Flexible substrate module and fabrication method
A digital radiographic image sensor includes a flexible first substrate with an image sensor array. A scintillator is formed over the array, and bonding pads in a peripheral region outside the array are connected to the array. A second substrate is attached to a bottom of the first substrate and includes a scribed or perforated break line to enable removal of a peripheral region of the second substrate.
1. A digital radiographic image sensor comprising:
a flexible first substrate;
an image sensor array formed on a first side of the first substrate;
a bonding pad formed in a peripheral region outside the array on the first side of the first substrate; and
a second substrate having a top surface attached to a second side of the first substrate opposite the first side, the second substrate comprising:
a scribed or perforated break line to enable removal of a peripheral region of the second substrate along the break line; and
the top surface having a first adhesive in a first portion thereof, wherein the adhesive contacts the second side of the first substrate directly opposite the image sensor array, and a second adhesive in a second portion thereof, wherein the second adhesive contacts the second side of the first substrate outside of the region directly opposite the image sensor array.
2. The image sensor panel of claim 1 , wherein the break line is scribed or perforated into a bottom surface of the second substrate opposite the top surface, the break line closer to an unbroken edge of the second substrate than to a center of the second substrate.
3. The image sensor panel of claim 2 , further comprising an ESD protection circuit in the peripheral region outside the array and outside the bonding pad on the first side of the first substrate, the ESD protection circuit configured to be cut off along a linear cut line between the bonding pad and the ESD protection circuit, the cut line closer to an uncut edge of the first substrate than the break line is to the unbroken edge of the second substrate.
4. The image sensor panel of claim 2 , wherein the first substrate and the bonding pad formed thereon extend beyond a broken edge of the second substrate.
5. The image sensor panel of claim 4 , wherein the broken edge of the second substrate is formed by the removal of the peripheral region of the second substrate along the break line.
6. The image sensor panel of claim 2 , further comprising an ESD protection circuit in the peripheral region outside the array and outside the bonding pad on the first side of the first substrate, the ESD protection circuit configured to be cut off along a cut line between the bonding pad and the ESD protection circuit, the cut line configured to be vertically aligned with the break line in the second substrate.
7. The image sensor panel of claim 6 , wherein a broken edge of the second substrate is formed by the removal of the peripheral region of the second substrate along the break line, and wherein the broken edge is aligned with a cut off edge of the first substrate, the cut off edge formed by cutting off the ESD protection circuit along the cut line.
8. The image sensor panel of claim 1 , wherein the first adhesive comprises a temperature tolerance greater than the second adhesive and greater adhesion than the second adhesive.
9. The image sensor panel of claim 1 , wherein a coefficient of thermal expansion of the second substrate is equivalent to that of the first substrate.
10. The image sensor panel of claim 1 , wherein a coefficient of thermal expansion of the second substrate is within 5× that of the first substrate.
11. The image sensor panel of claim 1 , wherein the second substrate further comprises regions of reduced aggregate thickness configured to allow a light source positioned beneath the second substrate to illuminate contact regions on the array.
12. The image sensor panel of claim 11 , wherein the contact regions comprise bonding pads or probe tester contact areas.
13. The image sensor panel of claim 1 , wherein the second substrate further comprises regions of increased temperature and pressure tolerance proximate peripheral regions of the second substrate.
14. The image sensor panel of claim 1 , wherein the second substrate comprises x-ray attenuation material, an x-ray attenuation layer, a conductive layer, a planarization layer, or a combination thereof.