Wave Height Stability in Wave Soldering
The wave in a wave soldering machine is a standing shape that the pump produces, and its height has to be stable for the joint to be repeatable. The height is affected by the pump, by the alloy level in the pot and by the dross that forms around the nozzle.
What Sets the Wave Height
The pump drives alloy through the nozzle, and the height that results depends on the pump speed, the nozzle geometry and the resistance of the flow path. As the nozzle wears and the alloy level falls, the same pump setting produces a different height.
The height is measured rather than read from the setting, because the setting describes the pump and the height describes the process. Our joint criteria notes describe the result the height is supporting.
Dross and the Flow Path
Dross forms on the surface of the pot and around the nozzle, and it restricts the flow. A nozzle that is partly blocked produces a wave that is lower on one side than the other, which shows up as joints that differ across the board.
Cleaning the nozzle is a routine operation with a defined interval, and the wave height is checked after the cleaning rather than before. Our board quality notes describe how the resulting joints are judged.
The alloy level in the pot changes the head that the pump works against, so a falling level changes the wave height. An automatic top up keeps the level inside a band, and the band is part of the process rather than a convenience.
Where the level is topped up by hand, the interval is defined and the height is checked after each addition. A pot that is allowed to fall and then refilled produces a cycle in the joint quality.
The contact depth is the amount of the board that is in the wave, and it is set by the height. A wave that is higher than intended increases the contact and can push alloy onto the top side of the board.
The height and the conveyor speed therefore set the contact time together, and a change in one is compensated by the other rather than corrected. Our profile verification notes describe how the contact time is measured.
A nozzle wears at the edges and the wear changes the shape of the wave rather than only its height. The sign is a wave that looks correct at the centre and different at the edge.
The nozzle is replaced on a schedule and on the evidence of the wave shape. Measuring the height at the centre and at both edges is enough to detect the change.
The measures that stabilise the wave are a defined nozzle cleaning interval, automatic or documented alloy top up, a pump setpoint recorded against a measured height, and a height measurement at more than one point.
Those four turn a process that drifts into one that is checked. A wave height that is only measured when a defect appears is being measured too late.
Process Control and Verification
On a design of this kind, pump is the item that decides how the rest of the board is arranged. A short note on the drawing about handling, storage or packaging is often worth more than an extra decimal place on a tolerance. Where a value sits close to a process limit, the drawing should say so, since the shop can then open the process window rather than working to a nominal figure that carries no tolerance.
A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used. Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design.
The measurements that matter are the repeatable ones: conductor width and spacing, annular ring, finished hole size, plating thickness and surface finish are all verifiable on a coupon that travels with the panel. Running a first article through the same checks as the production panel confirms that the two agree, and that comparison is the cheapest form of process control available at prototype stage.
Keeping a sample from the panel turns a dispute into a measurement, because the same coupon can be re-examined by both parties without rebuilding the batch. Reviewing the design before the data is released is cheaper than correcting it after the panel is in the tank, because every step downstream inherits the decision made at the front end.
Process Control and Verification
On a design of this kind, pump is the item that decides how the rest of the board is arranged. A short note on the drawing about handling, storage or packaging is often worth more than an extra decimal place on a tolerance. Where a value sits close to a process limit, the drawing should say so, since the shop can then open the process window rather than working to a nominal figure that carries no tolerance.
A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used. Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design.
The measurements that matter are the repeatable ones: conductor width and spacing, annular ring, finished hole size, plating thickness and surface finish are all verifiable on a coupon that travels with the panel.
Process Control and Verification
On a design of this kind, pump is the item that decides how the rest of the board is arranged. A short note on the drawing about handling, storage or packaging is often worth more than an extra decimal place on a tolerance. Where a value sits close to a process limit, the drawing should say so, since the shop can then open the process window rather than working to a nominal figure that carries no tolerance.
A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used.
Process Control and Verification
On a design of this kind, pump is the item that decides how the rest of the board is arranged. A short note on the drawing about handling, storage or packaging is often worth more than an extra decimal place on a tolerance. Where a value sits close to a process limit, the drawing should say so, since the shop can then open the process window rather than working to a nominal figure that carries no tolerance.
Does a higher wave give a better joint? It gives more contact and more alloy on the top side, so the height is set from the joint rather than from the maximum.
Can the height be adjusted with the pump alone? The pump sets it, and the alloy level and the nozzle condition change what the same setting produces.
What does gopcb provide for wave stability? We provide a measured wave height against a recorded pump setting, a defined cleaning interval with the height checked after it, alloy level controlled inside a band, height measured at more than one point, and contact time verified with the profile.
