EP 3 800 003 A1 (continued) Comparative  Example 1 Comparative  Example 2 Comparative  Example 3 Comparative  Example 4 Total 100 100 100 100 Insulation resistance 5.00E+08 3.00E+08 3.00E+13 2.00E+13 Amount of current during  water-drop test 351 351 351 351 Migration 3 3 3 3 <Current value measurement and water-drop test> [0052] 50  m l of each flux was applied to a board being a comb type electrode board type 2 (FR-4) and then dried at 100°C for 10 minutes. Thereafter, 10  m l of ion-exchange water was added dropwise on the flux. A voltage (applied voltage: DC 5 V) was applied to the board for 3 minutes and the current value was measured using 289Si manufactured by Fluke Corporation under conditions of 25°C and humidity 50%. Furthermore, a voltage (applied voltage: DC 5 V) was applied to the board for 10 minutes, and then, whether or not migration occurs was observed with a microscope. (Water-drop determination criteria) [0053] s : The migration does not occur from the negative electrode. Δ : The migration occurs from the negative electrode, but does not reach the positive electrode. 3 : The migration occurs from the negative electrode and reaches the positive electrode. <Insulation resistance value measurement> [0054] 50  m l of each flux was applied to a board being a comb type electrode board type 2 (FR-4) and dried at 100°C for 10 minutes, and then the insulation resistance value was measured under conditions of 25°C and humidity 50%. As an apparatus, 4329A manufactured by HP Development Company, L.P. was used. [0055] From the above-described experimental result, it could be confirmed that, in a case where the current value during the water-drop test is low, migration can be suppressed. It could be confirmed that, particularly in the liquid flux in which the amount of current during the water-drop test is 10  m A or less, migration does not occur. [0056] In general, it has been considered that, in a case wherethe insulation resistance valueis low,migration is likely to occur,butfromthe above-described experimentalresult,itcould be confirmedthat,even when the insulation resistance value is low, migration is difficult to occur in some cases. On the other hand, it could be confirmed that, in the flux composition in which the amount of current during the water-drop test is 100  m A or less, migration is less likely to occur. It could be confirmed that, particularly in the flux composition in which the amount of current during the water-drop test is 10  m A or less, migration does not occur. [0057] It could be confirmed that, in a case where an organic acid is further added to the rosin-modified product produced from rosin or a rosin derivative, an organic acid, and alkanolamine (see Examples 4 to 14), the current value in the water-drop test can be lowered, and the occurrence of migration can be more reliably suppressed. From the viewpoint of the effect of lowering the current value in the water-drop test, it could be confirmed that sebacic acid is used as an organic acid to be added, which is particularly advantageous. [0058] It could be confirmed that, in a case where phosphonic acid ester is further added to the rosin-modified product produced from rosin or a rosin derivative, an organic acid, and alkanolamine (see Examples 10 to 14), the current value in the water-drop test can be lowered to 10  m A or less, and the occurrence of migration can be further more reliably suppressed. It could also be confirmed that the amount of the phosphonic acid ester added exceeds 0.5% by weight and is 1.0% by weight or more based on the whole flux, which is advantageous (see Example 17) . [0059] It could be confirmed that, in a case where the content of the rosin-modified product produced from rosin or a rosin derivative, an organic acid, and alkanolamine is increased to 35% by weight or more based on the whole flux (see Examples 2, 3, and 16), the current value in the water-drop test can be lowered, and the occurrence of migration can be more reliably suppressed. On the other hand, it could be confirmed that, even when the content of the rosin-modified product is small and 15% by weight or less based on the whole flux and the insulation resistance value is in a range of 7 3 10$^{8}$ to 2 3 10$^{12}$, migration does not occur in the flux composition in a case where the amount of current during the 11