Display substrate, display panel and spliced screen

A display substrate divided into a display region and a bonding region, the display substrate comprising:

• a base substrate;
• and
• a pixel driving circuit on the base substrate and corresponding to the display region,
• wherein the display substrate further comprises an interlayer insulating layer and a signal lead-in wire on the base substrate,
• the signal lead-in wire at least comprises a first signal lead-in sub-wire on a side of the interlayer insulating layer away from the base substrate, the first signal lead-in sub-wire being connected to a first connection pad in the bonding region and configured to introduce an external signal to the pixel driving circuit, and
• the interlayer insulating layer comprises a plurality of sub-insulating layers defining a multi-stepped structure at a position where the display region is adjacent to the bonding region, such that the interlayer insulating layer has a multi-stepped outer profile at an interface between the bonding region and the display region, and the first signal lead-in sub-wire is formed conformally along the multi-stepped outer profile,
• wherein the interlayer insulating layer comprises four sub-insulating layers sequentially on a side of the data line away from the base substrate, the four sub-insulating layers being a first sub-insulating layer, a second sub-insulating layer, a third sub-insulating layer and a fourth sub-insulating layer, and
• the first and third sub-insulating layers are only in the display region, an orthographic projection of an edge of the third sub-insulating layer adjacent to the bonding region on the base substrate is defined within an orthographic projection of the first sub-insulating layer on the base substrate, and the edge of the third sub-insulating layer adjacent to the bonding region is away from an edge of the first sub-insulating layer adjacent to the bonding region by a distance.