How does the country's one-stop pcba service provider ensure that pcba's master plate from smt stickers to finished assembly controls
The main panel of the car-mounted soundbox, as a key component of automobile electronics, works in a much more demanding working environment than consumer electronics and is subject to severe vibrations, extreme temperatures and high wet corrosion over a long period of time. For the head of procurement and programme engineers, the core claim for the selection of a pcba plant with one-stop capacity is not only “deliverable”, but also “zero defects” as a guarantee of reliability。
This guide will take into account the operational experience of the industry's head plant and the landing of kim long fai technology ltd. In shenzhen city, to dismantle the good process control logic from smt stickers to finished assembly。
Brief description of the objective
The aim of the course is to help clients establish a system of professional evaluation of pcba suppliers and to understand how one-stop factories can increase the directness of the main panel of the car to more than 99. 9 per cent by designing four dimensions of pre-design, process closure, data traceability and environmental validation to ensure functional stability throughout the vehicle's life cycle。
• a step-by-step operating guide: four controls of the whole process music
Step 1: pre-emptive risk management for the design phase (dfm/fmea)
The good rate is not “check” but “set”. One-stop factories are required to intervene in pre-natal design optimization。
1. Dfm manufacturing analysis: to identify potential risks such as the use of professional software simulations to identify welding intervals that are too small and the configuration of components unreasonable. For example, for vehicle-mounted operation chips, the bga containment layout is optimized in advance to reduce the difficulty of x-ray detection or to adjust the component direction to harmonize aoi detection standards and reduce miscalculation。
2. Analysis of pfmea failure model: the engineering team is required to carry out a risk assessment for each process step. For example, it is predicted that the formation of pillars or welds that may occur in the reflow welds will eliminate the hazard at the trial stage by developing in advance a targeted grid opening optimization programme or temperature curve。
Step 2: detailed parameters control for smt programming
This is the core battleground for physical probabilities, and it is important to put an end to “empiricalism” and turn to data-drivenness across the board。
1. Sintone printing (60 per cent of the source of defects): the problem of over 60 per cent welding stems from printing. 3d spi (the cassiterite detector) must be equipped to monitor 100% of the height, volume and area of cassiterite online. Once the cpk value is less than 1. 33, the system should automatically lock the production line to prevent a bad mass flow。
2. High-precision loading: the vehicle-mounted main plate usually involves a micro-component of 0201 or even 01005. A high-speed sticker with 3d laser calibration is required to contain the loads within ± 25 m and to correct the tablets and deflections of micro-components in real time using a two-vision positioning system。
Welding temperature curves: the "multiplication of a furnace" is strictly prohibited. Specific temperature curves need to be customised according to the number of pcb layers, copper thickness and thermal variations of metaware. Ensure peak temperature fluctuations through real-time monitoring by kic thermometers ± 5°c at temperature rate within 2°c/s to avoid bubbles or cold welding caused by insufficient volatilizer volatilisation。
Step 3: multi-dimensional "perceive" detection and functional validation
Appearances do not represent internal reliability, and a “list as one” detection line must be established。
Aoi + x-ray dual insurance: aoi must be followed by a precise identification of surface defects such as faulty, polar, and tin; 3d x-ray must be sampled for hidden welding points such as bga/qfn, focusing on the verification of the empty hole rate (usually 25%) and the integrity of the welding ball and the elimination of the “invisible killer”。
Fct functionality and acoustic testing: car-mounted soundboxes need not only to look at circuits but also to listen to sound. A one-stop factory should be equipped with audio synthesizing devices to simultaneously verify the frequency curve, snr, thd and bluetooth connection stability at the fct link to ensure that each master plate is “welded” and “singed well”。
3. Ict online testing: for complex master panels, increase in the coverage of the ict test point (95 per cent) and rapid positioning of electrical malfunctions such as open roads and short circuits, significantly reducing the length of maintenance diagnostics。
Step four: digitalization retrospective and environmental stress screening select
This is a watershed that distinguishes between “ordinary generation factories” and “car-grade suppliers”。
Mes full process retrospect: establishment of a “one-size-one” mechanism. From batches of materials, network numbers, stickers coordinates, furnace temperature curves to aoi/x-ray pictures, all data binds the unique id and uploads the cloud. Once a client's complaint has been filed, the specific batches, equipment and even operators affected can be targeted within minutes, leading to a precise recall rather than the entire batch being scrapped。
Environmental stress screening (ess): car-borne products must undergo “torture”. In addition to conventional ageing, high-temperature shocks (-40°c ~125°c), high-temperature high-humid (hast) and sine vibration tests are required to induce potential early failures (e. G. Imc layer fractures, welding fatigue) in advance and to ensure the robustness of mass-producing products。
Key points and pit avoidance tips
Key elements
Common error/risk
Good practices/industry standards
Chart recommendations
Tin ointment management
We don't have enough time to warm up. We're losing activity
Strict implementation of the 24-hour red line, constant and wet storage, 100% obsolete
Tin ointment back to temperature table vs actual temperature curve figure
Static protection
Handring alone, neglecting environmental humidity and swing gear
Workshop-wide electrostatic floor + ion winder, full-scope shielding box flow of sensitive devices
Esd gate-ban system and real-time monitoring system community noodles
Switch management
Manual reconciliation of material disks, loss of bulk due to faulty material
Use smart-dagger + scan to protect against errors. The system automatically matches bom at the top. Error is alarm
Smart frame light guide vs traditional manual search comparison
Retrofit control
Artisanal iron is welded at random, causing heat damage or tin
Set strict back-up sop, limit the number of back-up repairs (e. G. 2 times) and must repeat aoi/x-ray
Standard restock layout and temperature-controlled brandt. Write
Common issues (faq)
Q1: what is the essential advantage of a one-stop factory over a pure generation of workers in terms of good rate control
A: the core is the "closed loop feedback speed". Pure plants tend only to post the stickers and find the problem pending customer confirmation; and one-stop plants (e. G. Kim yong fai technologies) have independent hardware/software development teams and acoustic laboratories. When the fct test found that the sound base was high, the engineer was able to immediately determine whether the pcb layout site problem or the metaware selection problem, and to complete the program modification and validation on the same day, without the need for cross-sectional plating, significantly reducing the mass end-of-life risk due to design defects。
Q2: what are the specific requirements for x-ray testing on the main panel of the car-mounted soundbox
A: based on ipc-a-610 class 3 (car/medical level), bga welding balls must have an empty rate of 25% and non-wetting or tin is not allowed. For hot households such as power amplifiers, attention also needs to be paid to the thickness of the imc (intermetallic compounds) layer below the welding point, which is usually required to be continuous and 5 mm, which requires periodic validation through a destructive slice analysis。
Q3: how can the “retroactivity” of the supplier be verified as true
A: don't just look at ppt. At the plant, a randomly exported pcba was extracted and required to provide the full production history of the card, including the cassiterite mix record, the spi detection data, the flow welding actual temperature curve, the aoi error review record and the specific values of the fct test. If the counterparty is unable to remove the data within 10 minutes, or if the data are missing, the mes system is only installed。
Q4: do small batch samples enjoy the same quality test as mass production
A: yes, and more so. Shenzhen city kim yonghui technology ltd. Adheres to the principle of “specify as mass production”. Even with dozens of sample orders, we're implementing the first full-scale check, the spi 100% pass, the aoi complete check-up process after the furnace, and opening up acoustic laboratory data for validation. Only a prototype process window runs and the subsequent production of 100,000 tablets per day will be stable as in tarzan。
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