Light-sensitive sheet comprising support, first light-sensitive layer and second light-sensitive layer

1. A light-sensitive sheet comprising a support, a first light-sensitive layer and a second light-sensitive layer in order, wherein each of the first and second light-sensitive layers independently contains a binder, a polymerizable compound and a photo-polymerization initiator, wherein light-sensitivity of the second light-sensitive layer is higher than light-sensitivity of the first light-sensitive layer, and wherein the light-sensitive sheet has a shape of a long film wound up into a roll.

2. The light-sensitive sheet as defined in claim 1 , wherein light energy required for completing hardening reaction of the first light-sensitive layer and light energy required for completing hardening reaction of the second light-sensitive layer satisfy the condition of:

0.005 >A/B >0.5

in which A is the light energy required for completing hardening reaction of the second light-sensitive layer, and B is the light energy required for completing hardening reaction of the first light-sensitive layer.

3. The light-sensitive sheet as defined in claim 1 , wherein light energy required for completing hardening reaction of the second light-sensitive layer and light energy required for initiating hardening reaction of the first light-sensitive layer satisfy the condition of:

1> C/A> 10

in which A is the light energy required for completing hardening reaction of the second light-sensitive layer, and C is the light energy required for initiating hardening reaction of the first light-sensitive layer.

4. The light-sensitive sheet as defined in claim 1 , wherein each of the first and second light-sensitive layers independently further contains a sensitizer, and an amount of the sensitizer contained in the second light-sensitive layer is larger than an amount of the sensitizer contained in the first light-sensitive layer.

5. The light-sensitive sheet as defined in claim 1 , wherein an amount of the photo-polymerization initiator contained in the second light-sensitive layer is larger than an amount of the photo-polymerization initiator contained in the first light-sensitive layer.

6. The light-sensitive sheet as defined in claim 1 , wherein an amount of the polymerizable compound contained in the second light-sensitive layer is larger than an amount of the polymerizable compound contained in the first light-sensitive layer.

7. The light-sensitive sheet as defined in claim 1 , wherein the first light-sensitive layer has a thickness in the range of 1 to 100 um, the second light-sensitive layer has a thickness in the range of 0.1 to 15 um, and the thickness of the first light-sensitive layer is larger than the thickness of the second light-sensitive layer.

8. The light-sensitive sheet as defined in claim 1 , wherein the first light-sensitive layer has absorption of light in the range of 0.1 to 1.0 at wavelength of 405 nm.

9. The light-sensitive sheet as defined in claim 1 , wherein the first light-sensitive layer or the second light-sensitive layer contains a compound having the absorption maximum within wavelength region of 380 to 430 nm.

10. The light-sensitive sheet as defined in claim 9 , wherein the compound having the absorption maximum within wavelength region of 380 to 430 nm is a sensitizer.

11. The light-sensitive sheet as defined in claim 1 , wherein the support comprises a transparent polymer film.

12. The light-sensitive sheet as defined in claim 1 , wherein the light-sensitive sheet comprises the support, the first light-sensitive layer, the second light-sensitive layer and a protective film in order, and wherein adhesion force between the support and the first light-sensitive layer and adhesion force between the protective film and the second light-sensitive layer satisfy the condition of:

Su>Pr

in which Su is the adhesion force between the support and the first light-sensitive layer, and Pr is the adhesion force between the protective film and the second light-sensitive layer.

13. The light-sensitive sheet as defined in claim 1 , wherein the light-sensitive sheet is used for preparation of a printed circuit board.