DIP Overview
DIP is a plug-in. The chip using this packaging method has two rows of pins, which can be directly soldered on a chip socket with a DIP structure or in a soldering position with the same number of solder holes. Its characteristics are that it can easily realize the perforation soldering of the PCB board and has good compatibility with the motherboard. However, due to its large packaging area and thickness, and the pins are easily damaged during the plug-in and unplug process, the reliability is poor.
DIP is the most popular plug-in package, and its application range includes standard logic IC, memory LSI, microcomputer circuits, etc. Small outline package (SOP). Derived SOJ (J-type pin small outline package), TSOP (thin small outline package), VSOP (very small outline package), SSOP (shrink SOP), TSSOP (thin shrink SOP) and SOT (small outline transistor), SOIC (small outline integrated circuit), etc.
DIP device assembly design defects
1. Large PCB package hole
The plug-in hole and package pin hole of the PCB are drawn according to the specification book. During the plate making process, the hole needs to be copper-plated, and the general tolerance is plus or minus 0.075mm. If the PCB package hole is larger than the pin of the physical device, it will cause the device to loosen, insufficient tinning, empty soldering, and other quality problems.
See the figure below: The device pin of WJ124-3.81-4P_WJ124-3.81-4P (KANGNEX) is 1.3mm, and the PCB package hole is 1.6mm. The large hole diameter leads to empty soldering during wave soldering.
Continuing from the above figure, purchase WJ124-3.81-4P_WJ124-3.81-4P (KANGNEX) components according to the design requirements, and the pin 1.3mm is correct.
2. Small PCB package hole
- The hole on the solder pad of the plug-in component in the PCB board is small, and the component cannot be inserted. The only solution to this problem is to enlarge the hole diameter and then insert the plug, but there will be no copper in the hole. This method can be used if it is a single-sided or double-sided board. The outer layer of the single-sided or double-sided board is electrically conductive, and it can be conductive after soldering. If the plug-in hole of the multi-layer board is small and the inner layer is electrically conductive, the PCB board can only be redone, because the inner layer conduction cannot be remedied by expanding the hole.
See the figure below: According to the design requirements, the components of A2541Hwv-3P_A2541HWV-3P(CJT) are purchased. The pin is 1.0mm, and the PCB package pad hole is 0.7mm, which makes it impossible to insert.
Continuing from the above figure, according to the design requirements, the components of A2541Hwv-3P_A2541HWV-3P(CJT) are purchased. The pin 1.0mm is correct.
3. The distance between the PCB package pins does not match the components
The PCB package pads of the DIP device not only have the same hole diameter as the pins, but also the spacing between the pins must be the same distance.
The inconsistency between the pin hole spacing and the device will cause the device to be unable to be inserted, except for components with adjustable pin spacing.
See the figure below: The PCB package pin hole spacing is 7.6mm, and the purchased component pin hole spacing is 5.0mm. The difference of 2.6mm makes the device unusable.
4. The PCB package hole spacing is too close, resulting in a tin short circuit
When designing and drawing the package, you need to pay attention to the distance between the pin holes. Even if the bare board can be generated with a small pin hole spacing, it is easy to cause a tin short circuit during wave soldering during assembly.
See the figure below: Tin short circuit may be caused by a small pin distance. There are many reasons for wave soldering tin short circuit. If the design end can prevent the assemblability in advance, the occurrence rate of the problem can be reduced.
A real case of insufficient tin on the pin of a DIP device
The problem of mismatch between the key size of the material and the size of the PCB pad hole
Problem description: After a product DIP was wave soldered, it was found that the tin on the fixed foot pad of the network socket was seriously insufficient, which was a blank soldering.
Impact of the problem: The stability of the network socket and the PCB board will deteriorate, and the signal pin will be stressed during the use of the product, which will eventually cause the connection of the signal pin and affect the product performance. There is a risk of failure during user use;
Problem extension: The stability of the network socket is poor, the connection performance of the signal pin is poor, and there are quality problems. Therefore, it may bring safety hazards to users, and the final loss is unimaginable.
wonderfulpcb DFM Services assembly analysis checks device pins
wonderfulpcb DFM Services assembly analysis function has a special inspection of the pins of DIP devices. The inspection items include the number of pins of through holes, THT pin limit, THT pin limit, and THT pin properties. The inspection items of the pins basically cover the possible problems in the pin design of DIP devices.
After the design is completed, use wonderfulpcb DFM Services assembly analysis to discover design defects in advance and solve design anomalies before product production. It can avoid design problems during the assembly process, delay production time, and waste R&D costs.
