JP4468671B2 - Mounted component protection device and mounted component protection in printed wiring board assembly process - Google Patents

Description

  The present invention relates to a mounted component protection method and apparatus in a printed wiring board assembly process, and a reflow apparatus with a mounted component protection function. More specifically, the printed circuit board reflow process (the process of mounting components on the surface of the printed circuit board) or the rework process (the printed circuit board that has been installed) is visually inspected and the operator manually solders the defective part. In the printed circuit board assembly process, the component mounted on the printed wiring board is protected from heat, and the component is prevented from being deteriorated or dropped. The present invention relates to a reflow apparatus.

  The printed circuit board reflow process includes a first reflow process and a second reflow process. The first reflow process is a process in which components are mounted on the first surface of the printed wiring board and soldered while the printed wiring board is passed through the solder melting tank by the conveyor. The second reflow process is the first surface. In this step, the component is mounted on the second surface of the printed wiring board on which the attachment of the component is completed, and the printed wiring board is soldered while being passed through the solder melting tank by the conveyor. In the reflow process, paste-like solder is attached to the component mounting location on the printed wiring board, and the component is attached so that the terminal of the component comes along the paste-like solder surface. The components are soldered by passing through and melting the solder.

  In the reflow process of the printed wiring board, if the heat resistance of the component mounted on the lower surface of the printed wiring board is low and there is a risk of quality deterioration during the second reflow process, mount the part after the reflow or review the reflow process In general, the surface on which the component is mounted is used as a secondary flow surface, or the component is usually designed to be mounted on the secondary flow surface in advance. The reason is that the parts attached at the time of the first reflow pass through the melting tank again at the time of the second reflow, so that the quality may be deteriorated accordingly.

  Also, in the reflow process of the printed wiring board, if the component to be mounted on the bottom surface of the printed wiring board is heavy and there is a risk of the solder melting and dropping during the second reflow process, is the component mounted after the reflow process? The reflow process is reviewed, and the surface on which the component is mounted is set as a second reflow surface, or is fixed with an adhesive, or is designed so that the component is mounted on the second reflow surface in advance.

  As another method, by cooling the lower surface space of the conveyor that conveys the printed wiring board in the reflow device and keeping the entire area of the lower surface of the printed wiring board at a low temperature, the components mounted on the lower surface of the printed wiring board are deteriorated, Or there exists a technique which prevents falling (for example, refer patent document 1). Still another method is to use a solder with a high melting point on the first reflow surface, and use a solder with a lower melting point than the solder used for the first reflow surface on the second reflow surface. There is a technique for preventing re-melting and preventing components mounted on a printed wiring board from being deteriorated or dropped (see, for example, Patent Document 2).

Moreover, in the rework process, when there is a risk that the component mounted on the lower surface of the component to be removed is deteriorated or dropped, it is necessary to remove the component once. .
JP-A-6-21641 (2nd page, 3rd page, FIG. 1) JP-A-6-85445 (2nd page, 3rd page, FIG. 1)

  However, in order to mount the aforementioned parts after reflow, manual soldering work is required, and the production efficiency is remarkably deteriorated. The method of changing the order of reflow cannot be adopted when a part having poor heat resistance or a heavy part is mounted on a new lower surface. In the method of fixing with an adhesive, there is a risk that the solder is remelted even if the component is fixed, and the connection quality is deteriorated.

  Also, there may be no space for applying the adhesive on the part. Designing the parts in advance so as to be mounted on the second reflow surface reduces the degree of freedom in design such as pattern routing and part placement. In the method of cooling the lower surface space of the conveyor that conveys the printed wiring board in the reflow tank, a large-scale function is added to the reflow apparatus, resulting in a significant increase in equipment costs. Moreover, since the lower surface space of the conveyor is cooled, accurate temperature control is difficult and partial cooling is impossible.

  In addition, using a solder having a high melting point on the first reflow surface and using a solder having a lower melting point than the solder used on the first reflow surface on the second reflow surface, the solder paste of the solder printer is replaced by first reflow and second reflow. It is necessary to change the setting of the reflow temperature or the like, or it is necessary to prepare equipment for each of the fast reflow and the second reflow, which causes a decrease in production efficiency and an increase in capital investment. In the rework process, removal of parts that are not to be reworked and re-mounting work are required, which is inefficient.

  On the other hand, in recent years, the use of lead-free solder is increasing as an environmental measure, but generally the melting point of lead-free solder is higher than that of conventional solder. Therefore, it is necessary to raise the temperature of the reflow furnace in the reflow process. As a result, components with low heat resistance temperature may be deteriorated in the second reflow process, and must be mounted manually after the reflow process. .

  In addition, there are an increasing number of cases where modules with electronic components mounted on a daughter board are used, but the modules are heavy because a plurality of electronic components are mounted. In addition to the risk of dropping, there is a risk that not only the solder on the printed wiring board but also the solder on the module is remelted, resulting in a connection failure in the module. However, due to the high density mounting of printed wiring boards, there is a strong demand for mounting heavy components on both sides of the printed wiring board.

  The present invention has been made in view of such problems, and in the reflow process or rework process of the printed wiring board, the component mounted on the printed wiring is protected from heat, and the component is deteriorated or dropped. It is an object of the present invention to provide a mounted component protection method and apparatus and a reflow device with a mounted component protection function in a printed wiring board assembly process capable of preventing the above.

FIG. 1 is a flowchart showing the principle of the method of the present invention. The present invention has a feedback circuit for controlling an arbitrary region to be a predetermined temperature for cooling a component attached to the lower surface of the printed wiring board during the second reflow in the reflow soldering process of the printed wiring board. Cooling means is provided (step 1), and the components attached to the lower surface of the printed wiring board are cooled by the cooling means during reflow (step 2).
( 1 ) The invention described in claim 1 is as follows. FIG. 2 is a principle configuration diagram of the present invention. In the figure, 1 is a printed wiring board, 2 is a component attached to the upper surface of the printed wiring board 1, 3 is a component attached to the lower surface of the printed wiring board 1, and 4 is also attached to the lower surface of the printed wiring board 1. This is a part to be cooled. Reference numeral 5 denotes a cooling means for cooling the component 4 and the component 4 provided around the component 4. The cooling means 5 is provided with a feedback circuit for controlling an arbitrary region to have a predetermined temperature.
( 2 ) The invention according to claim 2 is characterized in that the cooling means is attached to the warpage prevention jig and the printed wiring board is attached to the warpage prevention jig .
( 3 ) The invention according to claim 3 is an automatic conveyance type reflow apparatus for soldering a component to a printed wiring board, and has the mounted component protection apparatus according to claim 2 .

(1) According to the first aspect of the present invention, the components attached to the lower surface of the printed wiring board at the time of reflow are cooled at the time of reflow by the cooling means, so that deterioration or drop of the components can be prevented. Further, even when there is no empty space for arranging the cooling means on the printed wiring board, the temperature rise of the component to be cooled and the solder around the component can be suppressed, so that the component can be prevented from being deteriorated or dropped.
(2) According to the invention described in claim 2 , by attaching the cooling means and the printed wiring board to the warpage prevention jig, the temperature increase of the component to be cooled and the solder around the component can be suppressed in the reflow process. Therefore, it is possible to prevent the parts from being deteriorated or dropped at the same time as preventing warpage. Further, since the cooling circuit is arranged on the warpage preventing jig, it is economical because it is not necessary to prepare a dedicated pallet.
(3) According to the invention described in claim 3, since the pallet is automatically conveyed, it is not necessary to manually attach the printed wiring board to the packet. Can be prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 is a block diagram showing the configuration of the cooling circuit in the cooling means. This circuit constitutes the cooling means 5 of FIG. In the figure, 6 is a power source, 7 is a temperature detection element for detecting the ambient temperature, 8 is a temperature control circuit for controlling the temperature by receiving the output of the temperature detection element 7, and 9 is a cooling driven by the temperature control circuit 8. It is an element. There are various types of temperature detecting element 7, and for example, a thermocouple is used. As the cooling element 9, for example, a Peltier element is used. The operation of the circuit thus configured will be described as follows.

  In the reflow process, the circuit shown in FIG. The temperature detecting element 7 detects the temperature of the melting tank and gives it to the temperature control circuit 8. The temperature control circuit 8 receives the ambient temperature and drives the cooling element 9. This cooling element 9 is in direct contact with the component to be cooled via an insulator, or is in contact with the component to be cooled through a medium having good thermal conductivity. As a result, the component is cooled by the cooling element 9. As a result of cooling the component, the solder attached to the component does not melt and the component does not fall. Further, it is possible to prevent the characteristics from being deteriorated as a result of cooling the parts.

  FIG. 4 is a block diagram showing a first embodiment of the present invention. 2 and 3 are denoted by the same reference numerals. In this embodiment, a pallet 10 having a mechanism capable of arbitrarily moving the cooling element 9 is used. The pallet 10 is attached to the printed wiring board 1. 4 is a cooling target component, and 11 is a cooling circuit for cooling the cooling target component 4. As the cooling circuit 11, for example, a circuit as shown in FIG. 3 is used. In this embodiment, even when the printed wiring board 1 has no empty space, the cooling element 9 attached to the pallet 10 can be arbitrarily moved to cool the cooling target component 4. is there. With this configuration, even when there is no free space for placing the cooling means on the printed wiring board, the temperature rise of the component to be cooled and the solder around the component can be suppressed, preventing the deterioration or dropping of the component. it can. Further, since the cooling element can be arbitrarily arranged, it is effective for different types of printed wiring boards.

  FIG. 5 is a block diagram showing a second embodiment of the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals. In this embodiment, the cooling means and the printed wiring board are attached to the warp prevention metal fitting. As shown in the figure, the warp prevention jig 15 has a cooling circuit 11, a cooling element 9 is disposed below the cooling target component 4 mounted on the printed wiring board 1, and the cooling target component 4 is placed by the cooling element 9. It is designed to be cooled. The fixture 16 is for preventing the warp of the printed wiring board 1 provided in the warp prevention jig 15. With this configuration, by attaching the cooling means and the printed wiring board to the warpage prevention jig, the temperature increase of the component to be cooled and the solder around the component can be suppressed in the reflow process. Deterioration or fall can be prevented. Further, since the cooling circuit is arranged on the warpage preventing jig, it is economical because it is not necessary to prepare a dedicated pallet.

  FIG. 6 is a configuration diagram showing a third embodiment of the present invention, and shows a configuration example of a rework apparatus. The same components as those in FIG. 5 are denoted by the same reference numerals. The component 21 on the printed wiring board 1 is removed by applying hot air to the component 21 to be removed via the hot air passage 23. The hot air passage 23 is surrounded by a heat insulating wall 24. The printed wiring board 1 is fixed to the column 26. In this case, the cooling element 25 is attached to a height adjustment mechanism 27 that can be height-adjusted by a ball screw or the like, arranged below the cooling target component 22 to be cooled, and the cooling target component 22 is cooled by the cooling element 25. It is what I did. With this configuration, the temperature rise of the component to be cooled and the solder around the component can be suppressed, so that it is possible to eliminate the work of removing the component and re-mounting.

  FIG. 7 is a block diagram showing a fourth embodiment of the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals. As shown in the figure, a hole 29 is provided in the printed wiring board 1, and the cooling element 31 is attached to the hole 29 via a fitting 32 and a fastening component 33 such as a screw. Reference numeral 30 denotes a cooling target component. If comprised in this way, a cooling element can be easily attached or detached to a printed wiring board using the hole near components, and work will be made efficient.

  FIG. 8 is a block diagram showing a fifth embodiment of the present invention. As shown in the figure, a heat conductive sheet 36 is attached to a cooling element 37 such as a Peltier element, and a heat radiating fin 38 is attached to the opposite side. With this configuration, the cooling element 37 cools the component 35 via the heat conductive sheet 36, and the heat of the cooling element 37 is released by the radiation fin 38, effectively preventing the component from being deteriorated or dropped. it can.

  FIG. 9 is a block diagram showing a sixth embodiment of the present invention. 1 and 8 are denoted by the same reference numerals. (A) is a side view, (b) is a plan view. On the printed wiring board 1, a cooling circuit 40 composed of a power source, a temperature control component, and the like is attached to the printed wiring board 1 with a metal fitting 41 having elasticity. A cable 42 is wired from the cooling circuit 40 and is coupled to a Peltier element 37 that is a cooling element. The Peltier element 37 is fixed to the heat radiation fin 38 with an adhesive or the like. A heat conductive sheet 36 is attached to the cooling surface of the Peltier element 37.

  The heat radiating fins 38 are fixed to the printed wiring board 1 with screws 47. Accordingly, the Peltier element 37 is in close contact with the component 35 to be cooled via the heat conductive sheet 36. When the printed wiring board 1 is passed through the second reflow process, an appropriate voltage is applied to the cooling circuit 40, and the Peltier element 37 cools the component 35 to a temperature lower than the heat resistance temperature or a temperature at which the solder does not remelt. To prevent deterioration or fall.

  FIG. 10 is a block diagram showing a seventh embodiment of the present invention. The same components as those in FIG. 9 are denoted by the same reference numerals. This embodiment has the basic configuration shown in FIG. 4, and shows an enlarged portion to be cooled. The Peltier element 37 is fixed to the heat radiation fin 38 with an adhesive or the like. A heat conductive sheet 36 is attached to the cooling surface of the Peltier element 37.

  The Peltier element 37 is wired with a cable 42 having heat resistance by fluororesin processing or the like, and the cable 42 is connected to a cooling circuit (not shown). The radiating fin 38 is provided with an elastic body 54 such as a spring, and the elastic body 54 is fixed to the spacer 55. The spacer 55 is attached to the pallet 49 with screws 56. Accordingly, the Peltier element 37 is in close contact with the component 35 to be cooled on the printed wiring board 1 via the heat conductive sheet 36.

  By mounting the printed wiring board 1 on the pallet 49 and passing it through the second flow process, applying an appropriate voltage to the cooling circuit, the Peltier element 37 cools the component 35 to a temperature lower than the heat resistance temperature or a temperature at which the solder does not remelt. , Preventing the deterioration or fall of the component 35. For example, if the solder having a melting point of 180 ° C. melts when the reflow atmosphere temperature is 235 ° C., the temperature of the component 35 is kept at 160 ° C., thereby preventing the solder of the component 35 from being re-melted. Can do.

  In this embodiment, since the Peltier element has elasticity, is arranged on the lower surface of the component, and is detachable from the pallet, it can be mounted on different types of printed wiring boards with different heights. It can be used and can be versatile.

  FIG. 11 is a block diagram showing another configuration example of the cooling circuit of the present invention. The same components as those in FIG. 3 are denoted by the same reference numerals. The cooling circuit includes a power source 6, a thermistor 59 as a temperature detection element, a temperature control circuit 8, a Peltier element 9, and a resistor 61. The Peltier element 9 and the resistor 61 are connected in parallel. The resistor 61 adjusts the current flowing through the Peltier element 9. The operation of the circuit thus configured will be described as follows. First, since the resistance of the thermistor 59 is very high when the ambient temperature is low, no voltage is applied to the Peltier element 9. As a result, the circuit shown in FIG. On the other hand, when the ambient temperature increases, the resistance of the thermistor 59 becomes extremely small. As a result, a voltage is applied to the Peltier element 9, and a cooling operation is performed. In this case, the temperature control circuit 8 hardly functions as a control circuit. In this circuit, a temperature control IC or the like can be used as the temperature control circuit 8 so that temperature control with higher accuracy can be performed.

  FIG. 12 is a block diagram showing an eighth embodiment of the present invention. 6 and 10 are denoted by the same reference numerals. This embodiment has the basic configuration shown in FIG. The printed wiring board 1 is fixed to a column 64 provided on a base 63 of the rework apparatus. The Peltier element 37 is fixed to the heat radiation fin 38 with an adhesive or the like, and a heat conductive sheet 36 is attached to the cooling surface. The radiating fins 38 are attached to a height adjuster 65, and the height adjuster 65 adjusts the height so that the Peltier element 37 is in close contact with the component 22 to be cooled via the heat conductive sheet 36. .

  The cooling circuit 73 includes a power source, a temperature sensor, and the like, and is connected to the Peltier element 37 via a cable 74. Hot air is sent from the hot air passage 66 to the component 21 to be removed, and the component 21 is removed by melting the solder. In this embodiment, the hot air path 66 is surrounded by the heat insulating wall 24 so that the hot air does not hit the surrounding parts. When hot air is applied to the printed wiring board 1 to remove the component 21, an appropriate voltage is applied to the cooling circuit 73, and the Peltier element 37 cools the component 22 to a temperature lower than the heat resistance temperature or a temperature at which the solder does not remelt. Therefore, it is possible to prevent the component 22 from being deteriorated or dropped.

  As described above, according to the present invention, in the reflow process or the rework process of the printed wiring board, the component mounted on the printed wiring board is protected from heat, and the component is prevented from being deteriorated or dropped. It becomes possible.

(Supplementary Note 1) In the reflow soldering process of the printed wiring board, a cooling means for cooling the components attached to the lower surface of the printed wiring board during the second reflow is provided (step 1), and the printed wiring board is cooled by the cooling means. Cool the parts attached to the bottom surface during reflow (Step 2),
A mounted component protection method in a printed wiring board assembly process, characterized in that

  (Appendix 2) Mounting in a printed wiring board assembly process characterized by providing a cooling means for cooling components attached to the lower surface of the printed wiring board during the second reflow in the reflow soldering process of the printed wiring board Parts protection device.

  (Additional remark 3) Since a cooling means is attached even when there is no vacant space in a printed wiring board, the mechanism which can move this cooling means arbitrarily is provided on a pallet, and the printed wiring board is attached to this pallet. The mounted component protection apparatus in the printed wiring board assembly process according to 2.

  (Additional remark 4) The mounting means protection apparatus in the printed wiring board assembly process of Additional remark 2 characterized by attaching a cooling means to a curvature prevention jig and attaching a printed wiring board to a curvature prevention jig.

(Additional remark 5) In the automatic conveyance type reflow apparatus which solders components to a printed wiring board,
An automatic conveyance type reflow apparatus with a mounted component protection function, characterized in that a mechanism capable of arbitrarily moving the cooling means is provided on the pallet and has a warp prevention jig for preventing the cooling means from warping.

  (Appendix 6) In the rework process of the printed wiring board mounted on both sides, it has a cooling means on the opposite side of the rework side and a position adjustable mechanism for fixing the cooling means, and it is mounted on the lower surface of the part to be reworked during rework. The rework device with a mounted component protection function, wherein the mounted component is cooled.

  (Additional remark 7) The mounting component protection apparatus in the printed wiring assembly process of Additional remark 2 characterized by making the hole for attaching a cooling means beforehand at the time of the design of the said printed wiring board.

  (Additional remark 8) The said cooling means is comprised with the cooling circuit which drives a cooling element, a heat conductive sheet, a thermal cooling element, and a radiation fin, The printed wiring board assembly in any one of Additional remark 2 thru | or 4 characterized by the above-mentioned. Mounted component protection device in the process.

It is a flowchart which shows the principle of this invention method. It is a principle block diagram of this invention. It is a block diagram of the configuration of the cooling circuit. It is a block diagram which shows the 1st Example of this invention. It is a block diagram which shows the 2nd Example of this invention. It is a block diagram which shows the 3rd Embodiment of this invention. It is a block diagram which shows the 4th Example of this invention. It is a block diagram which shows the 5th Example of this invention. It is a block diagram which shows the 6th Embodiment of this invention. It is a block diagram which shows the 7th Example of this invention. It is a block diagram which shows the other structural example of the cooling circuit of this invention. It is a block diagram which shows the 8th Embodiment of this invention.

Explanation of symbols

1 Printed wiring board 2 Parts 3 Parts 4 Parts 5 Cooling means

Claims (3)

In the reflow soldering process of the printed wiring board, a cooling means for cooling the components attached to the lower surface of the printed wiring board during the second reflow is provided.
In the mounted component protection apparatus in the printed wiring board assembly process, the cooling means is provided with a feedback circuit for controlling an arbitrary region to have a predetermined temperature.
For attaching the cooling means even if there is no free space on the printed wiring board, a mechanism capable of moving arbitrarily the cooling means on the pallet, the printed wiring board assembly of the printed wiring board, characterized in that attached to the pallet Mounted component protection device in the process. 2. The mounted component protection apparatus in a printed wiring board assembly process according to claim 1, wherein the cooling means is attached to the warpage prevention jig, and the printed wiring board is attached to the warpage prevention jig . In the automatic transfer type reflow device that solders parts to the printed wiring board ,
Tower mounting component protection function reflow apparatus you further comprising a mounting component protection device according to claim 1.

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