Mitsubishi Electric DLP WD-82CB1, Руководство по обслуживанию

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Page 37
MODELS: WD-73640 / WD-73740 / WD-73840 / WD-73C11 / WD-73CA1 /
WD-82740 / WD-82840 / WD-82CB1 / WD-92840
Versi
on 3.0
Using Lead Free Solder
The symbol shown above indicates Lead (Pb) Free Solder was used during the construction of PWBs. Only Lead Free
Solder should be used when servicing these PWBs.
Solder must be compatible with that used by the manufacturer. Leaded solder can not be used on PWBs manufactured
with Pb-free solder. The Mitsubishi standard for service requires the use of Tin-Silver-Copper (Sn-96.5, Ag-3.0, Cu-0.5).
It can be obtained through the Parts Department.
Order part number: PB FREE SOLDER
Lead Free Solder has a higher melting point, and does not “wet” as well as leaded solder. This means it does not ad-
here as readily to the solder iron tip and the surface to be soldered. To counteract this, the flux used is more corrosive.
The following cautions must be taken when using Pb Free Solder.

Higher temperatures can cause the PWB to warp, detaching surface mount components.

Higher temperatures may cause thermal damage to components.

Higher temperatures can cause plastics such as connectors, relays, LEDs, electrolytic capacitors to melt or warp.

Higher temperatures can cause surface oxidation resulting in poor solder spread-ability and wet-ability.

The flux is more corrosive.

The time required for a good solder connection may take longer.

Poor wet-ability can cause solder balls.

Higher temperatures can cause flux spattering.

Soldering iron tip life is shortened.

Dull finish solder joints (not shiny) can appear to be a “cold” solder joint.
In general a tip temperature of 700° F will usually provide good results.
Displays used to indicate Pb-free
PWBs will be marked, indicating the level of Pb-free construction. Table 1 defines the levels by phase and shows the
different symbols that will be displayed on the PWB. Additionally, a PWB constructed using Pb-free solder may be simply
marked LFS.
When possible, the indication will be placed close to the part number that is screened onto the PCB (not the part label).
Pb-Free
Phase Definition Display
Short Display (When the
area is too small)
Phase-1 PCB's constructed using
Pb-free solder.
Phase-2 Solder, PCB surface
finishing and component
lead plating is Pb-free.
Components may have
internal Pb.
Phase-3 Solder, PCB surface
finishing and components
are Pb-free. (100% Pb-
free)
Table 1: Pb-Free Phases and Symbols
Pb PCA
Pb Joints
Pb S
Pb J
Pb P
Pb Solder
Pb Solder