Production method of connection structure
In order to lower the substantial heating temperature of a thermosetting adhesive and to realize favorable connection reliability during connecting an electrical element to a circuit board by anisotropic conductive connection with using solder particles, a product in which solder particles having a melting temperature Ts are dispersed in an insulating acrylic-based thermosetting resin having a minimum melt viscosity temperature Tv is used as an anisotropic conductive adhesive in producing a connection structure by connecting the circuit board and the electrical element to each other by anisotropic conductive connection.
1. A method for producing a connection structure in which an electrode of a circuit board and an electrode of an electrical element are connected to each other by anisotropic conductive connection, the method comprising a heating and pressurizing step of connecting the electrode of the circuit board and the electrode of the electrical element by placing the electrical element on the circuit board via an anisotropic conductive adhesive, and heating and pressurizing the placed electrical element, wherein
a product formed by dispersing solder particles having a melting temperature Ts in an insulating acrylic-based thermosetting resin is used as the anisotropic conductive adhesive, and a temperature at which the anisotropic conductive adhesive shows a minimum melt viscosity is Tv,
the following formulas (1) and (2) are satisfied
Tv<T1<Ts<T2 (1)
P1>P2 (2)
when:
the heating and pressurizing step includes a first heating and pressurizing step and a subsequent second heating and pressurizing step;
a heating temperature in the first heating and pressurizing step is defined as T 1 , and an applied pressure in the step is defined as P 1 ; and
a heating temperature in the second heating and pressurizing step is defined as T 2 , and an applied pressure in the step is defined as P 2 ,
in the first heating and pressurizing step, the anisotropic conductive adhesive is melted and caused to flow to be pressed out from a gap between the circuit board and the electrical element, and further to be precured, and
in the second heating and pressurizing step, the solder particles are melted to form a metallic bond between the electrode of the circuit board and the electrode of the electrical element and to substantially cure the anisotropic conductive adhesive.
2. The production method according to claim 1 , wherein the temperature Tv at which the anisotropic conductive adhesive shows a minimum melt viscosity is 70 to 150° C., the heating temperature T 1 in the first heating and pressurizing step is 80 to 160° C., the melting temperature Ts of the solder particles is 100 to 210° C., and the heating temperature T 2 in the second heating and pressurizing step is 130 to 220° C.
3. The production method according to claim 2 , wherein a difference between T 1 and Tv is 10 to 40° C., a difference between Ts and T 1 is 2 to 110° C., and a difference between T 2 and Ts is 2 to 100° C.
4. The production method according to claim 2 , wherein the solder particles are eutectic SnBi solder particles or eutectic SnIn solder particles.
5. The production method according to claim 3 , wherein the solder particles are eutectic SnBi solder particles or eutectic SnIn solder particles.
6. The production method according to claim 1 , wherein a difference between T 1 and Tv is 10 to 40° C., a difference between Ts and T 1 is 2 to 110° C., and a difference between T 2 and Ts is 2 to 100° C.
7. The production method according to claim 3 , wherein the solder particles are eutectic SnBi solder particles or eutectic SnIn solder particles.
8. The production method according to claim 1 , wherein the solder particles are eutectic SnBi solder particles or eutectic SnIn solder particles.