Advanced Packages
008004s: Impractical, but Possible
Realizing advanced electronics with the world’s smallest packages. by Michael Schneider

Is it worthwhile to design printed circuit boards with the smallest component package available today: the 008004? And how do you do it correctly?

Several months ago, a hardware engineer in a high-tech company that is developing virtual reality headsets approached me. “These are special glasses that can integrate into game consoles in hundreds of millions of homes worldwide,” he said with excitement. “This is innovative technology that will enable a totally different viewing and gaming experience than what’s available at present.”

Later in the conversation, he noted they are developing a common electronic circuit board for a project that, after successful programming, has been proved by means of an evaluation board.

On the surface it seems promising. He then qualified their progress, however, adding that because this circuit board has a wide range of applications but a very small footprint, there is no room on the board to place all the needed components. After I received the technical details of the circuit board and parts list, I understood the possibility of building this assembly, provided we use the smallest component package. This is a component with dimensions of quarter of a millimeter by an eighth of a millimeter, known in the industry as an 008004.

Use of electronics over recent years has expanded into a range of applications and accessories. Mobile accessories popping up in every corner and interest in turning inanimate products into communicative ones (e.g., the Internet of Things) are forcing an increasing need for more electronic functionality in a smaller area. Producing smaller components as a means to meet this challenge is insufficient. The dependency and relationship among the printed circuit board (PCB), materials and production processes require in-depth analysis of soldering processes and the points of failure while in the planning stage. Producers and planners of these components more than ever must closely cooperate to find creative and efficient solutions.

Maximum Functionality, Minimum Area
The 008004 started to appear in serial production about three years ago. The new package is half the area of an 01005 and therefore enables significant savings on the circuit board (FIGURE 1). These components, which for the most part are passives (resistors, capacitors), have particularly small dimensions and weights. The component is invisible to the human eye, and its dimensions are 0.25mm (length) by 0.125mm (width). The height is typically 0.125mm. The distance between the component pads is 0.115mm, and its weight is approximately 0.02mg.
An 008004 package (left) and a 01005 (right), assembled at the Nistec Center plant

Figure 1. An 008004 package (left) and a 01005 (right), assembled at the Nistec Center plant. (Magnification 1:40)

Essential Use Only
If not essential, it is preferable not to use this type of component. Our plant in Petach Tikva, Israel, has assembled scores of circuits with this package with great success. Yet, as a technologist in a printed circuit assembly plant, I must mention, in principle, I do not recommend use of these components, at least at this stage, unless the circuit board application and footprint require it. Instead, as much as possible, given the constraints of the area, design the circuit with an 01005 component, which is much simpler and easier for assembly and maintenance.

Some of the challenges working with an 008004 include:

  1. Manual repair is not possible. After machine soldering the board, it is not possible to repair the component manually. The component’s small area and negligible weight make manual soldering impossible. In the event the component must be repaired post-soldering, the board will have to be reassembled.
  1. Precise application of soldering paste. Correct application of the soldering paste is crucial to soldering success. This is even more important for tiny components such as 008004s. Use a particularly thin application stencil (0.075mm/0.003 mils) and design the stencil openings to component manufacturer recommendations. Note there could be different recommendations for different components, although they are the same size.
  2. Uniformity of the rest of the components on the board. Because 008004s require accurate and delicate work during soldering, other parts on the board should be selected meticulously. Reduce the variety of types of components to enable uniformity and thermal balance during soldering. For example, in a circuit that contains an 008004, one should not also integrate a larger and heavier BGA.
  3. Limited choice of assemblers. This is an advanced technology, and very few factories at present are capable of assembling these packages. Therefore, use of 008004s means working with a smaller number of assemblers.
  4. High price. An 008004 component can cost 50% more than larger packages in the same passive category. In the coming years, however, use of the component will increase, and the price will balance out with other components in the market.
‘50 Microns Accuracy’
The key to quality assembly of an 008004 component is accurate application of the solder paste. The maximum deviation is 50µm (0.05mm). In the assembly process, pay attention to the following:

  • Define the component footprint per the component manufacturer recommendations.
  • Use a 1:1 solder paste aperture ratio.
  • Define the pads for the 008004 without release of the solder mask. That is with an SMD (solder-mask-defined) configuration, not as is customary for NSMD (non-solder-mask-defined) components. Furthermore, ensure solder mask is defined between the pads.
  • Maintain a minimum distance of 6 mils between adjacent 008004 components.
Challenging, Yet Possible
Soldering an 008004 component in an unsound process could lead to a significant number of quality issues. Common issues include:

  1. Component lifting (tombstone). The component lifts during assembly. This is mainly caused by deviations in the solder paste application or imprecise component placement on the pads (FIGURE 2).
  2. Shorts (bridging). The component could attach to the adjacent component and cause a short. The root cause typically is inaccurate solder application or component positioning (FIGURE 3).
tombstoning 008004 components

Figure 2. 008004 components are prone to tombstoning.

component solder bridging
Figure 3. Solder bridging is another potential assembly defect.
an 008004 post-printing

Figure 4. An 008004 post-printing.

As electronic products require increased functionality in smaller form factors, the 008004 package, with its minimal area and weight, could be an excellent solution. Although soldering the component means contending with several complex technological challenges, correct definition of the component during assembly and a highly controlled assembly process make quality soldering possible. For hardware engineers developing these products, these components can be simply little gifts for big dreams.
Michael Schneider is technologist, Nistec Center (nistec.com); michaels@nistec.com.