Exhibit 10.12

AMENDMENT NO. 1 TO

EMPLOYMENT AGREEMENT

WHEREAS, Semiconductor Components Industries, LLC (“Company”) and Robert Charles
“Bob” Mahoney (“Executive”) entered into an Employment Agreement dated as of
July 11, 2006 (“Agreement”);

WHEREAS, all defined terms used herein shall have the meanings set forth in the
Agreement unless specifically defined herein;

WHEREAS, as of February 14, 2008 and February 13, 2008 the Board of Directors
(“Board”) and Compensation Committee (“Committee”) of ON Semiconductor
Corporation, respectively, considered and approved an increase, effective
January 1, 2008, of the maximum target bonus percentage for the Executive from
60% to 65% of his Base Salary during the applicable Performance Cycle under a
bonus Program established and approved by the Board; and

WHEREAS, the Company and the Executive now wish to amend the Agreement to
reflect the increase to the maximum target bonus percentage to 65% consistent
with the Board’s and Committee’s approvals and make certain related conforming
changes to the Agreement.

NOW, THEREFORE, for mutual consideration the receipt of which is hereby
acknowledged, the Agreement is hereby amended as follows:

1. Effective January 1, 2008, Section 2(b) of the Agreement related to
“Compensation” is hereby amended by replacing such section in its entirety with
the following:

“(b) In addition to the Base Salary, during the Employment Period, the Executive
shall be eligible to participate in the bonus program established and approved
by the Board (the “Program”) and, pursuant to the Program, the Executive may
earn a bonus (the “Bonus”) on an annual or other performance period basis (a
“Performance Cycle”) of up to a maximum target of 65% of Base Salary earned
during the applicable Performance Cycle or an additional amount as approved by
the Board under the Program and in each case based on certain performance
criteria; provided that the Executive is actively employed by the Company on the
date the Bonuses are paid under the Program, except as provided in Section 5(a)
herein. The Bonus may be paid annually or more frequently depending upon the
Performance Cycle, as determined by the Board and pursuant to the Program. The
Bonus will be specified by the Board, and the Bonus will be reviewed at least
annually by the Board.”

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2. This Agreement shall amend only the provisions of the Agreement as set forth
herein. Those provisions of the Agreement not expressly amended shall be
considered in full force and effect.

IN WITNESS WHEREOF, the Executive and the Company have executed this Amendment
as of the 29th day of April 2008.

 

COMPANY:     Semiconductor Components Industries, LLC     By:   /s/ COLLEEN
MCKEOWN       Name:    Colleen McKeown       Title:   Senior Vice President,
Global Human Resources EXECUTIVE:     Bob Mahoney, in his individual capacity  
  By:   /s/ ROBERT CHARLES MAHONEY       Name:    Robert Charles “Bob” Mahoney  
    Title:   Executive Vice President, Sales and Marketing