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LASER SOLDERING TECHNOLOGY OF SMD ELECTRONIC ASSEMBLY FOR INTEGRATION ON PICK AND PLACEMENT MACHINES.

Objective

-to develop a fully integrated surface mounting technology which is highly reliable and therefore cost effective. This is to be done by integration of the pick and placement and the laser soldering action in one process step (fault rates less than 100 ppm)
-to identify and optimize the parameters for the process of interconnecting surface mounted electronic component packages and printed circuit boards by means of a controlled laser soldering process at soldering rates which are compatible with pick and placement machines (placement rate of 6000 components per hour)
-to obtain a basic understanding of the physics and chemistry underlying the laser soldering process and to derive from the basic principles the limiting factors of laser soldering.
The achievements of this research so far are:
laser types and modes have been evaluated;
commercial laser soldering pastes have been analysed;
process conditions for laser soldering with commercial solder pastes have been established;
different options for beam handling have been evaluated.

Research was carried out in order to develop a fully integrated surface mounting technology which is highly reliable and therefore cost effective. This involved integration of the pick and placement and the laser soldering action in one process step. The process of interconnecting surface mounted electronic component packages and printed circuit boards were identified and optimized by means of a controlled laser soldering process at soldering rates which are compatible with pick and placement machines (placement rates of 6000 components h{-1}).
Due to the wavelength dependent advantages of the neodymium yttrium aluminium garret (Nd:YAG) laser investigations concentrated on experiments with this type of laser.

Fast laser soldering has been achieved. On electroplated solder using 2 25 W beams soldering times of 500 ms have been achieved for a VQFP 80 with lead pitch of 0.5 mm. For a single capacitor similar times are necessary.
Soldering with solder paste yields comparable soldering times as soldering on solid solder for the passive components. For integrated circuits the time is a factor 5 to 10 longer.
Solder surface can be modified with a laser in the Q switch mode. Low residue fluxes are sufficient on these surfaces.
Also, it was found that the fatigue life of laser soldered joints is similar to reflow soldered joints.

Coordinator

Nederlandse Philips Bedrijven BV
Address

5600 MD Eindhoven
Netherlands

Participants (3)

Bhp Laboratories Ltd
Ireland
Address
New Road, Thomondgate
61 Limerick
Bleiwerk Goslar GmbH & Co KG Besserer & Ernst
Germany
Address
Im Schleeke 8
3380 Goslar
Siemens AG
Germany
Address
Paul-gossen-straße 100
91052 Erlangen