JP6145644B2 - Printed wiring board - Google Patents

Description

  The present invention relates to a land shape of a printed wiring board to be soldered using a partial jet solder bath.

  A printed wiring board used for a control device is generally a board in which an insertion type terminal part and a surface mounting type terminal part are mixedly mounted.

  The soldering of the printed wiring board having the insertion type terminal component is generally performed by a DIP flow soldering method using a jet solder bath.

  On the other hand, with respect to the soldering of the surface mount type terminal components, the use of the DIP flow soldering method is limited due to quality problems such as a short circuit between the terminals while the surface mount components are continually being downsized.

  Therefore, recently, surface mount type terminal parts have been arranged on the same surface as the soldering surface of the insert type terminal parts. The method to do is put into practical use.

  In such a soldering method, it becomes possible to consolidate the exposed solder part on the back side of the printed wiring board, and the moisture-proof coating process is applied to the printed wiring board to improve the reliability, simplifying the moisture-proofing process The benefits that can be found.

  As shown in FIG. 2, the soldering lands 4 of the insertion-type terminal component 2 gather on the back surface (solder surface) of the printed wiring board 1 to form a soldering group 5. A plurality of soldering groups 5 are formed on the printed wiring board 1 by arrangement of components. In a range where the soldering group 5 of the insertion type terminal component 2 is not arranged, that is, a range A where partial jet soldering is not performed, the surface mount type terminal component 3 is arranged.

As shown in FIG. 3, the partial jet solder bath has one or more jet nozzles 6 having substantially the same shape as the opposing soldering group 5. The surface mount type terminal component 3 is mounted on the printed wiring board 1 in advance by a reflow soldering method, and the printed wiring board 1 is fixedly disposed above the jet nozzle 6 with a fixed gap and melted from the jet nozzle 6. The solder 7 is jetted and brought into contact with the soldering group 5 of the printed wiring board 1 for a certain period of time to adhere the solder 7 (see, for example, Patent Document 1).

  In general, the soldering land 4 of the insertion type terminal component 2 has a round shape.

  In the DIP flow soldering method using a jet solder bath, the entire printed wiring board passes over the solder that is jetted and is subject to thermal damage. Therefore, printed wiring that has surface-mounted terminal parts already soldered and resin parts that are thermally deformed. In the case of a board, a partial jet soldering method in which only a necessary portion of a printed wiring board is soldered is an effective means.

JP 2002-368404 A

  However, in the conventional technology as described above, the arrangement range of the surface mount type terminal component 3 is restricted due to the restrictions such as the size of the printed wiring board 1 and the arrangement of the insertion type terminal component 2. In order to effectively secure the range A in which the partial jet soldering is not performed, it is required to make the jet nozzle 6 small until it has substantially the same shape as the soldering group 5.

  The feature of the solder 7a discharged from the jet nozzle 6 is balanced between the discharge portion of the jet nozzle 6 and the printed wiring board 1 so as not to overflow outside the nozzle. The solder 7a does not rise in jet due to surface tension and tends not to contact the printed wiring board 1.

  In addition, the individual jet nozzles 6 corresponding to the soldering group 5 have a small heat capacity, and the solder 7a to be discharged tends to be exposed to the surrounding atmospheric gas and decrease in temperature around the outer wall of the jet nozzle 6.

  Therefore, when the jet nozzle 6 is made small so as to have substantially the same shape as the soldering group 5, the solderability is deteriorated in the land near the outer wall of the jet nozzle 6, and there is a problem that the solder amount is insufficient or the solder is not attached. is there.

  This invention is made | formed in view of the subject mentioned above, The objective is to improve the solderability in a partial jet soldering method, and to ensure the stable amount of solder.

  In order to solve the above-described problems, the printed wiring board according to the present invention is a land to be partially soldered in a soldering using a partial jet solder bath having a nozzle having substantially the same shape as the soldering group of the printed wiring board. Is a shape having a protrusion toward the center of the nozzle.

  The present invention is configured as described above. In the partial jet soldering method, there is an effect that solderability is improved and a stable amount of solder can be secured.

Correlation diagram of nozzle and soldering group of partial jet solder bath and plan view of land of printed wiring board according to embodiment of present invention Back view of printed wiring board Correlation diagram of nozzle and soldering group of conventional partial jet solder bath and plan view of land of printed wiring board

  In the present invention, the following modes can be provided.

  According to the aspect of the present invention, in the soldering using the partial jet solder bath having the nozzle having substantially the same shape as the soldering group of the printed wiring board, the land to be partially soldered is directed to the central portion of the nozzle. The shape has a protruding portion.

According to the above configuration, since the land is provided with the protrusion directed toward the center of the jet nozzle, the molten solder that is less affected by the temperature drop that is sufficiently sprayed near the center of the nozzle (other than the periphery of the outer wall) It can be pressed against the portion and pulled around the insertion terminal hole via the land protrusion. Therefore, the protrusion provided on the land has an effect of guiding the solder having good fluidity to the soldering portion of the insertion terminal of the land and increasing the amount of solder at the solder connection portion between the printed wiring board and the insertion type terminal component.

  Therefore, the printed wiring board which concerns on the aspect of this invention has an effect that it can improve solderability and can ensure the stable amount of solder in the soldering process performed using a partial jet solder tank.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiment.

(Embodiment 1)
First, the shape of the land 8 of the printed wiring board 1 to be soldered using the partial jet solder tank according to the present embodiment will be described with reference to FIG.

  FIG. 1 is a correlation diagram of the jet nozzle 6 and the soldering group 5 of the partial jet solder tank according to the present embodiment and a plan view of the land 8 of the printed wiring board 1. The soldering group 5 means a group of lands 8 in which the lands 4 in FIG. 2 are read as lands 8 having the characteristics of the present invention.

  As shown in FIG. 1, the partial jet solder bath has one or more jet nozzles 6 having substantially the same shape as the opposing soldering group 5. The surface mount type terminal component 3 is mounted on the printed wiring board 1 in advance by the reflow soldering method, and the printed wiring board 1 is fixedly disposed above the jet nozzle 6 with a fixed gap and melted from the jet nozzle 6. The solder 7 is jetted and brought into contact with the soldering group 5 of the printed wiring board 1 for a certain period of time, so that the solder 7 is adhered.

  Further, the soldering land 8 of the insertion type terminal component 2 is characterized by a shape in which a rectangular protrusion 8 a directed toward the center of the jet nozzle 6 is added to a round shape portion.

  About the printed wiring board comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  The solder 7a discharged from the jet nozzle 6 has the following two characteristics particularly around the nozzle outer wall.

  Since the jet nozzle 6 is balanced between the discharge portion of the jet nozzle 6 and the printed wiring board 1 so that the solder does not overflow into the area A where the surface-mounted terminal component 3 outside the jet nozzle 6 is mounted. In the vicinity of the outer wall, the ejected solder 7a does not rise due to surface tension and tends not to contact the printed wiring board 1 sufficiently.

  The individual jet nozzles 6 corresponding to the soldering group 5 have a smaller heat capacity than the jet solder nozzles used in the DIP flow soldering method, and the discharged solder 7a is exposed to the surrounding atmospheric gas around the outer wall of the jet nozzle 6. The temperature tends to decrease.

  Therefore, in the partial jet soldering method, if the jet nozzle 6 is made small so as to have substantially the same shape as the soldering group 5, the solderability at the land in the vicinity of the outer wall of the jet nozzle 6 is reduced, and the solder amount is insufficient. There is a tendency for non-adhesion to occur.

In the present embodiment, the land 8 includes a protrusion 8 a directed toward the center of the jet nozzle 6. The solder 7a discharged near the center of the jet nozzle 6 (other than the periphery of the outer wall) is sufficiently jetted and is stably pressed against the printed wiring board 1. In addition, the temperature is less likely to be affected by the ambient gas around the jet nozzle 6. The solder 7 having good conditions for soldering can be pressed against the protruding portion 8 a protruding toward the center of the jet nozzle 6, and the solder 7 is formed by the round shape portion of the land 8 through the protruding portion 8 a of the land 8. It can be pulled around a certain insertion terminal hole. Therefore, the protrusion 8a provided on the land 8 guides the solder 7 having good fluidity to the insertion terminal soldering portion of the land 8, and reduces the solder amount of the solder connection portion between the printed wiring board 1 and the insertion type terminal component. Has the effect of increasing.

  The length of the protruding portion 8a is a length L in a range where the discharged solder 7a has a gradient due to surface tension, and the width of the protruding portion 8a is the land width W of the round shape portion of the land 8. It has been experimentally confirmed that a good fillet is formed in the terminal portion which is a round shape portion.

  As mentioned above, the printed wiring board 1 which concerns on the form of this invention can improve solderability in the partial jet soldering method, and can ensure the stable amount of solder.

  Moreover, the jet nozzle 6 can be made small to substantially the same shape as the soldering group 5, and the limited area of the printed wiring board 1 can be used effectively.

  In the present embodiment, the soldering group 5 has been described as an assembly of four lands 8. However, the number of lands 8 constituting the soldering group 5 is not limited to this. Furthermore, the effect is the same even when an aggregate of a large number of lands 8 is defined as a soldering group 5 and a jet nozzle 6 is formed opposite thereto. However, it is apparent from the operation of the present embodiment that the land 4 provided with the protruding portion 8a may be limited to the land disposed in the vicinity of the outer wall periphery of the jet nozzle 6.

  The present embodiment is effective even when one land 8 is defined as a soldering group 5 and the jet nozzle 6 facing the land 8 is formed. This means that the center of the jet nozzle 6 does not necessarily depend on the design conditions of the printed wiring board 1 such as the position of the land 8 on the printed wiring board 1 and the relative conditions of the printed wiring board 1 and the jet nozzle 6. This is because there is a case where one land 8 cannot be opposed.

  Since the printed wiring board of the present invention can easily improve the solderability by devising the design of the land shape to be partially soldered, it can be used in any device that is soldered using a partial jet solder bath. Applicable to printed circuit boards.

DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Insertion type terminal component 5 Soldering group 6 Jet nozzle 7 Solder 8 Land 8a Protrusion part

Claims (1)

In what is soldered by using a partial jet solder bath having a nozzle having substantially the same shape as the soldering group of the printed wiring board, the land to be partially soldered has a shape having only a protrusion toward the central portion of the nozzle. A printed wiring board characterized by the above.

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