Learn about DIPs

DIP is a plug-in. The chip with this packaging method has two rows of pins, which can be directly soldered to a chip socket with a DIP structure or soldered to a soldering position with the same number of soldering holes. Its feature is that it can easily realize the perforation welding of the PCB board, and has good compatibility with the main board. However, due to its relatively large packaging area and thickness, and the pins are easily damaged during the plugging and unplugging process, the reliability is relatively low. Difference.

DIP is the most popular plug-in package, and its application range includes standard logic IC, memory LSI, microcomputer circuit, etc., small outline package (SOP), derived from SOJ (J-pin small outline package), TSOP (thin small Outline Package), VSOP (Very Small Outline Package), SSOP (Shrink SOP), TSSOP (Thin Shrink SOP), SOT (Small Outline Transistor), SOIC (Small Outline Integrated Circuit), etc.

DIP device assembly design defects

1. The PCB package hole is larger than the device

PCB plug-in holes and package pin holes are drawn according to the specifications. During the plate making process, copper plating is required in the holes, and the general tolerance is plus or minus 0.075mm. If the PCB package hole is too large than the pins of the physical device, it will lead to loose parts, insufficient tin, empty soldering and other quality problems.

As shown in the figure below, the device pins using WJ124-3.81-4P_WJ124-3.81-4P (KANGNEX) are 1.3mm, and the PCB package hole is 1.6mm. The hole diameter is too large to cause space-time soldering during wave soldering.

Connect to the picture above, purchase WJ124-3.81-4P_WJ124-3.81-4P (KANGNEX) components according to the design requirements, the pin 1.3mm is correct.

2. The PCB package hole is smaller than the device

The hole on the pad of the plug-in component in the PCB is small, and the component cannot be inserted. The solution to this problem can only be to expand the aperture and then plug in, but there will be no copper in the hole. This method can be used if it is a single or double panel. Both the single and double panels are electrically conductive on the outer layer, and soldering tin can conduct; multi-layer The plug-in hole of the board is small, and the PCB board can only be redone if there is electrical conduction in the inner layer, because the inner layer conduction cannot be remedied by reaming.

See the figure below, purchase A2541Hwv-3P_A2541HWV-3P (CJT) components according to the design requirements, the pin is 1.0mm, and the PCB package pad hole is 0.7mm, which makes it impossible to insert.

Connect to the picture above, purchase A2541Hwv-3P_A2541HWV-3P (CJT) components according to the design requirements, the pin 1.0mm is correct.

3. The package pin spacing is different from the device

The PCB package pads of DIP devices not only have the same aperture as the pins, but also have the same distance between the pins. If the spacing between the pin holes and the device is inconsistent, the device cannot be inserted, except for components with adjustable pitch.

As shown in the figure below, the pitch of the PCB package pins is 7.6mm, and the pitch of the purchased components is 5.0mm. The difference of 2.6mm makes the device unusable.

4. PCB package hole pitch is too close

Pay attention to the distance between the pin holes when designing and drawing the package on the PCB. Even if the pitch of the pin holes is small, even if the bare board can be produced, it is easy to cause a tin short circuit during assembly by wave soldering.

As shown in the figure below, the small pin distance may lead to tin short circuit. There are many reasons for wave soldering short circuit. If the assemblability can be prevented in advance at the design end, the incidence of problems can be reduced.