Background: Lead/tin solder has been used in the electronic industry for decades. In
recent years manufacturers have sought alternatives to lead/tin solder, partly in response to
recent scientific evidence showing that there is no lower limit for the adverse effects of
lead exposure in young children. LeadCheck® Swabs can provide a valuable low cost screening
tool for manufacturers wishing to confirm that components are lead free. Two test methods
follow. The first (and easiest) method is to simply use the LeadCheck® Swab as provided
to test solder connections. The second method was developed to allow testing of small
solder connections where the size of the LeadCheck® Swab tip makes testing difficult.
All of the test reagents and developing materials used in the methods described below
are provided in the LeadCheck® Circuit Board Test Kit (cat# PB-2M48CB).
I. Direct Test Method - For large test areas:
- Wipe the test area with isopropyl alcohol, a defluxer or other solvent to remove any dirt, oil or coating on the
solder surface. Allow the solvent to run off the board before testing.
- Activate a LeadCheck® Swab and rub the tip directly on the test area. The Swab tip will
instantly turn pink if lead is present.
Warning: Chemical residue from this test method may interfere
with the performance of the component tested.
click here to view a video of the direct testing method (4.5 meg file)
II. Indirect Test Method – For small test areas and areas sensitive to test chemicals.
- Abrade the surface to be tested with a fine grit sandpaper or emory cloth .
(Please note: sandpaper/emory cloth are not provided in the test kit).
- Aggressively rub one of the small, sharp tipped cotton swabs provided with the kit over the test area.
- Squeeze one drop of reactive dye from a LeadCheck® Swab into a well of the developing tray.
- Dip the sharp tipped swab that was exposed to the solder into the drop of reactive dye.
- Examine the tip carefully. Swab tips exposed to leaded solder will turn pink to red instantly.
Comments:
- Test several different areas of the board, using a new sharp tipped swab for each
test area. (A numbered
clay holding tray is supplied to accommodate developing multiple tests).
- For each sharp tipped swab used, place one drop of reactive dye
into a different well of the developing tray.
- Quickly dip each dry exposed swab into the reactive dye remembering that the greatest
sensitivity occurs within one minute of activating the LeadCheck® Swab.
- The reactive dye must be orange in color to be effective. If not, activate a new LeadCheck® Swab.
click here to view a video of the indirect testing method (6.0 meg file)
*LeadCheck® Swabs are a versatile and sensitive screening
tool for the detection of lead on any surface. This applications note provides a
suggested method to allow testing for a specific application. Additional information
and help are available by calling 800-262-5323 or 508-651-7881.
Direct Test of Circuit Board for Lead
Using LeadCheck® Swabs |
Rub the test area with an activated LeadCheck® Swab. |
If the tip of the LeadCheck® Swab is pink or red, there is lead. |
Indirect Test Method
(No chemicals touch the board) |
Vigorously rub a test area with the tip of a small swab. The diameter of the tip is about 3mm. |
Dip the swab tip that was exposed to the solder into the drop of reactive dye. |
Swab tips exposed to leaded solder will turn pink or red instantly. Any remaining dye,
if negative, will become pale yellow to colorless. |
Dry swabs can be used on different areas of the board. Use the numbered clay
tray to hold exposed swabs. Place a drop of dye from an activated LeadCheck® Swab either
directly on the exposed swab or rub the exposed swab into a drop of dye on the tray.
Positive swabs turn pink or red. |
|
