Issue link: https://iconnect007.uberflip.com/i/661282
46 SMT Magazine • April 2016 out, the replacement of a fine pitch 0.5 mm pitch QFP100 will be used as a test case. A skilled operator should be able to remove and replace this device per IPC 7711 guidelines within 20 minutes [4] . If this operator yields 95% in the re- work operation when working on a PCB with a costed BOM value of $250.00 assuming a 150-piece board rework job is at hand, the cost model calculates a $21.30 cost per component rework cost. The summary calculation is below: As this example illustrates, the major cost drivers in this cost model include the skill lev- el of the rework technician in terms of their throughput and yield (i.e., both fast and accu- rate), the complexity of the assembly as well as the cost of the rework technician's time. assuring a High level of Quality When Outsourcing rework Outside of the cost question in this make or buy decision other factors should be taken in to consideration when considering whether or not to outsource this kind of work. The qual- ity systems of the provider, the training of the contractor's staff as well as a deep-rooted un- derstanding of processes and applicable solder- ing standards should apply. For example, the contractor should understand the practices of the most recent applicable industry assembly (IPC J-STD-001), rework (IPC-7711), repair (IPC- 7721), parts MSD handling (JEDEC-033) and in- spection criteria (IPC-A-610) standards. Each of the rework technicians should, for the standard repair and rework operations such as repairing a lifted pad, removing and replacing an SOIC, be able to perform them per the IPC guidelines. Not only should the rework personnel be trained in the proper rework, repair and workmanship guidelines but they should also have demon- strated the ability to properly handle electronic assemblies while insuring that ESD (using EOS/ ESD 2020 as the standard) and MSD (IPC/JEDEC J-STD-033) guidelines are maintained. In addition to having the properly trained personnel, the contract rework and repair facil- ity should have leading edge equipment includ- ing X-ray inspection, cross sectioning capability and high magnification digital photo documen- tation. When to Outsource rework When does it make sense to consider using an outside contract services provider for rework and repair services? There are several instances when it makes sense to outsource this work. The first justification for outsourcing PCB rework is when the PCB rework or repair op- eration is beyond the skill level of your rework technicians. Examples of such work may in- clude: repairs of traces or pads that are smaller than 5 mils on a given side; replacement of 0.4 mm pitch or less QFPs; and micro QFN or 0201 replacement. The second instance in which the outsourc- ing of rework should be considered is when the amount of rework is beyond the capacity of your company to handle the rework in the time frame under which the contract calls for the re- work to be completed. The final case where it makes sense to con- sider outsourced PCB rework is where there is a one of a kind project such as a marketing or investor sample or a priceless developer's PCB Figure 1: QFP100, 0.5 mm pitch inside of shield—difficult rework project example. To ouTsourcE or noT To ouTsourcE Pcb rEWork