The need for open molded plastic packaging


When you need to meet a project or customer deadline, can you count on your outsourced Semiconductor Assembly and Testing (OSAT) vendor to get you the parts when you need them? Whether the answer is ‘no’ or ‘it depends’ you will understand the value of having open molded plastic packaging – plastic packaging with open cavities – readily available for quick assembly.

OSATs are very efficient at quickly producing large quantities of particular packaged devices. But what about the small quantities of many different packaged devices? The reality is that OSATs are not structured to support product development and device verification processes. This is where smaller, more nimble companies that stock open molded plastic packaging can provide cost effective solutions for customers who need low to medium volume packaging.

Choose the package

If you are a device design engineer in the US, where do you get your first set of new devices packaged so you can test them out and how do you choose the set? Not only is it convenient for the device to be packaged in the same form factor that will be used when it enters high volume manufacturing (HVM), but also reassuring, as it eliminates the need to guess how to perform. of the packaging tested the device will compare with that of the mass-produced packaging device.

This is an even better solution if the packages used for the prototypes correspond to outlines for which test sockets have already been developed. There are many acronyms for standard package outlines. Some of the more popular types in use today include the Wireless Quad Flat Pack (QFN), Slim Quad Flat Pack (TQFP), and Small Contour Integrated Circuit (SOIC).

The advantage of open mold

Since it is not possible to have all transfer molds readily available at a glance, for a multitude of reasons, the next best solution is to have open molded plastic packaging in stock in all. the different contours. The assembler can place the device in the cavity, solder the pads to the conductors, then encapsulate the whole with a plastic material. The plastic encapsulation will place the device in an environment almost identical to how it will be assembled by OSAT in large volumes with injection molded plastic. Ceramic or glass-to-metal sealed packages with open cavities can also be used, but there will be a difference in electrical performance since the electrical path is made of materials which are different from the high volume package configuration.

An additional advantage of using the open molded plastic packaging instead of injection molded packaging is that the open cavity allows the device and metal links to be left exposed. When validating the product, especially for applications that have high frequency signal transmissions, the device design engineer may wish to visualize the wire links. Viewing and accessing wire links can help the design engineer to optimize performance. The length of the wire link and the shape of the wire link loop can contribute to the electrical performance of the device. Therefore, being able to deliver some packaged devices without encapsulation is a real benefit as it can help reduce the number of iterations to determine optimal performance. Another obvious advantage of using open molded plastic packaging is that it can accommodate devices that require air gaps above them. Imaging devices, sensors, MEMS, and MMICs are some examples of devices that may require air gaps.

Where to pack

Even when you’ve selected your package type, you still need to decide where to pack new devices. If the pad with the new design is produced in the United States, does it make sense to ship it overseas for assembly and then send it back to you so you can evaluate the performance? Even though the large OSAT offers a quick turnaround time, it can be quite time consuming, especially if it takes several iterations before you are happy with the performance of the packaged device. If time to market is important, you don’t want to be handcuffed with this kind of supply chain scenario. It may work a little better if the insert is made overseas near your assembler, but a long iterative validation process can drive your sales department crazy.

There are many companies in the United States that provide outside assembly services. Most of them focus on something other than high volume injection molded packaging, for example assembly services that require special processes or a product that has not yet reached a volume high enough to be of interest to consumers. OSAT.

How does a US-based assembly company come up with a solution? What do they need besides being located on the same continent? It goes without saying that they must be able to assemble the devices. What else is needed? In a perfect world, the US-based assembler will have injection or transfer molding equipment with tooling for every imaginable packaging outline you might need to test your device. And the material must be available at all times. If there is a queue of several days or weeks, OSAT might be the best solution.

However, there are companies in the United States with a virtually unlimited number of open molded plastic packaging in stock, in all kinds of packaging configurations. The key to providing a successful alternative to OSATs overseas is the time it takes for the US company to complete assembly work. They must have short turnaround times on prototype builds. Excess capacity is not necessarily as critical as having the manufacturing flexibility to meet increases in demand.

A talented and versatile workforce is one of the key elements of flexibility. Another is the equipment set. Investments in the latest equipment have been made to keep pace with advanced semiconductor technologies. Newer equipment will tend to be faster and offer more flexibility. Finally, if the assembly and packaging company can offer some level of wafer processing, that makes the US-based solution even more attractive.


Open molded plastic packaging enables quick turnaround times for packaged device prototypes. Often die designers are pressured to validate the performance of their new designs as quickly as possible. Time-to-market is often essential. The infrastructure and geographic location of OSATs make it difficult to support rapid prototyping for US-based semiconductor design companies. With the availability of open molded plastic packaging, companies with flexible assembly operations can provide the necessary assistance.

Rosie Medina

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Rosie Medina is Vice President of Sales and Marketing at QP Technologies.

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