US 6,465,757 B1Granted

Laser joining method and a device for joining different workpieces made of plastic or joining plastic to other materials

AssigneeLeister Process Technologies

InventorJie-Wei Chen

Life of this patent

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Abstract

A method and a device for laser joining of plastics or for joining plastics to other materials, which are brought into contact with pressure, with the workpiece closest to the laser beam source being largely transparent for the laser beam, and the second workpiece being as absorbent as possible. By producing a laser beam shaped in the form of a line on the contact surface between the workpieces and by a relative movement of the laser beam relative to the workpieces, designed according to the desired joint seam structure, the workpieces are bonded together accurately only in the desired joining areas. This permits a highly accurate bonding with the smallest possible joint seam distances, so that even parts for micro-systems engineering can also be produced with a short cycle time.

Claims16

Dependent claims

A laser joining method of joining different workpieces made of plastic, or joining plastic to other materials, which comprises:

making a top workpiece of a material that is transparent to the laser beam facing a laser source with a laser beam;
making a second workpiece of a material that is absorbent for the laser beam, so that adjacent contact surfaces of the two workpieces begin to melt and are bonded together in subsequent cooling under pressure;
including the step of arranging a mask of a material that is impermeable for the laser beam adjacent the workpieces between the laser source and the workpieces to be joined for bonding the workpieces in a joining area of the contact surfaces;
wherein the structure of said mask is larger than the wavelength of the laser beam used, and the laser source is directed at the contact surfaces to provide an essentially vertical laser beam curtain at essentially a right angle through the mask in such a way that a laser line joining area is formed on said contact surfaces, heating and joining the workpieces by moving the laser beam and the workpieces relative to each other to move the laser line and to provide an extended joining area, wherein the laser beam is arranged at a right angle above the joining area of the contact surfaces, and wherein a linear laser beam is created by at least one semiconductor laser.

1 more element

A device for joining various planar workpieces with at least one workpiece with a microstructure made of plastic or joining plastics to other materials, including a planar top workpiece and a planar second workpiece, which comprises:

a laser beam from a laser source;
said laser beam is a laser beam with a fine elongated cross section being focused as a fine laser line on the joining area between said workpieces;
a micro-structured mask made of a material that is impermeable to lasers adjacent the workpieces and between workpieces to be joined and the laser source;
where the microstructure of the mask is larger than the wavelength of the laser beam used;
said top workpiece facing the laser source made of a material that is transparent for the laser beam;
and said second workpiece made of a material that is absorbent for the laser beam, so that adjacent contact surfaces of the two workpieces melt and are bonded together in subsequent cooling under pressure;
means for clamping the workpieces to be joined together with the mask comprising a top pressure plate and a lower bottom plate, where at least the top pressure plate is transparent for said laser beam;
means for a movement of the laser beam and the workpieces relative to one another to heat and join the workpieces by moving the focus line and to provide an extended joining area, wherein the laser beam is arranged at a right angle above the joining area of the contact surfaces, and wherein said laser beam is generated by at least one semiconductor laser.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/488,819Filed 20 Jan 2000
Priority: EP 9910181628 Jan 1999
Granted: 15 Oct 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification34 codes

B29C 66/836
Characterised by the movement of the joining or pressing tools: moving relative to and tangentially to the parts to be joined, e.g. transversely…
B23K 26/066
By means of optical elements, e.g. lenses, mirrors or prisms: by using masks
B29C 65/1635
Characterised by the way of heating the interface: at least passing through one of the parts to be joined, i.e. laser transmission welding
B29C 65/1654
Characterised by the way of heating the interface: scanning at least one of the parts to be joined