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M.Nuzaihan

General Semiconductor Packaging Process Flow. Wafer Backgrinding, Die Preparation, Die Attach, Wire Bonding, Die Overcoat, Molding, Sealing, Marking, DTFS, Lead Finish, Electrical Testing, Tape & Reel, Dry Packing, Boxing and Labeling. M.Nuzaihan. DMT 243 – Chapter 3.

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M.Nuzaihan

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  1. General Semiconductor Packaging Process Flow Wafer Backgrinding, Die Preparation, Die Attach, Wire Bonding, Die Overcoat, Molding, Sealing, Marking, DTFS, Lead Finish, Electrical Testing, Tape & Reel, Dry Packing, Boxing and Labeling. M.Nuzaihan DMT 243 – Chapter 3

  2. Silicon gel covering-up the die surface General Semiconductor Packaging Process Flow Die Overcoat • Die Overcoat: • Is the process of applying a pliant but moisture-resistive material over the surface. • Purpose: • To minimize package stresses on the surface of the die. • To prove additional protection corrosion. • Silicone materials are very • effective for this purpose. M.Nuzaihan DMT 243 – Chapter 3

  3. General Semiconductor Packaging Process Flow Die Overcoat Die coating may be selectiveor non-selective. Selective die coating: - dispenses overcoat material on certain areas of the die only. Non-selective or full die coating: - Covers the entire surface of the die with overcoat material. The amount of overcoat material dispensed on the die surface should be calculated properly, as excess overcoat material that rise above the ball bond may exert tremendous shearing stresses on the wire, resulting in neck breaks. M.Nuzaihan DMT 243 – Chapter 3

  4. General Semiconductor Packaging Process Flow Molding Molding: Is the process of encapsulating the device in plastic material. Transfer molding: Is one of the most widely used molding processes. Its capability to mold small parts with complex features. In this process, - the molding compound is first preheated prior to its loading into the molding chamber. - After pre-heating, the molding compound is forced by a hydraulic plunger into the pot where it reaches melting temperature and becomes fluid. - The plunger then continues to force the fluid molding compound into the runners of the mold chase. These runners serve as canals where the fluid molding compound travels until it reaches the cavities, which contain the leadframes for encapsulation. M.Nuzaihan DMT 243 – Chapter 3

  5. General Semiconductor Packaging Process Flow Molding M.Nuzaihan DMT 243 – Chapter 3

  6. General Semiconductor Packaging Process Flow A Typical Transfer Molding Process M.Nuzaihan DMT 243 – Chapter 3

  7. General Semiconductor Packaging Process Flow Molding M.Nuzaihan DMT 243 – Chapter 3

  8. Incomplete mold Delamination at the leadframe and compound interface (external) General Semiconductor Packaging Process Flow Molding-related Failure Mechanisms M.Nuzaihan DMT 243 – Chapter 3

  9. crack Crack Package crack General Semiconductor Packaging Process Flow Molding-related Failure Mechanisms M.Nuzaihan DMT 243 – Chapter 3

  10. General Semiconductor Packaging Process Flow Sealing • Sealing • is the process of encapsulating a hermetic package, usually by capping or putting a lid over the base or body of the package. • The method of sealing is generally dependent on the type of package. • Ceramic DIPs, or cerdips, are sealed by topping the base of the package with a cap using seal glass. • Other ceramic packages such as sidebrazed packages, LCC's, and PGA's are sealed by covering the package with a combo lid through solder sealing M.Nuzaihan DMT 243 – Chapter 3

  11. General Semiconductor Packaging Process Flow Sealing Side Braze Packages Leadless Chip Carrier Packages Ceramic PGA Packages Ceramic SOIC M.Nuzaihan DMT 243 – Chapter 3

  12. General Semiconductor Packaging Process Flow Marking • Marking: • is the process of putting identification, traceability, and distinguishing marks on the package of an IC. The device name, company logo, date code, and lot id are examples of information commonly marked on the IC's package. Some marks are put on the package during assembly and some marks are put on the package during Test. • There are two common marking processes, namely: • ink marking • laser marking. M.Nuzaihan DMT 243 – Chapter 3

  13. Example of silicon rubber stamp for ink marking General Semiconductor Packaging Process Flow Ink Marking The most common ink marking process for semiconductor products is pad printing. Pad printing consists of transferringan ink pattern from the plate, which is a flat block with pattern depressions that are filled with ink, to the package, using a silicone rubber stamp pad. Silicone rubber repels ink, making the transfer of the ink pattern clean and efficient. It is also resilient and elastic, making it possible to print even on uneven surfaces Main advantage is reworkable… Disadvantage is size limitation… M.Nuzaihan DMT 243 – Chapter 3

  14. General Semiconductor Packaging Process Flow Laser marking Laser marking, refers to the process of engraving marks on the marking surface using a laser beam. There are many types of lasers, but the ones used or in use in the semiconductor industry include the CO2 laser, the YAG laser, and diode lasers. Main advantage is accuracy (small size is not a problem)… Disadvantage is not reworkable… M.Nuzaihan DMT 243 – Chapter 3

  15. General Semiconductor Packaging Process Flow Lead Finish • Leadfinish • is the process of applying a coat of metal over the leads of an IC to: • protect the leads against corrosion; • protect the leads against abrasion; • improve the solderability of the leads; • improve the appearance of the leads. • There are two widely used leadfinish techniques in the semiconductor industry,namely, plating and coating. M.Nuzaihan DMT 243 – Chapter 3

  16. General Semiconductor Packaging Process Flow Lead Finish Coating is the process of depositing a filler metal (usually solder - SnPb) over a surface, achieving metallurgical bonding through surface wetting. The filler metal should have a melting temperature below 315 degrees Celsius for the process to be classified as coating. Tin platingis a form of pure metal electroplating, which is the process of depositing a coating of metal on a surface by passing a current through a conductive medium, or electrolyte. There are two types of plating, i.e., pure metal plating such as tin (Sn) plating and alloy plating such as tin/lead (Sn/Pb) plating. M.Nuzaihan DMT 243 – Chapter 3

  17. General Semiconductor Packaging Process Flow Lead Finish - Plating Mechanism Material to be plated Source material M.Nuzaihan DMT 243 – Chapter 3

  18. General Semiconductor Packaging Process Flow DTFS (Deflash/Trim/Form/Singulate) Deflash/Trim/Form/Singulation (DTFS) consists of the four steps indicated in its name. These steps are defined below • Deflash- removal of flashes from the package of the newly molded parts. Flashes are the excess plastic material sticking out of the package edges right after molding. • Trim - cutting of the dambars that short the leads together. • Form - forming of the leads into the correct shape and position. • Singulation - cutting of the tie bars that attach the individual units to the leadframe, resulting in the individual separation of each unit from the leadframe M.Nuzaihan DMT 243 – Chapter 3

  19. Example of DTFS machine General Semiconductor Packaging Process Flow DTFS (Deflash/Trim/Form/Singulate) M.Nuzaihan DMT 243 – Chapter 3

  20. General Semiconductor Packaging Process Flow Electrical Testing Electrical testingis the identification and segregation of electrical failures from a population of devices. An electrical failure is any unit that does not meet the electrical specifications defined for the device. Electrical testing consists of providing a series of electrical excitation (force) to the device under test (DUT) and measuring the response of the DUT. For every set of electrical stimuli (response), the measured response is compared to the expectedresponse, which is usually defined in terms of a lower and an upper limit. Any DUT that exhibits a response outside of the expected range of response is considered a failure. M.Nuzaihan DMT 243 – Chapter 3

  21. Example of tester and handler General Semiconductor Packaging Process Flow Electrical Testing In production mode, electrical testing is usually performed using a test system or platform, consisting of a tester and a handler The tester performs the electrical testing itself, while the handler takes care of transferring the unit to the test site M.Nuzaihan DMT 243 – Chapter 3

  22. General Semiconductor Packaging Process Flow Strip Testing Strip Testing refers to the process wherein semiconductor devices are electrically tested while they are still in their lead frame strips, i.e., before they are singulated into individual units. Prior to testing, however, the devices in the strip have already undergone the lead trimming process for electrical isolation of their leads. M.Nuzaihan DMT 243 – Chapter 3

  23. Example of carrier tapes Example of reel General Semiconductor Packaging Process Flow Tape & Reel Tape and Reel is a process of packing surface mount devices (SMD's) by loading them into individual pockets comprising what is known as a pocket tape or carrier tape. The units are sealed in the carrier tape with a cover tape, usually by heat or pressure. The carrier tape is wound around a reel for convenient handling and transport. The reel is enclosed in a reel box before it is finally shipped to the customer. M.Nuzaihan DMT 243 – Chapter 3

  24. General Semiconductor Packaging Process Flow Dry Packing Dry packingis the process of putting moisture-sensitive plastic surface-mount devices in moisture-resistant bags or moisture barrier bags to prevent them from absorbing moisture from the atmosphere. Moisture ingress into plastic packages can result in popcorn cracking during board mounting. Popcorn cracking refers to package cracking caused by rapid vaporization of internal package moisture. M.Nuzaihan DMT 243 – Chapter 3

  25. Examples of moisture barrier bags Example of ‘pop corn’ or internal delamination for SMD’s General Semiconductor Packaging Process Flow Dry Packing M.Nuzaihan DMT 243 – Chapter 3

  26. General Semiconductor Packaging Process Flow Boxing and Labeling Boxing and Labeling: is the process of packing the lot (a group of devices built under a single process cycle as one batch) in its final box and attaching the required lot identification labels for storage in the finished goods warehouse or shipment to the customer. Boxing and labeling procedures and materials differ from company to company, customer to customer, or even package to package. M.Nuzaihan DMT 243 – Chapter 3

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