|         |                                                        |
|---------|--------------------------------------------------------|
| • | Record revenue in fiscal third quarter of $670 million |

|         |                      |
|---------|----------------------|
| • | Diluted EPS of $0.69 |

|         |                                                                                                                 |
|---------|-----------------------------------------------------------------------------------------------------------------|
| • | Initiates fiscal fourth quarter 2015 revenue guidance of $650 - $680 million with diluted EPS of $0.64 to $0.72 |

|                                                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                                                                                                                                                                                                                                                                                                                           |  |  |  |  |  |
|                                                                                                                                                                                                                                                                                                                      | Three Months Ended |
|                                                                                                                                                                                                                                                                                                                      | July 4, 2015 |   | July 4, 2015 |   | October 3, 2015 |
| Summary GAAP Items                                                                                                                                                                                                                                                                                                        | Q3F15 Results |   | Q3F15 Preliminary** |   | Q4F15 Guidance |
|                                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |
| Revenue (millions)                                                                                                                                                                                                                                                                                                        | $670 |   | $670 |   | $650 to $680 |
| Operating margin                                                                                                                                                                                                                                                                                                          | 4.3% |   |   |   | 4.2% to 4.5% |
| Diluted EPS                                                                                                                                                                                                                                                                                                               | 0.69* |   | $0.67 to $0.70 |   | $0.64 to $0.72*** |
|                                                                                                                                                                                                                                                                                                                      |   |   |   |   |   |
| Summary Non-GAAP Items                                                                                                                                                                                                                                                                                                    |   |   |   |   |   |
| Return on invested capital (ROIC)                                                                                                                                                                                                                                                                                         | 14.1% |   |   |   |   |
| Economic Return                                                                                                                                                                                                                                                                                                           | 3.1% |   |  |   |  |
|                                                                                                                                                                                                                                                                                                                      |
| *Includes $0.10 per share of stock-based compensation expense**Preliminary results issued on July 13, 2015; guidance provided on April 22, 2015 was revenue of $670 to $700 million and EPS of $0.71 to $0.79***Includes $0.10 per share of stock-based compensation expense but excludes any unanticipated special items |

|         |                                                                                                                                    |
|---------|------------------------------------------------------------------------------------------------------------------------------------|
| • | Won 34 programs during the quarter representing approximately $147 million in annualized revenue when fully ramped into production |

|         |                                                                                   |
|---------|-----------------------------------------------------------------------------------|
| • | Trailing four quarter wins total approximately $716 million in annualized revenue |

|         |                                                                              |
|---------|------------------------------------------------------------------------------|
| • | Purchased $7.5 million of our shares at an average price of $44.40 per share |

----

|                                                                                                  |
|--------------------------------------------------------------------------------------------------|
|                                                                                                  |  |  |  |  |  |  |  |  |  |  |  |
| Quarterly Comparison                                                                             | Three Months Ended |
|                                                                                             | July 4, 2015 |   | April 4, 2015 |   | June 28, 2014 |
| ($ in thousands, except per share data)                                                          | Q3F15 |   | Q2F15 |   | Q3F14 |
|                                                                                             |   |   |   |   |   |
| Revenue                                                                                          |  | $669,585 |  |   |  | $651,285 |  |   |  | $620,505 |  |
| Gross profit                                                                                     |  | $59,087 |  |   |  | $59,777 |  |   |  | $58,593 |  |
| Operating profit                                                                                 |  | $28,631 |  |   |  | $29,452 |  |   |  | $28,198 |  |
| Net income                                                                                       |  | $23,794 |  |   |  | $23,594 |  |   |  | $24,584 |  |
| Diluted EPS                                                                                      |  | $0.69 |  |   |  | $0.69 |  |   |  | $0.71 |  |
| Adjusted net income*                                                                             |  | $23,794 |  |   |  | $23,594 |  |   |  | $25,799 |  |
| Adjusted diluted EPS*                                                                            |  | $0.69 |  |   |  | $0.69 |  |   |  | $0.74 |  |
|                                                                                             |   |   |   |   |   |
| Gross margin                                                                                     | 8.8 | % |   | 9.2 | % |   | 9.4 | % |
| Operating margin                                                                                 | 4.3 | % |   | 4.5 | % |   | 4.5 | % |
| Adjusted operating margin*                                                                       | 4.3 | % |   | 4.5 | % |   | 4.7 | % |
| ROIC*                                                                                            | 14.1 | % |   | 14.5 | % |   | 14.6 | % |
| Economic Return*                                                                                 | 3.1 | % |   | 3.5 | % |   | 3.6 | % |
|                                                                                             |
| *Refer to Non-GAAP Supplemental Information Tables 1 and 2 for a reconciliation to GAAP measures |

|                            |
|----------------------------|
|                            |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| Market Sector (millions)   | Three Months Ended |
|                       | July 4, 2015 |   | April 4, 2015 |   | June 28, 2014 |
|                       | Q3F15 |   | Q2F15 |   | Q3F14 |
| Networking/Communications  | $ | 222 |  | 33 | % |   | $ | 210 |  | 32 | % |   | $ | 203 |  | 33 | % |
| Healthcare/Life Sciences   | 180 |  | 27 | % |   | 191 |  | 29 | % |   | 177 |  | 28 | % |
| Industrial/Commercial      | 176 |  | 26 | % |   | 160 |  | 25 | % |   | 154 |  | 25 | % |
| Defense/Security/Aerospace | 92 |  | 14 | % |   | 90 |  | 14 | % |   | 87 |  | 14 | % |
| Total revenue              | $ | 670 |  |   |   | $ | 651 |  |   |   | $ | 621 |  |   |

----

|                                                                                                                                                   |
|---------------------------------------------------------------------------------------------------------------------------------------------------|
|                                                                                                                                                   |  |  |  |  |  |
| Cash Conversion Cycle                                                                                                                             | Three Months Ended |
|                                                                                                                                              | July 4, 2015 |   | April 4, 2015 |   | June 28, 2014 |
|                                                                                                                                              | Q3F15 |   | Q2F15 |   | Q3F14 |
| Days in accounts receivable                                                                                                                       | 48 |   | 48 |   | 48 |
| Days in inventory                                                                                                                                 | 88 |   | 86 |   | 84 |
| Days in accounts payable                                                                                                                          | 62 |   | 63 |   | 67 |
| Days in cash deposits                                                                                                                             | 12 |   | 12 |   | 8 |
| Annualized cash cycle*                                                                                                                            | 62 |   | 59 |   | 57 |
| *We calculate cash cycle as the sum of days in accounts receivable and days in inventory, less days in accounts payable and days in cash deposits |

|                                |
|--------------------------------|
|                                |  |
| What:           | Plexus Fiscal Third Quarter 2015 Earnings Conference Call and Webcast |
| When:           | Thursday, July 23 at 8:30 a.m. Eastern Time |
| Where:     | Participants are encouraged to join the live webcast at the investor relations section of the Plexus website, www.plexus.com or directly at http://edge.media-server.com/m/p/sex9wib2/lan/en Conference Call:  +1.888.771.4371 with passcode: 40017940 |
| Replay:         | The webcast will be archived on the Plexus website and available via telephone replayat +1.888.843.7419 or +1.630.652.3042 with passcode: 40017940 |

----

----

|                                                 |
|-------------------------------------------------|
|                                                 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| PLEXUS                                          |
| CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS |
| (in thousands, except per share data)           |
| (unaudited)                                     |
|                                            |   |   |   |
|                                            | Three Months Ended |   | Nine Months Ended |
|                                            | July 4, |   | June 28, |   | July 4, |   | June 28, |
|                                            | 2015 |   | 2014 |   | 2015 |   | 2014 |
| Net sales                                       | $ | 669,585 |  |   | $ | 620,505 |  |   | $ | 1,985,560 |  |   | $ | 1,712,026 |  |
| Cost of sales                                   | 610,498 |  |   | 561,912 |  |   | 1,805,282 |  |   | 1,549,096 |  |
|                                            |   |   |   |   |   |   |   |
| Gross profit                                    | 59,087 |  |   | 58,593 |  |   | 180,278 |  |   | 162,930 |  |
|                                            |   |   |   |   |   |   |   |
| Operating expenses:                             |   |   |   |   |   |   |   |
| Selling and administrative expenses             | 30,456 |  |   | 29,180 |  |   | 91,722 |  |   | 83,106 |  |
| Restructuring costs                             | — |  |   | 1,215 |  |   | 1,691 |  |   | 10,865 |  |
| Operating profit                                | 28,631 |  |   | 28,198 |  |   | 86,865 |  |   | 68,959 |  |
|                                            |   |   |   |   |   |   |   |
| Other income (expense):                         |   |   |   |   |   |   |   |
| Interest expense                                | (3,280 | ) |   | (3,055 | ) |   | (10,440 | ) |   | (8,952 | ) |
| Interest income                                 | 866 |  |   | 770 |  |   | 2,552 |  |   | 2,092 |  |
| Miscellaneous                                   | 471 |  |   | 1,271 |  |   | 549 |  |   | 2,182 |  |
|                                            |   |   |   |   |   |   |   |
| Income before income taxes                      | 26,688 |  |   | 27,184 |  |   | 79,526 |  |   | 64,281 |  |
|                                            |   |   |   |   |   |   |   |
| Income tax expense                              | 2,894 |  |   | 2,600 |  |   | 9,059 |  |   | 3,518 |  |
|                                            |   |   |   |   |   |   |   |
| Net income                                      | $ | 23,794 |  |   | $ | 24,584 |  |   | $ | 70,467 |  |   | $ | 60,763 |  |
|                                            |   |   |   |   |   |   |   |
| Earnings per share:                             |   |   |   |   |   |   |   |
| Basic                                           | $ | 0.71 |  |   | $ | 0.73 |  |   | $ | 2.10 |  |   | $ | 1.80 |  |
| Diluted                                         | $ | 0.69 |  |   | $ | 0.71 |  |   | $ | 2.05 |  |   | $ | 1.75 |  |
|                                            |   |   |   |   |   |   |   |
| Weighted average shares outstanding:            |   |   |   |   |   |   |   |
| Basic                                           | 33,653 |  |   | 33,837 |  |   | 33,617 |  |   | 33,810 |  |
| Diluted                                         | 34,454 |  |   | 34,670 |  |   | 34,400 |  |   | 34,686 |  |

----

|                                           |
|-------------------------------------------|
|                                           |  |  |  |  |  |  |  |  |  |  |  |
| PLEXUS                                    |
| NON-GAAP SUPPLEMENTAL INFORMATION TABLE 1 |
| (in thousands, except per share data)     |
| (unaudited)                               |
|                                      |   |   |   |   |   |
|                                      | Three Months Ended |
|                                      | July 4, |   | April 4, |   | June 28, |
|                                      | 2015 |   | 2015 |   | 2014 |
| Operating profit, as reported             | $ | 28,631 |  |   | $ | 29,452 |  |   | $ | 28,198 |  |
| Operating margin, as reported             | 4.3 | % |   | 4.5 | % |   | 4.5 | % |
|                                      |   |   |   |   |   |
| Non-GAAP adjustments:                     |   |   |   |   |   |
| Restructuring costs*                      | — |  |   | — |  |   | 1,215 |  |
|                                      |   |   |   |   |   |
| Operating profit, as adjusted             | $ | 28,631 |  |   | $ | 29,452 |  |   | $ | 29,413 |  |
| Operating margin, as adjusted             | 4.3 | % |   | 4.5 | % |   | 4.7 | % |
|                                      |   |   |   |   |   |
| Net income, as reported                   | $ | 23,794 |  |   | $ | 23,594 |  |   | $ | 24,584 |  |
|                                      |   |   |   |   |   |
| Non-GAAP adjustments:                     |   |   |   |   |   |
| Restructuring costs*                      | — |  |   | — |  |   | 1,215 |  |
|                                      |   |   |   |   |   |
| Net income, as adjusted                   | $ | 23,794 |  |   | $ | 23,594 |  |   | $ | 25,799 |  |
|                                      |   |   |   |   |   |
| Diluted earnings per share, as reported   | $ | 0.69 |  |   | $ | 0.69 |  |   | $ | 0.71 |  |
|                                      |   |   |   |   |   |
| Non-GAAP adjustments:                     |   |   |   |   |   |
| Restructuring costs                       | — |  |   | — |  |   | 0.03 |  |
|                                      |   |   |   |   |   |
| Diluted earnings per share, as adjusted   | $ | 0.69 |  |   | $ | 0.69 |  |   | $ | 0.74 |  |
|                                      |   |   |   |   |   |
|                                      |   |   |   |   |   |
| *Summary of restructuring costs           |   |   |   |   |   |
| Severance costs                           | $ | — |  |   | $ | — |  |   | $ | 669 |  |
| Fixed asset impairment                    | — |  |   | — |  |   | 25 |  |
| Other exit costs                          | — |  |   | — |  |   | 521 |  |
| Total restructuring costs                 | $ | — |  |   | $ | — |  |   | $ | 1,215 |  |

----

|                                           |
|-------------------------------------------|
|                                           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| PLEXUS                                    |
| NON-GAAP SUPPLEMENTAL INFORMATION TABLE 2 |
|  (in thousands)                      |
| (unaudited)                               |
|                                      |   |   |   |   |   |   |   |   |
| ROIC and Economic Return Calculations     | Nine Months         Ended |   | Six Months Ended |   | Nine Months         Ended |
|                                      | July 4, |   | April 4, |   | June 28, |
|                                      | 2015 |   | 2015 |   | 2014 |
| Operating profit                          |   | $ | 86,865 |  |   |   | $ | 58,234 |  |   |   | $ | 68,959 |  |
| Restructuring costs                       |   | 1,691 |  |   |   | 1,691 |  |   |   | 10,865 |  |
| Adjusted operating profit                 |   | $ | 88,556 |  |   |   | $ | 59,925 |  |   |   | $ | 79,824 |  |
|                                      | ÷ | 3 |  |   |   |   |   | ÷ | 3 |  |
|                                      |   | 29,519 |  |   |   |  |  |  |   | 26,608 |  |
|                                      | x | 4 |  |   | x | 2 |  |   | x | 4 |  |
| Annualized operating profit               |   | $ | 118,076 |  |   |   | $ | 119,850 |  |   |   | $ | 106,432 |  |
| Tax rate                                  | x | 11 | % |   | x | 10 | % |   | x | 9 | % |
| Tax impact                                |   | 12,988 |  |   |   | 11,985 |  |   |   | 9,579 |  |
| Operating profit (tax effected)           |   | $ | 105,088 |  |   |   | $ | 107,865 |  |   |   | $ | 96,853 |  |
|                                      |   |   |   |   |   |   |   |   |
| Average invested capital                  | ÷ | $ | 745,030 |  |   | ÷ | $ | 745,441 |  |   | ÷ | $ | 661,835 |  |
|                                      |   |   |   |   |   |   |   |   |
| ROIC                                      |   | 14.1 | % |   |   | 14.5 | % |   |   | 14.6 | % |
| Weighted average cost of capital          |   | 11.0 | % |   |   | 11.0 | % |   |   | 11.0 | % |
| Economic Return                           |   | 3.1 | % |   |   | 3.5 | % |   |   | 3.6 | % |

----

|                                                                                                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                                                                                                                                                                                                                                                                  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| Average Invested Capital Calculations                                                                                                                                                                                                                            |   |   |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                             |   |   | July 4, |   | April 4, |   | January 3, |   | September 27, |
|                                                                                                                                                                                                                                                             |   |   | 2015 |   | 2015 |   | 2015 |   | 2014 |
| Equity                                                                                                                                                                                                                                                           |   |   | $ | 835,063 |  |   | $ | 808,468 |  |   | $ | 792,298 |  |   | $ | 781,133 |  |
| Plus:                                                                                                                                                                                                                                                            |   |   |   |   |   |   |   |   |   |
| Debt - current                                                                                                                                                                                                                                                   |   |   | 4,281 |  |   | 4,774 |  |   | 4,793 |  |   | 4,368 |  |
| Debt - non-current                                                                                                                                                                                                                                               |   |   | 259,284 |  |   | 260,025 |  |   | 260,990 |  |   | 262,046 |  |
| Less:                                                                                                                                                                                                                                                            |   |   |   |   |   |   |   |   |   |
| Cash and cash equivalents                                                                                                                                                                                                                                        |   |   | (354,830 | ) |   | (356,296 | ) |   | (239,685 | ) |   | (346,591 | ) |
|                                                                                                                                                                                                                                                             |   |   | $ | 743,798 |  |   | $ | 716,971 |  |   | $ | 818,396 |  |   | $ | 700,956 |  |
|                                                                                                                                                                                                                                                             |   |   |   |   |   |   |   |
| Third quarter fiscal 2015 average invested capital (July 4, 2015, April 4, 2015, January 3, 2015 and September 27, 2014) was $745,030. Second quarter fiscal 2015 average invested capital (April 4, 2015, January 3, 2015 and September 27, 2014) was $745,441. |
|                                                                                                                                                                                                                                                                  |   |   | June 28, |   | March 29, |   | December 28, |   | September 28, |
|                                                                                                                                                                                                                                                             |   |   | 2014 |   | 2014 |   | 2013 |   | 2013 |
| Equity                                                                                                                                                                                                                                                           |   |   | $ | 760,184 |  |   | $ | 736,493 |  |   | $ | 722,021 |  |   | $ | 699,301 |  |
| Plus:                                                                                                                                                                                                                                                            |   |   |   |   |   |   |   |   |   |
| Debt - current                                                                                                                                                                                                                                                   |   |   | 4,232 |  |   | 3,901 |  |   | 3,796 |  |   | 3,574 |  |
| Debt - non-current                                                                                                                                                                                                                                               |   |   | 263,056 |  |   | 256,090 |  |   | 256,949 |  |   | 257,773 |  |
| Less:                                                                                                                                                                                                                                                            |   |   |   |   |   |   |   |   |   |
| Cash and cash equivalents                                                                                                                                                                                                                                        |   |   | (330,314 | ) |   | (323,695 | ) |   | (324,156 | ) |   | (341,865 | ) |
|                                                                                                                                                                                                                                                             |   |   | $ | 697,158 |  |   | $ | 672,789 |  |   | $ | 658,610 |  |   | $ | 618,783 |  |
|                                                                                                                                                                                                                                                             |   |   |   |   |   |   |   |   |   |
| Third quarter fiscal 2014 average invested capital (June 28, 2014, March 29, 2014, December 28, 2013, and September 28, 2013) was $661,835.                                                                                                                      |

----

|        |
|--------|
|        |  |  |  |  |  |  |  |  |
|   | PLEXUS |
|   | CONDENSED CONSOLIDATED BALANCE SHEETS |
|   | (in thousands, except per share data) |
|   | (unaudited) |
|   |   | July 4, |   | September 27, |
|   |   | 2015 |   | 2014 |
|   | ASSETS |   |   |   |
|   | Current assets: |   |   |   |
|   | Cash and cash equivalents | $ | 354,830 |  |   | $ | 346,591 |  |
|   | Accounts receivable | 349,922 |  |   | 324,072 |  |
|   | Inventories | 588,453 |  |   | 525,970 |  |
|   | Deferred income tax | 6,399 |  |   | 6,449 |  |
|   | Prepaid expenses and other | 26,012 |  |   | 27,757 |  |
|   |   |   |   |   |
|   | Total current assets | 1,325,616 |  |   | 1,230,839 |  |
|   |   |   |   |   |
|   | Property, plant and equipment, net | 322,821 |  |   | 334,926 |  |
|   | Deferred income tax | 3,493 |  |   | 3,675 |  |
|   | Other | 40,309 |  |   | 39,586 |  |
|   |   |   |   |   |
|   | Total assets | $ | 1,692,239 |  |   | $ | 1,609,026 |  |
|   |   |   |   |   |
|   | LIABILITIES AND SHAREHOLDERS’ EQUITY |   |   |   |
|   | Current liabilities: |   |   |   |
|   | Current portion of long-term debt and capital lease obligations | $ | 4,281 |  |   | $ | 4,368 |  |
|   | Accounts payable | 416,190 |  |   | 396,363 |  |
|   | Customer deposits | 76,049 |  |   | 56,155 |  |
|   | Deferred income tax | 567 |  |   | 647 |  |
|   | Accrued liabilities: |   |   |   |
|   | Salaries and wages | 48,681 |  |   | 52,043 |  |
|   | Other | 34,556 |  |   | 37,739 |  |
|   |   |   |   |   |
|   | Total current liabilities | 580,324 |  |   | 547,315 |  |
|   |   |   |   |   |
|   | Long-term debt and capital lease obligations, net of current portion | 259,284 |  |   | 262,046 |  |
|   | Deferred income tax | 5,189 |  |   | 5,191 |  |
|   | Other liabilities | 12,379 |  |   | 13,341 |  |
|   |   |   |   |   |
|   | Total non-current liabilities | 276,852 |  |   | 280,578 |  |
|   |   |   |   |   |
|   | Commitments and contingent liabilities |   |   |   |
|   | Shareholders’ equity: |   |   |   |
|   | Preferred stock, $.01 par value, 5,000 shares authorized, none issued or outstanding | — |  |   | — |  |
|   | Common stock, $.01 par value, 200,000 shares authorized, |   |   |   |
|   | 50,549 and 49,962 shares issued, respectively, |   |   |   |
|   | and 33,690 and 33,653 shares outstanding, respectively | 505 |  |   | 500 |  |
|   | Additional paid-in-capital | 494,790 |  |   | 475,634 |  |
|   | Common stock held in treasury, at cost, 16,859 and 16,309 shares, respectively | (502,488 | ) |   | (479,968 | ) |
|   | Retained earnings | 836,852 |  |   | 766,385 |  |
|   | Accumulated other comprehensive income | 5,404 |  |   | 18,582 |  |
|   |   |   |   |   |
|   | Total shareholders’ equity | 835,063 |  |   | 781,133 |  |
|   |   |   |   |   |

----

|        |
|--------|
|        |  |  |  |  |  |  |  |  |
|   | Total liabilities and shareholders’ equity | $ | 1,692,239 |  |   | $ | 1,609,026 |  |

|                                           |
|-------------------------------------------|
|                                           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| PLEXUS                                    |
| REVENUE BY REPORTABLE GEOGRAPHIC SEGMENTS |
| (in thousands)                            |
| (unaudited)                               |
|                                      |   |   |   |   |   |
|                                      | Three Months Ended |
|                                      | July 4, 2015 |   | April 4, 2015 |   | June 28, 2014 |
|                                      | Q3F15 |   | Q2F15 |   | Q3F14 |
| Americas                                  | $ | 365,861 |  | 55 |  % |   | $ | 328,753 |  | 50 |  % |   | $ | 324,544 |  | 52 |  % |
| Asia-Pacific                              | 313,900 |  | 47 |  % |   | 319,156 |  | 49 |  % |   | 295,625 |  | 48 |  % |
| Europe, Middle East, and Africa           | 33,885 |  | 5 |  % |   | 35,773 |  | 6 |  % |   | 27,563 |  | 4 |  % |
| Elimination of inter-segment sales        | (44,061 | ) | (7 | )% |   | (32,397 | ) | (5 | )% |   | (27,227 | ) | (4 | )% |
| Total revenue                             | $ | 669,585 |  |   |   | $ | 651,285 |  |   |   | $ | 620,505 |  |   |