The present inventors have conducted elaborated studies with {HEAD ~ the aim} of developing a polyamide acid, {TAIL ~ i.e. polyimide precursor}, having photosensitive groups in its main chain which is endowed with about 20 100 times as high a photosensitivity as that of prior products and a heat resistance of 400° C. or above after dehydration cyclization 
The present inventors have conducted elaborated studies with { HEAD ~ the aim } of developing a polyamide acid , { TAIL ~ i.e. polyimide precursor } , having photosensitive groups in its main chain which is endowed with about 20 100 times as high a photosensitivity as that of prior products and a heat resistance of 400 ° C. or above after dehydration cyclization
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