EXHIBIT 99.1

      Nippon Mining Holdings, Inc. Adopts 10b5-1 Plan for Shares
                        of AMIS Holdings, Inc.

    POCATELLO, Idaho--(BUSINESS WIRE)--Aug. 23, 2004--AMIS Holdings,
Inc. ("AMIS" or "Company") (Nasdaq:AMIS), parent company of AMI
Semiconductor, a leader in the design and manufacture of integrated
mixed-signal solutions, today announced that Nippon Mining Holdings,
Inc. ("Nippon"), a significant stockholder, has adopted a pre-arranged
stock trading plan in accordance with Rule 10b5-1 of the Securities
and Exchange Act of 1934, as amended. The plan allows for the sale of
up to 3,330,000 shares of AMIS common stock, in a systematic manner,
over a one-year period. The plan commences on October 1, 2004.
    Nippon adopted the plan in order to diversify its assets. In
accordance with the trading plan, the sales will occur from time to
time, and will be under the direction of UBS Securities LLC. The
shares to be sold under the plan represent 47.85 percent of the total
shares currently owned by Nippon. In addition, Nippon currently holds
an exercisable warrant for 4,603,032 shares of AMIS common stock.
    "AMI Semiconductor was a long-term investment for Nippon from the
start and after having been involved with AMIS for nearly 16 years,
they have found it necessary to diversify their portfolio," said Chris
King, president and chief executive officer for AMIS Holdings, Inc.
"However, since our initial public offering, AMIS has achieved
positive earnings each quarter. Now, Nippon will reap the benefits of
our business relationship and continue to share in AMI Semiconductor's
future success."
    SEC Rule 10b5-1 allows corporate executives to establish
pre-arranged plans to sell a specified number of shares of company
stock in accordance with a plan schedule. These plans permit
executives to change their investment portfolio gradually. This
minimizes the market effects of stock sales by spreading sales out
over a more extended period of time rather than carrying out sales
during limited trading windows following quarterly earnings
announcements. It also avoids concerns about initiating stock
transactions while aware of material nonpublic information. Once a
plan is established, the stockholder does not retain or exercise any
discretion over sales of stock under the plan and the pre-planned
trades can be executed at later dates as set forth in the plan,
without regard to any subsequent material nonpublic information that
the stockholder might receive.

    About AMI Semiconductor

    AMI Semiconductor (AMIS) is a leader in the design and manufacture
of silicon solutions for the real world. As a widely recognized
innovator in state-of-the-art integrated mixed-signal products,
mixed-signal foundry services and structured digital products AMIS is
committed to providing customers with the optimal value, quickest
time-to-market semiconductor solutions. Offering unparalleled
manufacturing flexibility and dedication to customer service, AMI
Semiconductor operates globally with headquarters in Pocatello, Idaho,
European corporate offices in Oudenaarde, Belgium, and a network of
sales and design centers located in the key markets of the United
States, Europe and the Asia Pacific region. For more information,
please visit the AMIS Web site at www.amis.com.

    CONTACT: AMI Semiconductor
             Jimmie Hutchens, 208-234-6732
             jimmie_hutchens@amis.com
             or
             Tamera Drake, 208-234-6890
             Tamera_Drake@amis.com