenser.

  According to the present invention, the cream solder is selectively replenished to the lands where the amount of cream solder is insufficient by using an air dispenser. An arbitrary amount of solder can be supplied to the location. In addition, since the cream solder itself has adhesive force and utilizes the fact that it is deformed into an arbitrary shape, it can be replenished to the part where the cream solder is not originally applied, such as on the lead terminal of an electronic component. . Furthermore, the cream solder can be replenished to a portion where the amount of the solder solder has already been applied but the amount is insufficient, such as on the land on which the lead terminal of the electronic component is placed.

  A method for manufacturing a mounting board according to the present invention includes a preparation step of preparing two or more electronic components having different forms and a printed circuit board on which lands corresponding to the two or more electronic components are formed, and a plurality of lands, respectively. A soldering process in which cream solder is applied by screen printing, and a land having an insufficient amount of cream solder applied in the coating process in order to solder an electronic component mounted on the land among a plurality of lands, A replenishment step of selectively replenishing cream solder using an air dispenser to at least one of the electronic components mounted on the land, and a mounting step of placing two or more electronic components on each of the lands. Heat the cream solder applied in the application process and the cream solder replenished in the replenishment process to heat two or more electricity. Including, a reflow process to fix the parts.

  According to the present invention, the cream solder is selectively replenished to the lands where the amount of cream solder is insufficient by using an air dispenser. An arbitrary amount of solder can be supplied to the location. In addition, since the cream solder itself has adhesive force and utilizes the fact that it is deformed into an arbitrary shape, it can be replenished to the part where the cream solder is not originally applied, such as on the lead terminal of an electronic component. . Furthermore, the cream solder can be replenished to a portion where the amount of the solder solder has already been applied but the amount is insufficient, such as on the land on which the lead terminal of the electronic component is placed. Therefore, an appropriate amount of cream solder can be supplied to each electronic component to be mounted, and the electronic component can be mounted on the printed circuit board.

  The mounting substrate according to the present invention can be obtained by the manufacturing method described above. Therefore, it is possible to provide a mounting board on which electronic components are appropriately mounted while avoiding unnecessary enlargement of the board.

  According to the present invention, it is possible to supply an appropriate amount of solder to a land on which an electronic component is mounted while suppressing an increase in the size of a printed circuit board.

  The knowledge of the present invention can be easily understood by considering the following detailed description with reference to the accompanying drawings shown for illustration only. Subsequently, embodiments of the present invention will be described with reference to the accompanying drawings. Where possible, the same parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a flowchart showing a mounting board manufacturing method using the solder supply method according to the present embodiment. The manufacturing method of the mounting substrate according to the present embodiment uses the solder supply method according to the present embodiment, and includes an electronic component mounting step S3, a reflow step S5, and an appearance inspection step S6. The solder supply method according to the present embodiment includes a printed circuit board preparation step S1, a solder application step S2 by screen printing, and a solder replenishment step S4 by an air dispenser.

  Subsequently, each step will be described in detail with reference to FIGS. 2 and 4 are diagrams for explaining each step in the solder supply method and the mounting board manufacturing method according to the present embodiment, and are schematic cross-sectional views of the printed board. FIG. 3 is a schematic view of an air dispenser used in the solder supply method according to the present embodiment.

  First, in the preparation step S1, a printed board 11 on which a wiring pattern is formed is prepared. As shown in FIG. 2A, the printed circuit board 11 is formed with lands 12 and 13 for soldering for mounting electronic components. Electronic components to be mounted are mixed from a very small chip component to a large component such as a transformer component. The land 12 is formed as a land for small parts and has a relatively small surface area. The land 13 has a relatively large surface area as a land for a large component.

  Next, in the application step S2, cream solder is applied to the lands 12 and 13 of the printed circuit board 11 prepared in the preparation step S1 by screen printing. As shown in FIG. 2A, a screen printing mask 31 is placed at a predetermined position on the printed circuit board 11. Through holes 32 and 33 having shapes corresponding to the lands 12 and 13 are formed at positions corresponding to the lands 12 and 13 in the mask 31.

  On the mask 31, the squeegee 35 is slid in the direction of the arrow Y1, and the cream solder 34 is filled into the through holes 32 and 33. After the through holes 32 and 33 are filled with the cream solder 34 and the solder layers 14 and 15 are formed, the mask 31 is removed (FIG. 2B).

  In this state, the amount of solder in the solder layer 14 formed on the land 12 is a predetermined amount appropriate for the corresponding small component. The appropriate predetermined amount is an amount necessary for bonding the electronic component to the land of the printed circuit board 11 with sufficient strength.

  Further, the amount of solder in the solder layer 15 formed on the land 13 is less than a predetermined amount appropriate for the corresponding large component, and the amount of solder is insufficient. That is, the thickness of the mask 31 is adjusted according to a predetermined amount of solder for small parts.

  After the coating step S2, the small component 16 is mounted on the solder layer 14 and the large component 17 is mounted on the solder layer 15 in the mounting step S3. The small component 16 and the large component 17 have different forms. In the present embodiment, both ends of the lower side surface of the main body of the small component 16 are mounted on the two solder layers 14 respectively. In addition, the large component 17 is mounted on the two solder layers 15 with terminals 19 respectively formed at both ends of the lower surface of the component body 18. The terminal 19 extends outward from both ends of the lower surface of the component body 18, and the lower side of the extended portion is in contact with the solder layer 15.

  After the mounting step S3, in the replenishment step S4, solder is applied to the land 13 in which the amount of solder applied in the application step S2 is insufficient or the large component 17 mounted on the land 13 with the air dispenser 40 shown in FIG. refill. The air dispenser 40 includes a syringe 41, a metal needle 42, an adjustment mechanism 43, and a controller 44.

  The syringe 41 is filled with cream solder, and a metal needle 42 is connected to the tip. Cream solder is discharged from the tip of the metal needle 42 by the pressure of air introduced into the syringe 41. The adjustment mechanism 43 is configured to hold the syringe 41 and to move the syringe 41 in the vertical direction indicated by the arrow Y2. The controller 44 adjusts the amount of cream solder discharged from the metal needle 42 according to the position of the printed circuit board 11.

  The printed circuit board 11 is fixed on the table 36 disposed under the air dispenser 40. The table 36 moves front and rear, left and right on the horizontal plane so that the tip of the metal needle 42 of the air dispenser 40 is at a predetermined position on the printed circuit board 11. The predetermined position is a position corresponding to a land where the amount of solder applied in the application step S2 is less than the predetermined amount, and is a known position.

  The table 36 moves to a predetermined position, cream solder corresponding to the position is discharged from the air dispenser 40, and a predetermined amount of cream solder is supplied to a predetermined position on the printed circuit board 11.

  As shown in FIG. 4A, cream solder is replenished by the air dispenser 40 to the land 13 where the amount of solder applied in the application step S2 is less than a predetermined amount, whereby the replenished solder layer 20 is formed. A refill solder layer 20 is formed on the land 19 on the terminal 19 of the large component 17. The amount of solder in the supplementary solder layer 20 is adjusted so as to be an appropriate predetermined amount in order to obtain sufficient strength for bonding the land 13 and the large component 17 together with the solder layer 15.

  In addition, when connecting the lead wire to the printed circuit board 11, cream solder can be filled from above the lead wire using the air dispenser 40. Through the above steps S1 to S4, an appropriate predetermined amount of solder can be supplied to the lands 12 and 13 of the printed circuit board 11, respectively.

  After the replenishment step S4, in the reflow step S5, the printed circuit board 11 is inserted into a reflow furnace, and the solder layers 14 and 15 and the replenishment solder layer 20 are melted. After melting the solder layer 14, the land 12 and the small component 16 are joined by the solder 21 formed by cooling. In addition, after melting the solder layer 15 and the supplemental solder layer 20, the land 13 and the large component 17 are joined by the solder 22 formed by cooling.

  After the reflow step S5, in the inspection step S6, an appearance inspection is performed on the bonding state of the printed circuit board 11 and each electronic component. In this way, a mounting board 23 in which each electronic component is mounted on the printed board 11 as shown in FIG. 4B is completed.

  A small component 16 and a large component 17 having different forms are mounted on the mounting substrate 23. The amount of solder 22 that bonds the large component 17 to the land 13 of the printed circuit board 11 is larger than the amount of solder 21 that bonds the small component 16 to the land 12 of the printed circuit board 11. Also, the solder 22 for mounting the large component 17 on the mounting substrate 23 is formed so as to cover a part on the terminal 19.

  In the solder supply method of the present embodiment, cream solder is applied by screen printing to each of a plurality of lands corresponding to two or more electronic components having different forms in the application step S2, so that an appropriate amount of solder in each land Therefore, after the screen printing, there are lands where the amount of solder is insufficient.

  As a conventional technique, there is a method of replenishing pelletized pellet solder after cream solder screen printing. In this case, in order to hold the pellet solder at a predetermined position until the reflow process, it is necessary to mount it on the screen-printed cream solder. That is, since the pellet solder itself does not have adhesive force, it cannot be mounted on the terminal of the electronic component, on the lead wire or the like.

  Therefore, in order to mount a sufficient amount of pellet solder using the conventional technique, it is necessary to increase the land area and apply cream solder to a larger area during screen printing. Thus, in the above conventional technique, it is necessary to increase the land area, and the printed circuit board is unnecessarily enlarged.

  In contrast to the above conventional technique, in the solder supply method of the present embodiment, the cream solder is selectively replenished to the land 13 where the amount of the cream solder is insufficient by using the air dispenser 40. It is possible to supply an arbitrary amount of solder to an arbitrary location with respect to the land 13 in which the amount of is insufficient. In addition, since the cream solder itself has adhesive force and utilizes the fact that it is deformed into an arbitrary shape, it can be replenished to the part where the cream solder is not originally applied, such as on the lead terminal of an electronic component. . Furthermore, the cream solder can be replenished to a portion where the amount of the solder solder has already been applied but the amount is insufficient, such as on the land on which the lead terminal of the electronic component is placed.

  In the mounting board manufacturing method of the present embodiment, since the solder supply method is used, an appropriate amount of cream solder is supplied to each electronic component to be mounted, and the electronic component can be mounted on the printed board. it can.

  The mounting substrate 23 according to this embodiment can be obtained by the manufacturing method described above. Therefore, it is possible to provide a mounting substrate on which the small component 16 and the large component 17 are appropriately mounted while avoiding unnecessary enlargement of the substrate.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, an electronic component mounting step S3 may be performed after the cream solder replenishment step S4 by the air dispenser 40. In that case, the replenishment solder layer 20 is formed on the solder layer 15 in the replenishment step S4. Thereafter, in the mounting step S <b> 3, the terminals 19 of the large component 17 are stacked on the supplementary solder layer 20. In the mounting board manufactured as described above, the amount of solder for bonding the large component 17 to the land 13 of the printed circuit board 11 is larger than the amount of solder for bonding the small component 16 to the land 12 of the printed circuit board 11.

It is a flowchart which shows the manufacturing method of the mounting board | substrate using the solder supply method which concerns on this embodiment. It is a figure for demonstrating each process of the solder supply method which concerns on this embodiment, and the manufacturing method of a mounting substrate. It is the schematic of the air dispenser used in the solder supply method concerning this embodiment. It is a figure for demonstrating each process of the solder supply method which concerns on this embodiment, and the manufacturing method of a mounting substrate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Printed circuit board, 12, 13 ... Land, 14, 15 ... Solder layer, 16 ... Small component, 17 ... Large component, 20 ... Supplementary solder layer, 21 ... Solder, 22 ... Solder, 31 ... Mask, 32, 33 ... Through hole, 34 ... cream solder, 35 ... squeegee, 36 ... table, 40 ... air dispenser, 41 ... syringe, 42 ... metal needle, 43 ... adjustment mechanism, 44 ... controller.

Claims (3)

A preparatory step of preparing a printed circuit board on which a plurality of lands corresponding to each of the two or more electronic components are formed in order to mount two or more electronic components having different forms by soldering;
An application step of applying cream solder to each of the plurality of lands by screen printing;
Of the plurality of lands, in order to solder an electronic component mounted on the land, the land having an insufficient amount of cream solder applied in the application step, and the electronic component mounted on the land A replenishment step of selectively replenishing cream solder using an air dispenser for at least one of the following:
A solder supply method. A preparation step of preparing two or more electronic components having different forms and a printed circuit board on which lands corresponding to the two or more electronic components are formed;
An application step of applying cream solder to each of the plurality of lands by screen printing;
Among the plurality of lands, in order to solder an electronic component mounted on the land, a land having an insufficient amount of cream solder applied in the application step, at least of the electronic component mounted on the land On the other hand, a replenishment step of selectively replenishing cream solder using an air dispenser,
A mounting step of mounting each of the two or more electronic components on each of the lands;
A reflow step of fixing the two or more electronic components by heating the cream solder applied in the application step and the cream solder replenished in the replenishment step;
A method for manufacturing a mounting board, comprising: A mounting substrate obtainable by the manufacturing method according to claim 2.

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