How To Improve The Straight-Through Rate Of SMT Processing?

SMT processing has an important indicator for processing quality evaluation, that is the straight-through rate. In the SMT processing, SMT processing through rate refers to the proportion of one-time pass from the first process  to the last process. This parameter can directly reflect the SMT processing factory processing capacity, also can directly reflect the SMT processing factory quality control, the higher the straight-through rate, the higher the capacity.



In order to ensure SMT processing through rate, we hear the most is to improved Design For Manufacturability (DFM), but to really improve the SMT processing through rate also need the following five process optimization methods:

  1. Upgrading the PCB board stencil design.
  2. Choosing the right type of solder paste.
  3. Improving the operation of the printing process.
  4. Improving the room/reflow temperature profile.
  5. Choosing tooling and improving process methods.


For each process defects, our company gives the following ideas, I hope it will help you.


The main reason for bridging: more solder paste

Solution ideas:

(1) Reduce the amount of solder paste

(2) “Large pad narrow opening” design, to guide the spread of solder, especially suitable for stencil window can no longer reduce the occasion


The main reason for open soldering: the bottom of the pin and the pad gap is large

Solution ideas:

(1) Increase the thickness of the stencil

(2) Expand the size of the pad


The main reason for mechanical fracture of BGA solder joints: operational stress

Solution ideas:

(1) The use of tooling, reduce the manual installation of screws, sub-board, crimping operation stress

(2) The components (solder joints) for reinforcement.


The main reason for the generation of solder beads: solder paste flow to the non-soldering surface, mainly occurring around the bottom surface joints, such as chip components, QFN, etc.

Solution ideas:

(1) Internal shrinkage stencil window to avoid the flow of melted solder outside the solder joint

(2) The elimination of solder resistance around the pads, to reserve the space for excess solder to be.


About Grande

Grande specializes in providing overall PCBA electronic manufacturing services, including electronic components procurement to PCB production and processing, SMT patch, DIP plug-in, PCBA testing, finished product assembly .Turnkey one-stop PCBA services.
The company gives full play to its competitive advantages in scale procurement and quality control, and signs long-term cooperation agreements with many electronic component manufacturers at home and abroad to ensure the quality and stable supply of raw material sources, and transfer the preferential treatment to customers.
Maintaining the purchasing advantages of IC, resistors, capacitors, inductors, transistors and other components for a long time can greatly save customers’ inventory costs, improve production turnover efficiency and save time. At present, we provide PCBA processing services for customers in the United States, the United Kingdom, Japan, Russia, France, Canada, Australia, Romania, Switzerland and other countries and regions.
We provide PCBA processing services, focusing on the quality of circuit boards and PCBA quality control system.
Own PCB factory (obtained the very strict TS16949 certification for the automotive industry)
With decades of experience in the procurement of electronic components, we maintain long-term cooperation with large brands to ensure the original packaging and procurement channels of components. In the packaging process of components, Senju and Loctite solder pastes are used to ensure the reliability of soldering. With automatic printing machines, Panasonic high-speed placement machines, upper and lower eight temperature zone reflow soldering, AOI automatic optical detectors, etc., it can effectively guarantee quality and reliability during electronic packaging.
It also has complete management processes such as IPC, IPQC and OQA, with clear job responsibilities and strict implementation of IPC electronic assembly acceptance standards. Regarding PCBA testing, we have professional engineers to perform 100% batch testing using various test racks, including path, noise, amplitude, signal, temperature, humidity, drop or perform customer-detailed test plans. All efforts aim to become a refined PCBA processing manufacturer.
Grande Factory