Multiple Resistor Rework

We appreciate your desire to find the most time effective method of reworking these boards.

However, we believe that your most efficient method will be to have one assembler remove all of the parts, and a second assembler place/hand solder the parts.

We've done rework of this nature before, and haven't been able to find any better/more accurate method of performing the rework. We've tried removing all the components, applying sticky flux to the board and using a machine to place the new parts...then reflow. In the end, the set-up, programming, removal, placement, reflow, inspection, and touch-up operations have generally taken as much time as removal and hand soldering.

One way to potentially speed this up is to use resistive tweezers for the soldering, rather than two irons. But, I suspect that that will depend on individual solderer techniques and preferences.

cheers ..rob

reply »

Hi Stephen,

Once they've been soldered down, you're stuck with doing touch labor on each and every one. But you might be suprised how quickly this can be done with the right tools. Are they all the same value resistor? If so, that should make things go even quicker. I would recommend a set of "Hot-tweezers" for the job. Do have access to a pair of these?

reply »

Lots of small parts, lots of hand soldering, lots of tired eyes inspecting on lots of boards: yields lots of room for error.

How about this: * Part removal ** Cut each resistor between the pads using dykes ** Using a soldering iron [or hot air pen], melt the solder at each connection and flick the half component from the board with the iron [or tweezers] [Remember this is really tedious, shit-work. So maybe assemble a multi-person flow line to crush this part of the project and get it over with. Get a team of 5 qualified people, tell them what needs to be done, let them work the details, and get them what they need, and stay-out of their way.] * Dress the pads where the components were removed * New part attach ** Using an automated dispenser, add solder to each pad where a component has been removed ** Place components using a modified version of the original placement program ** Reflow using the original thermal recipe * Inspect and test according to the original plan

reply »