Method for producing a reliable solder joint interconnection
AssigneeInternational Business Machines Corporation
InventorsDavid V. Caletka, Kevin Knadle, Charles G. Woychik
Life of this patent
Estimating the term…
Abstract
A method and an arrangement for measuring the cooling rate and temperature differential between the top and bottom surfaces of a printed circuit board. The method is intended to facilitate control over the temperature differential which is encountered between the top and bottom of the printed circuit board so as to prevent warpage thereof during the formation of solder joints in a reflow solder oven.
Claims20
A method for measuring the cooling rate and temperature differential between a top surface and a bottom surface of a printed circuit board, said method comprising the steps of:
- providing said printed circuit board having a plurality of through-holes therein and including a module on said top surface thereon, said module having a plurality of lead free solder joints, at least one of said plurality of lead free solder joints being located relative to at least one of said plurality of through-holes;
- extending a thermocouple wire through said at least one through-hole;
- positioning a first thermocouple within said at least one through-hole, within or proximate said at least one of said plurality of lead free solder joints and connecting said thermocouple wire to said first thermocouple;
- positioning a second thermocouple on said bottom surface proximate said at least one through-hole and connecting said second thermocouple to said thermocouple wire to form a thermocouple pair with said first thermocouple;
- reflowing said plurality of lead free solder joints;
- cooling said at least one lead free solder joint through a solidification temperature range;
- and
- measuring said temperature differential between said top and said bottom surfaces with said first and second thermocouples substantially through said solidification temperature range.
An arrangement for measuring the cooling rate and temperature differential between a top surface and a bottom surface of a printed circuit board comprising:
- a module on said top surface of said printed circuit board, said printed circuit board including a plurality of through-holes therein, said module having a plurality of lead free solder joints, at least one of said lead free solder joints being located relative to at least one of said plurality of said through-holes;
- a thermocouple wire positioned in said at least one through-hole;
- a first thermocouple positioned within said at least one through-hole, within or proximate said at least one of said plurality of lead free solder joints and connected to said thermocouple wire;
- a second thermocouple positioned on said bottom surface proximate said through-hole and connected to said thermocouple wire to form a thermocouple pair with said first thermocouple;
- a heater adapted for reflowing said plurality of lead free solder joints;
- a cooler adapted for cooling said at least one lead free solder joint through a solidification temperature range;
- and
- a device adapted for measuring said temperature differential between said top and said bottom surfaces with said first and second thermocouples substantially through said solidification temperature range.
Dependencies are inferred from the claim text.