Mitsubishi Electronics WD-62927, WD-52628 Displays used to indicate Pb-free, Pb-Free Display

MODELS: WD-52627 / 52628 / 62627 / 62628 / 62827 / 62927 / 73727 / 73827 / 73927

Using Lead Free Solder

Pb Solder			• The flux is more corrosive.
			• The time required for a good solder connection may
The above symbol indicates Lead (Pb) Free solder was			take longer.
used during the construction of PWBs. Only Lead			• Poor wet-ability can cause solder balls.
Free solder should be used when servicing these			• Higher temperatures can cause flux spattering.
PWBs.			• Soldering iron tip life is shortened.
			• Dull finish solder joints (not shiny) can appear to be
Solder must be compatible with that used by the			a “cold” solder joint.
manufacturer. Leaded solder can not be used on		In general a tip temperature of 700° F will usually provide
PWBs manufactured with Pb-free solder. The Mitsub-
ishi standard for service requires the use of Tin-Silver-		good results.
Copper (Sn-96.5, Ag-3.0, Cu-0.5). It can be obtained
through the Parts Department.		Displays used to indicate Pb-free
Order part number: PB FREE SOLDER
		PCBs will be marked, indicating the level of Pb-free con-
Lead Free solder has a higher melting point, and does		struction. Table 1 defines the levels by phase and shows
not “wet” as well as leaded solder. This means it does		the different symbols that will be displayed on the PCB.
not adhere as readily to the solder iron tip, and the		Additionally, a PCB constructed using Pb-free solder may
surface to be soldered. To counteract this, the flux		be simply marked LFS.
used is more corrosive.		When possible, the indication will be placed close to the
The following cautions must be taken when using Pb		part number that is screened onto the PCB (not the part
Free solder.		label). Figure 1 is an example of a PCB showing the
• Higher temperatures can cause the PWB to		display and its location.
warp, detaching surface mount
	Pb-Free				Short Display (When the
components.
	Phase	Definition		Display	area is too small)
• Higher temperatures may	Phase-1 PCB's constructed using			Solder	Pb S
cause thermal damage to	Pb-free solder.		Pb
components.

•Higher temperatures can cause

plastics, such as connectors,	Phase-2	Solder, PCB surface
relays, LEDs electrolytic		finishing and component	Pb	Joints	Pb	J
		lead plating is Pb-free.
capacitors, etc. to melt or
		Components may have
warp.		internal Pb.
• Higher temperatures can cause	Phase-3	Solder, PCB surface
surface oxidation resulting in		finishing and components	Pb	PCA	Pb	P
		are Pb-free. (100% Pb-
poor solder spread-ability and
wet-ability.		free)
		Table 1: Pb-Free Phases and Symbols
Pb-Free
Display

Figure 2: Pb-Free display on PWB

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