Pattern forming method, alkali-developable thermosetting resin composition, printed circuit board and manufacturing method thereof
[Problem] Provided are: a pattern forming method by which a pattern can be formed by development using a thermosetting resin composition and a cured layer having excellent curability can be obtained; a thermosetting resin composition used in the pattern forming method; and a printed circuit board. [Means for Solution] The pattern forming method according to the present invention is characterized by comprising the steps of: (A) forming a resin layer composed of an alkali-developable thermosetting resin composition comprising a photobase generator on a substrate; (B) activating the photobase generator contained in the alkali-developable thermosetting resin composition by irradiation with a light in a pattern form so as to cure an irradiated part; and (C) forming a negatively patterned layer by removing a non-irradiated part by alkali development.
1. A pattern forming method, comprising:
forming a resin layer composed of an alkali-developable thermosetting resin composition comprising a photobase generator on a substrate;
irradiating the resin layer with a light in a negative pattern such that the photobase generator contained in the resin layer is activated, and that an irradiated portion of the resin layer is cured by a base generated by the photobase generator;
heating the resin layer having the irradiated portion being cured; and
removing by alkali development a non-irradiated portion of the resin layer such that a negatively patterned layer is formed,
wherein the irradiating is performed such that, when the alkali-developable thermosetting resin composition in the irradiated portion and the alkali-developable thermosetting resin composition in the non-irradiated portion are subjected to a DSC measurement,
the alkali-developable thermosetting resin composition in the irradiated portion exhibits an exothermic peak, and the alkali-developable thermosetting resin composition in the non-irradiated portion does not exhibit an exothermic peak, or
the alkali-developable thermosetting resin composition in the irradiated portion and the alkali-developable thermosetting resin composition in the non-irradiated portion each exhibit an exothermic peak such that 1) an exothermic onset temperature of the alkali-developable thermosetting resin composition in the irradiated portion is lower than that of the alkali-developable thermosetting resin composition in the non-irradiated portion or 2) an exothermic peak temperature of the alkali-developable thermosetting resin composition in the irradiated portion is lower than that of the alkali-developable thermosetting resin composition in the non-irradiated portion.
2. The pattern forming method according to claim 1 , wherein the irradiating is performed such that
the exothermic onset temperature of the alkali-developable thermosetting resin composition in the irradiated portion is lower than that of the alkali-developable thermosetting resin composition in the non-irradiated portion or the exothermic peak temperature of the alkali-developable thermosetting resin composition in the irradiated portion is lower than that of the alkali-developable thermosetting resin composition in the non-irradiated portion.
3. The pattern forming method according to claim 1 , further comprising:
irradiating the resin layer with ultraviolet light after the removing of the non-irradiated portion.
4. The pattern forming method according to claim 1 , further comprising:
performing heat-curing after the removing of the non-irradiated portion.
5. The pattern forming method according to claim 1 , further comprising:
performing laser processing.
6. The pattern forming method according to claim 1 , further comprising:
performing desmearing.
7. A printed circuit board, comprising:
a patterned layer formed by the pattern forming method according to claim 1 .
8. The pattern forming method according to claim 1 , wherein the irradiating is performed such that the alkali-developable thermosetting resin composition in the irradiated portion and the alkali-developable thermosetting resin composition in the non-irradiated portion have a difference of not less than 10° C. in the exothermic onset temperature or the exothermic peak temperature.
9. The pattern forming method according to claim 1 , wherein the irradiating is performed such that the alkali-developable thermosetting resin composition in the irradiated portion and the alkali-developable thermosetting resin composition in the non-irradiated portion have a difference of not less than 20° C. in the exothermic onset temperature or the exothermic peak temperature.
10. The pattern forming method according to claim 1 , wherein the irradiating is performed such that the alkali-developable thermosetting resin composition in the irradiated portion and the alkali-developable thermosetting resin composition in the non-irradiated potion have a difference of not less than 30° C. in the exothermic onset temperature or the exothermic peak temperature.
11. The pattern forming method according to claim 1 , wherein the irradiating comprises applying a laser light or a scattering light which has a maximum wavelength in a range of 350 to 410 nm.
12. The pattern forming method according to claim 11 , wherein the irradiating is performed such that an exposure dose is 300 to 1,500 mJ/cm 2 .
13. The pattern forming method according to claim 12 , further comprising:
irradiating the resin layer with ultraviolet light after the removing of the non-irradiated portion.
14. The pattern forming method according to claim 13 , wherein the irradiating of the resin layer with ultraviolet light is performed such that an exposure dose is 150 to 2,000 mJ/cm 2 .
15. The pattern forming method according to claim 13 , wherein the irradiating of the resin layer with ultraviolet light is performed such that an exposure dose is 500 to 1,000 mJ/cm 2 .
16. A printed circuit board, comprising:
a patterned layer formed by irradiating, with a light in a negative pattern, a resin layer composed of an alkali-developable thermosetting resin composition comprising a photobase generator, heating the resin layer and then developing the resin layer; and
an opening formed on the patterned layer by laser processing,
wherein the irradiating is performed such that, when the alkali-developable thermosetting resin composition in the irradiated portion and the alkali-developable thermosetting resin composition in the non-irradiated portion are subjected to a DSC measurement,
the alkali-developable thermosetting resin composition in the irradiated portion exhibits an exothermic peak, and the alkali-developable thermosetting resin composition in the non-irradiated portion does not exhibit an exothermic peak, or
the alkali-developable thermosetting resin composition in the irradiated portion and the alkali-developable thermosetting resin composition in the non-irradiated portion each exhibit an exothermic peak such that 1) an exothermic onset temperature of the alkali-developable thermosetting resin composition in the irradiated portion is lower than that of the alkali-developable thermosetting resin composition in the non-irradiated portion or 2) an exothermic peak temperature of the alkali-developable thermosetting resin composition in the irradiated portion is lower than that of the alkali-developable thermosetting resin composition in the non-irradiated portion.
17. The printed circuit board according to claim 16 , wherein the patterned layer is prepared by forming a resin layer by coating and drying the alkali-developable thermosetting resin composition; activating the photobase generator contained in the resin layer by irradiation with a light in a pattern form; and then removing an non-irradiated portion by development such that a negative pattern is formed.