With the microwave get more frequent uses, PTFE as the multilayer microwave devices, as well as the demand for high-speed backplane will be more and more. According to this, we organized the company's R amp; D group of PTFE technology research and development £¬to production of PTFE on both sides of the plate model.

Experimental Design

1 sample request

DK = 2.55+/-0.04£¬Df=0.0018(10G Hz), the thickness of 0.8mm, material supplier is ARLON (USA), material model is DICLAD 527( PTFE), there are two layers between the requirements of the position + /-0.01mm.

1.1 Material Selection

1.1.1 plate classification

Plates are classified into five types:

¢Ù PTFE + glass cloth. Poor machinability.

¢Ú PTFE + non-woven glass cloth. Good ?machinability.

¢Û PTFE + machinability ceramics fill the best.

¢Ü PTFE + + glass ceramic cloth filler. Performance slightly better than pure PTFE plus processing of glass cloth .

¢Ý PTFE adhesive film is divided into: PTFE-chip bonding, BT wrapped PTFE Prepreg, PTFE Prepreg.

According to the model performance requirements, as well as material prices and other factors, we make the following materials:

According to the customer to choose PTFE + glass cloth as this type of processing materials.

1.1.2 plate features

a. physical and chemical properties

PTFE materials have excellent electrical properties, good chemical stability. Its low dielectric constant, and in between 2.4 to 2.6, with the obvious changes in the frequency, 1MHz and 10GHz of the dielectric constant did not change the basic, so common in microwave communications and high-speed digital processing. We have here the main applications of this performance. add ceramic filler after high dielectric constant.

b. processing features

PTFE sheet metal processing and very poor. Soft texture and easy to deformation; PTFE material itself polar small, poor absorption of. As a result, we can know that the PTFE material has the following problems:

¢Ù PTFE material itself polar small, cloth and glass substrate between the copper foil substrate and the bonding between the poor and therefore difficult immersion copper, solder printing more difficult, the panel also can't intolerance mechanical impact , PTFE and glass cloth between the layered easily.

¢Ú materials soft and easy to shape glass fiber and copper foil on the support of small, together with the description of the problem, ¢Ù reasons, the mechanical deformation and easily bored when the glass-cutting effect is not good, not once cut off, leading to There are not cut off the existence of glass fiber. At the same time, PTFE is also not easy to cut off the PTFE cuttings.

1.1.3 the results of material selection

According to the model and test requirements, we choose to test materials, materials related to the scope of DK = 2.4 ~ 2.6. A sample material for DK=2.55+/-0.04£¬Df=0.0018(10G Hz).

2 Factors analysis

By the properties of materials, we know that material PTFE two-panel processing of the main issues focused on the drilling, PTH, Solder printing ink, HAL, and so on. We are the light of these tests are designed for.

3 Process Design

3.1 Drilling hole

As the fiberglass relatively soft, prone to glitches, the need to compare the hard-cover and a special plate. As the fiberglass PTFE to be less support, the need for drilling into the slower speed (the speed of drilling into the test to determine than FR-4 board into the boring slow down the rate of 30%, 20% increase in speed). As the fiberglass resin bond between each other so there is no binding force, not a bored easily cut off the glass did not cut off, plating the formation of tumor-plated. At the same time, due to the soft PTFE material, PTFE material may appear residues and did not cut holes in the wall. As the process of drilling cuttings found wrapped around the problem bit, since ¦µ1.0mm ~ ¦µ2.5mm are wrapped around the bit. And from the first hole tied with the start bit. Therefore, the parameters of the transfer is not a problem, but the issue of the type of drill bit, decided to discuss the production of new-bit to solve this problem (after the model adopted by the recognition removed by hand methods to deal with provisional). (Gong to use a new knife-like spiral double-edged cutter)

As a PTFE packing materials, glass cloth, and so choose different, so each material may be bored is not the same parameters.

For the above analysis, we will test on the main pad, the cover choice test drilling parameters:

a. mat, cover options:

At present, flat pad is a good selection of phenolic resin materials, board materials such relatively hard, but the phenolic resin glass transition temperature lower and more prone to corruption drill, drill bit wear large.

b. test parameters:

¢Ù test method

Test for the first time to test the parameters of drilling materials, the material properties of drilling can not be a more accurate understanding of the trial in order to have the PTFE-based drilling parameters, according to the knife into a single volume (volume of feed speed and comprehensive Parameters), the linear velocity (speed), the rate of retreat knife combination of the three parameters in the light of experience and theoretical analysis, can remove some of the smaller probability parameters. On this basis, to choose the direction of optimization parameters, in the direction of further large-scale parameters, the test after the completion of the drilling to determine the basic parameters of the range. Again in the small range of parameters for determining a more precise combination of parameters. And then selected a suitable drilling parameters. In accordance with the normal way to determine the maximum number of holes.

¢Ú tool selection

We will use the following test tool diameter:

§¶0.5mm, §¶1.0mm, §¶1.5mm, §¶2.0mm, §¶3.0mm, §¶3.2mm, §¶4.5mm.

¢Û test

End-hole drilling, high-pressure washing twice, 25 times the light hole under a magnifying glass to observe, to judge records, immersion copper plating. And then use a magnifying glass 25 times to observe the situation hole. For the last slice to observe the situation bored. Winding through the drill bit and study the situation and determine the drill bit wear knife to use the largest number of holes. On the final parameters of the 5th hole after plating thermal shock test to determine its reliability.

3.2 hole - plating

Due to the small polar PTFE material, and not easily combined with other materials, so immersion copper difficulties, the need to find ways to immersion copper,

Therefore, the need for PTFE board to deal with PLASMA or PTFE to deal with the special medicine to carry out pre-immersion copper, increased polar hole PTFE material in order to ensure the reliability of PTH.

As the PTFE soft materials, electroplating, plating bath in the swing so easy to board a bad break or decline in the reliability of the board. Clamping fixture using thin plating.

3.3 Solder - leveling

PTFE material itself and ink combined with a very small force, because of time pressure core PTFE material, the surface coating layer a layer of activated to ensure that the combination of copper and power. Etching, the layer can be activated to ensure that the combination of PTFE and ink, but the activation level exposure in the air, quickly lapsed as a result of oxidation. Therefore, etching is completed, should complete the printing of solder in order to avoid surface-activation failure, which led to the ink and face plate bonding well. The need for etching, printing ink to the length of time to complete an assessment.

Ink impact of factors have combined force of mechanical damage, such as brush wear, scratches, impact and so on, the solder pre-treatment with micro-erosion methods, the use of machinery and can not be dealt with face plates.

3.3.1 assessment of the post-etching ink to print when the time interval

After etching, and so were 6 hours, 8 hours, 12 hours, 16 hours, 24 hours, 36 hours to start printing ink.

Baking sheet, to observe whether there is a bubble on the surface and so on. At the same time, with 3M adhesive tape stripping test, test ink adhesion. Determine the reliability of the interval.

In the absence of links to the outside PLASMA Association, we have adopted to deal with the special PTFE medicine for immersion before the copper-hole wall adjustment, the process is as follows:

¡ú PTFE-hole drilling outer wall adjustment agent ¡úimmersion copper ¡úimmersion copper (pre-activated from the start) ¡ú all-plated board.

If PLASMA deal with, the following processes (including two copper immersion need to test the reliability of the argument):

¡úouter drilling two high-pressure washing and drying ¡úPLASMA ¡ú immersion copper ¡ú thickening copper ¡ú immersion copper ¡úimmersion copper ¡ú all-copper-plated board.

As a model to production-oriented, we should be constantly developed and improved technology for the term of office has been in the development of innovation, innovation and development, so that we can fly higher, farther, to be more competitive, Have better development prospects.