Title: Electroless tin and tin-lead alloy plating baths

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Claims: I claim:

1. A salt composition, when diluted with 1 liter of water and sufficient hydrochloric acid to provide a solution having a pH of 0.5 to 1, is suitable for immersion plating of tin-lead alloys at increased rates, the salt composition comprising the proportions of:

    ______________________________________
    a.  hydrous stannous chloride
                          from about 10 to about 150 g,
        (SnCl.sub.2 . 2H.sub.2 O)
    b.  lead chloride     from about 1 to about 12 g,
        (PbCl.sub.2)
    c.  sodium hypophosphite
                          from about 10 to about 100 g,
        (NaH.sub.2 PO.sub.2 . H.sub.2 O)
                          and
    d.  thiourea          from about 15 to about 100 g,
        (NH.sub.2 . CS . NH.sub.2)
    ______________________________________

2. A salt composition for immersion plating a tin-lead alloy, when diluted with 1 liter of water and sufficient hydrochloric acid to provide a solution having a pH of 0.5 to 1, said salt composition comprising the proportions of:

    ______________________________________
    a.  hydrous stannous chloride
                          from about 5 to about 100 g,
        (SnCl.sub.2 . 2H.sub.2 O)
    b.  lead chloride     from about 2 to about 25 g,
        (PbCl.sub.2)
    c.  sodium hypophosphite
                          from about 60 to about 100 g,
        (NaH.sub.2 PO.sub.2 . H.sub.2 O)
                          and
    d.  thiourea          from about 100 to about 150 g.
        (NH.sub.2. CS . NH.sub.2)
    ______________________________________

3. A composition according to claim 1 further comprising gelatin from about 0.1 g.

4. A composition according to claim 1 further comprising an alkylphenoxy polyethanol surfactant from about 0.1 g.

5. A composition according to claim 2 further comprising gelatin from about 0.1 g.

6. A composition according to claim 2 further comprising an alkylphenoxy polyethanol surfactant from about 0.1 g.
Other info:

Inventors: Davis, Thomas Francis (Harrisburg, PA, US)

Application Number: 574979
Filing Date: 1975-05-06
Publication_date: 1978-06-06
Assignee: AMP Incorporated (Harrisburg, PA)
Primary Class(es): 106/1.22 427/437
Other Classes:
US Patent Ref:

2369620	Feb, 1945	Sullivan et al.	427/436.
3050410	Aug, 1962	Greene	106/1.
3303029	Feb, 1967	Shipley	106/1.

Other Refs:
Primary Examiner: Hayes, Lorenzo B.
Assistant Examiner:
Attorney: Kita; Gerald K.