Exhibit 99.1

FOR IMMEDIATE RELEASE

Plexus Reports Record Fiscal Second Quarter Revenue of $573 Million, EPS of $0.56

Initiates Q3 Fiscal 2012 Revenue Guidance of $590—$620 Million

NEENAH, WI, April 18, 2012 — Plexus Corp. (NASDAQ: PLXS) today announced:

Q2 Fiscal 2012 Results (quarter ended March 31, 2012):

Q3 Fiscal 2012 Guidance:

Dean Foate, President and CEO, commented, “Fiscal second quarter revenues were up 8% sequentially to $573 million with EPS of $0.56. Both revenue and diluted EPS were above the mid-point of our guidance range. The strong revenue growth we delivered in the quarter set a record level for the company and marked a return to sequential growth. Our return on invested capital of 14.4% was nicely above our weighted average cost of capital by 190 basis points, but below our enduring target of 500 basis points above weighted average cost of capital. Currently, our revenue growth is driven largely by new program wins that come with transition costs versus end-market growth of fully-ramped programs where operating performance is generally better. With the exception of our Networking/Communications sector, which remains volatile, we experienced a relatively stable demand environment during the quarter. Each of our other market sectors performed consistent with or above our expectations.”

Mr. Foate continued, “During the quarter we won 28 new programs in our Manufacturing Solutions group that we anticipate will generate approximately $316 million in annualized revenue when fully ramped into production. Included in the $316 million is approximately $100 million of revenue from the strategic manufacturing arrangement with Kontron AG announced in January 2012. Overall, our Manufacturing Solutions new program wins revenue was a record result and represented the third sequential quarter of strong performance. Of course, all future revenues are subject to the timing and ultimate realization of customer forecasts and orders. While we have aggressively harvested opportunities from our funnel of qualified manufacturing opportunities, it still remains strong at $1.9 billion.”

Ginger Jones, Senior Vice President and CFO, commented, “Gross margin was 9.5% for the fiscal second quarter, above our expectations when we originally set guidance for the quarter. The stronger performance was a result of a favorable mix of revenue driving better leverage from our operations. Selling and administrative expenses were above our original guidance for the quarter, largely a result of amortization of an intangible asset related to the Kontron arrangement. Overall, operating margin for the fiscal second quarter was better than expected at 4.5%. Our estimated tax rate for fiscal 2012 is up slightly at 10%, which is consistent with our guidance range for the year.”

Ms. Jones continued, “Fiscal second quarter cash cycle days was 66 days, including customer deposits, a healthy improvement of four days from the fiscal first quarter result of 70 days. The sequential improvement in cash cycle days was largely the result of an increase in days in payables, while inventory days and customer deposits stayed flat and days in receivables was up one day. As a consequence, we generated $41 million of free cash flow during the quarter.”

Mr. Foate added, “We are establishing fiscal third quarter 2012 revenue guidance of $590 to $620 million with EPS of $0.60 to $0.66, excluding any unanticipated restructuring charges and including approximately $0.08 per share of stock-based compensation expense. This guidance range suggests that we currently anticipate that healthy sequential revenue growth will deliver a modest improvement in operating performance.”

Mr. Foate concluded, “Looking further ahead, while we remain focused on returning to our 5% operating margin target, our current view is that operating margin will be modestly below our target through fiscal 2012. This reflects our current growth profile, which is highly dependent on new program ramps, versus robust end-market growth. While we currently believe that the majority of our market sectors are stabilizing and in some cases improving, we anticipate that our Networking/Communications sector will remain volatile. Despite uncertain end-markets, we continue to enjoy a healthy environment for new business opportunities and are keenly focused on taking advantage of these opportunities to drive growth. Our current expectation is that sequential revenue growth will continue through the fiscal fourth quarter of 2012. We remain committed to both revenue growth and return on invested capital performance that is solidly above our weighted average cost of capital, as we believe this performance is fundamental to delivering long-term shareholder value.”

Plexus provides non-GAAP supplemental information such as return on invested capital (“ROIC”). ROIC is used for internal management assessments because it provides additional insight into ongoing financial performance. In addition, we provide ROIC because we believe it offers insight into the metrics that are driving management decisions as well as management’s performance under the tests that it sets for itself. Please refer to the attached reconciliations of non-GAAP supplemental data.

MARKET SECTOR BREAKOUT

Plexus reports revenue based on the market sector breakout set forth in the table below, which reflects the Company’s focus on its global business and market development sector strategy.

FISCAL Q2 SUPPLEMENTAL INFORMATION

Conference Call/Webcast and Replay Information:

For further information, please contact:

Ginger Jones, Senior VP and Chief Financial Officer

920-751-5487 or ginger.jones@plexus.com

About Plexus Corp. – The Product Realization Company

Plexus (www.plexus.com) delivers optimized Product Realization solutions through a unique Product Realization Value Stream service model. This customer-focused services model seamlessly integrates innovative product conceptualization, design, commercialization, manufacturing, fulfillment and sustaining services to deliver comprehensive end-to-end solutions for customers in the Americas, European and Asia-Pacific regions.

Plexus is the industry leader in servicing mid-to-low volume, higher complexity customer programs characterized by unique flexibility, technology, quality and regulatory requirements. Award-winning customer service is provided to over 130 branded product companies in the Networking/Communications, Medical, Industrial/Commercial and Defense/Security/Aerospace market sectors.

Safe Harbor and Fair Disclosure Statement

The statements contained in this release which are guidance or which are not historical facts (such as statements in the future tense and statements including “believe,” “expect,” “intend,” “plan,” “anticipate,” “goal,” “target” and similar terms and concepts), including all discussions of periods which are not yet completed, are forward-looking statements that involve risks and uncertainties. These risks and uncertainties include, but are not limited to: the risk of customer delays, changes, cancellations or forecast inaccuracies in both ongoing and new programs; the poor visibility of future orders, particularly in view of current economic conditions; the economic performance of the industries, sectors and customers we serve; the effects of the volume of revenue from certain sectors or programs on our margins in particular periods; the risk that the Kontron agreement does not result in the revenues or margins anticipated by us; our ability to secure new customers, maintain our current customer base and deliver product on a timely basis; the risk that our revenue and/or profits associated with customers who are acquired by third parties will be negatively affected; the particular risks relative to new or recent customers or programs, which risks include customer and other delays, start-up costs, potential inability to execute, the establishment of appropriate terms of agreements, and the lack of a track record of order volume and timing; the risks of concentration of work for certain customers; our ability to manage successfully a complex business model characterized by high customer and product mix, low volumes and demanding quality, regulatory, and other requirements; the risk that new program wins and/or customer demand may not result in the expected revenue or profitability; the fact that customer orders may not lead to long-term relationships; the effects of shortages and delays in obtaining components as a result of economic cycles or natural disasters; raw materials and component cost fluctuations, particularly due to sudden increases in customer demand; the risks associated with excess and obsolete inventory, including the risk that inventory purchased on behalf of our customers may not be consumed or otherwise paid for by the customer, resulting in an inventory write-off; the weakness of the global economy and the continuing instability of the global financial markets and banking system, including the potential inability of our customers or suppliers to access credit facilities; the effect of changes in the pricing and margins of products; the effect of start-up costs of new programs and facilities, such as our plans to expand in Romania and recent, planned and potential future expansions; the risk of unanticipated costs, unpaid duties and penalties related to an ongoing audit of our import compliance by U.S. Customs and Border Protection; increasing regulatory and compliance requirements; possible unexpected costs and operating disruption in transitioning programs; the potential effect of fluctuations in the value of the currencies in which we transact business; the potential effect of world or local events or other events outside our control (such as drug cartel-related violence in Mexico, changes in oil prices and terrorism); the impact of increased competition; and other risks detailed in the Company’s Securities and Exchange Commission filings (particularly in Part I, Item 1A of our annual report on Form 10-K for the fiscal year ended October 1, 2011).

(financial tables follow)

PLEXUS CORP.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands, except per share data)

(unaudited)

ROIC Calculation

PLEXUS CORP.

CONDENSED CONSOLIDATED BALANCE SHEETS

(in thousands, except per share data)

(unaudited)

# # #