Composition for pressure bonding, and bonded structure of conductive bodies and production method therefor
A composition for pressure bonding contains a metal powder and a solid reducing agent and has a compressibility of 10% to 90%, the compressibility being expressed by a relationship formula using the thickness A of a dried coating film formed by drying the composition in an air atmosphere at 110° C. under atmospheric pressure for 20 minutes and the thickness B of a sintered body formed by treating the dried coating film in a nitrogen atmosphere at 280° C. under a pressure of 6 MPa for 20 minutes. The solid reducing agent may be BIS-TRIS. Also provided is a bonded structure of conductors in which a bonding portion via which two conductors are bonded together is formed by treating, under pressure, the two conductors and a coating film formed of the composition for pressure bonding provided therebetween.
1. A composition for pressure bonding, comprising:
a copper powder;
a solid reducing agent; and
a liquid medium having a boiling point of less than 300° C. at 1 atm,
wherein the solid reducing agent has a chemical structure having at least one amino group and a plurality of hydroxyl groups,
a content ratio of the solid reducing agent is 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the copper powder,
the composition has a viscosity of 20 Pa·s to 200 Pa·s at a shear rate of 10 s −1 and 25° C., and
the composition has a compressibility of 10% to 90%, the compressibility being expressed by:
Compressibility (%)=(( A−B )/ A )×100,
wherein A represents a thickness of a dried coating film formed by drying the composition in an air atmosphere at 110° C. under atmospheric pressure for 20 minutes, and
B represents a thickness of a sintered body formed by treating the dried coating film in a nitrogen atmosphere at 280° C. under a pressure of 6 MPa for 20 minutes.
2. The composition for pressure bonding according to claim 1 , wherein the copper powder contains flat particles.
3. The composition for pressure bonding according to claim 2 , wherein
the flat particles have an aspect ratio a/b of 2 to 80, and
the aspect ratio a/b is defined by a ratio of a length of a major axis a of one of the flat particles to a length of a minor axis b of the one of the flat particles.
4. The composition for pressure bonding according to claim 1 , wherein the copper powder contains dendritic particles.
5. The composition for pressure bonding according to claim 1 , wherein the solid reducing agent is an amino alcohol compound.
6. The composition for pressure bonding according to claim 1 , wherein the liquid medium contains polyethylene glycol.
7. The composition for pressure bonding according to claim 1 , wherein
the solid reducing agent is an amino alcohol compound represented by one of formulas (1) and (2) below,
wherein each of R 1 to R 6 independently represents one of:
a hydrogen atom;
a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms; and
a hydrocarbon group having 1 to 10 carbon atoms and having a hydroxyl group,
R 7 represents one of:
a hydrocarbon group having 1 to 10 carbon atoms; and
a hydrocarbon group having 1 to 10 carbon atoms and having a hydroxyl group,
in the formula (1), four or more of R 1 to R 5 contain a hydroxyl group, and
in the formula (2), four or more of R 1 to R 6 contain a hydroxyl group.