## Description 

## BACKGROUND 

Technical Field 

[0001] The present invention relates to a rosin-modified product, a flux composition, a liquid flux, a flux cored solder, and a solder paste. 

[0002] The present application claims the priority of Japanese Patent Application No. 2019-182995 filed on October 3, 2019, the contents of which are entirely incorporated by reference. 

Related Art 

[0003] Electrodes are formed to fit terminals such as leads of electronic components on a board such as a printed circuitboard on which the electronic componentsare mounted. Fixation and electricalconnection between the electronic components and the board are performed mainly by soldering. On such a board, ion migration (hereinafter, referred to as "migration") may occur due to causes such as attachment of a water droplet between the electrodes to which direct voltage is applied at soldered parts of the terminals of the electronic components and the electrodes of the board. 

[0004] Themigration refersto a phenomenonin which metalionsdissolved from apositive electrode receive electrons at a negative electrode between the electrodes to which direct voltage is applied and reduced metal grows from the negative electrode, so that the reduced metal extends up to the positive electrode to short-circuit both electrodes. Thus, when the migration occurs, both electrodes are shortcircuited so that functions as the board are lost. 

[0005] In general, a flux used for soldering has such an efficacy that it chemically removes a metal oxide existing on a surface of a solder and a surface of the metal to be soldered at a temperature at which the solder melts and can move a metalelementthrougha boundarytherebetween,and by using theflux,itispossible toforman intermetalliccompound between the surface of the solder and the surface of the metal to be soldered so that strong bonding is obtainable. 

[0006] The flux includes components that are not decomposed or evaporated by heating of the soldering and the components remain asa flux residue around a soldered part after the soldering. Asone ofcauses of the aforementioned migration, attachment of a water droplet between the electrodes is mentioned. Since rosin included in the flux as a main component has water repellency, the migration does not directly occur because of the water repellent effect of the rosin even if a water droplet is attached on the flux residue as long as the flux residue including rosin as a main component is formed on the soldered part. 

[0007] However, if cracks occur in the flux residue, moisture permeates from the cracked part of the flux residue into the flux residue so that this moisture causes the migration to occur. 

[0008] In this regard, a measure against the migration occurring due to a water droplet or the like has hitherto been taken by configuring the structure of the board as a structure preventing a water droplet from being attached to a surface to be soldered. Alternatively, it has been also taken by performing a moisture-proofing coating on the surface to be soldered. 

[0009] On the other hand, in a technology of suppressing an occurrence of migration by the flux residue, a technology of adding phosphoric acid ester into the flux has been proposed (see JP 5445716 B2). 

## SUMMARY 

[0010] The hydrophobic film of phosphoric acid ester adsorbed to the soldered part suppresses the attachment of a water droplet or the like to the soldered part on which the flux residue is formed, and even in a case where cracks occur in the flux residue when the soldered part is exposed to inferior circumstances, it is possible to suppress the attachment of a water droplet or the like to the soldered part and to suppress the occurrence of migration due to the attachment of a water droplet or the like. 

[0011] However, even in the flux disclosed in JP 5445716 B2, in a case where the flux residue is small, when a water droplet or the like is attached to the soldered part on which the film of phosphoric acid ester is formed to be thin, it is difficult to suppress the occurrence of migration. 

[0012] The present invention has been made to solve such problems, and an object thereof is to provide a rosin- modified product and the like that do not only allow the flux residue to cover the soldered part but also suppress the occurrence of migration, in the soldered part on which the flux residue is formed. 

[Concept 1] 

[0013] A rosin-modified product may be a reactant of a rosin or a rosin derivative and an alkanolamine represented 

