Welding Area Treatment; Module Installation; Specifications Of Rework - Huawei MU709 Series Hardware Manual

HUAWEI MU709 Series HSPA+ LGA Module
Hardware Guide
Figure 6-9 Equipment used for rework

6.9.4 Welding Area Treatment

Step 1 Remove the old solder by using a soldering iron and solder braid that can wet the
solder.
Step 2 Clean the pad and remove the flux residuals.
Step 3 Solder pre-filling: Before the module is installed on a board, apply some solder paste
to the pad of the module by using the rework fixture and stencil or apply some solder
paste to the pad on the PCB by using a rework stencil.

6.9.5 Module Installation

Install the module precisely on the motherboard and ensure the right installation
direction of the module and the reliability of the electrical connection with the PCB. It is
recommended that the module be preheated in order to ensure that the temperature
of all parts to be soldered is uniform during the reflow process. The solder quickly
reflows upon heating so the parts are soldered reliably. The solder joints undergo
proper reflow duration at a preset temperature to form a favorable Inter-metallic
Compound (IMC).

6.9.6 Specifications of Rework

Temperature parameter of rework: for either the removing or welding of the module,
the heating rate during the rework must be equal to or smaller than 3° C/s, and the
peak temperature between 240° C–250° C. The following parameters are
recommended during the rework.
Issue 09 (2017-12-15)
It is recommended that a fixture and a mini-stencil be made to apply the solder paste in the
rework.
It is recommended that a special clamp be used to pick the module when the module is
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installed on the pad after applied with some solder.
A special rework device must be used for the rework.
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