Today, one question from my boss, “Is there any difference or influence on the process and design if we like to convert the SMD parts to DIP type and go through the PIH(Paste-In-Hole) process?”
Later, I realized that the question aimed to avoid the damage of connector caused by customers’ misuse.
Sometimes, Paste-In-Hole (PIH) is also called Pin-In-Paste (PIP).
First, since the traditional insertion parts through PIH process is necessary to be manufactured with high-temperature reflow process, the part design should fulfill the considerations listed as follows:
Today, most of electronic parts are developed into smaller size. The small chips are downsized from 1206 to 0805, 0603, 0402, 0201, even to 01005. The size of chip is smaller; the required solder volume is less.
Moreover, the required stencil thickness becomes thinner from 0.18mm to 0.10mm. Some parts, however, cannot be downsized unlimitedly, such as external connectors. For example, a line socket of telephone, a network line socket, a smart card reader, and other devices require a certain amount of solder volume to ensure the soldering strength and quality. In addition, some traditional insertion parts (Dual in line package process, DIP) with paste-in-hole process require extra solder volume as well.
Today, the SMD parts become smaller and smaller. Their sizes can be developed to 0402, 0201, and even 01005 (Note 1). Moreover, the pitch between the pins of a common IC (integrated circuit) is shorten to fine pitch of 0.5mm, even 0.3 mm. The improvement becomes a challenge for the SMT process.
A great challenge for each SMT engineer is how to weld these thin electronic parts on circuit boards without any non-wetting or short-circuit. In addition, it is more difficult to solder few larger parts and a lot of thin ones on a circuit board than to solder thin parts without any larger ones.
Since the electronic product design moves from desktop to portable devices, the manufacturer also make electronic component as small as possible to meet this popular trend. Besides, the PCB thickness also become thinner and the associated soldering pads on the PCB are tiny size. This make the SMT manufacturing process more difficult and challenge.
You may know that portable device always has BGA malfunction risk during impact drop test. Most of company dispense the underfill glue to fix this kind of BGA crack issue. My company did the same thing too. WorkingBear think there shall be another way to enhance the soldering pad strength to eliminate the underfill glue since underfill process spend money and waste labor hours.
As the career of Manufacturing Process Engineering(MPE), WorkingBear always find there is tug of war between Designer, Marketing and Manufacturer. The Marketing always like the design be thin, sleek, and modern looking. The designer always think fabrication is easy. The manufacturer always like the assembly be robust, solid, rigid, and not easily scratch on the surface. But both of them same ask low cost.
So, here comes two common questions from R&D and marketing people.
- Why thinner PCB will ask special carrier or template for the reflow process?
- Aren’t all PCBs reflowed as a panel, which requires a support fixture for de-panelization?
Since WorkingBear is MPE, so I will answer these two questions as manufacturing point.