Analysis and selection of SMT placement machine
Third, the component placement machine resolution and accuracy
Obviously, the resolution and precision component placement machine for small pitch components (fine-pitch-parts) of the application is very important parameter, the accuracy is generally for the fine resolution of the visual system and equipment in the X -, Y-, and Z-direction stability function, in short, to place the action in the component, put pieces of the tip in 3-D before moving to the set position, the system must first "see" and confirm the components they want to place the correct location.
All test components must be placed in the machine resolution of 0.00004 "to 0.00008" in this context, and the accuracy is about 0.0004 "to 0.002", the result shows that the use of small space, the data is the smaller the better. The other parameters (such as full motion under the nozzle assembly accuracy between the pad and the solder balls on the bit error standard) will affect the equipment level. In this view, the current crop of high-speed machine can load the component spacing of 0.0034 "to 0.012", we can have the following formula by the assembly can allow the inference of minimum component spacing: Accuracy * (100 / pad and solder ball on the bit error percentage) * 2 = the suitable spacing ex: 0.001 "* 100/25 * 2 = 0.008"
It seems from the above example, if an accuracy of 0.001 "component placement machine, in 25% of bit error, the suitable for use in the spacing of 0.008" of the component, if suppliers are allowed to use the error degree of 33%, then the machine used by the component spacing on 0.006 "of.
Fourth, the component placement machine accuracy and verification
Component placement machine accuracy and continuity can be branded in the glass by the method of plating (chrome-on-glass) to verify, its approach is engraved in the glass to make a branded line, and then placed in this glass component placement machine, the use of substrate (substrate) and component placement reference point (fiducial) to guide the machine alignment, the completion of the entire assembly process, then the view through the optical microscope and optical measurement scale for multiple locations, and then full-speed movement and to determine its accuracy.
Branded in the glass-plated (chrome-on-glass) test method is a manual process, however if the machine has a certain degree of accuracy on this subject, or a very effective method of authentication. One thing is very important, is when the machine just machines, is conducting this type of artificial bits accuracy to confirm the action is bound to be very exact, so as not to affect the operation of the order of accuracy. But not all such devices will be similar at the beginning of the action, and not every one of the devices are coated with a baked glass scale to help with the correction accuracy.
In addition, the thermal stability of the component placement machine power will also affect its accuracy, this flip-chip component placement machine Jabil is the use of granite in the base station and the ceramic support beam to minimize such impact, in that case If the equipment to handle the often time-spacing of 0.004 courage "of the component, whether self-correction is quite important for heat, although some manufacturers do not emphasize their equipment such correction, but in the relevant text of the play in from time to time stressed the importance of thermal correction.
Fifth, the rate set pieces
Commonly referred to as a large set piece rates do not include board delivery and visual alignment steps and therefore the speed of various manufacturers have announced very soon, but if the above two actions are included with the calculation, the speed will be rapid reduced. For example: If the project does not contain the two, the general rate in 2000pph around, but if coupled with the rate on these two projects is a sharp decline in the 800pph.
Looking at the components nowadays learned in the implementation of the component placement machine, dip flux, visual alignment and set pieces took about 2.5 to 8 seconds or so, if able to dip flux, solder paste or conductive adhesive separation and other related processes , so that the component placement machine is not set in operation, you can shorten the effective time of set pieces. In addition, if the move to shorten the distance between the nozzle can achieve the same effect.