Negative-working ultra thick film photoresist

negative working, aqueous base developable, photosensitive photoresist composition comprising:

• a) a polymer containing the four repeat units of structures (1), (2), (3), and (4), but no other types of repeat units
• wherein, v, x, y and z, respectively, represent the mole % of each repeat unit of structures (1), (2), (3) and (4) in the polymer, wherein, v ranges from 20 to 40 mole %, x ranges from 20 to 60 mole %, y ranges from 5 to 20 mole %, z ranges from 3 to 20 mole % wherein, R1, R2, R3, and R4, are independently selected from the group consisting of H and CH3, and R5 is a Ci to C4 alkyl moiety, wherein the summation of the mole % v, x, y and z, must add up to 100 mole %;
• b) a radical photo-initiator component, which is comprised of at least one radical photo-initiator which is activated by a broad absorption of radiation from 360 nm to 440 nm;
• c) a crosslinker component selected either from, a mixture of crosslinkers structure (5), (6) and (7), or a single crosslinker of structure (8), wherein, R6, R7, R8, R10 are independently selected from H or methyl, and R9 is selected from methyl or ethyl, wherein, the wt. ratio of total wt. of said crosslinker component c) to total wt. of said polymer a), ranges from 0.71 up to 1.2;
• wherein, the wt. ratio of total wt. of said crosslinker component c) over total wt. of said radical photo-initiator component b) is from 9 to 40
• d) a radical inhibitor component containing at least one radical inhibitor;
• e) an optional surfactant component containing at least one surfactant material;
• f) an optional dissolution promoter component;
• and
• g) a solvent;
• wherein, the composition is free of colorants, pigments, lake pigments, organic particles, inorganic particles, metal oxide particles, metal particles, composite oxide particles, metal sulfide particles, metal nitride particles, metal acid nitride particles, inorganic salt particles, organic salt particles, colloidal particles, fibers, oxiranes, oxiranes based crosslinkers, polysiloxane polymers.