JP2005303061A - Electronic part soldering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic part soldering method for soldering an electronic part to a circuit board in a simplified way without damaging the electronic part in a process for mounting the electronic part, by heating to a high temperature terminals installed on the periphery of the electronic part body with an IR beam projected from above the circuit board. <P>SOLUTION: A heat insulator 7 is arranged on the electronic part body surface 6, and the terminals 3 of the electronic part 1 mounted on the circuit board 2 are left exposed. An oil layer 8 is formed between the electronic part 1 and the heat insulator 7 for eliminating a space between the two, and an IR beam 5 is projected from above the heat insulator 7 for soldering the terminals 3 to the circuit board 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a soldering method in which an electronic component is placed on a circuit board and a terminal provided on the outer edge of the electronic component body is heated and soldered by infrared rays irradiated on the circuit board from above. The present invention relates to a method for soldering an electronic component in which a heat insulating material is disposed on a surface of a main body and heated and soldered.

  Conventionally, for example, as shown in Patent Document 1 below, a technique for mounting an IC package on a circuit board has been disclosed. According to this technique, an IC package is placed on a circuit board in a state where each terminal of the IC package is aligned with each land to which solder cream is applied. And a circuit board is put in an infrared reflow furnace, infrared rays are irradiated from upper direction, and the whole is heated more than the melting temperature of a solder cream. As a result, the solder cream on the lands is melted and then cooled to solidify the solder cream, and the terminals are connected and fixed to the lands. In this case, the IC package is adapted to block irradiated infrared rays with a heat insulating cover. The heat insulating cover is connected to the main body through an adhesive at four corners, and a gap is formed between the heat insulating cover and the main body. Therefore, only a small amount of heat absorbed by the heat insulating cover is transferred to the main body. Further, since air can freely flow in the gap between the heat insulating cover and the main body, air that has risen in temperature by absorbing heat from the heat insulating cover also convects on the back surface of the heat insulating cover and is replaced with air having a lower temperature. Therefore, the temperature rise of the main body is greatly suppressed, and the occurrence of cracks can be reliably prevented. Further, the heat insulating cover is fixed to the main body only by the adhesive and can be easily removed from the main body.

  In the above-mentioned patent document 1, another conventional example is disclosed. In this case, a large number of voids are formed inside the heat insulating cover. The heat insulating cover has an adhesive property, and is adhered and fixed to the surface of the main body by the adhesive property. This heat insulating cover includes a large number of voids inside. Therefore, although the heat insulating cover is in close contact with the main body, the absorbed heat is hardly transmitted to the main body due to the heat insulating action by the air in the gap. As a result, the temperature rise of the main body can be suppressed and the occurrence of cracks can be prevented. Moreover, it is fixed to the main body only by the adhesive property of the heat insulating cover itself and can be easily removed.

  In Patent Document 1 described above, still another conventional technique is disclosed. In this method, an adhesive is applied to the entire surface of the main body without giving adhesive properties to the heat insulating cover having voids. This provides a heat insulation effect as described above.

Further, as another conventional technique, one disclosed in Patent Document 2 below is disclosed. This prevents the temperature of the component from rising when the component is soldered on the substrate. As this method, a heat insulating layer is attached to the upper surface of the component. As a mounting method, the heat insulating layer is attached to a part with a cap shape, or is attached using a seal.
JP 2000-31342 (paragraph [0010] to paragraph [0014]) JP 2001-274033 A (paragraph [0040], paragraph [0051])

  However, in the prior art shown in Patent Document 1, a heat insulating effect is expected by providing a space between the heat insulating cover and the main body or by forming a space in the heat insulating cover itself. However, recently, lead-free solder is used for environmental measures. This lead-free solder requires a higher temperature in reflow (solder mounting) than eutectic solder. On the other hand, it is difficult to improve heat resistance of electronic components mounted on a circuit board from the viewpoint of cost.

  Therefore, in the conventional technique shown in Patent Document 1, since the gap has a small volume, it immediately reaches a high temperature even if convection is taken into consideration. Therefore, it is conceivable that the main body is heated instead. Further, since the thermal expansion coefficients of the heat insulating cover and the main body are not considered at all, depending on the adhesive, both of them are fixed relatively firmly, and there is a possibility that stress is applied to the main body due to the difference in the thermal expansion coefficient. In particular, when an adhesive is applied to the entire surface of the main body, there is a high risk of stress generation. For this reason, the IC package as the main body is damaged.

  Similarly, in the prior art disclosed in Patent Document 2, since the difference in the coefficient of thermal expansion is not taken into consideration, there is a possibility that stress is generated in the component by being fixed by the seal. And since sticking and removing work of a sticker is troublesome, it is difficult to apply to the recent soldering mounting which is automated. Further, it is disadvantageous in cost to prepare a seal made of a material that can withstand high temperatures.

  Thus, there has been a problem in the prior art that there is nothing suitable for soldering mounting performed at a relatively high temperature. SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic component soldering method capable of achieving soldering mounting performed at a high temperature by a simple operation.

  In order to solve the above-mentioned problem, the invention of the electronic component soldering method according to claim 1 of the present application is such that the electronic component is placed on the circuit board, and the terminals provided on the outer edge of the electronic component main body are disposed above the circuit board. In the soldering method of heating and soldering by infrared rays irradiated from the terminal, the terminals are exposed on the surface of the main body of the electronic component and a heat insulating material is disposed (for example, step 102), and a space is provided between the electronic component and the heat insulating material. The oil layer is removed and provided (for example, step 103), and infrared rays are irradiated from above the heat insulating material to solder the terminals to the circuit board.

  Since the present invention takes the above-described method, there is no space between the main body surface of the electronic component and the heat insulating material positioned on the main body surface of the electronic component. There are various effects.

  First, since there is no air layer between the surface of the electronic component body and the heat insulating material, even when heated by infrared rays from above the electronic component, high temperature air convects and substantially touches the electronic component body surface. Absent. Therefore, the temperature rise of the electronic component can be prevented.

  Secondly, the heat insulating material is not only stably positioned on the electronic component main body due to the viscosity of the oil layer, but also slips due to the oil layer even if the coefficient of thermal expansion between the electronic component main body and the heat insulating material is different. No stress is generated on the component body. Therefore, it is possible to prevent an accident that an electronic component is damaged by infrared heating.

  Third, in the soldering operation, the heat insulating material is stably fixed by the oil layer only by being positioned on the surface of the main body of the electronic component. When the heat insulating material is removed after the soldering process is completed, the heat insulating material is gently fixed to the electronic component main body by the oil layer, so that the heat insulating material can be removed with a small force. Therefore, the attachment / detachment of the heat insulating material is suitable for automation.

  The best mode for carrying out the present invention is the embodiment described below.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side view showing a state in which a heat insulating material in an embodiment of the present invention is arranged on the surface of a main body of an electronic component, and FIG. 2 is a flowchart showing a soldering process in the embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes an electronic component whose outer shape is formed by a flat and rectangular IC package, and 2 is a circuit board. The electronic component 1 is arranged on the circuit board 2 and provided on the outer edge of the electronic component 1. The terminal 3 is fixed to a predetermined location on the circuit board 2 with solder 4. This soldering is performed by irradiating infrared rays 5 from above and heating. At this time, in order to prevent the electronic component 1 from being heated by being directly irradiated with infrared rays, a flat heat insulating material 7 is disposed on the main body surface 6 of the electronic component 1 except for the terminal 3 portion.

  The soldering process will be described with reference to FIG. First, as a preparation process, the electronic component 1 is positioned on the circuit board 2 in the process 101. In this case, solder cream is applied in advance to the portion of the circuit board 2 to which the terminals 3 are connected. In the next step 102, oil is dropped on the main body surface 6 of the electronic component 1 and the heat insulating material 7 is disposed thereon. This oil having a relatively low viscosity is selected and is stably positioned with surface tension in a state where it is hung on the central portion of the body surface 6 of the electronic component 1. And it presses lightly from the upper direction of the heat insulating material 7. FIG. As a result, as shown in FIG. 1, the oil extends entirely between the electronic component 1 and the heat insulating material 7 to form an oil layer 8. In step 103, the oil layer 8 is in a state in which a space containing air is not generated between the electronic component 1 and the heat insulating material 7. At the same time, the heat insulating material 7 is gently fixed to the main body surface 6 of the electronic component 1 by the viscosity of the oil layer 8.

  After the preparation process is completed in this way, in step 104, the infrared cream 5 is irradiated to heat and melt the solder cream, and in the subsequent process 105, it is cooled and solidified. The terminal 3 is fixed to the circuit board 2 by the solder 4 by this solidification. In step 104, as shown in FIG. 1, the heating state is irradiated with infrared rays 5 from above, but the body surface 6 of the electronic component 1 is prevented from being irradiated with infrared rays 5 by a heat insulating material 7. On the other hand, the terminal 3 is directly irradiated with the infrared rays 5 and heated. Further, an oil layer 8 is formed between the electronic component 1 and the heat insulating material 7, and the surface of the electronic component 1 is not touched by high-temperature air. Further, since the oil layer 8 itself has no bubbles, it is stable even when heated. For this reason, the oil layer 8 may expand and burst due to heating, causing displacement of the heat insulating material 7, or generating voids to allow hot air to touch the main body surface 6 of the electronic component 1. Absent.

  After the connection and fixing with the terminal 3 circuit board 2 by the solder 4 in the step 105 is completed, the heat insulating material 7 is removed from the surface of the electronic component 1 in the next step 106. In this removal operation, the heat insulating material 7 is gently fixed to the electronic component 1 by the oil layer 8, and therefore can be removed with a small force.

  Therefore, the control system of the present invention hangs oil having a relatively low viscosity on the main body surface 6 of the electronic component 1 in the preparation steps of Step 101 to Step 103, and places the heat insulating material 7 thereon, The heat insulating material 7 is positioned in a stable state on the main body surface 6 of the electronic component 1. And between the electronic component 1 and the heat insulating material 7, the oil layer 8 is filled, and there is no room for air to enter. For this reason, in the soldering process 104, even if the electronic component 1 is heated by infrared rays from above, the heated air does not substantially touch the body surface 6 of the electronic component 1 so that the electronic component 1 does not reach a high temperature.

  Further, the oil layer 8 not only stably positions the heat insulating material 7 on the main body surface 6 of the electronic component 1 due to viscosity, but also the heat insulating material 7 is directly heated by the infrared rays 5 to expand and expand the electronic component 1. Even if the expansion of the heat insulating material 7 is different, the oil layer 8 slips between them, so that no stress is generated on the electronic component 1. Therefore, an accident that the electronic component 1 is damaged does not occur.

  Further, in the soldering operation, the heat insulating material 7 is stably fixed by the oil layer 8 only by being positioned on the main body surface 6 of the electronic component 1. Then, when the heat insulating material 7 is removed after the soldering process is completed, the heat insulating material 7 is gently fixed to the electronic component 1 by the oil layer 8, so that the heat insulating material 7 can be removed with a small force.

  In this way, soldering at a high temperature can be performed with a simple operation without requiring a relatively large force as a whole. For this reason, the electronic component soldering method according to the embodiment of the present invention is suitable for automation at high temperatures.

FIG. 1 is a side view showing a state in which a heat insulating material in an embodiment of the present invention is arranged on the surface of a main body of an electronic component. FIG. 2 is a flowchart showing a soldering process in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic component 2 Circuit board 3 Terminal 4 Solder 5 Infrared 6 Main body surface 7 Heat insulating material 8 Oil layer

Claims (1)

In a soldering method in which an electronic component is placed on a circuit board and a terminal provided on an outer edge of the electronic component body is heated and soldered by infrared rays applied to the circuit board from above, a soldering method is provided on the surface of the electronic component body. The terminal is exposed to provide a heat insulating material, a space is removed between the electronic component and the heat insulating material to provide an oil layer, and infrared rays are irradiated from above the heat insulating material to place the terminal on the circuit board. A method of soldering an electronic component, characterized by soldering.

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