Abstract: A process for producing and/or checking an assembly of a substrate stack includes: planarly arranging at least one first substrate against a second substrate to form the substrate stack, the at least one first substrate and the second substrate being arranged directly against one another or on one another, so that at least one contact area is formed between the least one first substrate and the second substrate at which the at least one first substrate is in direct planar contact with the second substrate, the at least one first substrate including a transparent material; detecting a radiative reflection which comes about through irradiation of the substrate stack with a radiative input on the at least one contact area; and ascertaining a first bond quality index (Q1) of the contact area from the radiative reflection.

Abstract: An article is produced by welding a first piece to a second piece by a laser beam. The first piece includes an open cavity and a first sealing surface. The second piece has a second sealing surface. The first piece and second piece are inside chamber with a controllable internal pressure that is changed to cause a flow of a gas from the open cavity. The open cavity is closed by moving at least one of the pieces. The first sealing surface forms a partially gas tight preliminary joint with the second sealing surface. The first piece and the second piece define an interface. The chamber is opened after the preliminary joint has been formed. A welded seam is formed by focusing a laser beam to the interface after the chamber is opened. The first sealing surface and the second sealing surface are substantially planar.

Abstract: A substrate stack includes: at least two substrates including a base substrate and a cover substrate; at least one first laser weld line for welding the base substrate and the cover substrate; and at least one second beam spot or at least one second laser weld line at least one of situated next to the at least one first laser weld line or positioned such that a stress reduction in the at least one first laser weld line is achieved by the at least one second beam spot or second laser weld line, thus improving the mechanical stability of the substrate stack.