![]() ![]() Connect the thermocouples (drilled locations) to a temperature recorder.Antistatic solder wave fixtures may be used to prevent warp. The board should be secure but allowed to move with thermal expansion. Secure the board in place with appropriate tooling, clamps, and pins.Be mindful of the component height and clearance area around the component. Select an appropriate nozzle and install it.These thermocouples may be merely taped in place. Additional thermocouples will also be placed on the top of the circuit board, about two inches from the site, and on the bottom side under the site. (See Figure 4) Otherwise, secure it in place with high-temperature tape and thermal adhesive. Ideally, the thermocouple is secured in place by the solder of the pad that the thermocouple is placed in. Note: The BGA replacement profile may require more time and even more heat (usually not more than 20 seconds time) to not only reflow all joints but to properly evacuate flux gases and create uniform joints across the package.A consistent temperature starting point is necessary for repeatable results. A steady state operating temperature or threshold must be established prior to launching the reflow cycle.4 to 6 sample BGA components for development may be required.One fully assembled development board is required.It is recommended as guidance for profile development. Note: Your solder paste manufacturer will have a recommended time/temperature curve for these applications. ![]() Temperature adjustments may be required when processing components soldered using higher temperature lead-free solders. Note: This procedure references temperatures used when processing BGA components soldered using tin-lead solders. ![]() If a series of circuit boards are to be reworked, the first several should be handled with extreme care until a reliable procedure is established. Copper delamination, separation of pads, barrels of inner layers.Įach circuit board must be treated individually and scrutinized carefully for its reaction to heat. When subjected to high temperatures, they are susceptible to the following types of damage:Ģ. Carefully evaluate pre-bake requirements.Ĭaution - Circuit Board Sensitivity: Circuit boards are made from a great variety of materials. Plastic BGAs are especially sensitive to moisture absorption. Evaluate the component's tolerance to heat prior to using this method. Consult the equipment manual for more information.Ĭaution - Component Sensitivity: This method may subject the component to extreme temperatures. Once dried, it can be peeled off after use.įigure 5: Temperature data using analysis software.Ĭaution - Operator Safety: A thorough review of the equipment manual and comprehensive training is mandatory. This mask cures at room temperature in 5 minutes. This mask can create free-form heat shielding or seal the edges of the Heat Shield Blanket or Heat Shield Plates. This product is a high-temperature, quick cure, synthetic latex, peel-able solder mask supplied in syringes with dispensing needles. When using Heat Shield Plate material to deflect heat, leave a small space between the Heat Shield Plate and the protected component or area to avoid direct contact transfer of heat. Heat Shield Plates are easy to size, cut, form, and bond or tape into place using the high-temperature mask or high-temperature tape supplied in the kit. These are light gauge 5" x 7" aluminum sheets used primarily when simple heat deflection is required. Heat Shield Blankets can be used in conjunction with Heat Shield Plates to create a more robust thermal shield with a more rigid structure. It will withstand continuous heat in the leaded and lead-free solder melt temperature range and short-term exposure at temperatures up to 1000☏/538☌. Heat Shield Blanket is designed to reflect 90% of the radiant heat energy. These are 5" x 7" sheets of fiberglass fabric, aluminum foil laminate with a pressure-sensitive adhesive backing. The rework technician must constantly be aware of the effect of heat on the target device or circuit, plus how it affects components near the target device on both sides of the assembly. Collateral heat damage or unintended reflow of adjacent component solder connections can result in component damage, oxidation, de-wetting, pad damage, wicking, starved joints, and scorching. Nonabrasive, low-linting wipes for cleanup.ĭuring component rework, protection of nearby components is often mandatory to avoid collateral heat damage or inadvertent reflow. ![]()
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